REBAR TYING ROBOT

TECHNICAL FIELD

The art disclosed herein relates to a rebar tying robot.

BACKGROUND ART

Japanese Patent Application Publication No. 2019-39174 describes a rebar tying robot configured to perform a rebar tying operation in which the rebar tying robot performs alternately and repeatedly an operation of moving over a plurality of primary rebars and a plurality of secondary rebars intersecting the plurality of primary rebars and an operation of tying the plurality of primary rebars and the plurality of secondary rebars together at points where the plurality of primary rebars and the plurality of secondary rebars intersect. The rebar tying robot has a rebar tying unit, a conveying unit configured to convey the rebar tying unit, and a control unit configured to control an operation of the conveying unit. The conveying unit has a longitudinal movement mechanism configured to move the rebar tying robot in a front-rear direction and a lateral movement mechanism configured to move the rebar tying robot in a left-right direction.

SUMMARY OF INVENTION
Technical Problem

It may be desired to cause a rebar tying robot, such as the one described in Japanese Patent Application Publication No. 2019-39174, to halt a rebar tying operation in the middle of the rebar tying operation and to move from the position at which the rebar tying operation was halted to a specific position. The present specification provides a technology that allows a rebar tying robot to halt a rebar tying operation in the middle of the rebar tying operation and to move from the position at which the rebar tying operation was halted to a specific position.

Solution to Technical Problem

A rebar tying robot disclosed herein may be configured to perform a rebar tying operation in which the rebar tying robot performs alternately and repeatedly an operation of moving over a plurality of primary rebars and a plurality of secondary rebars intersecting the plurality of primary rebars and an operation of tying the plurality of primary rebars and the plurality of secondary rebars together at points where the plurality of primary rebars and the plurality of secondary rebars intersect. The rebar tying robot may comprise a rebar tying unit, a conveying unit configured to convey the rebar tying unit, and a control unit configured to control an operation of the conveying unit. The conveying unit may comprise a longitudinal movement mechanism configured to move the rebar tying robot in a front-rear direction, a lateral movement mechanism configured to move the rebar tying robot in a left-right direction, and a positional information detection mechanism configured to detect a current position of the rebar tying robot relative to the plurality of primary rebars and the plurality of secondary rebars. The control unit may be configured to execute a return process in which the control unit drives at least one of the longitudinal movement mechanism and the lateral movement mechanism such that the rebar tying robot moves from the current position of the rebar tying robot detected by the positional information detection mechanism to a specific position without performing the rebar tying operation. When a predetermined condition is met during the rebar tying operation, the control unit may execute the return process.

According to the configuration above, it is possible to cause the rebar tying robot to halt the rebar tying operation in the middle of it and to move from the position at which the rebar tying operation was halted to a specific position.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a rebar tying robot 100 according to first and second embodiments as viewed from the upper front left side;

FIG. 2 is a perspective view of a rebar tying machine 2 used in the rebar tying robot 100 according to the first and second embodiments as viewed from the upper rear left side;

FIG. 3 is a perspective view of an internal structure of a body 4 of the rebar tying machine 2 used in the rebar tying robot 100 according to the first and second embodiments as viewed from the upper rear right side;

FIG. 4 is a cross-sectional view of a front portion of the body 4 of the rebar tying machine 2 used in the rebar tying robot 100 according to the first and second embodiments;

FIG. 5 is a perspective view of internal structures of the body 4 and an upper portion of a grip 6 of the rebar tying machine 2 used in the rebar tying robot 100 according to the first and second embodiments as viewed from the upper front left side;

FIG. 6 is a perspective view of a power supply unit 102 of the rebar tying robot 100 according to the first and second embodiments as viewed from the upper front right side, where a cover 112 is open;

FIG. 7 is a perspective view of the rebar tying robot 100 according to the first and second embodiments as viewed from the upper rear right side, where the rebar tying machine 2 is attached to an operation unit 104;

FIG. 8 is a perspective view of the rebar tying robot 100 according to the first and second embodiments as viewed from the lower rear right side, where the rebar tying machine 2 is attached to a grip mechanism 132;

FIG. 9 is a side view of the operation unit 104 and the rebar tying machine 2, where the rebar tying machine 2 is lifted in the rebar tying robot 100 according to the first and second embodiments;

FIG. 10 is a side view of the operation unit 104 and the rebar tying machine 2, where the rebar tying machine 2 is lowered in the rebar tying robot 100 according to the first and second embodiments;

FIG. 11 is a perspective view of the rebar tying robot 100 according to the first and second embodiments as viewed from the lower front right side;

FIG. 12 is a perspective cross-sectional view of the rebar tying robot 100 according to the first and second embodiments in the vicinity of a tensioner pulley 224 as viewed from the upper front left side;

FIG. 13 is a perspective view of a side stepper 196 of the rebar tying robot 100 according to the first and second embodiments as viewed from the lower rear right side;

FIG. 14 is a perspective view of a front portion of the side stepper 196 of the rebar tying robot 100 according to the first and second embodiments as viewed from the upper rear right side;

FIG. 15 is a cross-sectional view of a front crank mechanism 276 of the rebar tying robot 100 according to the first and second embodiments as viewed from the rear side;

FIG. 16 is a perspective view of a rear portion of the side stepper 196 of the rebar tying robot 100 according to the first and second embodiments as viewed from the upper front right side;

FIG. 17 is a front view of the rebar tying robot 100 according to the first and second embodiments, where step bars 272, 274 are lifted;

FIG. 18 is a front view of the rebar tying robot 100 according to the first and second embodiments, where the step bars 272, 274 are lowered;

FIG. 19 is a diagram schematically illustrating a grid map GM according to map information retained by a control unit 126 in the rebar tying robot 100 according to the first and second embodiments;

FIG. 20 is a top view schematically illustrating an example of a relative position relationship between the grid map GM and primary and secondary rebars R1 and R2 in the rebar tying robot 100 according to the first and second embodiments;

FIG. 21 is a diagram schematically illustrating how the control unit 126 specifies a current position sub region DR and a fore angle α in the rebar tying robot 100 according to the first and second embodiments;

FIG. 22 is a diagram schematically illustrating how the control unit 126 distinguishes between tied sub regions DA and untied sub regions DB in the rebar tying robot 100 according to the first and second embodiments;

FIG. 23 is a flowchart of a process executed by the control unit 126 in the rebar tying robot 100 according to the first and second embodiments;

FIG. 24 is a flowchart of a return process executed by the control unit 126 in the rebar tying robot 100 according to the first and second embodiments;

FIG. 25 is a diagram schematically illustrating cost information, a return position, and a return path recorded in the grid map GM in a return position and path specifying process by the control unit 126 in the rebar tying robot 100 according to the first embodiment;

FIG. 26 is a diagram schematically illustrating a designated position recorded in the grid map GM by the control unit 126 and paths G1, G2, and G3, which are candidates for return path, in the rebar tying robot 100 according to the first embodiment;

FIG. 27 is a flowchart of a return process executed by the control unit 126 in the rebar tying robot 100 according to the second embodiment;

FIG. 28 is a diagram schematically illustrating how the control unit 126 specifies a return position and a return path based on a predetermined rule in the return position and path specifying process in the rebar tying robot 100 according to the second embodiment;

FIG. 29 is a diagram schematically illustrating how the control unit 126 specifies a return position and a return path based on another predetermined rule in the return position and path specifying process in the rebar tying robot 100 according to the second embodiment;

FIG. 30 is a diagram schematically illustrating how the control unit 126 specifies a return position and a return path based on yet another predetermined rule in the return position and path specifying process in the rebar tying robot 100 according to the second embodiment;

FIG. 31 is a diagram schematically illustrating how the control unit 126 specifies a return position and a return path based on still another predetermined rule in the return position and path specifying process in the rebar tying robot 100 according to the second embodiment;

FIG. 32 is a diagram schematically illustrating another cost information, candidate return positions, and return path recorded in the grid map GM in a return position and path specifying process by a control unit 126 in a rebar tying robot 100 according to a variant;

FIG. 33 is a diagram schematically illustrating yet another cost information, candidate return positions, and return path recorded in the grid map GM in a return position and path specifying process by a control unit 126 in a rebar tying robot 100 according to a variant; and

FIG. 34 is a diagram schematically illustrating still another cost information, candidate return positions, and return path recorded in the grid map GM in a return position and path specifying process by a control unit 126 in a rebar tying robot 100 according to a variant.

DESCRIPTION OF EMBODIMENTS

Representative, non-limiting examples of the present disclosure will now be described in further detail with reference to the attached drawings. This detailed description is merely intended to teach a person of skill in the art further details for practicing aspects of the present teachings and is not intended to limit the scope of the present disclosure. Furthermore, each of the additional features and teachings disclosed below may be utilized separately or in conjunction with other features and teachings to provide improved rebar tying robots as well as methods for using and manufacturing the same.

Moreover, combinations of features and steps disclosed in the following detailed description may not be necessary to practice the present disclosure in the broadest sense, and are instead taught merely to particularly describe representative examples of the present disclosure. Furthermore, various features of the above-described and below-described representative examples, as well as the various independent and dependent claims, may be combined in ways that are not specifically and explicitly enumerated in order to provide additional useful embodiments of the present teachings.

All features disclosed in the description and/or the claims are intended to be disclosed separately and independently from each other for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter, independent of the compositions of the features in the embodiments and/or the claims. In addition, all value ranges or indications of groups of entities are intended to disclose every possible intermediate value or intermediate entity for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter.

In one or more embodiments, the control unit may be further configured to execute a continuation possibility determining process in which the control unit determines whether it is possible to continue the rebar tying operation. The predetermined condition may include a first predetermined condition that the control unit determines in the continuation possibility determining process that it is not possible to continue the rebar tying operation.

When a problem, such as insufficient remaining amount of wire, occurs during the rebar tying operation and the rebar tying operation therefore cannot continue, a user needs to do maintenance work on the rebar tying robot to solve the problem. At this time, it may be difficult for the user to approach the rebar tying robot depending on the position of the rebar tying robot. According to the configuration above, when a problem that makes the rebar tying operation unable to be continued occurs in the rebar tying robot, the rebar tying robot can be automatically moved to a specific position where the user can easily do the maintenance work. The user can easily do the maintenance work on the rebar tying robot to solve the problem.

In one or more embodiments, the control unit may be configured to receive a command signal from an external. The predetermined condition may include a second predetermined condition that the control unit receives the command signal from the external.

According to the configuration above, the rebar tying operation can be halted in the middle of it by a user's command, such as when the user wishes to halt the operation, and to move the rebar tying robot to the specific position which is convenient to the user.

In one or more embodiments, the specific position may include a position designated by a user.

According to the configuration above, the rebar tying robot can be moved to the position designated by the user.

In one or more embodiments, the specific position may include a position of a rebar end designated by a user. In the present specification, “rebar ends” mean intersection points of the primary rebars and the secondary rebars that are closest to respective ends of the primary rebars and respective ends of the secondary rebars. Thus, it should be noted that “rebar ends” in the present specification are different from ends of the rebars.

According to the configuration above, the rebar tying robot can be moved to the rebar end designated by the user. The user can thus safely retrieve the rebar tying robot and do problem-solving work from the outside of the primary and secondary rebars.

In one or more embodiments, the specific position may include a position of a rebar end where a movement path from the current position is the shortest.

According to the configuration above, the rebar tying robot can be moved most efficiently to the position of the rebar end.

In one or more embodiments, the positional information detection mechanism may be further configured to detect a tied region and an untied region across the plurality of primary rebars and the plurality of secondary rebars. The specific position may include a position of a rebar end where a movement path from the current position is the shortest among rebar ends within the tied region.

According to the configuration above, the rebar tying robot moves over the tied region which is stronger than the untied region in the return process. Thus, the rebar tying robot can be moved more safely to the position of the rebar end.

In one or more embodiments, the rebar tying robot may be configured to perform alternately and repeatedly an operation of moving over the plurality of primary rebars and the plurality of secondary rebars in a direction in which the plurality of primary rebars extends and an operation of tying the plurality of primary rebars and the plurality of secondary rebars together at the points where the plurality of primary rebars and the plurality of secondary rebars intersect in the rebar tying operation. The specific position may include a position of a rebar end where a movement path from the current position is the shortest among rebar ends located in the front-rear direction as viewed from the current position.

The rebar tying robot, which alternately and repeatedly performs the operation of moving over the primary rebars and the secondary rebars in the direction in which primary rebars extend and the operation of tying the primary rebars and the secondary rebars together at their intersection points, can often move more stably in the front-rear direction than in the left-right direction. According to the configuration above, it is possible to minimize the frequency for the rebar tying robot to drive the lateral movement mechanism. It is thus possible to move the rebar tying robot more safely to the position of the rebar end.

In one or more embodiments, the rebar tying robot may be configured to perform alternately and repeatedly an operation of moving over the plurality of primary rebars and the plurality of secondary rebars in a direction in which the plurality of primary rebars extends and an operation of tying the plurality of primary rebars and the plurality of secondary rebars together at the points where the plurality of primary rebars and the plurality of secondary rebars intersect in the rebar tying operation. The positional information detection mechanism may be further configured to detect a tied region and an untied region across the plurality of primary rebars and the plurality of secondary rebars. The specific position may include a position of a rebar end where a movement path from the current position is the shortest among rebar ends that are located in the front-rear direction as viewed from the current position and within the tied region.

The rebar tying robot, which alternately and repeatedly performs the operation of moving over the primary rebars and the secondary rebars in the direction in which primary rebars extend and the operation of tying the primary rebars and the secondary rebars together at their intersection points, can often move more stably in the front-rear direction than in the left-right direction. According to the configuration above, it is possible to minimize the frequency for the rebar tying robot to drive the lateral movement mechanism. Further, the rebar tying robot moves over the tied region which is stronger than the untied region in the return process. It is thus possible to move the rebar tying robot more safely to the position of the rebar end.

In one or more embodiments, the control unit may be configured to execute a specific position specifying process in which the control unit calculates, for each of at least one candidate position which is a candidate for the specific position, a cost for the rebar tying robot to move from the current position to the candidate position and specifies the specific position from among the at least one candidate position based on calculated costs of the at least one candidate position. In the return process, the control unit may be configured to drive at least one of the longitudinal movement mechanism and the lateral movement mechanism such that the rebar tying robot moves from the current position to the specific position.

According to the configuration above, the control unit can specify the specific position based on the cost calculation even when there are multiple candidates for the specific position. In the present specification, “cost” means any value that is set in relation to various elements associated with the movement of the rebar tying robot. For example, the cost is a value set according to a risk associated with the movement of the rebar tying robot. As another example, the cost is a value set according to a power consumption associated with the movement of the rebar tying robot.

In one or more embodiments, the control unit may be configured to specify a candidate position whose cost is the lowest among the at least one candidate position as the specific position.

According to the configuration above, even when there are multiple candidates for the specific position, the control unit can specify the position whose cost is the lowest as the specific position.

In one or more embodiments, the control unit may be configured to calculate, for each of at least one candidate movement path which is a candidate for a movement path from the current position to the at least one candidate position, a cost for the rebar tying robot to move from the current position to the candidate position and calculate the costs of the at least one candidate position based on calculated costs of the at least one candidate movement path.

According to the configuration above, the control unit can calculate costs of the candidate positions for the specific position based on the costs of the movement paths. The control unit can thus specify the specific position taking the movement paths into consideration.

In one or more embodiments, the control unit may be configured to calculate a cost of a candidate movement path whose cost is the lowest among the at least one candidate movement path as the cost of the candidate position.

According to the configuration above, the control unit can specify the position where the cost of the movement path from the current position of the rebar tying robot is the lowest as the specific position. Thus, the rebar tying robot can be moved to the specific position with the lowest cost.

In one or more embodiments, in the specific position specifying process, the at least one candidate position may be selected from positions of a plurality of rebar ends.

According to the configuration above, the control unit can specify, by the cost calculation, the position of a rebar end where the cost of the movement path from the current position of the rebar tying robot is the lowest among the positions of rebar ends as the specific position. Thus, the rebar tying robot can be moved to the position of rebar end with the lowest cost.

In one or more embodiments, the control unit may be configured to execute a specific movement path specifying process in which the control unit calculates, for each of at least one candidate movement path which is a candidate for a movement path from the current position to the specific position, a cost for the rebar tying robot to move from the current position to the specific position and specifies a specific movement path from among the at least one candidate movement path based on calculated costs of the at least one candidate movement path. In the return process, the control unit may be configured to drive at least one of the longitudinal movement mechanism and the lateral movement mechanism such that the rebar tying robot moves from the current position to the specific position along the specific movement path.

According to the configuration above, the control unit can specify the movement path based on the cost calculation even when there are multiple candidates for the movement path.

In one or more embodiments, the control unit may be configured to specify a candidate movement path whose cost is the lowest among the at least one candidate movement path as the specific movement path.

According to the configuration above, it is possible to specify the path whose cost is the lowest as the movement path even when there are multiple candidates for the movement path. Thus, the rebar tying robot can be moved to the specific position with the lowest cost.

In one or more embodiments, the positional information detection mechanism may be further configured to detect a tied region and an untied region across the plurality of primary rebars and the plurality of secondary rebars. The control unit may be configured to set a cost for the rebar tying robot to move over the untied region higher than a cost for the rebar tying robot to move over the tied region.

According to the configuration above, the control unit can execute the cost calculation on the ground that a risk of moving over the untied region is larger than a risk of moving over the tied region. This enables the cost calculation on the ground of the strength of movement path with respect to the movement risk from the current position of the rebar tying robot.

In one or more embodiments, the rebar tying robot may be configured to perform alternately and repeatedly an operation of moving over the plurality of primary rebars and the plurality of secondary rebars in a direction in which the plurality of primary rebars extends and an operation of tying the plurality of primary rebars and the plurality of secondary rebars together at the points where the plurality of primary rebars and the plurality of secondary rebars intersect in the rebar tying operation. The control unit may be configured to set a cost for the rebar tying robot to move in the left-right direction higher than a cost for the rebar tying robot to move in the front-rear direction.

According to the configuration above, the control unit can execute the cost calculation on the ground that a risk of moving in the left-right direction is larger than a risk of moving in the front-rear direction. This enables the cost calculation on the ground of the stability of movement means with respect to the movement risk from the current position of the rebar tying robot.

First Embodiment

As shown in FIG. 1, a rebar tying robot 100 according to the present embodiment comprises a rebar tying machine 2, a power supply unit 102, an operation unit 104, and a conveying unit 106. The rebar tying robot 100 is a robot configured to move over a plurality of primary rebars R1 arranged parallel to each other along a horizontal direction and a plurality of secondary rebars R2 arranged parallel to each other along a horizontal direction, while tying the primary rebars R1 and the secondary rebars R2 together at points where the primary rebars R1 and the secondary rebars R2 intersect by using the rebar tying machine 2. As the primary rebars R1 and the secondary rebars R2 are viewed from above, a direction in which the secondary rebars R2 extend is perpendicular to a direction in which the primary rebars R1 extend. Further, the secondary rebars R2 are arranged on top of the primary rebars R1. The primary rebars R1 are arranged, for example, at intervals of 100 mm to 300 mm, and the secondary rebars R2 are arranged, for example, at intervals of 100 mm to 300 mm. For example, the rebar tying robot 100 has a dimension of about 900 mm in a front-rear direction and a dimension of about 600 mm in a left-right direction.

(Configuration of Rebar Tying Machine 2)

Hereinbelow, a configuration of the rebar tying machine 2 will be described with reference to FIGS. 2 to 5. It should be noted that a front-rear direction, a left-right direction, and an up-down direction in the explanation of FIGS. 2 to 5 are not a front-rear direction, a left-right direction, and an up-down direction with the rebar tying robot 100 as the reference, but are a front-rear direction, a left-right direction, and an up-down direction with the rebar tying machine 2 as the reference.

As shown in FIG. 2, the rebar tying machine 2 is a power tool for tying rebars R intersecting each other (such as the primary rebars R1 and the secondary rebars R2) by a wire W. The rebar tying machine 2 can be detached from the rebar tying robot 100 and used by a user as a handheld tool and can also be used while attached to the rebar tying robot 100. The rebar tying machine 2 comprises a housing 3. The housing 3 includes a body 4, a grip 6 arranged below the body 4, and a battery receptacle 8 arranged below the grip 6. A battery pack B may be attached to a lower portion of the battery receptacle 8 as shown in FIG. 2, or a battery adapter 108 may be attached thereto as shown in FIG. 1. The battery pack B includes secondary battery cells (not shown), such as lithium-ion battery cells, and is configured to be charged by a charger (not shown). The body 4, the grip 6, and the battery receptacle 8 are integrally formed.

As shown in FIG. 3, a reel 10 on which the wire W is wound is detachably housed in an upper rear portion of the body 4. As shown in FIG. 2, the housing 3 includes a reel cover 5 having a shape that covers an upper portion of the reel 10. The reel cover 5 is rotatably retained by cover retainers 7 arranged at a rear left portion and a rear right portion of the body 4. The reel cover 5 opens and closes by rotating with respect to the body 4.

As shown in FIGS. 3 to 5, the rebar tying machine 2 comprises a feeder mechanism 12, a guide mechanism 14, a brake mechanism 16, a cutter mechanism 18, a twister mechanism 20, and a control device 80.

As shown in FIG. 3, the feeder mechanism 12 feeds out the wire W supplied from the reel 10 to the guide mechanism 14 located at a front portion of the body 4. The feeder mechanism 12 includes a feed motor 22, a driving roller 24, and a driven roller 26. The wire W is held between the driving roller 24 and the driven roller 26. The feed motor 22 may, for example, be a DC brush motor. An operation of the feed motor 22 is controlled by the control device 80. The feed motor 22 rotates the driving roller 24. When the feed motor 22 rotates the driving roller 24, the driven roller 26 rotates in the reverse direction and the wire W held by the driving roller 24 and the driven roller 26 is fed out toward the guide mechanism 14, and the wire W is thereby drawn out from the reel 10.

As shown in FIG. 4, the guide mechanism 14 guides the wire W fed by the feeder mechanism 12 around the rebars R in a loop shape. The guide mechanism 14 includes a guide pipe 28, an upper curl guide 30, and a lower curl guide 32. The rear end of the guide pipe 28 opens to a space between the driving roller 24 and the driven roller 26. The wire W fed out by the feeder mechanism 12 is guided into the guide pipe 28. The front end of the guide pipe 28 opens to the inside of the upper curl guide 30. The upper curl guide 30 includes a first guiding passage 34 for guiding the wire W from the guide pipe 28 and a second guiding passage (not shown) for guiding the wire W from the lower curl guide 32.

As shown in FIG. 4, a plurality of guide pins 38 that guide the wire W such that they give a downward curl to the wire W and a cutter 40, which constitutes a part of the cutter mechanism 18 to be described later, are located in the first guiding passage 34. The wire W from the guide pipe 28 is guided by the guide pins 38 in the first guiding passage 34, passes through the cutter 40, and is fed out toward the lower curl guide 32 from the front end of the upper curl guide 30.

As shown in FIG. 5, the lower curl guide 32 includes a feed-returning plate 42. The feed-returning plate 42 guides the wire W from the front end of the upper curl guide 30 back to the rear end of the second guiding passage of the upper curl guide 30.

The second guiding passage of the upper curl guide 30 is arranged adjacent to the first guiding passage 34. The second guiding passage guides the wire W from the lower curl guide 32 and feed it out from the front end of the upper curl guide 30 toward the lower curl guide 32.

The wire W fed out by the feeder mechanism 12 is wound in a loop shape around the rebars R by the upper curl guide 30 and the lower curl guide 32. The number of turns of the wire W around the rebars R can be preset by the user. Once the feeder mechanism 12 has fed out the wire W by a feed amount corresponding to the set number of turns, the feed motor 22 is stopped to stop the feeding of the wire W.

The brake mechanism 16 shown in FIG. 3 stops rotation of the reel 10 in response to the feeder mechanism 12 stopping the feeding of the wire W. The brake mechanism 16 includes a solenoid 46, a link 48, and a brake arm 50. An operation of the solenoid 46 is controlled by the control device 80. Engagement portions 10a with which the brake arm 50 engages are arranged on the reel 10 at predetermined angular intervals in the radial direction. When the solenoid 46 is not electrically actuated, the brake arm 50 is separated from the engagement portions 10a of the reel 10. When the solenoid 46 is electrically actuated, the brake arm 50 is driven via the link 48 and the brake arm 50 engages with an engagement portion 10a of the reel 10. When the feeder mechanism 12 is to feed out the wire W, the control device 80 does not electrically actuate the solenoid 46 to separate the brake arm 50 from the engagement portions 10a of the reel 10. Thus, the reel 10 can rotate freely and the feeder mechanism 12 can draw out the wire W from the reel 10. Further, when the feeder mechanism 12 stops feeding out the wire W, the control device 80 electrically actuates the solenoid 46 to cause the brake arm 50 to engage with an engagement portion 10a of the reel 10. As a result, rotation of the reel 10 is prohibited. Thus, the wire W can be prevented from sagging between the reel 10 and the feeder mechanism 12, which would be caused by the reel 10 continuing to rotate by inertia even after the feeder mechanism 12 has stopped feeding out the wire W.

The cutter mechanism 18 shown in FIGS. 4 and S cuts the wire W with the wire W wound around the rebars R. The cutter mechanism 18 includes the cutter 40 and a link 52. The link 52 rotates the cutter 40 by cooperating with the twister mechanism 20 to be described later. The wire W passing through the cutter 40 is cut by the rotation of the cutter 40.

The twister mechanism 20 shown in FIG. 5 ties the rebars R with the wire W by twisting the wire W wound around the rebars R. The twister mechanism 20 includes a twisting motor 54, a reduction gear mechanism 56, a screw shaft 58 (see FIG. 4), a sleeve 60, a push plate 61, and a pair of hooks 62.

The twisting motor 54 may, for example, be a DC brushless motor. An operation of the twisting motor 54 is controlled by the control device 80. Rotation of the twisting motor 54 is transmitted to the screw shaft 58 through the reduction gear mechanism 56. The twisting motor 54 is rotatable in a forward direction and in a reverse direction, and the screw shaft 58 is also rotatable in a forward direction and a reverse direction accordingly. The sleeve 60 is arranged to surround a periphery of the screw shaft 58. In the state in which rotation of the sleeve 60 is prohibited, the sleeve 60 moves forward when the screw shaft 58 rotates in the forward direction, while the sleeve 60 moves rearward when the screw shaft 58 rotates in the reverse direction. The push plate 61 moves integrally with the sleeve 60 forward or rearward according to the forward or rearward movement of the sleeve 60. Further, when the screw shaft 58 rotates in the state in which the rotation of the sleeve 60 is permitted, the sleeve 60 rotates together with the screw shaft 58.

When the sleeve 60 advances to a predetermined position from its initial position, the push plate 61 drives the link 52 of the cutter mechanism 18 and the cutter 40 thereby rotates. The pair of hooks 62 is arranged at the front end of the sleeve 60, and opens and closes according to the position of the sleeve 60 in the front-rear direction. When the sleeve 60 moves forward, the pair of hooks 62 closes and grasps the wire W. After this, when the sleeve 60 moves rearward, the pair of hooks 62 opens and releases the wire W.

The control device 80 rotates the twisting motor 54 with the wire W wound around the rebars R. At this occasion, the rotation of the sleeve 60 is prohibited, so that the sleeve 60 moves forward by the rotation of the screw shaft 58 and the push plate 61 and the pair of hooks 62 also move forward, as a result of which the pair of hooks 62 closes and grasps the wire W. Then, when the rotation of the sleeve 60 is permitted, the sleeve 60 rotates by the rotation of the screw shaft 58, and along with this the pair of hooks 62 rotates. As a result, the wire W is twisted and the rebars R are tied together.

When the twisting of the wire W is completed, the control device 80 rotates the twisting motor 54 in the reverse direction. At this occasion, the rotation of the sleeve 60 is prohibited, and after the pair of hooks 62 opens and the wire W is released, the sleeve 60 moves rearward by the rotation of the screw shaft 58 and the push plate 61 and the pair of hooks 62 also move rearward. As a result of the rearward movement of the sleeve 60, the push plate 61 drives the link 52 of the cutter mechanism 18, which returns the cutter 40 to its initial posture. After this, when the sleeve 60 moves back to the initial position, the rotation of the sleeve 60 is permitted, and the sleeve 60 and the pair of hooks 62 rotate by the rotation of the screw shaft 58 and return to their initial angles.

The control device 80 can specify a remaining amount of the wire W wound on the reel 10 (see FIG. 3) and detect abnormalities in the rebar tying machine 2. The remaining amount of the wire W wound on the reel 10 can be specified, for example, by subtracting a cumulative sum of feed amounts of the wire W fed out by the feeder mechanism 12 from a remaining amount of the wire W wound on an unused reel 10. The feed amounts of the wire W fed out by the feeder mechanism 12 can be calculated, for example, based on detection signals from a rotation sensor (not shown) that detects the number of rotations of the feed motor 22 or the driving roller 24. Further, the control device 80 is configured to communicate with a control unit 126 of the rebar tying robot 100, which will be described later, and can send signals to the control unit 126 of the rebar tying robot 100 in the event that a rebar tying operation cannot be continued in the rebar tying machine 2. The rebar tying operation cannot be continued, for example, when the remaining amount of the wire W wound on the reel 10 becomes less than a predetermined lower limit value or when an abnormality is detected in the rebar tying machine 2.

As shown in FIG. 2, a first operation section 64 is arranged at an upper portion of the body 4. The first operation section 64 includes a main switch 74 for switching on/off of main power, a main power LED 76 that shows whether the main power is in on state or off state, and the like. The first operation section 64 is connected to the control device 80.

A second operation section 90 is arranged on an upper front surface of the battery receptacle 8. The user can set the number of turns of the wire W to be wound around the rebars R, a torque threshold for twisting the wire W, and the like through the second operation section 90. The second operation section 90 includes setting switches 98 for setting the number of turns of the wire W to be wound around the rebars R and the torque threshold for twisting the wire W, display LEDs 96 for displaying the current settings, and the like. The second operation section 90 is connected to the control device 80.

As shown in FIGS. 2 to 5, with the rebar tying machine 2 detached from the rebar tying robot 100, the user uses the rebar tying machine 2 by holding the grip 6. A trigger 84 which can be pulled by the user is arranged at an upper front portion of the grip 6. As shown in FIG. 5, a trigger switch 86 that detects on/off of the trigger 84 is arranged inside the grip 6. The trigger switch 86 is connected to the control device 80. When the user pulls the trigger 84 and the trigger switch 86 is thereby turned on, the rebar tying machine 2 performs a series of operations of winding the wire W around the rebars R by the feeder mechanism 12, the guide mechanism 14, and the brake mechanism 16, cutting the wire W and twisting the wire W wound around the rebars R by the cutter mechanism 18 and the twister mechanism 20.

(Configuration of Power Supply Unit 102)

As shown in FIG. 1, the power supply unit 102 is supported by the conveying unit 106. The power supply unit 102 includes a housing 110 and a cover 112. The control unit 126 is housed in the housing 110. The control unit 126 controls operations of the power supply unit 102, the operation unit 104, and the conveying unit 106. Further, the control unit 126 can detect abnormalities in the power supply unit 102, the operation unit 104, and the conveying unit 106. Moreover, the control unit 126 is configured to communicate with the control device 80 of the rebar tying machine 2 (see FIG. 5) and an external controller (not shown) and can send and receive signals to and from the control device 80 and the external controller.

The external controller (not shown) may be a dedicated controller for the rebar tying robot 100 or a general-purpose communication terminal such as a smartphone, a tablet terminal, or the like. The external controller can send the control unit 126 a command signal that commands to halt the rebar tying operation while the rebar tying robot 100 is performing the rebar tying operation. The external controller can also send the control unit 126 a command signal that designates a position to which the rebar tying robot 100 is to return in a return process (see FIG. 24) which is executed after the rebar tying operation has been halted. The user can designate any sub region D on a grid map GM (see FIG. 19), which will be described later, as a position to which the rebar tying robot 100 is to return.

As shown in FIG. 6, a battery housing chamber 110a is defined in the housing 110. The battery housing chamber 110a includes a plurality of battery receptacles 114. A plurality of battery packs B can be detachably attached to the plurality of battery receptacles 114, respectively. The cover 112 is attached to the housing 110 via hinges 115 arranged at a rear portion of the housing 110 near the upper end of the battery housing chamber 110a. The cover 112 is pivotable on a pivot axis extending in the left-right direction relative to the housing 110. As shown in FIG. 6, in the state in which the cover 112 is opened relative to the housing 110, the plurality of battery packs B can be detachably attached to the plurality of battery receptacles 114 by being slid in the up-down direction. As shown in FIG. 1, in the state in which the cover 112 is closed relative to the housing 110, peripheries of the plurality of battery packs B attached to the plurality of battery receptacles 114 are surrounded by the housing 110 and the cover 112. In this state, the plurality of battery packs B inside the battery housing chamber 110a can be prevented from getting wet even when the power supply unit 102 gets wet with water.

The cover 112 is biased by a torsion spring, which is not shown, in a closing direction relative to the housing 110. A latch member 116 which the user can operate is arranged on the cover 112. As shown in FIG. 6, a latch receiver 110b corresponding to the latch member 116 is arranged on the housing 110. When the user closes the cover 112 and pivots the latch member 116, the latch member 116 engages with the latch receiver 110b, so that the cover 112 is maintained in the closed state relative to the housing 110. When the user pivots the latch member 116 in the reverse direction in that state, the engagement between the latch member 116 and the latch receiver 110b is released, so that the user can open the cover 112 relative to the housing 110.

A plurality of remaining charge indicators 118, a remaining charge display button 120, and an operation execution button 122 are arranged on an upper surface of the housing 110 frontward of the battery housing chamber 110a. The remaining charge indicators 118 are arranged corresponding to the battery receptacles 114, respectively, and each display remaining charge in the battery pack B attached to its corresponding battery receptacle 114. The remaining charge display button 120 is a button for the user to switch on/off the display of the remaining charge by the plurality of remaining charge indicators 118. The operation execution button 122 is a button for the user to switch between the rebar tying robot 100 performing an operation and stopping the operation.

A power supply cable 124 is connected to the upper surface of the housing 110 frontward of the battery housing chamber 110a. The battery adapter 108 is connected to the power supply cable 124. While the battery adapter 108 is attached to the rebar tying machine 2, power from the plurality of battery packs B is supplied to the rebar tying machine 2.

A key receptacle 119 to which a key 117 can be detachably attached is arranged in the battery housing chamber 110a. The key 117 can be attached or detached by being inserted into or withdrawn from the key receptacle 119. In the state in which the key 117 is detached from the key receptacle 119, power supply from the plurality of battery packs B to the rebar tying machine 2, the operation unit 104, and the conveying unit 106 is cut off. In the state in which the key 117 is attached to the key receptacle 119, power supply from the plurality of battery packs B to the rebar tying machine 2, the operation unit 104, and the conveying unit 106 is permitted.

(Configuration of Operation Unit 104)

As shown in FIGS. 7 and 8, the operation unit 104 includes a lift mechanism 130 and a grip mechanism 132.

As shown in FIG. 7, the lift mechanism 130 includes a lower base member 134, an upper base member 136, support pipes 138, 140, a lifter 142, a screw shaft 144, a motor connector 146, a lift motor 148, a sensor supporting member 150, an upper limit detection sensor 152, and a lower limit detection sensor 154. The lower base member 134 is supported by the conveying unit 106. The lower ends of the support pipes 138, 140 are fixed to the lower base member 134. The upper ends of the support pipes 138, 140 are fixed to the upper base member 136. The support pipes 138, 140 are arranged parallel to each other. The support pipes 138, 140 are arranged such that they are inclined in both the front-rear direction and the left-right direction with respect to the up-down direction of the rebar tying robot 100. Hereinbelow, a direction along which the support pipes 138, 140 extend may be termed a lifting direction. Through holes 142a, 142b through which the support pipes 138, 140 pass are defined in the lifter 142. Retaining members 156, 158 that slidably retain the support pipes 138, 140 are fixed to the through holes 142a, 142b. The retaining members 156, 158 may, for example, be linear bushes in which solid lubricant is embedded, linear ball bearings, or oilless bearings. The lifter 142 is arranged between the lower base member 134 and the upper base member 136 with each of the support pipes 138, 140 slidably passing through a corresponding one of the retaining members 156, 158. The screw shaft 144 is arranged between the support pipes 138, 140. The lower end of the screw shaft 144 is rotatably supported by the lower base member 134. In the vicinity of the upper end of the screw shaft 144, the screw shaft 144 is rotatably supported by the upper base member 136. The screw shaft 144 is arranged parallel to the support pipes 138, 140. An external thread is defined on an outer surface of a portion of the screw shaft 144 between the lower base member 134 and the upper base member 136. A through hole 142c through which the screw shaft 144 passes is defined in the lifter 142. A nut 160 is fixed to the through hole 142e. An internal thread corresponding to the external thread of the screw shaft 144 is defined on the nut 160. The screw shaft 144 penetrates the lifter 142 with its external thread screw-fitted with the internal thread of the nut 160. The upper end of the screw shaft 144 is coupled to the lift motor 148 via the motor connector 146. The lift motor 148 may, for example, be a DC brush motor. When the lift motor 148 rotates in a forward direction, the lifter 142 is lowered in a direction from the upper base member 136 toward the lower base member 134 by rotation of the screw shaft 144. On the other hand, when the lift motor 148 rotates in the reverse direction, the lifter 142 is lifted in a direction from the lower base member 134 toward the upper base member 136 by rotation of the screw shaft 144. The sensor supporting member 150 is fixed to the lower base member 134 at its lower end and is fixed to the upper base member 136 at its upper end. The upper limit detection sensor 152 and the lower limit detection sensor 154 are both fixed to the sensor supporting member 150. The upper limit detection sensor 152 is normally off but is turned on by contacting the lifter 142 when the lifter 142 is lifted to an upper limit position. The lower limit detection sensor 154 is normally off but is turned on by contacting the lifter 142 when the lifter 142 is lowered to a lower limit position. When the rebar tying machine 2 is to be lowered, the control unit 126 of the rebar tying robot 100 rotates the lift motor 148 in the forward direction, and stops the lift motor 148 when the lower limit detection sensor 154 is turned on. The control unit 126 also stops the lift motor 148 when a load of the lift motor 148 is increased abruptly by the rebar tying machine 2 colliding with the primary rebars R1, the secondary rebars R2, or other obstacles while the rebar tying machine 2 is lowered. The load of the lift motor 148 may be specified, for example, from a current value of the lift motor 148. When the rebar tying machine 2 is to be lifted, the control unit 126 rotates the lift motor 148 in the reverse direction and stops the lift motor 148 when the upper limit detection sensor 152 is turned on.

As shown in FIGS. 9 and 10, in the rebar tying robot 100 of the present embodiment, when the rebar tying machine 2 is lowered, the primary rebars R1 and the secondary rebars R2 become closer to the rebar tying machine 2 at positions closer to the lower carl guide 32 than to the upper curl guide 30. Thus, in lowering the rebar tying machine 2, the primary rebars R1 and the secondary rebars R2 can be suppressed from colliding with the upper curl guide 30. Further, in the rebar tying robot 100 of the present embodiment, when the rebar tying machine 2 is lifted, the primary rebars R1 and the secondary rebars R2 become distant from the rebar tying machine 2 toward positions closer to the lower curl guide 32 than to the upper curl guide 30. Thus, in lifting the rebar tying machine 2, the primary rebars R1 and the secondary rebars R2 can be suppressed from being caught on the upper curl guide 30.

As shown in FIG. 8, the grip mechanism 132 includes a first support plate 162, a second support plate 164, coupling shafts 166, 168, a pivot pin 170, a torsion spring 172, a support pin 174, a link 176, a plunger 178, an actuator 180, and a torsion spring 182. The first support plate 162 is arranged to face one outer surface of the grip 6 of the rebar tying machine 2 (such as a right outer surface as viewed from the rebar tying machine 2). The second support plate 164 is arranged to face another outer surface of the grip 6 of the rebar tying machine 2 (such as a left outer surface as viewed from the rebar tying machine 2). The first support plate 162 and the second support plate 164 are fixed to each other via the coupling shafts 166, 168 with the grip 6 of the rebar tying machine 2 interposed between them. A plurality of protrusions (not shown) that fits with a plurality of recesses 6a (see FIG. 2) defined on the outer surfaces of the grip 6 of the rebar tying machine 2 is defined on a surface of the first support plate 162 facing the grip 6 and a surface of the second support plate 164 facing the grip 6. Thus, the grip 6 of the rebar tying machine 2 is positionally fixed relative to the first support plate 162 and the second support plate 164.

The first support plate 162 is coupled to the lifter 142 of the lift mechanism 130 via the pivot pin 170. One end of the pivot pin 170 is fixed to the lifter 142. The other end of the pivot pin 170 is pivotably supported by the first support plate 162. Thus, the rebar tying machine 2 supported by the first support plate 162 and the second support plate 164 can be lifted or lowered according to lifting or lowering motion of the lifter 142 and can pivot on the pivot pin 170 relative to the lifter 142. The support pin 174 is fixed to the lifter 142 and extends from the lifter 142 toward the first support plate 162. An elongated hole 162a in which the support pin 174 is inserted and a protrusion 162b protruding toward the lifter 142 are defined in/on the first support plate 162. The elongated hole 162a defines a pivoting range for the rebar tying machine 2 to pivot on the pivot pin 170. The torsion spring 172 is arranged outside the pivot pin 170 and biases the protrusion 162b relative to the support pin 174 in a direction along which the protrusion 162b separates away from the support pin 174 (that is, biases the first support plate 162 relative to the lifter 142). If the rebar tying machine 2 cannot pivot relative to the lifter 142, a large impact acts on the operation unit 104 when an obstacle collides with the rebar tying machine 2. Since the rebar tying machine 2 is pivotable relative to the lifter 142 as described above, a large impact can be suppressed from acting on the operation unit 104 even when the rebar tying machine 2 collides with an obstacle.

The link 176 is supported by the second support plate 164. The link 176 is pivotable on a pivot axis extending in the left-right direction relative to the second support plate 164. The link 176 includes a presser portion 176a and an operation portion 176b. The presser portion 176a is arranged to face the trigger 84 of the rebar tying machine 2. The operation portion 176b is coupled to the actuator 180 via the plunger 178. The actuator 180 may, for example, be a solenoid. An operation of the actuator 180 is controlled by the control unit 126 of the rebar tying robot 100. The torsion spring 182 biases the link 176 relative to the second support plate 164 in a direction along which the presser portion 176a separates away from the trigger 84. When the actuator 180 is off, the presser portion 176a is separated away from the trigger 84 by the biasing force of the torsion spring 182. When the actuator 180 is turned on, the link 176 pivots in a direction in which the operation portion 176b approaches the actuator 180, and the presser portion 176a thereby presses the trigger 84. Thus, the trigger 84 of the rebar tying machine 2 is pulled.

(Configuration of Conveying Unit 106)

As shown in FIG. 11, the conveying unit 106 includes a carrier 190, a right crawler 192, a left crawler 194, a side stepper 196, and rebar detection sensors 198, 200, 202.

The carrier 190 includes a base plate 204, a right frame 206, a left frame 208, a right plate 210, a left plate 212, a front frame 214, and a rear frame 216. The base plate 204 is arranged along the front-rear direction and the left-right direction. As shown in FIG. 1, the power supply unit 102 is supported by the conveying unit 106 by the housing 110 being fixed to an upper surface of the base plate 204. A through hole 204a is defined in the base plate 204. As shown in FIG. 11, the operation unit 104 is supported by the conveying unit 106 by the lower base member 134 being fixed to an edge of the through hole 204a. When the operation unit 104 lifts or lowers the rebar tying machine 2, the rebar tying machine 2 passes through the through hole 204a.

The right frame 206 and the left frame 208 are fixed to a lower surface of the base plate 204. The right frame 206 extends in the front-rear direction at the right end of the base plate 204. The left frame 208 extends in the front-rear direction at the left end of the base plate 204. In the front-rear direction, the front end of the right frame 206 and the front end of the left frame 208 are located at the same position as the front end of the base plate 204, and the rear end of the right frame 206 and the rear end of the left frame 208 are located at the same position as the rear end of the base plate 204. The right plate 210 is fixed to a right surface of the right frame 206. The right plate 210 is arranged along the front-rear direction and the up-down direction. The left plate 212 is fixed to a left surface of the left frame 208. The left plate 212 is arranged along the front-rear direction and the up-down direction. In the up-down direction, the upper end of the right plate 210 and the upper end of the left plate 212 are located at the same position as the upper surface of the base plate 204. In the front-rear direction, the front end of the right plate 210 and the front end of the left plate 212 protrude frontward beyond the front end of the base plate 204, and the rear end of the right plate 210 and the rear end of the left plate 212 protrude rearward beyond the rear end of the base plate 204. The front frame 214 couples a portion of the right plate 210 near its front end to a portion of the left plate 212 near its front end at a position frontward of the front end of the base plate 204. The rear frame 216 couples a portion of the right plate 210 near its rear end to a portion of the left plate 212 near its rear end at a position rearward of the rear end of the base plate 204. The front frame 214 and the rear frame 216 extend in the left-right direction. In the up-down direction, the front frame 214 and the rear frame 216 are positioned lower than the right frame 206 and the left frame 208.

The right crawler 192 includes a front pulley 218, a rear pulley 220, a plurality of auxiliary pulleys 222, a tensioner pulley 224, a rubber belt 226, a right crawler motor 228, and a gearbox 230. Teeth configured to mesh with the rubber belt 226 are defined on an outer surface of the front pulley 218, an outer surface of the rear pulley 220, and outer surfaces of the plurality of auxiliary pulleys 222. The rubber belt 226 is strapped over the front pulley 218, the rear pulley 220, the plurality of auxiliary pulleys 222, and the tensioner pulley 224. The front pulley 218 is rotatably supported by the right plate 210 via a bearing 232 in the vicinity of the front end of the right plate 210. The rear pulley 220 is rotatably supported by the right plate 210 via a bearing 234 in the vicinity of the rear end of the right plate 210. The auxiliary pulleys 222 are rotatably supported by the right plate 210 via corresponding bearings 236 between the front pulley 218 and the rear pulley 220. The auxiliary pulleys 222 are arranged along the front-rear direction. The outer diameter of the front pulley 218 is substantially the same as the outer diameter of the rear pulley 220, and the outer diameter of the auxiliary pulleys 222 is smaller than the outer diameters of the front pulley 218 and the rear pulley 220. In the up-down direction, the lower end of the front pulley 218, the lower end of the rear pulley 220, and the lower ends of the auxiliary pulleys 222 are located at the substantially same position.

As shown in FIG. 12, the tensioner pulley 224 is rotatably supported by a movable bearing 237. The movable bearing 237 is supported by the right plate 210 such that the movable bearing 237 can move in the up-down direction. The base plate 204 and the right frame 206 are cut away in the vicinity of the movable bearing 237 so that they do not interfere with the movable bearing 237. An adjustment bolt 238, a nut 240, and a bolt supporting member 242 are arranged below the movable bearing 237. The bolt supporting member 242 is fixed to the right plate 210. A through hole 242a through which a shank 238a of the adjustment bolt 238 passes is defined in the bolt supporting member 242. An internal thread corresponding to an external thread on the shank 238a is defined on an inner surface of the through hole 242a. The nut 240 is arranged below the bolt supporting member 242. A head 238b of the adjustment bolt 238 is arranged below the nut 240, and the shank 238a of the adjustment bolt 238 is screw-fitted with the nut 240 and with the through hole 242a of the bolt supporting member 242. Thus, the position of the adjustment bolt 238 in the up-down direction is fixed by a so-called double nut structure. The upper end of the shank 238a of the adjustment bolt 238 abuts a lower surface of the movable bearing 237. By adjusting the position of the adjustment bolt 238 in the up-down direction with the rubber belt 226 strapped over the tensioner pulley 224, a position of the movable bearing 237 relative to the right plate 210 in the up-down direction can be adjusted. In this way, a degree of tension of the rubber belt 226 can be adjusted.

As shown in FIG. 11, the right crawler motor 228 is supported by the right plate 210 via the bearing 232 and the gearbox 230. The right crawler motor 228 may, for example, be a DC brushless motor. The right crawler motor 228 is coupled to the front pulley 218 via a reduction gear (not shown) housed in the gearbox 230. When the right crawler motor 228 rotates in a forward direction or the reverse direction, the front pulley 218 rotates in the forward direction or the reverse direction, and the rubber belt 226 accordingly rotates in the forward direction or the reverse direction on the outside of the front pulley 218, the rear pulley 220, the plurality of auxiliary pulleys 222, and the tensioner pulley 224.

The left crawler 194 includes a front pulley 244, a rear pulley 246, a plurality of auxiliary pulleys 248, a tensioner pulley 250, a rubber belt 252, a left crawler motor 254, and a gearbox 256. Teeth configured to mesh with the rubber belt 252 are defined on an outer surface of the front pulley 244, an outer surface of the rear pulley 246, and outer surfaces of the auxiliary pulleys 248. The rubber belt 252 is strapped over the front pulley 244, the rear pulley 246, the plurality of auxiliary pulleys 248, and the tensioner pulley 250. The front pulley 244 is rotatably supported by the left plate 212 via a bearing 258 in the vicinity of the front end of the left plate 212. The rear pulley 246 is rotatably supported by the left plate 212 via a bearing 260 in the vicinity of the rear end of the left plate 212. The auxiliary pulleys 248 are rotatably supported by the left plate 212 via corresponding bearings 262 between the front pulley 244 and the rear pulley 246. The auxiliary pulleys 248 are arranged along the front-rear direction. The outer diameter of the front pulley 244 is substantially the same as the outer diameter of the rear pulley 246, and the outer diameter of the plurality of auxiliary pulleys 248 is smaller than the outer diameters of the front pulley 244 and the rear pulley 246. In the up-down direction, the lower end of the front pulley 244, the lower end of the rear pulley 246, and the lower ends of the auxiliary pulleys 248 are at the substantially same position.

As shown in FIG. 12, the tensioner pulley 250 is rotatably supported by a movable bearing 264. The movable bearing 264 is supported by the left plate 212 such that the movable bearing 264 can move in the up-down direction. The base plate 204 and the left frame 208 are cut away in the vicinity of the movable bearing 264 so that they do not interfere with the movable bearing 264. An adjustment bolt 266, a nut 268, and a bolt supporting member 270 are arranged below the movable bearing 264. The bolt supporting member 270 is fixed to the left plate 212. A through hole 270a through which a shank 266a of the adjustment bolt 266 passes is defined in the bolt supporting member 270. An internal thread corresponding to an external thread on the shank 266a is defined on an inner surface of the through hole 270a. The nut 268 is arranged below the bolt supporting member 270. A head 266b of the adjustment bolt 266 is arranged below the nut 268, and the shank 266a of the adjustment bolt 266 is screw-fitted with the nut 268 and with the through hole 270a of the bolt supporting member 270. Thus, the position of the adjustment bolt 266 in the up-down direction is fixed by a so-called double nut structure. The upper end of the shank 266a of the adjustment bolt 266 abuts a lower surface of the movable bearing 264. By adjusting the position of the adjustment bolt 266 in the up-down direction with the rubber belt 252 strapped over the tensioner pulley 250, a position of the movable bearing 264 relative to the left plate 212 in the up-down direction can be adjusted. In this way, a degree of tension of the rubber belt 252 can be adjusted.

As shown in FIG. 11, the left crawler motor 254 is supported by the left plate 212 via the bearing 258 and the gearbox 256. The left crawler motor 254 may, for example, be a DC brushless motor. The left crawler motor 254 is coupled to the front pulley 244 via a reduction gear (not shown) housed in the gearbox 256. When the left crawler motor 254 rotates in a forward direction or the reverse direction, the front pulley 244 rotates in the forward direction or the reverse direction, and the rubber belt 252 accordingly rotates in the forward direction or the reverse direction on the outside of the front pulley 244, the rear pulley 246, the plurality of auxiliary pulleys 248, and the tensioner pulley 250.

As shown in FIG. 13, the side stepper 196 includes step bars 272, 274, a front crank mechanism 276, a rear crank mechanism 277, a stepper motor 279, a gearbox 281, a worm gear casing 283, and a rotation transmitting shaft 285. The step bars 272, 274 are bar-shaped members with substantially rectangular cross sections and extend in the front-rear direction. As shown in FIG. 11, in the left-right direction, the step bar 272 is arranged between the center and the right end of the base plate 204, and the step bar 274 is arranged between the center and the left end of the base plate 204.

As shown in FIGS. 13 and 14, the front crank mechanism 276 includes a support plate 278, pulleys 280, 282, a belt 284, crank arms 286, 288, crank pins 290, 292 (see FIG. 15), a crank plate 294, rollers 296, 298, and a guide plate 300. The support plate 278 is fixed to the lower surface of the base plate 204 in the vicinity of the front end of the base plate 204. The support plate 278 is arranged along the left-right direction and the up-down direction. The pulley 280 is arranged rearward of the support plate 278 in the vicinity of the right end of the support plate 278. The pulley 282 is arranged rearward of the support plate 278 in the vicinity of the left end of the support plate 278. The pulleys 280, 282 are each supported rotatably by the support plate 278. The diameter of the pulley 280 is substantially the same as the diameter of the pulley 282. The belt 284 is strapped over each of the pulleys 280, 282. Thus, when one of the pulleys 280, 282 rotates in a forward direction or the reverse direction, the other pulley also rotates in the forward direction or the reverse direction at substantially the same rotational speed.

The crank arms 286, 288, the crank pins 290, 292, the crank plate 294, the rollers 296, 298, and the guide plate 300 are arranged frontward of the support plate 278. As shown in FIG. 15, the crank arms 286, 288 include fitting holes 286a, 288a to which shafts 280a, 282a of the pulleys 280, 282 are fitted, and elongated holes 286b, 288b extending in a longitudinal direction of the crank arms 286, 288. When the pulleys 280, 282 rotate, the crank arms 286, 288 rotate about the shafts 280a, 282a integrally with the pulleys 280, 282. The crank pins 290, 292 are slidably inserted in the elongated holes 286b, 288b. The crank pins 290, 292 are fixed to the crank plate 294 with the crank pins 290, 292 penetrating the crank plate 294. The crank plate 294 is arranged frontward of the crank arms 286, 288. The crank plate 294 extends in the left-right direction and the up-down direction. The rollers 296, 298 (see FIG. 14) are attached to the crank pins 290, 292 at positions frontward of the crank plate 294. As shown in FIG. 14, the rollers 296, 298 are in guide grooves 302, 304 defined in a rear surface of the guide plate 300. The guide plate 300 is fixed to the lower surface of the base plate 204 at a position frontward of the crank plate 294. The guide plate 300 extends in the left-right direction and the up-down direction. As shown in FIG. 15, the guide grooves 302, 304 of the guide plate 300 have substantially rectangular shapes with rounded corners. The guide grooves 302, 304 define a side-stepping track S shown by a broken line in FIG. 15. The side-stepping track S has a substantially rectangular shape with rounded corners and includes upper and lower edges extending along the left-right direction and right and left edges extending along the up-down direction.

In the front crank mechanism 276, when the pulleys 280, 282 rotate, the crank pins 290, 292 move in a rotating direction of the crank arms 286, 288 by rotation of the crank arms 286, 288. At this time, since the rollers 296, 298 are in the guide grooves 302, 304, the crank pins 290, 292 move along the side-stepping track S defined by the guide grooves 302, 304 while sliding inside the elongated holes 286b, 288b. Thus, the crank plate 294 to which the crank pins 290, 292 are fixed also moves along the side-stepping track S defined by the guide grooves 302, 304.

As shown in FIG. 16, the rear crank mechanism 277 includes a support plate 306, pulleys 308, 310, a belt 312, crank arms 314, 316, crank pins 318, 320 (see FIG. 15), a crank plate 322, rollers 324, 326, and a guide plate 328. The support plate 306 is fixed to the lower surface of the base plate 204 in the vicinity of the rear end of the base plate 204. The support plate 306 is arranged along the left-right direction and the up-down direction. The pulley 308 is arranged frontward of the support plate 306 in the vicinity of the right end of the support plate 306. The pulley 310 is arranged frontward of the support plate 306 in the vicinity of the left end of the support plate 306. The pulleys 308, 310 are each supported rotatably by the support plate 306. The diameter of the pulley 308 is substantially the same as the diameter of the pulley 310 and is substantially the same as the diameters of the pulleys 280, 282 of the front crank mechanism 276. The belt 312 is strapped over the pulleys 308, 310. Thus, when one of the pulleys 308, 310 rotates in a forward direction or the reverse direction, the other pulley rotates in the forward direction or the reverse direction at substantially the same rotational speed.

The crank arms 314, 316, the crank pins 318, 320, the crank plate 322, the rollers 324, 326, and the guide plate 328 are arranged rearward of the support plate 306. As shown in FIG. 15, the crank arms 314, 316 include fitting holes 314a, 316a to which shafts 308a, 310a of the pulleys 308, 310 are fitted and elongated holes 314b, 316b extending in a longitudinal direction of the crank arms 314, 316. When the pulleys 308, 310 rotate, the crank arms 314, 316 rotate about the shafts 308a. 310a integrally with the pulleys 308, 310. The crank pins 318, 320 are slidably inserted in the elongated holes 314b, 316b. The crank pins 318, 320 are fixed to the crank plate 322 with the crank pins 318, 320 penetrating the crank plate 322. The crank plate 322 is arranged rearward of the crank arms 314, 316. The crank plate 322 extends in the left-right direction and the up-down direction. The rollers 324, 326 (see FIG. 16) are attached to the crank pins 318, 320 at positions rearward of the crank plate 322. As shown in FIG. 16, the rollers 324, 326 are in guide grooves 330, 332 defined in a front surface of the guide plate 328. The guide plate 328 is fixed to the lower surface of the base plate 204 at a position rearward of the crank plate 322. The guide plate 328 extends in the left-right direction and the up-down direction. As shown in FIG. 15, the guide grooves 330, 332 of the guide plate 328 each have a substantially rectangular shape with rounded corners. The guide grooves 330, 332 define a side-stepping track S shown by a broken line in FIG. 15. The side-stepping track S has a substantially rectangular shape with rounded corners and includes upper and lower edges extending along the left-right direction and right and left edges extending along the up-down direction. The side-stepping track S defined by the guide grooves 330, 332 is the same as the side-stepping track S defined by the guide grooves 302, 304.

In the rear crank mechanism 277, when the pulleys 308, 310 rotate, the crank pins 318, 320 move in a rotating direction of the crank arms 314, 316 by rotation of the crank arms 314, 316. At this time, since the rollers 324, 326 are in the guide grooves 330, 332, the crank pins 318, 320 move along the side-stepping track S defined by the guide grooves 330, 332 while sliding inside the elongated holes 314b, 316b. Thus, the crank plate 322 to which the crank pins 318, 320 are fixed also moves along the side-stepping track S defined by the guide grooves 330, 332.

As shown in FIG. 13, the step bars 272, 274 are fixed to the crank plate 294 of the front crank mechanism 276 at their front ends and fixed to the crank plate 322 of the rear crank mechanism 277 at their rear ends. Further, the pulley 280 of the front crank mechanism 276 is coupled to the pulley 308 of the rear crank mechanism 277 by the rotation transmitting shaft 285. Thus, the pulleys 280, 282 of the front crank mechanism 276 and the pulleys 308, 310 of the rear crank mechanism 277 rotate in synchrony with each other, and the crank plate 294 of the front crank mechanism 276 and the crank plate 322 of the rear crank mechanism 277 move in synchrony. A zero-point detection sensor (not shown) is provided in one of the front crank mechanism 276 and the rear crank mechanism 277 (e.g., the front crank mechanism 276). The zero-point detection sensor includes, for example, a permanent magnet (not shown) fixed to the crank plate 294 and a Hall element (not shown) fixed to the guide plate 300. The zero-point detection sensor can detect whether the crank plates 294, 322 are at a zero-point position, which is the center of the upper edge of the side-stepping track S in the left-right direction.

As shown in FIG. 13, the worm gear casing 283 is arranged rearward of the pulley 282 of the front crank mechanism 276. The worm gear casing 283 is fixed to the support plate 278 of the front crank mechanism 276. The gearbox 281 is arranged rightward of the worm gear casing 283 and is fixed to the worm gear casing 283. The stepper motor 279 is arranged rightward of the gearbox 281 and is supported by the gearbox 281. The stepper motor 279 may, for example, be a DC brush motor. The stepper motor 279 is coupled to the pulley 282 via a reduction gear (not shown) housed in the gearbox 281 and a worm gear (not shown) housed in the worm gear casing 283. When the stepper motor 279 rotates in a forward direction or the reverse direction, the pulleys 280, 282, 308, 310 rotate in the forward direction or the reverse direction, by which the crank plates 294, 322 move rightward or leftward along the side-stepping track S and the step bars 272, 274 also move rightward or leftward along the side-stepping track S. As shown in FIG. 1, a through hole 204b is defined in the base plate 204 to avoid interference with the stepper motor 279, the gearbox 281, and the worm gear casing 283.

As shown in FIG. 17, in the state in which the crank plates 294, 322 are located at the upper edges of the side-stepping track S (see FIG. 15) and the step bars 272, 274 are lifted up, the crank plates 294, 322 and the step bars 272, 274 are separated from the primary rebars R1 and the secondary rebars R2. In this state, since the right crawler 192 and the left crawler 194 are in contact with the primary rebars R1 and the secondary rebars R2, the rebar tying robot 100 can move in the front-rear direction by driving the right crawler 192 and the left crawler 194.

When the stepper motor 279 is rotated in the state shown in FIG. 17, the crank plates 294, 322 move along the side-stepping track. S (see FIG. 15) and the step bars 272, 274 accordingly move downward, and as a result the crank plates 294, 322 and the step bars 272, 274 contacts the secondary rebars R2. When the stepper motor 279 is further rotated in this state, the crank plates 294, 322 and the step bars 272, 274 further move downward, as a result of which the right crawler 192 and the left crawler 194 separate from the secondary rebars R2 as shown in FIG. 18. By further continuing to rotate the stepper motor 279, the rebar tying robot 100 moves rightward or leftward by a step width corresponding to a width of the side-stepping track S in the left-right direction, after which the crank plates 294, 322 and the step bars 272, 274 move upward, by which the right crawler 192 and the left crawler 194 contact again the primary rebars R1 and the secondary rebars R2 and the crank plates 294, 322 and the step bars 272, 274 separate from the secondary rebars R2. When the zero-point detection sensor detects that the crank plates 294, 322 have moved to the zero-point position, the rotation of the stepper motor 279 stops. As above, by driving the side stepper 196, the rebar tying robot 100 can move rightward or leftward by a predetermined step width.

The side-stepping track S defined by the guide grooves 302, 304, 330, 332 is not limited to the aforementioned substantially rectangular shape, but may have various other shapes. The side-stepping track S may have any shape so long as that, upon when the step bars 272, 274 move along the side-stepping track S, lower ends of the step bars 272, 274 move to positions lower than the lower ends of the right crawler 192 and the left crawler 194, and then the lower ends of the step bars 272, 274 move in the left-right direction and then the lower ends of the step bars 272, 274 move to positions higher than the lower ends of the right crawler 192 and the left crawler 194. For example, the side-stepping track S may have a circular shape, oval shape, triangular shape with its bottom edge on the lower side, or polygonal shape with five or more vertices.

As shown in FIG. 11, the rebar detection sensor 198 is arranged on a front surface of the front frame 214 in the vicinity of the center of the front frame 214 in the left-right direction. The rebar detection sensor 200 is arranged on a rear surface of the rear frame 216 in the vicinity of the center of the rear frame 216 in the left-rear direction. The rebar detection sensor 202 is arranged on a left end portion of the lower surface of the base plate 204 in the vicinity of the center of the base plate 204 in the front-rear direction. The rebar detection sensors 198, 200, 202 are each oriented face-down. The rebar detection sensors 198, 200, 202 are, for example, TOF (Time of Flight) sensors that can acquire distance image data in which the sensors measured distances to an object for each pixel. The control unit 126 of the rebar tying robot 100 can detect positions of the primary rebars R1 and the secondary rebars R2 relative to each of the rebar detection sensors 198, 200, 202 based on the distance image data acquired by the rebar detection sensors 198, 200, 202.

(Identification of Current Position and Orientation)

As shown in FIG. 19, the control unit 126 retains map information related to the surrounding environment in the form of a grid map GM. An X direction and a Y direction in the grid map GM are orthogonal to each other. As will be described later, the control unit 126 refers to the grid map GM to specify the current position and orientation of the rebar tying robot 100 relative to the primary rebars R1 and the secondary rebars R2. The current position herein means the center position of the base plate 204 in the front-rear direction and the left-right direction. The orientation herein means a front-rear direction and a left-right direction of the rebar tying robot 100. In FIG. 19 onward, the current position of the rebar tying robot 100 is indicated by a cross cursor C.

As shown in FIG. 20, in the present embodiment, the grid map GM is formed of segment lines that vertically divide rebar intervals between the primary rebars R1 and rebar intervals between the secondary rebars R2 into equal halves. The region where the primary rebars R1 and the secondary rebars R2 are present is divided into sub regions D having the same area by the above-mentioned segment lines in a check pattern. Here, intersection points of the primary rebars R1 and the secondary rebars R2 are each located at the center of corresponding sub region D, and the centers of sub regions D that are in contact with the outer boarder of the grid map GM correspond to positions of rebar ends R0. The X direction indicates one direction in which the secondary rebars R2 extend, and the Y direction indicates one direction in which the primary rebars R1 extend.

As shown in FIG. 21, the control unit 126 specifies, in the grid map GM, the current position of the rebar tying robot 100 relative to the primary rebars R1 and the secondary rebars R2 as a sub region D including the current position of the rebar tying robot 100 (current position sub region DR). The control unit 126 specifies an angle between the front direction of the rebar tying robot 100 and the Y direction in the grid map GM (fore angle α), which is positive counterclockwise. Here, 0°≤α<360°. The control unit 126 specifies the front-rear direction and the left-right direction of the rebar tying robot 100 from the fore angle α.

Before operating the rebar tying robot 100, the user gives initial values of the current position sub region DR and the fore angle α to the rebar tying robot 100 through the external controller (not shown) or the like. While the rebar tying robot 100 is operating and moving over the primary rebars R1 and the secondary rebars R2, the control unit 126 continuously updates the fore angle α based on changes in relative positions of the primary rebars R1 and the secondary rebars R2 detected by the rebar detection sensors 198, 200, 202. In this way, the control unit 126 can specify the front-rear direction and the left-right direction of the rebar tying robot 100 during an operation. Further, the control unit 126 can also specify a moving direction of the rebar tying robot 100.

When a new intersection point of a primary rebar R1 and a secondary rebar R2 is detected by the rebar detection sensors 198, 200, 202, the control unit 126 updates the current position sub region DR to a new current position sub region DR which is a sub region D located in the moving direction of the rebar tying robot 100 among the sub regions D surrounding the current position sub region DR. In this way, the control unit 126 can specify the current position of the rebar tying robot 100 during an operation.

(Determination on Tied Small Regions and Untied Small Regions)

As shown in FIG. 22, the control unit 126 can also determine, in the grid map GM, sub regions D including tied intersection points (tied sub regions DA) and sub regions D including untied intersection points (untied sub regions DB). When it is detected by the rebar detection sensors 198, 200, 202 that an intersection point of a primary rebar R1 and a secondary rebar R2 has been tied, the control unit 126 updates the sub region D including that intersection point as a tied sub region DA. When it is detected by the rebar detection sensors 198, 200, 202 that an intersection point of a primary rebar R1 and a secondary rebar R2 has not been tied, the control unit 126 updates the sub region D including that intersection point as an untied sub region DB. Alternatively, every time an intersection point included in an untied region DB is tied, the control unit 126 updates the untied region DB including the tied intersection point as a tied sub region DA. In this way, the control unit 126 determines the tied sub regions DA and the untied sub regions DB in the grid map GM.

(Operation of Rebar Tying Robot 100)

When the user operates the operation execution button 122 to instruct the rebar tying robot 100 to operate, the control unit 126 executes a process shown in FIG. 23.

In S2, the control unit 126 starts acquiring and updating positional information. The positional information is the current position sub region DR and fore angle α that indicate the current position and orientation of the rebar tying robot 100 relative to the primary rebars R1 and the secondary rebars R2. The control unit 126 continues to acquire and update the positional information until it ends the acquisition and update of positional information in S14, which will be described later. After S2, the process proceeds to S4.

In S4, the control unit 126 starts a rebar tying operation. In the rebar tying operation, the control unit 126 controls the rebar tying robot 100 such that it ties intersection points of the plurality of primary rebars R1 and the plurality of secondary rebars R2 in a predetermined order. Details of the rebar tying operation will be described later. After S4, the process proceeds to S6.

In S6, the control unit 126 determines whether it is possible to continue the rebar tying operation by the rebar tying robot 100 or not. The determination whether it is possible to continue the rebar tying operation or not may be made based on whether the control unit 126 detects or not an abnormality in the power supply unit 102, the operation unit 104, and the conveying unit 106. Alternatively, the determination may be made based on whether or not the control unit 126 receives from the control device 80 a signal indicating that an event that inhibits continuation of the rebar tying operation has occurred in the rebar tying machine 2. If it is determined that it is impossible to continue the rebar tying operation by the rebar tying robot 100 (in case of NO), the process proceeds to S50.

In S50, the control unit 126 executes a return process (see FIG. 24). In the return process, the rebar tying robot 100 halts the rebar tying operation and moves toward a return position (or a designated position). Details of the return process will be described later. After S50, the process proceeds to S14.

If it is determined that it is possible to continue the rebar tying operation by the rebar tying robot 100 in S6 (in case of YES), the process proceeds to S8. In S8, the control unit 126 determines whether or not a command signal that commands to halt the rebar tying operation has been received from the user through the external controller. If it is determined that the command signal commanding to halt the rebar tying operation has been received (in case of YES), the process proceeds to S50. If the command signal commanding to halt the rebar tying operation has not been received (in case of NO), the process proceeds to S10.

In S10, the control unit 126 determines whether or not the tying operation has been done for all intersection points of the plurality of primary rebars R1 and the plurality of secondary rebars R2. If it is determined that the tying operation has not been done for all the intersection points (in case of NO) yet, the process returns to S6.

If it is determined in S10 that the tying operation has been done for all the intersection points of the plurality of primary rebars R1 and the plurality of secondary rebars R2 (in case of YES), the process proceeds to S12. In S12, the rebar tying operation, which was started in S4, is terminated. After S12, the process proceeds to S14.

In S14, the acquisition and update of positional information, which was started in S2, is terminated. After S14, the process of FIG. 23 is terminated.

(Rebar Tying Operation)

In the rebar tying operation which is started in S4 of FIG. 23, the control unit 126 controls the rebar tying robot 100 such that it ties intersection points of the plurality of primary rebars R1 and the plurality of secondary rebars R2 in a predetermined order.

In the present embodiment, the rebar tying robot 100 follows a predetermined order in which the rebar tying robot 100 moves along a primary rebar R1′, which is a tying operation target, while tying intersection points of the primary rebar R1′ and the secondary rebars R2, and after the tying operation is completed for the primary rebar R1′, which is the tying operation target, the rebar tying robot 100 moves onto another primary rebar R1 for which the tying operation has not been done yet, which is a new tying operation target, and repeats these actions thereafter. Hereinbelow, the rebar tying operation by the rebar tying robot 100 following this order will be described in detail.

Upon the start of process for the rebar tying operation, the control unit 126 moves the rebar tying robot 100 in the left-right direction along the secondary rebars R2 by driving the side stepper 196 until the position of the primary rebar R1′ in the left-right direction, which is a tying operation target among the plurality of primary rebars R1, is detected by the rebar detection sensor 198 as being near the rebar tying robot 100.

When the position of the primary rebar R1′ in the left-right direction, which is the tying operation target, is detected by the rebar detection sensor 198 as being near the rebar tying robot 100, the control unit 126 moves the rebar tying robot 100 forward or rearward with a speed difference given between the right crawler 192 and the left crawler 194. In this way, the rebar tying robot 100 adjusts the position and angle of the rebar tying machine 2 relative to the position of an intersection point of the primary rebar R1′ and a secondary rebar R2 such that the position and angle of the rebar tying machine 2 fall within ranges that allow the rebar tying machine 2 to perform the tying operation. After the positional adjustment of the rebar tying machine 2, the control unit 126 moves the rebar tying robot 100 in the front-rear direction along the primary rebar R1′ by driving the right crawler 192 and the left crawler 194 at the same speed. Every time an intersection point of the primary rebar R1′ and a secondary rebar R2 is detected, the control unit 126 suspends driving the right crawler 192 and the left crawler 194 for the tying operation by the rebar tying machine 2. When an intersection point of the primary rebar R1′ and a secondary rebar R2 is detected, the control unit 126 drives the lift mechanism 130 to lower the rebar tying machine 2 and set the rebar tying machine 2 at the intersection point of the primary rebar R1′ and the secondary rebar R2 and drives the grip mechanism 132 to have the rebar tying machine 2 performing the tying operation for the primary rebar R1′ and the secondary rebar R2. After that, the control unit 126 drives the lift mechanism 130 to lift the rebar tying machine 2 and resumes driving the right crawler 192 and the left crawler 194.

Once all intersection points of the primary rebar R1′ and the secondary rebars R2 have been tied, the control unit 126 determines that the tying operation has been completed for the primary rebar R1′ and repeats the above-described actions for another primary rebar R1 for which the tying operation has not been completed yet as a new tying operation target.

Once all intersection points of the plurality of primary rebars R1 and the plurality of secondary rebars R2 have been tied, the control unit 126 determines that the rebar tying operation has been completed and terminates the process for the rebar tying operation.

(Return Process)

In the return process shown in S50 of FIG. 23, the control unit 126 executes the process shown in FIG. 24.

As shown in FIG. 24, in S52, the control unit 126 halts the rebar tying operation, which was started in S4 (see FIG. 23). That is, after S52, the control unit 126 does not stop driving the right crawler 192, the left crawler 194, and the side stepper 196 and does not drive the lift mechanism 130 nor the grip mechanism 132 even when an intersection point of a primary rebar R1 and a secondary rebar R2 is detected. After S52, the process proceeds to S54.

In S54, the control unit 126 determines whether a position to which the rebar tying robot 100 is to return has been designated or not. The determination whether a position to which the rebar tying robot 100 is to return has been designated or not is, for example, a determination whether a command signal that designates a position to which the rebar tying robot 100 is to return has been received from the external controller or not. If it is determined that a position to which the rebar tying robot 100 is to return has been designated (in case of YES), the control unit 126 records a sub region D designated by the command signal (designated position) in the grid map GM, and the process proceeds to S58. Since the user can designate any sub region D on the grid map GM, a sub region D including a rebar end R0 may be the designated position.

If it is determined that a position to which the rebar tying robot 100 is to return has not been designated (in case of NO), the process proceeds to S56. In S56, the control unit 126 executes a return position and path specifying process. In the return position and path specifying process, the control unit 126 specifies, from among a plurality of candidate return positions, a return position where a cost of a return path from the current position sub region DR is the lowest. The control unit 126 records this specified return position and return path with the lowest cost in the grid map GM. Details of the return position and path specifying process will be described later. After S56, the process proceeds to S60.

In S58, the control unit 126 executes a return path specifying process. In the return path specifying process, if there are multiple return paths from the current position sub region DR to the designated position, the control unit 126 specifies a return path with the lowest risk of moving from the current position sub region DR based on cost calculation and records the specified return path in the grid map GM. Details of the return path specifying process will be described later. After S58, the process proceeds to S60.

In S60, the control unit 126 refers to the grid map GM and starts driving the right crawler 192, the left crawler 194, and the side stepper 196 such that the rebar tying robot 100 moves toward the return position (or the designated position). At this time, the control unit 126 drives the right crawler 192, the left crawler 194, and the side stepper 196 such that the return path specified in S56 or 858 is followed. After S60, the process proceeds to S62.

In S62, the control unit 126 determines whether the rebar tying robot 100 has reached the return position (or the designated position) or not. For example, the control unit 126 determines whether the rebar tying robot 100 has reached the return position (or the designated position) or not by determining whether the current position sub region DR is the sub region D with the return position (or the designated position) recorded in the grid map OM or not. If it is determined that the rebar tying robot 100 has not reached the return position (or the designated position) (in case of NO), the process executes S62 again.

If it is determined that the rebar tying robot 100 has reached the return position (or the designated position) in S62 (in case of YES), the process proceeds to S64. In S64, the control unit 126 stops driving the right crawler 192, the left crawler 194, and the side stepper 196. Thus, the rebar tying robot 100 stops at the return position (or the designated position). After S64, the process of FIG. 24 is terminated.

(Return Position and Path Specifying Process)

In the return position and path specifying process according to the present embodiment (see S56 in FIG. 24), the sub regions D including respective rebar ends R0 are candidate return positions in order to facilitate retrieval of the rebar tying robot 100 and problem-solving work. In the return position and path specifying process according to the present embodiment, movement costs and region costs are set in order to allow for calculation of risks associated with movement of the rebar tying robot 100.

When the rebar tying robot 100 moves over the primary rebars R1 and the secondary rebars R2, the rebar tying robot 100 moves in the front-rear direction along the primary rebars R1 by driving the right crawler 192 and the left crawler 194 or moves in the left-right direction along the secondary rebars R2 by driving the side stepper 196. Thus, on the grid map GM, the rebar tying robot 100 moves to the return position by repeating movement to an adjacent sub region D. For movement from the current position sub region DR to the sub regions D including respective rebar ends R0, there may be multiple candidates for return path (candidate return S paths) for each of the sub regions D including respective rebar ends R0.

Thus, upon the start of the return position and path specifying process shown in S56 of FIG. 24, the control unit 126 executes cost calculation for each of candidate return paths for the sub regions D including respective rebar ends R0. The cost calculation is executed by referring to the grid map GM and adding up products of movement costs and region costs for adjacent sub regions D from the current position sub region DR to each sub region D in contact with the outer boarder of the map (each sub region D including a rebar end R0). Here, a movement cost means a cost that is set according to a moving direction of the rebar tying robot 100. In the present embodiment, a movement cost for the front-rear direction is set as ‘1’ and a movement cost for the left-right direction is set as ‘2’ because the left-right direction movement provided by driving the side stepper 196 is associated with a greater risk than that of the front-rear direction movement provided by driving the right crawler 192 and the left crawler 194. Further, a region cost means a cost that is set according to strength of an intersection point of a primary rebar R1 and a secondary rebar R2 included in each sub region D. In the present embodiment, a region cost for the tied sub regions DA is set as ‘1’ and a region cost for the untied sub regions DB is set as ‘3’ because the tied sub regions DA are stronger than the untied sub regions DB.

As a result of the above cost calculation, the control unit 126 records in the grid map GM, for each of the sub regions D including respective rebar ends R0, cost information on movement along a lowest-cost candidate return path. That is, a piece of cost information is allocated to each of the sub regions D including respective rebar ends R0. The cost information indicates how the above cost addition was performed from the current position sub region DR to a sub region D including a rebar end R0. For each of the sub regions D including respective rebar ends R0, the control unit 126 specifies the cost of the lowest-cost candidate return path as a cost of the sub region D including rebar end R0.

After recording the cost information in the grid map GM, the control unit 126 specifies a lowest-cost sub region D from among the sub regions D including respective rebar ends R0 and specifies the specified sub region D as the return position. The control unit 126 specifies the lowest-cost candidate return path for the specified return position as the return path. The control unit 126 records the specified return position and return path in the grid map GM.

In the example of FIG. 25, the cost information, return position, and return path recorded in the grid map GM are visually shown. The control unit 126 specifies a sub region D48 with the lowest cost of 4 as the return position from among the sub regions D in contact with the outer boarder of the map (the sub regions D including respective rebar ends R0) and specifies a path G0 as the return path.

(Return Path Specifying Process)

In the return path specifying process according to the present embodiment (see S58 in FIG. 24), movement costs and region costs are set in order to allow for calculation of risks associated with movement of the rebar tying robot 100.

When the rebar tying robot 100 moves over the primary rebars R1 and the secondary rebars R2, the rebar tying robot 100 moves in the front-rear direction along the primary rebars R1 by driving the right crawler 192 and the left crawler 194 or moves in the left-right direction along the secondary rebars R2 by driving the side stepper 196. Thus, when the rebar tying robot 100 is to move from the current position sub region DR to the designated position, there may be multiple candidates for return path (candidate return paths) as shown in FIG. 26.

Thus, upon the start of the return path specifying process shown in S58 of FIG. 24, the control unit 126 executes cost calculation for the above-mentioned multiple candidate return paths by adding up products of movement costs and region costs for adjacent sub regions D from the current position sub region DR to the designated position. As a result, the control unit 126 specifies a lowest-cost candidate return path as the return path and records the specified return path in the grid map GM. Here, the movement costs and region costs are set in the same way as those in the return position and path specifying process (see S56 in FIG. 24).

In the example of FIG. 26, the designated position recorded in the grid map GM and candidate return paths are visually shown. Assuming that the designated position is a sub region D48 and there are three candidate return paths G1, 02, G3, the control unit 126 calculates the cost of the path G1 as 4, the cost of the path G2 as 5, and the cost of the path G3 as 7. The control unit 126 specifies the lowest-cost path G1 as the return path.

Second Embodiment

A rebar tying robot 100 according to the present embodiment comprises a similar configuration to that of the rebar tying robot 100 according to the first embodiment. Hereinbelow, differences of the rebar tying robot 100 according to the present embodiment from the rebar tying robot 100 according to the first embodiment will be described.

(Return Process)

In the rebar tying robot 100 according to the present embodiment, the control unit 126 executes a process shown in FIG. 27 in the return process shown in S50 of FIG. 23.

In S152, the control unit 126 halts the rebar tying operation, which was started in S4 (see FIG. 23). That is, after S152, the control unit 126 does not stop driving the right crawler 192, the left crawler 194, and the side stepper 196 and does not drive the lift mechanism 130 nor the grip mechanism 132 even when an intersection point of a primary rebar R1 and a secondary rebar R2 is detected. After S152, the process proceeds to S154.

In S154, the control unit 126 executes a return position and path specifying process. In the return position and path specifying process, the control unit 126 refers to the grid map GM and specifies a return position and a return path according to a predetermined rule, and records the specified return position and return path in the grid map GM. Details of the return position and path specifying process will be described later. After S154, the process proceeds to S156.

In S156, the control unit 126 refers to the grid map GM and starts driving the right crawler 192, the left crawler 194, and the side stepper 196 such that the rebar tying robot 100 moves toward the return position. Here, the control unit 126 drives the right crawler 192, the left crawler 194, and the side stepper 196 such that the return path specified in S154 is followed. After S156, the process proceeds to S158.

In S158, the control unit 126 determines whether the rebar tying robot 100 has reached the return position or not. For example, the control unit 126 determines whether the rebar tying robot 100 has reached the return position or not by determining whether the current position sub region DR is the sub region D with the return position recorded in the grid map GM or not. If it is determined that the rebar tying robot 100 has not reached the return position (in case of NO), the process executes S158 again.

If it is determined that the rebar tying robot 100 has reached the return position in S158 (in case of YES), the process proceeds to S160. In S160, the control unit 126 stops driving the right crawler 192, the left crawler 194, and the side stepper 196. Thus, the rebar tying robot 100 stops at the return position. After S160, the process of FIG. 27 is terminated.

(Return Position and Path Specifying Process)

Upon the start of the return position and path specifying process shown in S156 of FIG. 27, the control unit 126 refers to the grid map GM and specifies a return position and a return path based on a predetermined rule. The user can select one of rules shown in FIGS. 28 to 31 and set it as the above-mentioned rule. In the present embodiment, the user set the rule through the external controller (not shown) or the like.

In the rule shown in FIG. 28, the control unit 126 refers to the grid map GM and specifies a sub region D where the movement path from the current position sub region DR is the shortest among the sub regions D including respective rebar ends R0 as the return position. The control unit 126 specifies the shortest path to the return position as the return path. The control unit 126 records the specified return portion and return path in the grid map GM. In the example of FIG. 28, assuming that the current position sub region DR is a sub region D75, the control unit 126 specifies a sub region D95 as the return position and specifies a path G4 as the return path. Assuming that the current position sub region DR is a sub region D43, the control unit 126 specifies a sub region D41 as the return position and specifies a path G5 as the return path.

In the rule shown in FIG. 29, the control unit 126 refers to the grid map GM and specifies a sub region D where the movement path from the current position sub region DR is the shortest among tied sub regions DA including rebar ends R0 as the return position. The control unit 126 specifies the shortest path passing only tied sub regions DA among paths to the return position as the return path. The control unit 126 records the specified return position and return path in the grid map GM. In the example of FIG. 29, assuming that the current position sub region DR is a sub region D45, the control unit 126 specifies a sub region D15 which is a tied sub region DA as the return position and specifies a path G6 as the return path.

In the rule shown in FIG. 30, the control unit 126 refers to the grid map GM and specifies a sub region D that is located in the front-rear direction as viewed from the current position sub region DR and where the movement path from the current position sub region DR is the shortest among the sub regions D including respective rebar ends R0 as the return position. The control unit 126 specifies the shortest path to the return position as the return path. The control unit 126 records the specified return position and return path in the grid map GM. In the example of FIG. 30, assuming that the current position sub region DR is a sub region D75, a sub region D78 is specified as the return position and a path G7 is specified as the return path. Assuming that the current position sub region DR is a sub region D43, a sub region D41 is specified as the return position and a path G8 is specified as the return path.

In the rule shown in FIG. 31, the control unit 126 refers to the grid map GM and specifies a sub region D that is located in the front-rear direction as viewed from the current position sub region DR and where the moving path from the current position sub region DR is the shortest among tied sub regions DA including rebar ends R0 as the return position. The control unit 126 specifies the shortest path passing only tied sub regions DA among paths to the return path as the return path. The control unit 126 records the specified return position and return path in the grid map GM. In the example of FIG. 31, assuming that the current position sub region DR is a sub region D45, a sub region D41 which is a tied sub region DA is specified as the return position and a path G9 is specified as the return path.

(Variants)

In the embodiments above, the rebar tying robot 100 follows the predetermined order in which the rebar tying robot 100 moves along a primary rebar R1′, which is a tying operation target, while tying intersection points of the primary rebar R1′ and the secondary rebars R2, and after the tying operation is completed for the primary rebar R1′, which is the tying operation target, the rebar tying robot 100 moves onto another primary rebar R1 for which the tying operation has not been done yet, which is a new tying operation target, and repeats these actions thereafter. Unlike this, the rebar tying robot 100 may follow a predetermined order in which the rebar tying robot 100 moves along a primary rebar R1 closest to a rebar end R0 among untied primary rebars R1 while tying its intersection points, and after the tying operation has been done for this primary rebar R1, the rebar tying robot 100 moves along a secondary rebar R2 closest to a rebar end R0 among untied secondary rebars R2 while tying its intersection points, and repeats these actions thereafter.

In the embodiments above, the rebar tying robot 100 ties all intersection points of the primary rebars R1 and the secondary rebars R2. Unlike this, when repeating the tying operation to intersection points of a primary rebar R1′ and the secondary rebars R2, the rebar tying robot 100 may tie every other intersection point of the primary rebar R1′ and the secondary rebars R2. In this case, the rebar tying robot 100 may select intersection points to be tied by the tying operation such that at least one of intersection points adjacent to each other is tied finally.

In the embodiments above, the reel 10 is attached to the rebar tying machine 2 and the rebar tying machine 2 ties the rebars R using the wire W supplied from the reel 10. Unlike this, a wire supply unit (not shown) including a large reel (not shown) may be mounted on the conveying unit 106 of the rebar tying robot 100 and the rebar tying machine 2 may tie the rebars R using a wire W supplied from the wire supply unit. In this case, the control unit 126 may be configured to detect a remaining amount of the wire W in the wire supply unit. The remaining amount of the wire W in the wire supply unit can be specified, for example, by subtracting the cumulative sum of feed amounts of the wire W fed out by the feeder mechanism 12 from the remaining amount of the wire W wound on an unused large reel. The feed amounts of the wire W fed out by the feeder mechanism 12 can be calculated, for example, based on detection signals from a rotation sensor (not shown) that detects the number of rotations of the feed motor 22 or the driving roller 24.

In the embodiments above, the control unit 126 of the rebar tying robot 100 may detect remaining charge of the battery packs B attached to the respective battery receptacles 114. In the process shown in S6 of FIG. 23, the control unit 126 may determine that it is possible to continue the rebar tying operation if the remaining charge of each battery pack B is greater than a predetermined threshold, and may determine that it is impossible to continue the rebar tying operation if the remaining charge of each battery pack B is equal to or less than the predetermined threshold.

In the embodiments above, the commercially available rebar tying machine 2 (e.g., TR180D available from Makita Corporation) is detachably attached to the rebar tying robot 100. Unlike this, a dedicated rebar tying unit (not shown) may be detachably attached to the rebar tying robot 100. In this case, the rebar tying unit may be configured integrally with the operation unit 104.

In the embodiments above, an emergency stop button (not shown) for the user to emergently stop the operation of the rebar tying robot 100 may be provided on the rebar tying robot 100 (e.g., on the housing 110 of the power supply unit 102). In this case, when the emergency stop button is pushed by the user, the control unit 126 stops the right crawler motor 228, the left crawler motor 254, the stepper motor 279, and the lift motor 148 and turns off the actuator 180. When the user pushes the operation execution button 122 again after removing a hazard, the control unit 126 first drives the stepper motor 279 to return the front crank mechanism 276 and the rear crank mechanism 277 to the zero-point position and drives the lift motor 148 to return the lift mechanism 130 to its upper limit position. After this, the control unit 126 executes the normal control to operate the rebar tying robot 100. The emergency stop button may be provided in the vicinity of outer periphery of the rebar tying robot 100, such as in the 20 vicinity of an end portion thereof in the front-rear direction or the left-right direction, to allow the user to easily push it in an emergency. A plurality of emergency stop buttons may be provided. Further, the control unit 126 may cause the rebar tying robot 100 to perform the same actions when receiving an emergency stop command signal and an operation execution command signal through the external controller.

In the embodiments above, an operation display indicator (not shown) that displays an operation state of the rebar tying robot 100 may be provided on the rebar tying robot 100 (e.g., on the housing 110 of the power supply unit 102). In this case, the operation display indicator may display a tying operation state to the user. The tying operation state may include, for example, a state in which all intersections of the primary rebars R1 and the secondary rebars R2 are to be tied and a state in which every other intersection of the primary rebars R1 and the secondary rebars R2 is to be tied. The operation display indicator may display an abnormal stop state of the rebar tying robot 100 to the user. The operation display indicator may display to the user that the control unit 126 is executing the return process (see FIG. 24, FIG. 27) in the rebar tying robot 100. The operation display indicator may display to the user that the rebar tying robot 100 is static at the return position as a result of the control unit 126 having executed the return process (see FIG. 24, FIG. 27). The operation display indicator may display an operation state of the rebar tying robot 100, for example, by emission color(s) of one or more light emitters, blinking patters thereof, or a combination of these. If the operation display indicator is provided on the housing 110, the operation display indicator may be arranged at a high position so as to be clearly visible from a distance.

In the embodiments above, the conveying unit 106 of the rebar tying robot 100 comprises the right crawler 192 and the left crawler 194 as a longitudinal movement mechanism configured to move the rebar tying robot 100 in the front-rear direction. Unlike this, the conveying unit 106 of the rebar tying robot 100 may comprise a longitudinal movement mechanism of another type.

In the embodiments above, the conveying unit 106 of the rebar tying robot 100 comprises the side stepper 196 as a lateral movement mechanism configured to move the rebar tying robot 100 in the left-right direction. Unlike this, the conveying unit 106 of the rebar tying robot 100 may comprise a lateral movement mechanism of another type.

In the embodiments above, the external controller (not shown) sends the control unit 126 the command signal that commands to halt the rebar tying operation and the command signal that designates a position to which the rebar tying robot 100 is to return. Unlike this, the external controller may send the control unit 126 command signals of other types.

In the embodiments above, the control unit 126 of the rebar tying robot 100 retains the map information in form of the grid map GM. Unlike this, the control unit 126 of the rebar tying robot 100 may retain the map information in another form.

In the embodiments above, the candidate return positions are the sub regions D including respective rebar ends R0. Unlike this, the candidate return positions may be sub regions D other than the sub regions D including respective rebar ends R0. For example, as shown in FIG. 32, sub regions D designated by the user (D26, D52, D87) may be candidate return positions. In the example of FIG. 32, the control unit 126 specifies the lowest-cost sub region D52 among the sub regions D designated by the user (D26, D52, D87) as the return position and specifies a path G10 as the return path.

In the embodiments above, the control unit 126 of the rebar tying robot 100 specifies the lowest-cost sub region D among the candidate return positions (the sub regions D including respective rebar ends R0) as the return position. Unlike this, as shown in FIG. 33, the control unit 126 may specify a sub region D other than the lowest-cost sub region D among the candidate return positions (the sub regions D including respective rebar ends R0) as the return position. Generally, the power consumption for movement by driving the right crawler 192 and the left crawler 194 is often smaller than the power consumption for movement by driving the side stepper 196. In the example of FIG. 33, the costs are set according to risks associated with the movement of the rebar tying robot 100 but not set according to the power consumption. In this case, the control unit 126 specifies a sub region D61, as the return position, which is a destination of a path G11 which has a relatively low cost and allows for movement only by driving the right crawler 192 and the left crawler 194. According to this configuration, the control unit 126 can specify the return position taking the movement risks and power consumption into consideration.

In the embodiments above, the candidate return positions are selected as the plurality of sub regions D. Unlike this, there may be a single candidate return position. For example, as shown in FIG. 34, an initial value DS of the current position sub region DR may be the candidate return position. That is, the position at which the rebar tying robot 100 started operating may be the candidate return position. In this case, the control unit 126 specifies a path G12 as the return path.

In the embodiments above, the cost for front-rear direction movement is set as ‘I’ and the cost for left-right direction movement is set as ‘2’. Unlike this, the cost for front-rear direction movement and the cost for left-right direction movement may be varied as needed.

In the embodiments above, the cost for tied sub regions DA is set as ‘1’ and the cost for untied sub region DB is set as ‘3’. Unlike this, the cost for tied sub regions DA and the cost for untied sub region DB may be varied as needed. In addition, the region costs may be set in other point of views, for example, the region cost for sub regions D where obstacles present is set high.

In the embodiments above, the movement costs and the region costs are set. Unlike this, costs may be set for the other elements associated with movement of the rebar tying robot 100.

In the embodiments above, the user selects and sets a rule based on which the control unit 126 specifies the return position and the return path from among the rules shown in FIG. 28 to FIG. 31. Unlike this, the user may select and set a rule other than the rules shown in FIG. 28 to FIG. 31.

(Correspondence Relationships)

As described above, in one or more embodiments, the rebar tying robot 100 is configured to perform the rebar tying operation in which the rebar tying robot 100 performs alternately and repeatedly the operation of moving over the plurality of primary rebars R1 and the plurality of secondary rebars R2 intersecting the plurality of primary rebars R1 and the operation of tying the plurality of primary rebars R1 and the plurality of secondary rebars R2 together at intersection points of the plurality of primary rebars R1 and the plurality of secondary rebars R2. The rebar tying robot 100 comprises the rebar tying machine 2 (an example of rebar tying unit), the conveying unit 106 configured to convey the rebar tying machine 2, and the control unit 126 configured to control the operation of the conveying unit 106. The conveying unit 106 comprises the right crawler 192 and the left crawler 194 (an example of longitudinal movement mechanism) configured to move the rebar tying robot 100 in the front-rear direction, the side stepper 196 (an example of lateral movement mechanism) configured to move the rebar tying robot 100 in the left-right direction, and the control unit 126 and the rebar detection sensors 198, 200, 202 (an example of positional information detection mechanism) configured to detect the current position sub region DR (an example of the current position of the rebar tying robot 100 relative to the plurality of primary rebars R1 and the plurality of secondary rebars R2). The control unit 126 is configured to execute the return process in which the control unit 126 drives at least one of the right crawler 192 and the left crawler 194 and the side stepper 196 such that the rebar tying robot 100 moves from the current position of the rebar tying robot 100 detected by the control unit 126 and the rebar detection sensors 198, 200, 202 to the return position (designated position) (an example of specific position) without performing the rebar tying operation. When a predetermined condition is met during the rebar tying operation, the control unit 126 executes the return process.

According to the configuration above, it is possible to cause the rebar tying robot 100 to halt the rebar tying operation in the middle of it and to move from the position where the rebar tying operation was halted to the return position (designated position).

In one or more embodiments, the control unit 126 is further configured to determine whether it is possible to continue the rebar tying operation or not (an example of continuation possibility determining process). The predetermined condition includes a first predetermined condition that the control unit 126 determines in the determination whether it is possible to continue the rebar tying operation or not that it is not possible to continue the rebar tying operation.

When a problem, such as insufficient remaining amount of the wire W, occurs during the rebar tying operation and the rebar tying operation therefore cannot continue, the user needs to do maintenance work on the rebar tying robot 100 to solve the problem. At this time, it may be difficult for the user to approach the rebar tying robot 100 depending on the position of the rebar tying robot 100. According to the configuration above, the rebar tying robot 100 can be automatically moved to the return position (designated position) where the user can easily do the maintenance work when an event that makes the rebar tying operation unable to be continued (an example of problem that makes the rebar tying operation unable to be continued) occurs in the rebar tying robot 100. The user can easily do the maintenance work on the rebar tying robot 100 to solve the problem.

In one or more embodiments, the control unit 126 is configured to receive the command signal that commands to halt the rebar tying operation (an example of command signal) from the external controller. The predetermined condition includes a second predetermined condition that the control unit 126 determines that the command signal commanding to halt the rebar tying operation has been received from the external controller.

According to the configuration above, the rebar tying operation can be halted in the middle of it by the user's command through the external controller, such as when the user wishes to halt the operation, and move the rebar tying robot 100 to the return position (designated position) which is convenient for the user.

In one or more embodiments, the designated position (an example of specific position) includes a sub region D designated by a command signal (an example of position designated by a user).

According to the configuration above, the rebar tying robot 100 can be moved to the sub region D designated by the command signal (an example of position designated by the user). In one or more embodiments, the designated position includes a sub region D including a rebar end R0 designated by a command signal (an example of position of a rebar end designated by a user).

According to the configuration above, the rebar tying robot 100 can be moved to the sub region D including the rebar end R0 designated by the command signal (an example of the rebar end designated by the user). The user can thus safely retrieve the rebar tying robot 100 and do problem-solving work from the outside of the primary rebars R1 and the secondary rebars R2.

In one or more embodiments, the return position (an example of specific position) includes a sub region D including a rebar end R0 (an example of position of a rebar end) where a movement path from the current position sub region DR (an example of the current position) is the shortest.

According to the configuration above, the rebar tying robot 100 can be moved most efficiently to the sub region D including the rebar end R0 (an example of the position of the rebar end).

In one or more embodiments, the control unit 126 and the rebar detection sensors 198, 200, 202 (an example of the positional information detection mechanism) are further configured to detect tied sub regions DA and untied sub regions DB in the grid map OM (exampled of a tied region and an untied region across the plurality of primary rebars R1 and the plurality of secondary rebars R2). The return position (an example of specific position) includes a sub region D including a rebar end R0 where the movement path from the current position sub region DR is the shortest among rebar ends R0 in the tied sub regions DA (an example of position of a rebar end where a movement path from the current position is the shortest among rebar ends within the tied region).

According to the configuration above, the rebar tying robot 100 moves over the tied regions DA which are stronger than the untied regions DB in the return process. Thus, the rebar tying robot 100 can be moved more safely to the sub region D including the rebar end R0 (example of the position of the rebar end).

The rebar tying robot 100, which alternately and repeatedly performs the operation of moving over the primary rebars R1 and the secondary rebars R2 in the direction in which the primary rebars R1 extend and the operation of tying the intersection points of the primary rebars R1 and the secondary rebars R2, is more stable in the front-rear direction movement by driving the right crawler 192 and the left crawler 194 than in the left-right direction movement by driving the side stepper 196. According to the configuration above, it is possible to minimize the frequency for the rebar tying robot 100 to drive the side stepper 196. It is thus possible to move the rebar tying robot 100 more safely to a sub region D including a rebar end R0 (an example of the position of the rebar end).

In one or more embodiments, the rebar tying robot 100 is configured to perform alternately and repeatedly the operation of moving in the direction in which the plurality of primary rebars R1 extends over the plurality of primary rebars R1 and the plurality of secondary rebars R2 and the operation of tying the intersection points of the plurality of primary rebars R1 and the plurality of secondary rebars R2. The control unit 126 and the rebar detection sensors 198, 200, 202 (an example of the positional information detection mechanism) is further configured to detect tied sub regions DA and untied sub regions DB in the grid map GM (examples of a tied region and an untied region across the plurality of primary rebars R1 and the plurality of secondary rebars R2). The return position (an example of specific position) includes a sob region D including a rebar end R0 where the movement path from the current position sub region DR is the shortest among rebar ends R0 that are located in the front-rear direction as viewed from the current position sub region DR and in tied sub regions DA (an example of a position of a rebar end where a movement path from the current position is the shortest among rebar ends that are located in the front-rear direction as viewed from the current position and within the tied region).

The rebar tying robot 100, which alternately and repeatedly performs the operation of moving over the primary rebars R1 and the secondary rebars R2 in the direction in which the primary rebars R1 extend and the operation of tying the intersection points of the primary rebars R1 and the secondary rebars R2, is more stably in the front-rear direction movement by driving the right crawler 192 and the left crawler 194 than in the left-right direction movement by driving the side stepper 196. According to the configuration above, it is possible to minimize the frequency for the rebar tying robot 100 to drive the side stepper 196. Further, the rebar tying robot 100 moves over the tied sub regions DA which are stronger than the untied sub regions DB in the return process. It is thus possible to move the rebar tying robot 100 more safely to a sub region D including a rebar end R0 (an example of the position of the rebar end).

In one or more embodiments, the control unit 126 is configured to execute the return position and path specifying process (an example of specific position specifying process) in which the control unit 126 calculates, for each of at least one candidate return position (an example of candidate position), which is a candidate for the return position (an example of specific position), a cost for the rebar tying robot 100 to move from the current position sub region DR to the candidate return position and specifies the return position from among the at least one candidate return position based on the calculated costs of the at least one candidate return position. In the return process, the control unit 126 is configured to drive at least one of the right crawler 192 and the left crawler 194 and the side stepper 196 such that the rebar tying robot 100 moves from the current position sub region DR to the return position along the return path.

According to the configuration above, the control unit 126 can specify the return position based on the cost calculation even when there are multiple candidate return positions for the return position.

In one or more embodiments, the control unit 126 is configured to specify a candidate return position whose cost is the lowest among at least one candidate return position as the specific position.

According to the configuration above, even when there are multiple candidate return positions (an example of candidates for the specific position), the control unit 126 can specify the position whose cost is the lowest as the specific position.

In one or more embodiments, the control unit 126 is configured to calculate, for each of at least one candidate movement path, which are candidates for return paths from the current position sub region DR to the candidate return positions, a cost for the rebar tying robot 100 to move from the current position sub region DR to the candidate return position and calculate the costs of the candidate return positions based on the calculated costs of the candidate return paths.

According to the configuration above, the control unit 126 can calculate costs of the candidate return positions, which are candidates for the return position, based on the costs of the movement paths. The control unit. 126 can thus specify the return position taking the movement paths into consideration.

In one or more embodiments, the control unit 126 is configured to calculate a cost of a candidate movement path whose cost is the lowest among the at least one candidate movement path as the cost of the candidate return position.

According to the configuration above, the control unit 126 can specify the candidate return position where the cost of the movement path from the current position sub region DR of the rebar tying robot 100 is the lowest as the return position. Thus, the rebar tying robot 100 can be moved to the return position with the lowest cost.

In one or more embodiments, in the return position and path specifying process, the at least one candidate return position is selected from sub regions D including rebar ends R0 (an example of positions of a plurality of rebar ends).

According to the configuration above, the control unit 126 can specify, by the cost calculation, a sub region D including a rebar end R0 where the cost of the movement path from the current position sub region DR is the lowest among the sub regions D including rebar ends R0. Thus, the rebar tying robot 100 can be moved to the sub region D including the rebar end R0 (an example of position of the rebar end) with the lowest cost.

In one or more embodiments, the control unit 126 is configured to execute a return path specifying process (an example of specific movement path specifying process) in which the control unit 126 calculates, for each of at least one candidate return path (an example of candidate movement path) which is a candidate for a return path (an example of movement path) from the current position sub region DR to the designated position (an example of specific position), a cost for the rebar tying robot 100 to move from the current position sub region DR to the designated position and specifies a return path (an example of specific movement path) from among the at least one candidate return path based on the calculated costs of the at least one candidate return path. In the return process, the control unit 126 is configured to drive at least one of the right crawler 192 and the left crawler 194 and the side stepper 196 such that the rebar tying robot 100 moves from the current position sub region DR to the designated position along the return path.

According to the configuration above, the control unit 126 can specify the return path even when there are multiple candidate return paths, which are candidates for the return path, based on the cost calculation.

In one or more embodiments, the control unit 126 is configured to specify a candidate return path whose cost is the lowest among the at least one candidate return path as the return path.

According to the configuration above, it is possible to specify a candidate return path whose cost is the lowest as the return path even when there are multiple candidate return paths, which are candidates for the return path. Thus, the rebar tying robot 100 can be moved to the designated position with the lowest cost.

In one or more embodiments, the control unit 126 and the rebar detection sensors 198, 200, 202 (an example of positional information detection mechanism) are further configured to detect tied sub regions DA and untied sub regions DB across the plurality of primary rebars R1 and the plurality of secondary rebars R2. The control unit 126 is configured to set a cost for the rebar tying robot 100 to move over the untied sub regions DB higher than a cost for the rebar tying robot 100 to move over the tied sub regions DA.

According to the configuration above, the control unit 126 can execute the cost calculation on the ground that a risk of moving over the untied sub regions DB is larger than a risk of moving over the tied sub regions DA. This enables the cost calculation on the ground of the strength of movement path with respect to the movement risk from the current position sub region DR.

According to the configuration above, the control unit 126 can execute the cost calculation on the ground that a risk of moving in the left-right direction is larger than a risk of moving in the front-rear direction. This enables the cost calculation on the ground of the stability of movement means with respect to the movement risk from the current position sub region DR.

REBAR TYING ROBOT

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