Patent Application
20190169818
The present invention relates to a work machine.
In a hydraulic excavator, a boom, an arm, a bucket, and the like of a work implement (hereinafter, also referred to as “front work implement”) are rotatably supported, so that a tip end of the bucket traces out a circular arc locus when the bucket is moved solely. Owing to this, in a case of forming a linear finished surface by the tip end of the bucket by, for example, an arm crowding action, then an operator needs to drive the boom, the arm, and the bucket in a combined fashion so that the tip end of the bucket traces out a linear locus; thus, the operator is required to have expertise.
To address this challenge, there is a technique for applying a function to control actuators to be driven either automatically or semiautomatically by a computer (controller) (hereinafter, referred to as machine control) to excavation work, and moving the tip end of the bucket along a design surface (hereinafter, also referred to as “target excavation surface”) during an excavation action (arm or bucket action). As the technique of this type, there is known one for automatically controlling a boom cylinder during the excavation action by operator's operation to add a boom raising action as appropriate, and limiting a tip end position of the bucket onto the design surface.
However, in a case of conducting work for laying earth on a flat or recessed geographical feature to raise a ground level (hereinafter, referred to as “filling work”), a filled upper surface after completion serves as the design surface. The tip end of the bucket is often located below the design surface during the filling work. Owing to this, when the arm crowding action is performed in a state in which the tip end of the bucket is located below the design surface (that is, within a filling range), the machine control to limit the tip end position of the bucket onto the design surface is executed, which possibly results in sudden start of the boom raising action.
To address the problem, Patent Document 1, for example, describes a work vehicle that includes: a design surface information acquiring section acquiring data about a design surface indicative of a target shape of a work object by a work implement; a cutting edge position computing section computing a position of a cutting edge of a bucket; and an action limiting section executing action limiting control by which a boom is forcibly raised in accordance with a relative position of the cutting edge of the bucket to the design surface, and the position of the cutting edge is limited to a region above the design surface, and Patent Document 1 describes that, in a state in which the cutting edge is located away from the design surface vertically below by a predetermined distance or longer, the action limiting section does not execute the action limiting control.
Patent Document 1: JP 5706050 B1
According to the work vehicle described in Patent Document 1, the action limiting section does not execute the action limiting control in the state in which the cutting edge of the bucket (tip end of the bucket) is located away from the target excavation surface (design surface) vertically below by a predetermined distance or longer. Owing to this, when the action limiting control (forced boom raising action) is suddenly executed (hereinafter, such a boom action is often referred to as “sudden action”) irrespectively of operator's intention in a case of changing the distance of the cutting edge to the target excavation surface from the state of being equal to or larger than the predetermined distance to a state of being smaller than the predetermined distance. As a result, the occurrence of the sudden boom raising action causes the operator who does not desire or expect the boom raising action to feel heavy discomfort. In addition, in a case of the presence of the cutting edge of the bucket near the predetermined distance, the boom raising action under the action limiting control is executed or not executed. In this way, the changeover between on and off of the control irrespective of operator's intention possibly, frequently occurs. Owing to this, there is a concern of increasing operator's discomfort.
An object of the present invention is, therefore, to provide a work machine capable of suppressing sudden occurrence of a boom raising action (occurrence of a sudden action) while a tip end of a work implement is located below a target excavation surface.
While the present application includes a plurality of means for solving the problems. As an example, there is provided a multijoint work machine including: a travel structure; a swing structure swingably attached onto the travel structure; a multijoint work implement that is attached to the swing structure and that includes a boom, an arm, and a bucket; an operation device that outputs an action direction to each of the travel structure, the swing structure, the boom, the arm, and the bucket in response to an operator's operation; and a controller that executes region limiting control to forcibly raise the boom in such a manner that a position of a tip end of the work implement is kept on a target excavation surface and within a region above the target excavation surface if the operation device issues the action direction to the arm or the bucket. The controller includes a target action determination section that determines which is selected as a control mode over a raising speed of the boom at a time of executing the region limiting control, a first mode or a second mode specified by a raising speed lower than a raising speed of the first mode if the tip end of the work implement is located below the target excavation surface, and controls the raising speed of the boom during the region limiting control on the basis of a result of determination.
According to the present invention, it is possible to suppress sudden occurrence of a boom raising action if a tip end of a work implement is located below a target excavation surface; thus, it is possible to suppress an operator from feeling discomfort.
Embodiments of the present invention will be described hereinafter with reference to the drawings. While an example of a hydraulic excavator provided with a bucket 10 as an attachment on a tip end of a work implement is described below, the present invention may be applied to a hydraulic excavator provided with an attachment other than the bucket. In the following description, when a plurality of same constituent elements are present, alphabets are often added to reference characters (numbers). However, the plurality of constituent elements are often denoted generically by omitting the alphabets. For example, when three pumps 300a, 300b, and 300c are present, these are often denoted generically by pumps 300.
The boom 8, the arm 9, the bucket 10, the upper swing structure 12, and the lower travel structure 11 configure driven members that are driven by a boom cylinder 5, an arm cylinder 6, a bucket cylinder 7, a swing hydraulic motor 4, and left and right travel motors 3a and 3b, respectively. Action directions to these driven members 8, 9, 10, 12, and 11 are output in response to operator's operations on a travel right lever 23a, a travel left lever 23b, an operation right lever 1a, and an operation left lever 1b (which are often generically referred to as operation levers 1, 23) mounted in an operation room on the upper swing structure 12.
An operation device 47a (refer to
A hydraulic fluid delivered from a hydraulic pump 2 is supplied to the travel right hydraulic motor 3a, the travel left hydraulic motor 3b, the swing hydraulic motor 4, the boom cylinder 5, the arm cylinder 6, and the bucket cylinder 7 via the flow control valves 15a, 15b, 15c, 15d, 15e, and 15f (refer to
Meanwhile, a boom angle sensor 30, an arm angle sensor 31, and a bucket angle sensor 32 are attached to a boom pin, an arm pin, and a bucket link 13 so that rotation angles α, β, γ (refer to
As illustrated in
The hydraulic excavator of the present embodiment is provided with a control system assisting an operator's excavation operation. Specifically, the hydraulic excavator 1 is provided with an excavation control system that exercises control to forcibly raise the boom 8 (often referred to as “region limiting control”) on the basis of a position relationship between the target excavation surface and the tip end of the work implement 1A such that a position of a tip end of the work implement 1A (claw tip of the bucket 10) is kept on the target excavation surface and within a region above the target excavation surface in a case of the presence of the action direction issued to the arm 9 or the bucket 10 from the operation device 45b or 46a. The excavation control system that can execute this region limiting control includes a limiting control switch 17 that is installed at a position at which the limiting control switch 17 does not obstruct an operator's view such as a position above an operation panel within the operation room and that changes over between validation and invalidation of the region limiting control, pressure sensors 70a and 70b that are provided in pilot lines 144a and 144b of the operation device 45a for the boom 8 and that detect a pilot pressure (control signal) as the operation amount of the operation lever 1a, pressure sensors 71a and 71b that are provided in pilot lines 145a and 145b of the operation device 45b for the arm 9 and that detect a pilot pressure (control signal) as the operation amount of the operation lever 1b, a solenoid proportional valve 54a that has a primary port side connected to a pilot pump 48 and that reduces a pilot pressure from the pilot pump 48 to output the reduced pilot pressure, a shuttle valve 82 that is connected to a secondary port side of the solenoid proportional valve 54a in the pilot line 144a of the operation device 45a for the boom 8, that selects a higher pressure from between the pilot pressure in the pilot line 144a and the control pressure output from the solenoid proportional valve 54a, and that guides the selected higher pressure to the hydraulic drive section 150a of the flow control valve 15a, a solenoid proportional valve 54b that is installed in the pilot line 144b of the operation device 45a for the boom 8 and that reduces the pilot pressure in the pilot line 144b in response to an electrical signal to output the reduced pilot pressure, and a controller 40 that is a computer capable of executing the region limiting control.
The pilot lines 145a and 145b for the arm 9 are provided with the pressure sensors 71a and 71b each detecting the pilot pressure and outputting the pilot pressure to the controller 40 and solenoid proportional valves 55a and 55b each reducing the pilot pressure on the basis of a control signal from the controller 40 and outputting the reduced pilot pressure. The pilot lines 146a and 146b for the bucket 10 are provided with pressure sensors 72a and 72b each detecting the pilot pressure and outputting the pilot pressure to the controller 40, and solenoid proportional valves 56a and 56b each reducing the pilot pressure on the basis of a control signal from the controller 40 and outputting the pilot pressure. It is noted that connection lines among the pressure sensors 71 and 72, the solenoid proportional valves 55 and 56, and the controller 40 are not depicted in
Shape information and position information about the target excavation surface stored in a ROM 93 or RAM 94 to be described later, detection signals of the angle sensor 30 to 32 and the tilt angle sensor 33, and detection signals of the pressure sensors 70 to 72 are input to the controller 40. Furthermore, the controller 40 outputs electrical signals for correcting the control signals (pilot pressures) for exercising excavation control (region limiting control) to limit a region to the solenoid proportional valves 54 to 56.
The work implement posture sensor 50 is configured with the boom angle sensor 30, the arm angle sensor 31, the bucket angle sensor 32, and the machine body tilt angle sensor 33. The target excavation surface setting device 51 is an interface to which information about the target excavation surface (including position information about the target excavation surface) can be input. The information may be input to the target excavation surface setting device 51 either by operator's manually inputting the information or by importing the information from outside via a network or the like. Furthermore, a satellite communication antenna is connected to the target excavation surface setting device 51, and the target excavation surface setting device 51 may compute excavator global coordinates. The operator's operation sensor 52 is configured with the pressure sensors 70a, 70b, 71a, 71b, 72a, and 72b that acquire the operating pressures generated by operator's operating the operation levers 1. The informing device 53 is configured with at least one of a display (display device) that displays the position relationship between the target excavation surface and the work implement 1A for the operator and a loudspeaker that informs the operator of the position relationship between the target excavation surface and the work implement 1A by a sound (including a voice). The solenoid proportional valves 54 to 56 are provided in the pilot pressure (operating pressure) hydraulic lines described with reference to
The work implement posture computing section 41 computes a posture of the work implement 1A on the basis of information from the work implement posture sensor 50. The posture of the work implement 1A can be defined on the basis of excavator reference coordinates of
The target excavation surface computing section 42 computes the target excavation surface 60 on the basis of information from the target excavation surface setting device 51. The target action computing section 43 computes a target action of the work implement 1A so that the bucket 10 moves on the target excavation surface and within the region above the target excavation surface, on the basis of information from the work implement posture computing section 41, the target excavation surface computing section 42, the target action determination section 49, and the operator's operation sensor 52. The solenoid proportional valve control section 44 computes commands to the solenoid proportional valves 54 to 56 on the basis of commands from the target action computing section 43. The solenoid proportional valves 54 to 56 are controlled on the basis of the commands from the solenoid proportional valve control section 44. Furthermore, the informing device 53 informs the operator of various information related to the machine control on the basis of information from the target action computing section 43.
The commands output from the target action computing section 43 to the solenoid proportional valve control section 44 include a boom raising command. The boom raising command is a command output to the solenoid proportional valve control section 44 at a time of forcibly raising the boom 8 so that the position of the tip end of the bucket 10 is kept on the target excavation surface 60 and within the region above the target excavation surface 60 at a time of executing the region limiting control. When the boom raising command is input to the solenoid proportional valve control section 44, then the solenoid proportional valve control section 44 outputs a valve opening command (command current) to the solenoid proportional valve 54a, and a hydraulic fluid (hereinafter, referred to as secondary pressure) generated in the solenoid proportional valve 54a is supplied to the hydraulic drive section 150a to drive the control valve 15a. The hydraulic operating fluid is thereby guided into a bottom-side hydraulic chamber of the boom cylinder 5 from the hydraulic pump 2 to raise the boom 8. A raising speed of the boom 8 (boom raising speed) at that time is controllable by a value of a secondary pressure of the solenoid proportional valve 54a, that is, a command from the solenoid proportional valve control section 44 to the solenoid proportional valve 54a.
The target action determination section 49 determines which is more preferably selected, a first mode (normal boom raising control) or a second mode (deceleration boom raising slow action control) as a control mode over the raising speed of the boom 8 during execution of the region limiting control if the tip end of the work implement 1A is located below the target excavation surface, and outputs a result of determination to the target action computing section 43. The target action computing section 43 outputs a command computed on the basis of this result of the determination to the solenoid proportional valve control section 44. The solenoid proportional valve control section 44 outputs the command to the solenoid proportional valve 54a on the basis of this command, and the boom raising speed is finally controlled in the control mode selected by the target action determination section 49.
In the present embodiment, the target action determination section 49 makes the determination on the basis of a downward penetration amount of the tip end of the work implement 1A (claw tip of the bucket 10) into the target excavation surface 60, selects the second mode (deceleration boom raising slow action control) if the penetration amount is equal to or higher than a predetermined value, and selects the first mode (normal boom raising control) if the penetration amount is lower than the predetermined value. Details of the target action determination section 49 will be described with reference to
In Step 101, the target action determination section 49 determines whether the operator causes the operation device 45b or 46b to issue the action direction to the arm 9 or the bucket 10, that is, whether the operation input is performed on the operation lever 1b or 1a on the basis of an output from the operator's operation sensor 52. If determining in Step 101 that the operation input is performed on the arm 9 or the bucket 10, the target action determination section 49 selects the deceleration boom raising slow action control as the control mode in Step 104. The target action determination section 49 thereby outputs a control mode command in the second mode to the target action computing section 43, and the boom raising speed during the boom raising control is controlled in the second mode by the solenoid proportional valve 54a.
Now, the normal boom raising control (first mode) and the deceleration boom raising slow action control (second mode) will be described. Normally, when the region limiting control described above is executed, then the boom raising command is output from the target action computing section 43, and the boom raising action is controlled in such a manner that the tip end of the bucket does not penetrate the target excavation surface 60 on the basis of the command. It is assumed that the control mode over the boom raising speed at this time is the normal boom raising control (first mode). On the other hand, the deceleration boom raising slow action control (second mode) is a control mode that is not intended to prevent the penetration of the tip end of the bucket into the target excavation surface 60 but that is selected to mitigate operator's discomfort, and the boom raising speed at that time is always set lower than the speed during the normal boom raising control in the same condition. For example, the speed in the second mode can be set to a value obtained by multiplying the speed in the first mode by a predetermined rate (for example, 20%). The speed in the second mode can be kept to a predetermined value in such a manner that the speed in the second mode is always controlled to be equal to or lower than the speed in the first mode. As the predetermined value in this case, a minimum value of the boom raising speed, that is, the boom raising speed while a minimum pilot pressure that enables the control valve 15a to move from a neutral position is acting on the hydraulic drive section 150a can be selected.
The boom speed control based on the deceleration boom raising slow action control can be exercised continuously until the bucket tip end is located above the target excavation surface 60. In other words, in this case, once the deceleration boom raising slow action control is selected, the deceleration boom raising slow action control is continuously selected while the bucket tip end is penetrating into the target excavation surface 60 even if the penetration amount of the bucket tip end into the target excavation surface 60 becomes lower than the predetermined value. It is noted that this is also applicable to other embodiments.
Furthermore, if the deceleration boom raising slow action control is selected in Step 104, the target action determination section 49 issues a command to the informing device 53 to inform the operator of the selection of the deceleration boom raising slow action control in Step 105. At this time, operator's changing over the limiting control switch 17 to a region limiting control invalid position stops the selection of the deceleration boom raising slow action control and the execution of the region limiting control.
On the other hand, if determining in Step 101 that the operation input is not performed on the arm 9 or the bucket 10, the target action determination section 49 does not execute the boom raising control (Step 107).
Moreover, if determining in Step 100 that the penetration amount of the bucket tip end into the target excavation surface is equal to or lower than the predetermined value, the process goes to Step 102. In and after Step 102, the target action determination section 49 executes the normal region limiting control. First, if the target action determination section 49 determines that the arm 9 or the bucket 10 is operated on the basis of an output from the operator's operation sensor 52 in Step 102, the process goes to Step 103.
In Step 103, the target action determination section 49 determines whether the boom raising command is issued from the target action computing section 43 on the basis of an input signal from the target action computing section 43. If determining in Step 103 that the boom raising command is issued, the target action determination section 49 selects the normal boom raising control to execute boom raising in Step 106. In other words, the target action determination section 49 issues a control mode command in the first mode to the target action computing section 43, and the boom raising speed during the boom raising control is controlled in the first mode by the solenoid proportional valve 54a.
If determining in Step 103 that the boom raising command is not output, or determining in Step 102 that the operation input is not performed on the arm 9 or the bucket 10, the target action determination section 49 does not execute the boom raising control.
After the process goes up to “RETURN” in the flowchart, the process returns to Step 100 and the target action determination section 49 repeats the process described above.
Effects by the present configuration will be described with reference to
As indicated by an arrow E, it is assumed herein that the hydraulic excavator travels on the ground 600 from left to right and that the tip end of the bucket 10 penetrates into a region below the target excavation surface 60. The hydraulic excavator normally travels without operating the front work implement 1A (front operation). In other words, the boom raising control is not executed by presence of Step 101 or 102 of
As disclosed in Japanese Patent No. 5706050, in a case of configuring the hydraulic excavator in such a manner that the region limiting control is not executed when the penetration amount D is equal to or higher than the predetermined value (which is assumed as D1 similarly to the present embodiment), the boom raising control is not executed while the work is conducted in a range in which the penetration amount D is equal to or higher than D1 even with the operator's operating the arm 9 in a state of the hydraulic excavator on a right side of
In the present embodiment configured as described above, by contrast, when the arm 9 is operated in the state of the hydraulic excavator on the right side of
Moreover, in the embodiment described above, if the second mode is selected, the controller 40 is configured to inform the operator of the selection through the informing device. This can further accelerate the operator's recognition of the region limiting control, so that it is possible to further suppress the occurrence of the forgetting or misunderstanding described above.
Furthermore, as mentioned above, in a case of configuring the controller 40 in such a manner that the boom speed control based on the deceleration boom raising slow action control (second mode) is continuously carried out until the tip end of the bucket is located above the target excavation surface 60, the boom raising control based on the deceleration boom raising slow action control is carried out while the bucket tip end is penetrating into the target excavation surface 60 even if the penetration amount D of the bucket tip end into the target excavation surface 60 is lower than the predetermined value D1. Owing to this, the speed of automatic boom raising does not suddenly change until the bucket tip end reaches the target excavation surface 60; thus, it is possible to mitigate operator's discomfort.
A second embodiment of the present invention will next be described. It is noted that a hardware configuration of a hydraulic excavator in the present embodiment is the same as that in the first embodiment and, therefore, not described and that functions overlapping those in the first embodiment are not sometimes described.
In the present embodiment, “determination” by the target action determination section 49 differs from that in the first embodiment, and the target action determination section 49 is configured to change the control mode over the boom raising speed during the boom raising control in the light of a reason for penetration into the target excavation surface. In other words, the target action determination section 49 changes the control mode over the boom raising speed, depending on the reason for the penetration into the target excavation surface such as the penetration due to travel or swing, the penetration due to a forward posture of the excavator, and the penetration due to other unexpected reasons (for example, the penetration due to deteriorated control accuracy during excavation).
Specifically, the target action determination section 49 determines which is preferably selected to control the boom speed during the boom raising control, the first mode or the second mode, on the basis of the action direction to the lower travel structure 11 or the upper swing structure 12 from the operation devices 46b, 47a, and 47b (operation levers 1b, 23a, and 23b) and the position relationship between the target excavation surface 60 and the tip end of the work implement 1A. In addition, the target action determination section 49 selects the second mode (deceleration boom raising slow action control) if the tip end of the work implement 1A moves below the target excavation surface 60 by the action direction to the lower travel structure 11 or the upper swing structure 12 from the operation devices 46b, 47a, and 47b (operation levers 1b, 23a, and 23b), and selects the first mode (normal boom raising control) if the action direction to the lower travel structure 11 or the upper swing structure 12 from the operation devices 47a and 47b or the operation device 46b is not present and if the tip end of the work implement 1A is located above the target excavation surface 60. Details of the target action determination section 49 will be described with reference to
First, in Step 200, the target action determination section 49 determines whether the penetration of the bucket tip end into the target excavation surface 60 was present in a control cycle just before a current control cycle. If determining that the penetration of the bucket tip end into the target excavation surface 60 was not present, the target action determination section 49 regards the current bucket tip end as being located above the target excavation surface 60 and a process goes to Step 201.
In Step 201, the target action determination section 49 determines whether a travel operation or a swing operation is present via the operation levers 23a and 23b or the operation lever 1b. If the target action determination section 49 determines herein that the travel operation or the swing operation is present, the process goes to Step 202.
In Step 202, the target action determination section 49 determines whether the penetration of the bucket tip end into the target excavation surface 60 is present on the basis of the position of the tip end of the bucket 10 input from the work implement posture computing section 41 and the position of the target excavation surface 60 input from the target excavation surface computing section 42. If determining in Step 202 that the penetration into the target excavation surface 60 is present, then the target action determination section 49 determines that a cause for the penetration is the travel or swing operation, and the process goes to Step 203.
In Step 203, the target action determination section 49 determines whether an operation input is performed on the arm 9 or the bucket 10 from the operation lever 1b or 1a. If determining herein that the operation input is performed on the arm 9 or the bucket 10, the target action determination section 49 selects the deceleration boom raising slow action control (second mode) as the control mode over the boom raising speed in Step 209. In addition, in Step 210, the target action determination section 49 issues a command to the informing device 53 to inform the operator of the selection of the deceleration boom raising slow action control due to the presence of the swing or travel. It is noted that the deceleration boom raising slow action control may be executed until the work implement 1A is located above the target excavation surface 60 similarly to the first embodiment.
If the target action determination section 49 determines in Step 201 that the travel operation or the swing operation is not present, the process goes to Step 204.
In Step 204, the target action determination section 49 determines whether the machine body tilt angle θ is greater than a predetermined angle θ1 in a forward tilting direction, on the basis of an output from the machine body tilt angle sensor 33. If the target action determination section 49 determines in Step 204 that the machine body tilt angle θ is greater than the predetermined angle θ1, the process goes to Step 215.
In Step 215, the target action determination section 49 determines whether the penetration of the bucket tip end into the target excavation surface 60 is present on the basis of the position of the tip end of the bucket 10 input from the work implement posture computing section 41 and the position of the target excavation surface 60 input from the target excavation surface computing section 42. If determining in Step 215 that the penetration into the target excavation surface 60 is present, then the target action determination section 49 determines that a cause for the penetration is a forward tilt posture of the machine body, and the process goes to Step 205.
In Step 205, the target action determination section 49 determines whether the operation input is performed on the arm 9 or the bucket 10. If the target action determination section 49 determines in Step 205 that the operation input is performed on the arm 9 or the bucket 10, the process goes to Step 206.
In Step 206, similarly to Step 103 of
If the target action determination section 49 determines that the penetration was present in Step 200, if the target action determination section 49 determines that the penetration into the target excavation surface 60 is not present in Step 202 or 215, or if the target action determination section 49 determines that the machine body tilt angle θ is equal to or less than a predetermined angle θ1 in Step 204, the process goes to Step 207. It is noted that cases of going to Step 207 include a case in which the penetration is not due to the travel, the swing, or the forward tilt posture but for some reason during the excavation work (for example, the deteriorated control accuracy during excavation).
The target action determination section 49 selects the normal boom raising control (first mode) in Step 213 if determining that the arm 9 or the bucket 10 is operated and the boom raising command is issued at that time in Steps 207 and 208. In addition, it is assumed that the target action determination section 49 does not execute the boom raising control in Step 211 if determining that the arm or bucket operation is not present in Step 203, 205, or 207 or if the boom raising command is not output in Step 206 or 208.
Effects of the present embodiment will be described. A case in which the tip end of the work implement 1A moves below the target excavation surface 60 due to the travel of the lower travel structure 11 or the swing of the upper swing structure 12 does not necessarily indicate that the bucket tip end penetrates into the target excavation surface 60 during the excavation work. In the present embodiment, therefore, the boom raising control is executed in the second mode lower in speed than the first mode in such a case, and the operator is informed that the control different from normal control is functioning. By doing so, if the boom raising action at the low speed occurs after the travel or the swing, it is possible to cause the operator to easily recognize that movement of the bucket tip end below the target excavation surface 60 is due to the travel or the swing. Therefore, if the operator does not desire to execute the region limiting control (boom raising control), the operator can easily and spontaneously suspend the region limiting control by the region limiting control switch 17.
Furthermore, if the bucket tip end penetrates into the target excavation surface 60 due to the bad geographical features and the tilting of the machine body, then the excavator has an unstable posture in many cases, and there is a concern of the deteriorated excavation accuracy under such circumstances. In the present embodiment, therefore, even with the penetration into the target excavation surface 60 without the action direction to the lower travel structure 11 or the upper swing structure 12, the target action determination section 49 is configured to regard the tilting of the machine body as the cause for the penetration and to suspend the boom raising control (region limiting control) if the machine body tilt angle θ is greater than the predetermined angle θ1 in the forward tilting direction. With this configuration, it is possible to avoid execution of the boom raising control with the excavator in the unstable posture and continue stable work.
Furthermore, in the present embodiment, the target action determination section 49 is configured to execute Step 207 if a determination result is NO in Steps 201 and 204; thus, even if the bucket tip end penetrates into the target excavation surface 60 for the cause other than the above causes (the travel, the swing, and the tilting of the machine body), the target action determination section 49 can control the boom speed in the first mode. With this configuration, if the bucket tip end penetrates into the region below the target excavation surface 60 for some cause (for example, the deteriorated control accuracy over the bucket tip end) during the excavation work, the bucket tip end can be promptly moved back to the target excavation surface 60; thus, it is possible to prevent deterioration of work efficiency for the excavation work.
Therefore, according to the present embodiment, it is possible to carry out appropriate boom raising control, depending on the various circumstances described above.
A third embodiment of the present invention will next be described. The present embodiment is a modification of the first embodiment. It is noted that a hardware configuration of a hydraulic excavator in the present embodiment is the same as that in the first embodiment and, therefore, not described and that functions overlapping those in the first and second embodiments are not described.
In the present embodiment configured as described so far, similarly to the second embodiment, it is possible to avoid execution of the boom raising control with the excavator in the unstable posture and continue stable work.
Examples of the first mode and the second mode that are the control modes over the boom raising speed during the execution of the region limiting control will be described with reference to
In
In
While the penetration amount D is associated with the boom raising speed VB for the brevity of description in the examples of
Meanwhile, while the penetration of the work implement 1A into the target excavation surface 60 has been described while taking the penetration amount of the bucket tip end by way of example in each of the embodiments described above, an object to be controlled is not limited to the bucket tip end. For example, not the bucket tip end but an arbitrary point on the bucket such as the back surface of the bucket may be set as the object to be controlled.
While the angle sensors are used for detecting the angles of the boom, the arm, and the bucket for information about the posture, stroke sensors detecting stroke lengths of the boom cylinder, the arm cylinder, and the bucket cylinder may be used to calculate the information about the posture of the excavator as an alternative to the angle sensors.
In the flowcharts of
While various types of control is exercised by setting the bucket tip end and the target excavation surface to a two-dimensional coordinate system (excavator coordinate system) set to the hydraulic excavator, the bucket tip end and the target excavation surface may be set to a three-dimensional coordinate system (world coordinate system) set to the ground (Earth) as an alternative to the two-dimensional coordinate system.
In the first embodiment, if a determination result is YES in Step 101, then the same determination (determination whether the boom raising command is output) as that in Step 103 may be additionally executed, and the process may go to Step 104 if a determination result is YES in the additional step and go to Step 107 if the determination result is NO in the additional step.
In the second embodiment, if a determination result is NO in Step 202 (travel operation/swing operation is not present), the process may go not to Step 204 but to Step 207. In other words, Steps 204, 205, 206, and 212 can be omitted.
While it is determined whether the travel or swing operation is present in Step 202, determination may be made only on the basis of the presence of the travel operation. Furthermore, if the bucket tip end is to penetrate into the target excavation surface by the swing on the assumption that the machine control is executed with objects to be controlled including the swing, the swing may be controlled or interrupted.
Moreover, while a determination condition of Step 204 is that the machine body tilt angle θ is equal to or greater than the predetermined angle θ1 in the forward tilting direction, the determination condition is not necessarily limited to the forward tilting direction. For example, the determination condition according to a backward tilting direction or a roll tilting (roll angle) may be used.
Various patterns are available for determination of the penetration into the target excavation surface due to the travel or the swing. For example, as an alternative to the above example, the target action determination section 49 may be configured to monitor the position relationship between the bucket tip end and the target surface during the travel operation or swing operation, and to execute the process of Step 203 upon confirmation of the movement of the bucket tip end from above the target excavation surface to below the target excavation surface.
While the case of suspending the boom raising control if the machine body tilt angle θ exceeds θ1 has been described in the second and third embodiments, the system may be configured such that the boom raising control is exercised in the second mode as an alternative to this case.
Description of Reference Characters
| Number | Date | Country | Kind |
|---|---|---|---|
| 2016-105280 | May 2016 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2017/014267 | 4/5/2017 | WO | 00 |
