Patent Application
20230034827
The present application is based on, and claims priority from JP Application Serial Number 2021-125117, filed Jul. 30, 2021, the disclosure of which is hereby incorporated by reference herein in its entirety.
The present disclosure relates to a control method for a robot system and a robot system.
JP-A-2-31850 discloses a robot system having a robot with a spray nozzle supported by a distal end of a robot arm via a head slide unit and painting a surface of an object by spraying paint from the spray nozzle. In the robot system, the entire object is painted by repetition of a moving step of moving the robot arm to set the spray nozzle to face an unpainted region of the object and a painting step of performing painting work of the unpainted region while moving the spray nozzle relative to the object using the head slide unit with the robot arm stopped.
However, for example, in a case where printing is performed on a curved surface using an inkjet head, when the inkjet head is moved relative to a printed surface using the slide unit, there is a problem that the separation distance between the printed surface and the inkjet head changes during the movement, and printing unevenness is caused within the printing region and an outcome of printing work is poor. This is more noticeable as the curvature of the printed region is larger.
A control method for a robot system according to an aspect of the present disclosure is a control method for a robot system including a moving stage, a tool attached to the moving stage, and a robot arm holding one of the moving stage and an object and performing predetermined work on the object using the tool, including performing the work while moving the tool relative to the object by the moving stage with the robot arm stopped, wherein a portion having a larger curvature has a smaller range of the work than a portion having a smaller curvature of the object.
A robot system according to an aspect of the present disclosure is a robot system including a moving stage, a tool attached to the moving stage, and a robot arm holding one of the moving stage and an object and performing predetermined work on the object using the tool, performing the work while moving the tool relative to the object by the moving stage with the robot arm stopped, wherein a portion having a larger curvature has a smaller range of the work than a portion having a smaller curvature of the object.
As below, preferred embodiments of a control method for a robot system and a robot system will be explained with reference to the accompanying drawings.
A robot system 100 shown in
The robot 200 is a six-axis robot having six drive axes. The robot 200 has a base 210 fixed to a floor, a robot arm 220 coupled to the base 210, and a tool 400 coupled to the robot arm 220 via a moving stage 300.
The robot arm 220 is a robotic arm in which a plurality of arms 221, 222, 223, 224, 225, 226 are pivotably coupled and includes six joints J1 to J6. Of the joints, the joints J2, J3, J5 are bending joints and the joints J1, J4, J6 are twisting joints. Further, motors M as drive sources and encoders E detecting rotation amounts of the motors M (pivot angles of the arms) are respectively provided in the joints J1, J2, J3, J4, J5, J6.
The tool 400 is coupled to the distal end portion of the arm 226 via the moving stage 300. That is, the moving stage 300 is held by the arm 226 and the tool 400 is attached to the moving stage 300. The tool 400 is not particularly limited, but may be appropriately set for intended work. In the embodiment, a printer head, particularly, an inkjet head 410 is used. The inkjet head 410 has an ink chamber and a vibrating plate placed on a wall surface of the ink chamber (not shown) and ink ejection holes 411 connecting to the ink chamber, and is configured so that ink within the ink chamber is ejected from the ink ejection holes 411 by vibration of the vibrating plate. Note that the configuration of the inkjet head 410 is not particularly limited. Further, the printer head is not limited to the inkjet head 410.
As shown in
Further, the movement mechanism 330 has an X movement mechanism 330X moving the X stage 320X in the directions along the X-axis relative to the base portion 310, a Y movement mechanism 330Y moving the Y stage 320Y in the directions along the Y-axis relative to the X stage 320X, and a θ movement mechanism 330θ rotating the θ stage 320θ around the Z-axis relative to the Y stage 320Y.
The X movement mechanism 330X, the Y movement mechanism 330Y, and the θ movement mechanism 330θ respectively have piezoelectric actuators 340 as drive sources. Thereby, the size and weight of the moving stage 300 may be reduced. Further, driving accuracy of the moving stage 300 is improved and the tool 400 is easily moved at a constant speed. Furthermore, direct driving may be performed without using reducers, and thereby, the size and weight may be further reduced. Note that the piezoelectric actuators 340 have configurations vibrating using expansion and contraction of piezoelectric elements, and the vibration is transmitted to the respective stages 320X, 320Y, 320θ to move the respective stages 320X, 320Y, 320θ. The drive sources are not particularly limited, but e.g. electromagnetic motors may be used.
The robot control apparatus 900 controls driving of the joints J1 to J6, the moving state 300, and the inkjet head 410 to control the robot 200 to perform predetermined work. The robot control apparatus 900 includes e.g. a computer having a processor (CPU) processing information, a memory communicably connected to the processor, and an external interface. Various programs that can be executed by the processor are stored in the memory, and the processor may read and execute the various programs etc. stored in the memory.
As above, the configuration of the robot system 100 is explained. The robot control apparatus 900 controls the respective units of the system, and thereby, for example, as shown in
As shown in
At the shape calculation step S1, the shape of the object Q, specifically, the shape of the printing face Q1 is calculated. In the embodiment, CAD data as 3D data of the object Q is acquired in advance and the shape of the printing face Q1 is calculated based on the CAD data. According to the method, the shape of the printing face Q1 may be calculated more simply and accurately.
Note that the method of calculating the shape of the printing face Q1 is not particularly limited. For example, a 3D camera or a plurality of 2D cameras may be added to the robot system 100, and the shape of the printing face Q1 may be calculated based on imaging data of the object Q acquired by the added camera. According to the method, the shape of the printing face Q1 may also be calculated more simply and accurately. In addition, the method includes a method of calculating the shape of the printing face Q1 using a depth sensor and a method of calculating the shape of the printing face Q1 by the phase shift method using a projector projecting a striped light pattern on the printing face Q1 and a camera imaging the printing face Q1 on which the light pattern is radiated.
At the region setting step S2, the printing face Q1 is divided into a plurality of regions R based on the shape of the printing face Q1 calculated at the shape calculation step S1. The portions having larger curvatures of the printing face Q1 are divided into the regions R having smaller areas. For example, in the example shown in
In the embodiment, as the curvature is larger, the area of the region R is continuously made smaller, however, the method of determining the area of the region R is not particularly limited. For example, the area of the region R may be made smaller in stages in such a manner that, when A1<curvature≤A2, the area of the region R is set to C1, when A2<curvature≤A3, the area of the region R is set to C2 (<C1), and, when A3<curvature≤A4, the area of the region R is set to C3 (<C2).
At the printing order determination step S3, the printing order of the four regions R1, R2, R3, R4 at the printing step S4 is determined. In the embodiment, the regions R1, R2, R3, R4 are sequentially printed in the order of the arrangement. Thereby, unnecessary motion of the robot 200 during the printing work is reduced and the printing step S4 may be efficiently performed. Accordingly, the takt time becomes shorter and the productivity is improved. Note that the printing order is not particularly limited to the order of arrangement, but may be e.g. the descending order of curvature, the ascending order of curvature, or the like.
Further, at the printing order determination step S3, activation conditions of the robot 200 in the respective regions R1, R2, R3, R4 are determined. The activation conditions are not particularly limited to, but include e.g. the attitudes of the robot arm 220 in the respective regions R1, R2, R3, R4, accelerations, decelerations, and maximum velocities of the inkjet head 410, and output conditions of ink ejection amounts, ink ejection intervals, etc. of the inkjet head 410.
At the printing step S4, printing is performed with respect to each of the regions R1, R2, R3, R4 according to the order determined at the printing order determination step S3 using the inkjet head 410. Specifically, the printing step S4 includes a unit printing step S401 of printing in the region R1, a unit printing step S402 of printing in the region R2, a unit printing step S403 of printing in the region R3, and a unit printing step S404 of printing in the region R4.
As described above, the respective unit printing steps S401 to S404 include the moving steps S41 of driving the robot arm 220 to set the inkjet head 410 to face the regions R1, R2, R3, R4, and working steps S42 of performing printing in the regions R1, R2, R3, R4 using the inkjet head 410 while moving the inkjet head 410 relative to the printing face Q1 by the moving stage 300 with the robot arm 220 stopped.
Note that the unit printing steps S402, S403, S404 are repetition of the unit printing step S401 and, as below, only the unit printing step S401 will be explained with reference to
First, as the moving step S41, as shown in
Then, the working step S42 is performed with the robot arm 220 stopped. At the working step S42, first, as shown in
Then, as shown in
Note that, as seen from
Here, as described above, the movement start position P1 is set outside of the region R1 to end the movement with the acceleration before the inkjet head 410 enters the region R1 and shift to the movement at the constant speed. Similarly, the movement end position P2 is set outside of the region R1 to start the movement with the deceleration after the inkjet head 410 exits the region R1 and stop the head. Thereby, the inkjet head 410 may be moved at the constant speed in the entire region R1 and the above described effect may be exerted more reliably. That is, the movement start position P1 is set in a position sufficient for movement of the inkjet head 410 at the constant speed before entry in the region R1 and the movement end position P2 is set in a position sufficient for deceleration and stoppage of the inkjet head 410 after exit from the region R1.
Subsequent to the unit printing step S401, the unit printing steps S402, S403, S404 are performed in the same manner, and thereby, printing on the entire printing face Q1 ends. As shown in
Next, effects of the printing method will be explained with reference to
Accordingly, in the embodiment, as shown in
Particularly, the respective regions R1, R2, R3, R4 are set so that the minimum separation distances Dmin, the maximum separation distances Dmax, and the distance differences ΔD may be nearly equal to one another, and thereby, the printing on the printing face Q1 may be uniformly and accurately performed. Note that the minimum separation distances Dmin, the maximum separation distances Dmax, and the distance differences ΔD are respectively not particularly limited, but may be appropriately set depending on the characteristics of the inkjet head 410, the movement speed of the inkjet head 410, or the like.
As above, the robot system 100 of the embodiment is explained. As described above, the control method for the robot system 100 is a control method for the robot system 100 including the moving stage 300, the tool 400 attached to the moving stage 300, and the robot arm 220 holding one of the moving stage 300 and the object Q and performing predetermined work on the object Q using the tool 400, including performing work while moving the tool 400 relative to the object Q by the moving stage 300 with the robot arm 220 stopped, wherein the portion having the larger curvature has the smaller work range, i.e. the smaller region R than the portion having the smaller curvature of the object Q. Thereby, relative movement of the tool 400 and the object Q may be accurately performed and the separation distance between the tool 400 and the object Q may be harder to be varied, and work on the object Q may be uniformly and accurately performed.
As described above, the robot arm 220 holds the moving stage 300. Thereby, work on the object Q is easily performed. Further, as described above, the moving stage 300 holds the tool 400. Thereby, work on the object Q is easily performed.
As described above, in the control method for the robot system 100, the moving stage 300 has the piezoelectric actuators 340 as the drive sources. Thereby, the size and weight of the moving stage 300 may be reduced. Further, driving accuracy of the moving stage 300 is improved and the tool 400 is easily moved at a constant speed.
As described above, in the control method for the robot system 100, the tool 400 is the inkjet head 410 as the printer head. Thereby, printing work on the object Q may be performed. Accordingly, the highly convenient robot system 100 is obtained.
As described above, in the control method for the robot system 100, the shape of the object Q is calculated based on the CAD data of the object Q.
As described above, in the control method for the robot system 100, the shape of the object Q may be calculated based on imaging data obtained by imaging of the object Q. Thereby, the shape of the object Q may be calculated more simply and accurately.
As described above, in the control method for the robot system 100, work is not performed while the tool 400 is accelerated or decelerated by driving of the moving stage 300. Thereby, driving control of the tool is easier and work accuracy is improved.
As described above, in the control method for the robot system 100, the movement start position P1 of the tool 400 during work is located outside of the region R1 outside of the work range. Thereby, the movement with the acceleration may be ended before the inkjet head 410 enters the region R1 and shifted to the movement at the constant speed. Accordingly, the accuracy of the work on the region R1 is improved.
As described above, the robot system 100 is the robot system 100 including the moving stage 300, the tool 400 attached to the moving stage 300, and the robot arm 220 holding one of the moving stage 300 and the object Q and performing predetermined work on the object Q using the tool 400, performing work while moving the tool 400 relative to the object Q by the moving stage 300 with the robot arm 220 stopped, wherein the portion having the larger curvature has the smaller work range, i.e. the smaller region R than the portion having the smaller curvature of the object Q. Thereby, the separation distance between the tool 400 and the object Q may be harder to be varied, and work on the object Q may be uniformly and accurately performed.
As above, the robot system 100 is explained, however, the robot system 100 is not particularly limited. For example, in the embodiment, the arrow N as the movement direction of the inkjet head 410 at the printing step S4 is along the arrangement direction of the regions R1, R2, R3, R4, however, for example, as shown in
A robot system 100 of the embodiment is the same as the robot system 100 of the above described first embodiment except that the printing step S4 is different. Accordingly, in the following description, the embodiment will be explained with a focus on the differences from the above described first embodiment and the explanation of the same items will be omitted. Further, in the respective drawings in the embodiment, the same configurations as those of the above described embodiment have the same signs.
First, like the above described first embodiment, as the moving step S41, the robot arm 220 is driven to set the inkjet head 410 to face the region R1. Then, the working step S42 is performed with the robot arm 220 stopped. At the working step S42, first, as shown in
Then, as shown in
According to the method, for example, in comparison to the above described first embodiment, the movement distance of the inkjet head 410 when printing in the region R1 is performed, i.e., the separation distance between the movement start position P1 and the movement end position P2 may be shortened. Accordingly, the time taken for the printing step S4 may be made shorter.
Note that, as shown in
As above, the unit printing step S401 is explained, and the unit printing steps S402, S403, S404 are the same. Note that, when the movement speeds of the movement at the constant speeds of the inkjet head 410 at the unit printing steps S401, S402, S403, S404 are V1, V2, V3, V4, respectively, V1>V2>V3>V4. That is, the movement speed of the movement at the constant speed of the inkjet head 410 is lower as the region R has the larger curvature.
The reason for this is explained by comparison between the regions R1, R4 in an understandable manner. As shown in
Accordingly, in the embodiment, as shown in
Note that, if the movement speeds of the movement at the constant speed of the inkjet head 410 are uniformly set to be lower in all regions R1, R2, R3, R4, the constant-speed movement regions G0 may be secured to be larger in the respective regions R1, R2, R3, R4, however, the time taken for the printing step S4 is longer and the productivity is lower. Accordingly, in the embodiment, as described above, the movement speed of the movement at the constant speed of the inkjet head 410 is set to be lower as the region R has the larger curvature, and thereby, work efficiency and work accuracy are balanced.
As described above, in the control method for the robot system 100 of the embodiment, the movement speed of the tool 400 is lower in the portion having the larger curvature than in the portion having the smaller curvature of the object Q. Thereby, efficiency and accuracy of work may be balanced.
According to the second embodiment, the same effects as those of the above described first embodiment may be exerted.
A robot system 100 of the embodiment is the same as the robot system 100 of the above described first embodiment except that the placement of the moving stage 300 and the tool 400 is different. Accordingly, in the following description, the embodiment will be explained with a focus on the differences from the above described first embodiment and the explanation of the same items will be omitted. Further, in the respective drawings in the embodiment, the same configurations as those of the above described embodiment have the same signs.
As shown in
According to the third embodiment, the same effects as those of the above described first embodiment may be exerted. Note that, in addition, for example, the hand 600 may be coupled to the arm 226 via the moving stage 300 and the inkjet head 410 may be fixed to the fixing member 700 apart from the robot arm 220. Further, the inkjet head 410 may be coupled to the arm 226 and the hand 600 may be coupled to the fixing member 700 via the moving stage 300 apart from the robot arm 220.
As above, the control method for the robot system and the robot system according to the present disclosure are explained based on the illustrated embodiments, however, the present disclosure is not limited to those. The configurations of the respective parts may be replaced by arbitrary configurations having the same functions. Further, any other configuration may be added to the present disclosure. Furthermore, the respective embodiments may be appropriately combined.
Moreover, the tool 400 is not limited to the inkjet head 410, but includes a tool for laser processing, a tool for soldering work, a tool for welding, and a tool for work performed in synchronization with a movement trajectory of a tool.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-125117 | Jul 2021 | JP | national |
