JP2023051620A - Tracking system control method and tracking system - Google Patents

Abstract

A control method for a tracking system and a tracking system capable of easily and accurately following a workpiece that moves relatively. A control method for a tracking system having a robot that performs work while following a relatively moving workpiece, wherein the robot is generated with a relative speed of 0 (zero) between the robot and the workpiece. A work locus for the work is corrected based on the relative speed. Also, in the control method of the tracking system, the workpiece is transported by the transport device. [Selection drawing] Fig. 1

Description

The present invention relates to a tracking system control method and a tracking system.

Patent Document 1 describes a conveyor that conveys a workpiece, a visual sensor that detects the position of the workpiece by imaging the workpiece on the conveyor, and a pickup that picks up the workpiece conveyed on the conveyor based on the detection result of the visual sensor. A tracking system having a robot is described.

JP 2019-141935 A

However, in the tracking system of Patent Document 1, the robot only picks up the work conveyed on the conveyor at a predetermined position, and follows the work conveyed on the conveyor, that is, while moving with the work. It is not assumed to perform the work of drawing a trajectory on the work.

A control method for a tracking system according to the present invention is a control method for a tracking system having a robot that performs work while following a relatively moving workpiece,
A work trajectory of the robot with respect to the workpiece generated by setting the relative velocity between the robot and the workpiece to 0 (zero) is corrected based on the relative velocity.

The tracking system of the present invention includes a robot that performs work while following a relatively moving work,
and a control device that corrects, based on the relative speed, a work trajectory of the robot with respect to the work that is generated by setting the relative speed between the robot and the work to 0 (zero).

1 is an overall configuration diagram showing a tracking system of a first embodiment; FIG. FIG. 10 is a diagram showing a robot; It is a figure which shows an example of a work locus. 4 is a flow chart for explaining a control method of the tracking system; FIG. 10 is a diagram showing a secondary correction work trajectory; FIG. 10 is a diagram showing a method of calculating a secondary correction work locus; FIG. 10 is a diagram for explaining a change in the starting point of the work locus; FIG. 11 is an overall configuration diagram showing a tracking system according to a second embodiment; FIG.

Preferred embodiments of a tracking system control method and a tracking system will be described below with reference to the accompanying drawings. In the following description, directions orthogonal to each other are defined as the X-axis, the Y-axis, and the Z-axis, and the Z-axis is along the vertical direction. The direction along the X-axis is also called "X-axis direction", the direction along the Y-axis is also called "Y-axis direction", and the direction along the Z-axis is also called "Z-axis direction".

<First embodiment>
FIG. 1 is an overall configuration diagram showing the tracking system of the first embodiment. FIG. 2 is a diagram showing a robot. FIG. 3 is a diagram showing an example of a work trajectory. FIG. 4 is a flow chart for explaining the control method of the tracking system. FIG. 5 is a diagram showing a secondary correction work trajectory. FIG. 6 is a diagram showing a method of calculating the secondary corrected work trajectory. FIG. 7 is a diagram for explaining how the starting point of the work locus is changed.

The tracking system 100 shown in FIG. 1 has a robot 200 , an imaging device 300 , a control device 400 and a transport device 600 . In the tracking system 100, the conveying device 600 conveys the work W along the conveying direction A along the horizontal direction, the control device 400 detects the conveying state of the work W based on the image G acquired by the imaging device 300, The robot 200 works while following the work W being transported based on the transport status of the work W.

The work W and the work performed on the work W are not particularly limited, but in the present embodiment, the work W is an outsole, and the work W is performed on the work W. This is the work of applying the adhesive B for adhering the upper. In other words, the tracking system 100 of this embodiment functions as part of the shoe manufacturing apparatus. The tracking system 100 can be effectively used by setting the work W and the work as described above.

≪Robot 200≫
As shown in FIG. 2, the robot 200 is a SCARA robot (horizontal articulated robot). The robot 200 has a base 210 fixed to the floor and a robot arm 220 connected to the base 210 . The robot arm 220 has a base end connected to the base 210, a first arm 221 that rotates about a first rotation axis J1 along the vertical direction with respect to the base 210, and a base end of the first arm 221. and a second arm 222 that is connected to the distal end of the first arm 221 and rotates about a second rotation axis J2 along the vertical direction with respect to the first arm 221 .

A working head 230 is provided at the tip of the second arm 222 . The working head 230 has a spline nut 231 and a ball screw nut 232 coaxially arranged at the tip of the second arm 222 and a spline shaft 233 inserted through the spline nut 231 and the ball screw nut 232 . The spline shaft 233 is rotatable about a third rotation axis J3 extending in the vertical direction with respect to the second arm 222, and is capable of moving up and down along the third rotation axis J3.

An end effector 240 is attached to the lower end of the spline shaft 233 . The end effector 240 is detachable and appropriately selected for the intended work. The end effector 240 of this embodiment is a dispenser that ejects the adhesive B from its lower end.

The robot 200 also includes a first driving device 271 that rotates the first arm 221 about the first rotation axis J1 with respect to the base 210, and a second arm 222 that rotates the second arm 222 with respect to the first arm 221. A second driving device 272 that rotates about the axis J2, a third driving device 273 that rotates the spline nut 231 to rotate the spline shaft 233 about the third rotation axis J3, and a ball screw nut 232 that rotates the spline. and a fourth driving device 274 that moves the shaft 233 up and down in the direction along the third rotation axis J3.

Also, the first, second, third and fourth drive devices 271, 272, 273 and 274 are provided with motors as drive sources and encoders for detecting the amount of rotation of the motors, respectively. During operation of the tracking system 100, the control device 400 performs feedback control to match the position of the robot arm 220 indicated by the output of each encoder with the target position, which is the control target. Thereby, the robot 200 can be caused to perform a predetermined work.

Although the robot 200 has been described above, the robot 200 is not particularly limited, and may be, for example, a six-axis robot having a robot arm having six rotation axes.

<<Conveyor 600>>
The transport device 600 is a belt conveyor, and as shown in FIG. and a conveying amount sensor 640 that outputs a signal to the control device 400 . The transport amount sensor 640 is, for example, an encoder. During operation of the tracking system 100, the control device 400 performs feedback control to match the transport speed of the workpiece W indicated by the output of the transport sensor 640 with the target transport speed, which is the control target. Thereby, the workpiece W can be stably conveyed at a desired speed.

<<Imaging device 300>>
The imaging device 300 is a camera that captures an image of the workpiece W from above the conveying device 600 and outputs the captured image G to the control device 400 . The imaging area Ec of the imaging device 300 is positioned upstream in the transport direction A from the work area Er of the robot 200 . The imaging device 300 has an angle of view including the work W conveyed on the belt 620, as indicated by the dashed line in FIG. A position in the image G output from the imaging device 300 is associated with a position in the transport path by the control device 400 . Therefore, when the work W exists within the angle of view of the imaging device 300, the control device 400 can specify the coordinates (position) of the work W based on the position of the work W in the image G. The control device 400 can also specify the posture of the work W by template matching that compares a number of pre-stored templates with the contour shape of the work W in the image G, for example. However, the method of identifying the position and orientation of the work W is not particularly limited.

<<control device 400>>
As shown in FIG. 1, the control device 400 controls driving of the robot 200, the imaging device 300, and the transport device 600, respectively. Such a control device 400 is composed of, for example, a computer, and has a processor (CPU) for processing information, a memory communicably connected to the processor, and an external interface for connection with an external device. Various programs executable by the processor are stored in the memory, and the processor can read and execute various programs stored in the memory. A part or all of the components of the control device 400 may be arranged inside the housing of the robot 200 . Also, the control device 400 may be configured by a plurality of processors.

The overall configuration of the tracking system 100 has been briefly described above. Next, a method of controlling the tracking system 100 will be described based on the flowchart shown in FIG. As shown in FIG. 4, the control method of the tracking system 100 includes a necessary information acquisition step S1, an image acquisition step S2, a trajectory correction step S3, and an operation step S4.

<<Required Information Acquisition Step S1>>
The necessary information acquisition step S1 is performed before starting the work of applying the adhesive to the work W, and for example, acquires various information necessary for the work from a host computer (not shown). Various types of information are not particularly limited, but for example, CAD data of the work W required for template matching for detecting the posture of the work W on the transport device 600, movement of the robot 200 when applying the adhesive B, In particular, the work trajectory M and the like that define the movement of the end effector 240 are included.

The work trajectory M is generated assuming that both the robot 200 and the work W are stationary, that is, their relative speeds are 0 (zero). The work trajectory M of the present embodiment is a trajectory along which the end effector 240 goes around the outer edge of the work W, as shown in FIG. The work trajectory M includes a plurality of work points P1, P2, P3, and P4 arranged along the outer edge of the work W arranged in a predetermined posture and position (hereinafter also referred to as "reference position/posture Q0"). , P5, P6, P7, P8, P9, P10, and P11, and the adjacent work points are connected by straight lines. Therefore, the work trajectory M becomes relatively simple, the yield of the adhesive applying work is improved, and the life of the robot 200 can be extended. In the work trajectory M, the work points P1 and P11 have the same coordinates, the work point P1 is the start point for starting work, and the work point P11 is the end point for finishing work.

The positions of the work points P1 to P11 can be determined based on the robot coordinate system set in the robot 200, for example. The robot coordinates of each of the work points P1 to P11 are three-dimensional coordinates (xn, yn, zn). contains. The work trajectory M is generated so that the separation distance between the work W and the end effector 240 is equal at each of the work points P1 to P11. As a result, the application amount of the adhesive B becomes uniform over the entire working locus M, and high-precision work becomes possible.

<<Image Acquisition Step S2>>
When the conveying device 600 is driven at a constant speed and the conveying of the work W by the conveying device 600 is started, the control device 400 causes the image pickup device 300 to move the work W to a predetermined frame while the work W passes through the imaging area Ec. A plurality of images G in which the work W is photographed are obtained by continuously imaging at a rate. Next, the control device 400 obtains the coordinates of the work W at each time from each acquired image G, and detects the conveying speed Vw of the work W based on the obtained coordinates. According to such a method, the conveying speed Vw can be detected easily and accurately. Here, as described above, the robot 200 is fixed to the floor or the like, so the transfer speed Vw corresponds to the relative speed between the robot 200 and the workpiece W. FIG.

When a large number of works W are continuously transported by the transport device 600, the transport speed Vw may or may not be detected for all the works W. FIG. Since the conveying device 600 is driven at a constant speed, it is also possible to detect only the first conveying speed Vw of the work W and use the detected conveying speed Vw as the conveying speed Vw of the subsequent work W. Also, the conveying speed Vw can be updated at predetermined time intervals and at predetermined workpiece number intervals. Further, the method of detecting the transport speed Vw is not particularly limited, and for example, the transport speed Vw can be detected based on a signal output from the transport amount sensor 640 provided in the transport device 600 . Also by such a method, the conveying speed Vw can be detected easily and accurately.

In addition, the control device 400 uses at least one image G to detect the posture of the work W by template matching that compares the contour of the work W shown in the image G with the previously stored CAD data. As a result, information on the position and orientation of the workpiece W (hereinafter also referred to as "position and orientation") is obtained.

<<Trajectory Correction Step S3>>
In the trajectory correction step S3, the control device 400 first corrects the work trajectory M based on the position and orientation of the work W obtained in the image acquisition step S2 (hereinafter also referred to as "actual position and orientation Q1"). That is, the control device 400 detects the deviation between the reference position/posture Q0 and the actual position/posture Q1, and corrects the work trajectory M based on the detected deviation. This corrected work trajectory M is hereinafter referred to as a primary corrected work trajectory M1.

Next, the control device 400 corrects the primary correction work locus M1 based on the conveying speed Vw of the work W obtained in the image acquisition step S2. As described above, the primary corrected work trajectory M1 is generated assuming that both the robot 200 and the work W are stationary. The adhesive B cannot be applied along the outer edge of the workpiece W even if the robot 200 is driven along M1. In other words, the adhesive application work cannot be performed properly. Therefore, the primary corrected work trajectory M1 is corrected based on the transfer speed Vw, that is, the relative speed between the work W and the robot 200 so that the adhesive application work can be performed appropriately even for the work W being transferred. There is a need to. This corrected primary corrected work locus M1 is hereinafter referred to as a secondary corrected work locus M2.

As shown in FIG. 5, the work point P1 (hereinafter also referred to as "work point P1'") on the secondary correction work locus M2 has the same coordinates as the work point P1 on the primary correction work locus M1. On the other hand, the work point P2 of the secondary correction work locus M2 (hereinafter referred to as "work point P2'") is the work point P2 of the primary correction work locus M1, from the work point P1 to the work point P2. The movement time of the robot 200 is shifted to the downstream side in the conveying direction A. Therefore, the straight line connecting the working point P1' and the working point P2' becomes the locus after correction.

Here, an example of a method of calculating the coordinates of the working point P2' is shown. As shown in FIG. 6, the separation distance between the work point P1 and the work point P2 in the X-axis direction (conveyance direction A) is Lx, the separation distance in the Y-axis direction is Ly, and the distance from the work point P1 to the work point P2 is Lx. Assuming that the movement time of the robot 200 is t, and the length of the straight line (correction trajectory) connecting the work point P1' and the work point P2' is L, the relationship is given by the following formula (1).

Also, if the robot 200 performs an ideal motion, the length L can be expressed using the movement time t as shown in the following equation (2). In equation (2), Vrb is the constant velocity of the robot 200, a+ is the acceleration of the robot 200 during acceleration, and a- is the acceleration of the robot 200 during deceleration.

By setting the following equation (3) from the above equations (1) and (2), the travel time t can be obtained, and the work point P2' can be calculated based on the obtained travel time t.

The method for calculating the working point P2' has been described above, and the remaining working points P3 to P11 are similarly corrected. In other words, the work point P3 of the secondary corrected work locus M2 (hereinafter also referred to as "work point P3'") corresponds to the work point P3 of the primary corrected work locus M1. is shifted to the downstream side in the conveying direction A for the movement time of . Therefore, the straight line connecting the working point P2' and the working point P3' becomes the trajectory after correction. The work point P4 of the secondary correction work locus M2 (hereinafter also referred to as "work point P4'") is the movement of the robot 200 from the work point P1 to the work point P4 with respect to the work point P4 of the primary correction work locus M1. It shifts to the downstream side in the conveying direction A by the amount of time. Therefore, the straight line connecting the working point P3' and the working point P4' becomes the trajectory after correction. The same is true for the working point P5' and beyond.

In the trajectory correction step S3 described above, the work trajectory M is corrected to generate the primary corrected work trajectory M1, and the primary corrected work trajectory M1 is further corrected to generate the secondary corrected work trajectory M2. Instead, the primary correction and the secondary correction may be performed simultaneously to directly generate the secondary corrected work trajectory M2 from the work trajectory M.

After generating the secondary correction work trajectory M2 in this way, the control device 400 determines whether the work point P11′, which is the end point of the secondary correction work trajectory M2, is located within the work area Er of the robot 200. . If the work point P11' is located outside the work area Er, the robot 200 cannot complete the adhesive application work. Therefore, the control device 400 notifies the user to that effect, and slows down the conveying speed Vw so that the work point P11' is included in the work area Er. Alternatively, the user is urged to slow down the transport speed Vw. As a result, the adhesive application work can be reliably completed within the work area Er.

<<Work step S4>>
In the work step S4, the robot 200 is driven based on the secondary corrected work trajectory M2 obtained in the trajectory correction step S3, and the adhesive B is ejected from the end effector 240 to follow the work W. Do the coating work. As a result, the adhesive B is applied along the outer edge of the work W, and the expected work is completed with high accuracy.

The control device 400 sequentially performs steps S1 to S4 as described above for a plurality of works W that are continuously conveyed. Here, it is conceivable that the position and orientation of the work Wn+1 to be transported n+1th may be different from that of the work Wn to be transported nth. In such a case, the start point of the secondary correction work locus M2 for the workpiece Wn+1 can be changed from the work point P1.

The robot 200 needs to move to the starting point of the work Wn+1 after finishing the work of applying the adhesive to the work Wn. Therefore, in such a case, the separation distance between the work point P11′ that is the end point of the work Wn and the work point P1′ that is the start point of the work Wn+1 (=the work point P1 of the primary correction work locus M1) is large. As a result, there is a possibility that the work start time for the work Wn+1 will be delayed, making it difficult to complete the adhesive application work within the work area Er.

Therefore, when the position and orientation of the work Wn+1 are different from those of the work Wn, the control device 400 selects the work point P11′ of the work Wn among the work points P1 to P11 of the primary correction work trajectory M1 of the work Wn+1. is smaller than the separation distance between the work point P11′ of the work Wn and the work point P1 of the work Wn+1, more preferably the work point with the smallest distance between the work point P11′ of the work Wn and the work point P11′ of the work Wn+1. can be detected and its working point can be set as the starting point of work Wn+1. In the configuration shown in FIG. 7, the work point P5 can be set as the starting point of the work Wn+1. According to this control method, the time from the completion of the work on the work Wn to the start of the work on the work Wn+1 is shortened, and the delay in the work start time on the work Wn+1 can be effectively suppressed. can be done.

The tracking system 100 and its control method have been described above. Such a control method of the tracking system 100 is a control method of the tracking system 100 having the robot 200 that performs the work while following the relatively moving work W, as described above. , that is, the work trajectory M for the work W of the robot 200 generated with the relative speed Vw of the work as 0 (zero) is corrected based on the transfer speed Vw. According to such a control method, it is possible to perform desired work even on the workpiece W that is relatively moving.

Further, as described above, in the control method of the tracking system 100, the workpiece W is transported by the transport device 600. FIG. This results in a tracking system 100 with a simpler configuration.

Further, as described above, in the control method of the tracking system 100, an image G including the work W is captured upstream of the work area Er of the robot 200 in the transport direction A of the work W, and based on the image G, the relative velocity, i.e., A conveying speed Vw of the work W is detected. As a result, the conveying speed Vw can be detected with high accuracy.

Further, as described above, in the control method of the tracking system 100, the position and orientation of the workpiece W are detected based on the image G. FIG. As a result, the work on the workpiece W can be performed more reliably.

Further, as described above, in the control method of the tracking system 100, the starting point of the work trajectory M is changed according to the attitude of the work W. FIG. As a result, the time from the completion of the work on the work Wn to the start of the work on the work Wn+1 can be shortened, and the delay in the work start time on the work Wn+1 can be effectively suppressed.

Further, as described above, in the control method of the tracking system 100, the conveying speed Vw of the workpiece W can also be detected based on the signal from the conveying amount sensor 640 provided in the conveying device 600. FIG. As a result, the conveying speed Vw can be detected with high accuracy.

Moreover, as described above, the work is to apply the adhesive to the work W. FIG. Thereby, the control method of the tracking system 100 can be effectively used.

Moreover, as described above, the work W is the sole of the shoe. Thereby, the control method of the tracking system 100 can be effectively used.

Further, as described above, the work trajectory M includes height information perpendicular to the conveying direction A of the work W, that is, the z-axis coordinate. As a result, it is possible to work on a three-dimensional object such as the work W with high accuracy.

Further, as described above, the work trajectory M is composed of continuous straight lines. As a result, the work trajectory M becomes relatively simple, so that the work yield can be improved and the life of the robot 200 can be extended.

Further, as described above, the tracking system 100 includes the robot 200 that performs the work while following the relatively moving work W, and the robot 200 that is generated with the relative speed, that is, the transport speed Vw of the work W as 0 (zero). and a control device 400 that corrects the work trajectory M for the workpiece W based on the conveying speed Vw. According to such a configuration, it is possible to perform desired work even on the workpiece W that moves relatively.

Further, the tracking system 100 has the transport device 600 that transports the work W, as described above. This results in a tracking system 100 with a simpler configuration.

<Second embodiment>
FIG. 8 is an overall configuration diagram showing the tracking system of the second embodiment.

The tracking system 100 of this embodiment is the same as the tracking system 100 of the first embodiment described above, except that the robot 200 works on a stationary workpiece W while moving. Therefore, in the following description, regarding this embodiment, the differences from the first embodiment described above will be mainly described, and the description of the same matters will be omitted. Moreover, in each figure in this embodiment, the same code|symbol is attached|subjected about the structure similar to embodiment mentioned above.

As shown in FIG. 8, in the tracking system 100 of this embodiment, the conveying device 600 is omitted, and each work W is mounted on a mounting table 500 and is stationary. On the other hand, the robot 200 has a movement mechanism 290, and while the robot 200 is moving, it continuously follows up each workpiece W on the mounting table 500. As shown in FIG. In other words, in this embodiment, the relative speed between the robot 200 and the workpiece W means the moving speed of the robot 200 .

Although the robot 200 having the moving mechanism 290 is not particularly limited, for example, an automatic guided vehicle (AGV), an autonomous mobile guided robot (AMR), or the like can be used. Alternatively, for example, a robot that can move on a guide rail may be used.

According to the second embodiment as described above, the same effects as those of the above-described first embodiment can be exhibited.

Although the control method of the tracking system and the tracking system of the present invention have been described above based on the illustrated embodiments, the present invention is not limited to this, and the configuration of each part can be any one having similar functions. It can be replaced with a configuration. Also, other optional components may be added to the present invention. Further, each embodiment may be combined as appropriate.

DESCRIPTION OF SYMBOLS 100... Tracking system, 200... Robot, 210... Base, 220... Robot arm, 221... First arm, 222... Second arm, 230... Working head, 231... Spline nut, 232... Ball screw nut, 233... Spline shaft, 240 end effector 271 first driving device 272 second driving device 273 third driving device 274 fourth driving device 290 moving mechanism 300 imaging device 400 control device 500 Mounting table 600 Conveying device 620 Belt 630 Conveying roller 640 Conveying amount sensor A Conveying direction B Adhesive Ec Imaging area Er Work area G Image J1 th 1 rotation axis, J2... 2nd rotation axis, J3... 3rd rotation axis, L... length, Lx... separation distance, Ly... separation distance, M... work locus, M1... primary correction work locus, M2... Secondary correction work locus P1 Work point P1′ Work point P2 Work point P2′ Work point P3 Work point P4 Work point P5 Work point P6 Work point P7 Work point P8 Work point P9 Work point P10 Work point P11 Work point P11′ Work point S1 Required information acquisition step S2 Image acquisition step S3 Trajectory correction step S4 work step, t... movement time, W... work, Wn... work, Wn+1... work

Claims (13)

A control method for a tracking system having a robot that performs work while following a relatively moving workpiece,
A control method for a tracking system, comprising: correcting a work trajectory of said robot with respect to said workpiece generated by setting a relative velocity between said robot and said workpiece to 0 (zero), based on said relative velocity. 2. The method of controlling a tracking system according to claim 1, wherein the workpiece is transported by a transport device. 3. The method of controlling a tracking system according to claim 2, wherein an image including the work is taken upstream of the work area of the robot in the conveying direction of the work, and the relative velocity is detected based on the image. 4. A control method for a tracking system according to claim 3, wherein the position and orientation of said workpiece are detected based on said image. 5. A control method for a tracking system according to claim 4, wherein the starting point of said work locus is changed according to the attitude of said work. 3. The method of controlling a tracking system according to claim 2, wherein the relative speed is detected based on a signal from a conveying amount sensor provided in the conveying device. 7. The method of controlling a tracking system according to claim 1, wherein said work is applying an adhesive to said workpiece. 8. The method of controlling a tracking system according to claim 7, wherein the work is a shoe sole. 9. The method of controlling a tracking system according to claim 1, wherein the work trajectory includes height information orthogonal to the conveying direction of the work. 10. The method of controlling a tracking system according to any one of claims 1 to 9, wherein the work trajectory is composed of continuous straight lines. A robot that works while following a relatively moving workpiece,
and a control device that corrects a work trajectory of the robot with respect to the workpiece, which is generated by setting the relative velocity between the robot and the workpiece to 0 (zero), based on the relative velocity. 12. The tracking system according to claim 11, further comprising a transport device for transporting the work. 12. The tracking system according to claim 11, wherein said robot has a moving mechanism.

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