JP5541020B2 - Robot evaluation control method and robot control apparatus - Google Patents

Description

  The present invention relates to a method for evaluating the danger and safety of a motion region space in which an articulated robot operates, and a control device for performing the same evaluation.

  For an articulated robot, it is important to confirm how the motion position and motion trajectory change because it is necessary to ensure safety during operation. Therefore, not only offline teaching, but teaching is performed using the robot at the site where the robot is installed. Therefore, an operation of moving the position of the hand of the robot in various ways is frequently performed during teaching on site.

  Here, as the number of robot axes increases, it becomes more difficult to predict how the posture will change when the robot's hand position is changed. The risk of collision with In particular, when the position of the hand is advanced (advanced) in a certain direction and then the position is returned (returned) in the opposite direction, the robot is likely to take a posture different from the posture that appears in the advancement.

  However, since the user (operator) has already seen the posture in the case of advance, it is easy to assume that the movement is simply the opposite in the case of return, and it becomes late to notice the change in posture. In the first place, the “return” as described above is performed at the stage where teaching of the position and the motion trajectory is performed by trial and error, so that attention is likely to be reduced, and it is fully conceivable that the robot collides with the equipment.

  For example, Patent Document 1 reads the shape data of a robot or a peripheral object from CAD or the like, displays the layout, sets the cage area, calculates the 3D position of each arm at the initial position, and obtains the initial occupied area. Execute the motion simulation, calculate the 3D position repeatedly, find the set sum of the occupied areas, and when the robot finishes moving, display the total occupied area, overlapping area, protruding area, non-occupied area, etc. in different colors A technique for correcting an object layout, changing a cage region, or the like is disclosed.

JP 2005-81445 A

  However, the technique of Patent Document 1 is a so-called 3D simulation, in which the operation of the robot is determined before entering the field, and sufficient information is provided to make the arrangement of peripheral equipment 3D. It is assumed that. Therefore, it cannot be applied when teaching is performed on-site as described above, or when information regarding the arrangement of peripheral facilities is not sufficiently provided.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an evaluation control method for assisting a user to avoid a collision between a robot and equipment when teaching is performed at a site where the robot is installed, and The object is to provide a robot control device.

  According to the robot evaluation control method according to claim 1, a motion region space in which an articulated robot operates is regarded as a set of cubic unit spaces, and a three-dimensional coordinate value defining an outer surface of each unit space is determined. Then, a box area that covers the hand portion of the robot is set by a space having a size larger than the unit space. Before starting the operation of the robot, all unit space evaluations are set to “danger”, and the unit space that is entirely contained inside the box area by operating the robot Change the evaluation of the space to “safe”.

  That is, at the stage before starting the robot operation, the evaluation of all unit spaces is set to “danger” on the assumption that the arrangement state of the equipment around the robot is unknown. When the robot starts to move, the box area that covers the hand portion moves along with the movement, and as a result, there is no danger for the unit space that is entirely contained within the box area. Therefore, change the evaluation to “safe”. As a result, when the robot is moved and its hands reach various positions in the movement area space, the evaluation of the unit space gradually increases from the original “danger” to “safe”. To do. Therefore, when teaching is performed at the site where the robot is installed, it can be performed while evaluating the safety of the operation area space, so be careful when the user passes through the unit space that is evaluated as “dangerous”. By paying, it is possible to avoid collision with surrounding equipment.

  According to the robot evaluation control method of the second aspect of the present invention, the box area is set also for the joint portion of the robot, and the unit space through which the joint passes by changing the posture when the robot operates is similarly evaluated. The user can pay attention to changes in the posture of the robot.

  According to the robot evaluation control method of the third aspect, the size of the unit space is set large for the one located near the robot and set small for the one located far from the robot. In other words, when installing the robot on site, it should be installed on the premise that there are no obstacles in the vicinity, so the unit space on the near side is increased in size and the unit space on the far side is reduced in size. By doing so, it is possible to evaluate in detail the far-side space portion where the possibility of a collision is relatively high.

According to the robot evaluation control method according to claim 4, when the robot moves, when the robot passes through a unit space whose evaluation is “dangerous”, the operation speed is set to be slow, and the unit whose evaluation is “safe”. When passing through space, set the operation speed faster. In other words, in the unit space that is evaluated as “dangerous”, it is assumed that it is unclear whether or not an obstacle is actually present, so that the operation speed of the robot is slowed down and the user confirms the passing status of the area. Can afford.
On the other hand, since there is no problem in re-passing the unit space whose evaluation is “safe”, the operation speed of the robot is increased. Therefore, when the user inadvertently operates the robot and the robot passes through the unit space evaluated as “dangerous”, sufficient time can be taken to take action such as stopping the operation if the user determines that it is dangerous. Therefore, the possibility of avoiding a collision can be increased.

  6. The robot evaluation control method according to claim 5, wherein the position of the robot after a predetermined time elapses from the reference time when the robot operates, and the box from the reference time position to the predicted position after the predetermined time elapses. When the movement trajectory of the region is predicted, each unit space in which at least a part is included in the movement trajectory is sequentially evaluated. If there is a unit space that is evaluated as “dangerous”, the operation speed is set to be slow until it passes through the unit space. If all unit spaces are evaluated as “safe”, or If the evaluation of all the unit spaces after passing through the unit space where “hazard” is “safe” is set to be “safe”, the operation speed of the robot up to the predicted position is set to be high.

  Therefore, as in the fourth aspect, when the user carelessly operates the robot and the robot passes through the unit space evaluated as “dangerous”, the operation is stopped if the user determines that it is dangerous. To avoid collisions. Then, by evaluating the unit space intersecting with the box area to some extent while the robot moves from the reference time position to the predicted position after a predetermined time, the operation speed can be determined to some extent comprehensively. it can.

The flowchart which is a 1st Example and shows the evaluation process of a cube Flowchart showing the process for determining the robot's operating speed (joystick operation) Fig. 2 equivalent (in case of variable movement) The figure which shows the state which set box area | region B1, B2 in the robot main body Diagram showing a cube set in the motion area space Plan view of operating area space Diagram showing the system configuration of a vertical articulated robot Functional block diagram Plan view of the operation area space according to the second embodiment

(First embodiment)
Hereinafter, a first embodiment will be described with reference to FIGS. FIG. 7 shows the system configuration of a vertical articulated (6-axis) robot. This robot body 1 has a 6-axis arm on a base (rotation axis) 2 in this case. A shoulder 3 is rotatably connected to the base 2 via a first joint J1. The lower end portion of the lower arm 4 extending upward via the second joint J2 is rotatably connected to the shoulder portion 3, and further, the distal end portion of the lower arm 4 is connected to the second end via the third joint J3. 1 Upper arm 5 is rotatably connected.
A second upper arm 6 is rotatably connected to the tip of the first upper arm 5 via a fourth joint J4, and a wrist 7 is rotated to the tip of the second upper arm 6 via a fifth joint J5. A flange 8 is rotatably connected to the wrist 7 via a sixth joint J6. In each of the joints J1 to J6, the shoulder portion 3 to the flange 8 are rotationally driven by a servo motor 26 (see FIG. 8).

  The robot body 1 and the control device (controller, unit space setting means, space evaluation means, operation speed setting means) 11 are connected by a connection cable 12. Accordingly, the servo motor that drives each axis of the robot body 1 is controlled by the control device 11. A personal computer (personal computer) 13 is connected to the control device 11 via a cable 14 and executes high-speed communication with the personal computer 13 such as transmission of the current position of the hand of the robot body 1 and reception of operation commands. It is like that. The personal computer 13 includes a storage device (storage means) such as a memory or a hard disk.

The joystick 15 is connected to the personal computer 13 via the cable 16. The user (operator) instructs the moving direction of the hand of the robot body 1 (tip of the flange 8, TCP: Tool Center Point) by the direction in which the joystick 15 is operated and tilted. The designated direction is transmitted to the control device 11 via the personal computer 13, and the control device 11 controls the hand of the robot body 1 to move in the designated direction on the XY plane.
As shown in FIG. 8, the control device 11 includes a CPU 21, a drive circuit 22, and a position detection circuit 23. The CPU 22 is connected to a ROM 24 for storing a robot language for creating a system program and an operation program, and a RAM 25 for storing an operation program, and a personal computer 13 is connected via a communication interface (not shown). .

  The position detection circuit 23 is for detecting the position of the shoulder portion 3 to the flange 8, and is connected to a rotary encoder 27 provided in a servo motor 26 that is a driving source of each axis. The position detection circuit 23 detects the rotation angle of each axis based on the detection signal input from the rotary encoder 27 and outputs the detected position detection information to the CPU 21. Then, the CPU 21 drives the servo motor 26 of each axis using the position detection information input from the position detection circuit 23 as a feedback signal when operating the shoulder unit 3 to the flange 8 based on the operation program.

  Next, the operation of the present embodiment will be described with reference to FIGS. In the present embodiment, as shown in FIG. 5, the region in which the robot body 1 operates is set as a three-dimensional stack of cubic unit spaces (hereinafter referred to as cubes). Three-dimensional coordinate values that define six surfaces or twelve straight lines are determined. That is, it is virtualized as such on the software of the control device 11.

  On the other hand, as shown in FIG. 4, for the robot body 1, box areas B1 and B2 are set so as to cover the hand (the wrist 7; including the sixth joint J6) and the joint J3 corresponding to the elbow. (It is virtualized in software like a cube). For example, the center of the box area B1 is set at the hand, and the center of the box area B2 is ½ of the thickness of the lower arm 4 and the first upper arm 5 on the axis of the joint J3. Set to position.

In this case, the volume (size) of the box regions B1 and B2 is set larger than the volume of the cube, and is about 1000 times, for example. When the position of the hand, flange 8 or elbow; joint J3 is changed by operating the robot body 1, the positions of the box areas B1 and B2 are also changed on the software in accordance with the change of the position. Therefore, when the robot body 1 operates, the box areas B1 and B2 come into contact with or intersect with a plurality of cubes as shown in FIGS.
The control device 11 evaluates whether each cube is “dangerous” or “safe” when the robot body 1 operates. In the default state before the robot body 1 starts operation, all cubes are set to “danger”. As a result of the virtual movement of the box areas B1 and B2 by the operation of the robot body 1, a cube that is entirely contained in any of the box areas B1 and B2 is evaluated as “safe”.

  FIG. 1 is a flowchart showing the contents of the above-described evaluation process centered on the CPU 21 of the control device 11 when teaching is performed. The hand of the robot body 1 is started to move toward the target position (step S1), and is moved to the next command value (step S2). Then, at the moved position, the rotation angle of each axis is detected based on the detection signal input from the rotary encoder 27 of each axis, and the current hand and elbow positions are specified. The position in the motion area space of B2 is specified. Further, the contact state (positional relationship) between the box regions B1 and B2 and the cube is confirmed (step S3).

  That is, it is determined whether or not a cube that is partly in contact with the box areas B1 and B2 or is entirely taken into the box areas B1 and B2 has already been evaluated as “safe”. Step S4). Since all are evaluated as “dangerous” in the initial state (NO), it is subsequently determined whether or not the cubes are all contained in the box areas B1 and B2 (step S5).

For cubes determined as “YES” in step S5, the evaluation is changed to “safe” (step S6), and for cubes determined as “NO”, the evaluation is not changed and the process proceeds to step S7. Even in the case where the cube has already been evaluated as “safe” in step S4 (YES), the process proceeds to step S7. Then, it is determined whether or not S4 and S5 have been checked for all cubes in and around the box areas B1 and B2 (step S7). If not all have been checked (NO), the process proceeds to step S4. Return.
If all the cubes are checked in step S7 (YES), it is determined in subsequent step S8 whether or not the hand of the robot body 1 has reached the target position. If the target position has not been reached (NO), the process returns to step S2, and if the target position has been reached (YES), the process is terminated.

  Here, FIG. 6 is a plan view of the motion area space, and shows a case where the hand of the robot body 1 has moved from the position P1 to the position P2 (shown as the position of the box area B1 in the drawing). Here, each cube is also considered to exist two-dimensionally, and each position is indicated by a matrix display of C (1, 1) to C (11, 10). Further, the above arrangement does not match the arrangement of the cube shown in FIG.

  As the hand moves from the position P1 to the position P2, the box areas B1 and B2 also move. At that time, cubes that are all contained within the box areas B1 and B2, and for example C (2,8), C (3,4), C (6,2) indicated by cross-hatching, the cube Can be evaluated as “safe” because the robot body 1 has passed without any problem. On the other hand, when the box areas B1 and B2 move, cubes that are only partially intersected with them, for example, C (1,8), C (2,4), C (7,2), etc. indicated by hatching are safe. Since it cannot be said that the sex has been sufficiently confirmed, the evaluation remains “dangerous” and is not changed. The process shown in FIG. 1 evaluates each cube in this way.

  FIG. 2 is a flowchart showing a process of changing the moving speed of the hand of the robot body 1 in accordance with the evaluation of each cube, and corresponds to the case where the user operates the joystick 15 to indicate the moving direction. When the user tilts the joystick 15 in any direction (step S11), a movement position 8 ms (predetermined time) after the hand is moved in the direction instructed by the operation is predicted (step S12). Then, the cube that contacts and crosses while moving to the predicted position is grasped (step S13). Here, “8 milliseconds” corresponds to a sampling time for controlling the movement position when the robot body 1 is operated, and may be appropriately changed according to individual design.

  Then, the cube to be contacted next is checked (step S14), and it is determined whether or not the evaluation of the cube is “safe” (step S15). If the evaluation of the cube is “safe” (YES), it is determined whether or not all the cubes grasped in step S13 are checked (step S16). If not all are checked (NO), the process proceeds to step S14. Return. If all of them are checked (YES), the operation speed of the robot body 1 is increased (initially set speed) (step S17) and moved. Then, it is determined whether or not the joystick 15 is in a state where it is tilted down by the user (step S18). If the joystick 15 is still tilted (YES), the process returns to step S12. finish.

  On the other hand, if the evaluation of the cube to be contacted next is “dangerous” in step S15 (NO), the operation speed of the robot body 1 is set to a low speed (for example, 10% of the maximum operation speed) (step S19). Let Then, the process proceeds to step S18. Therefore, the robot body 1 is evaluated as “dangerous” among all the cubes that intersect with the box areas B1 and B2 until the robot body 1 reaches the predicted position 8 ms after the position at the reference time point in step S12. If there is something, the robot body 1 moves at a low speed until it passes through the cube. If all the cubes that intersect between the position at the reference time point or passing through the cube evaluated as “dangerous” until reaching the predicted position are evaluated as “safe”, the robot body 1 Will move at high speed.

  FIG. 3 is a diagram corresponding to FIG. 2 when the user designates and inputs the movement destination of the robot body 1 using coordinate values without using the joystick 15 (variable movement). When the movement is started at the designated position (step S21), the movement position after 8 milliseconds is predicted on the locus from the current position toward the designated position (step S22), similarly to step S12. Subsequent steps S23 to S29 are substantially similar to steps S13 to S19, but in step S28, it is determined whether or not the designated position has been reached.

  As described above, according to the present embodiment, when the motion region space in which the robot body 1 operates is regarded as a set of cubes that are cubic unit spaces, and the three-dimensional coordinate values that define the outer surface of each cube are determined, A box region B1 that covers the hand portion of the robot body 1 is set by a space that is larger than the cube. Before the operation of the robot body 1 is started, all the evaluations of the cubes are set to “danger”, and the cube that is entirely contained in the box area B1 by the operation of the robot body 1 is as follows. The evaluation of the cube was changed to “safe”.

  Therefore, when teaching is performed at the site where the robot body 1 is installed, it can be performed while evaluating the safety of the operation area space, so be careful when the user passes a cube whose evaluation is “dangerous”. By paying, it is possible to assist so that a collision with surrounding facilities can be avoided. Also, the box region B2 is set for the elbow joint portion of the robot main body 1 and the cube in which the posture changes and the elbow joint passes when the robot main body 1 operates is similarly evaluated. Attention can also be paid to changes in posture.

  Further, when the robot body 1 operates, the operation speed is set to be slow when passing through a cube whose evaluation is “dangerous”, and the operation speed is set to be high when passing through a cube whose evaluation is “safe”. Therefore, when passing through a cube whose evaluation is “dangerous”, it is possible to give the user a margin for confirming the passing state of the area, and if the user judges that the passage is dangerous, the operation is stopped. Sufficient time can be taken to increase the possibility of avoiding a collision. On the other hand, the cube whose evaluation is “safe” has no problem in passing again, so the operation speed of the robot body 1 is increased.

  Then, the position of the robot body 1 after a lapse of a predetermined time from the reference time when the robot body 1 operates is predicted, and the movement trajectories of the box regions B1 and B2 from the position of the reference time to the predicted position after the lapse of the predetermined time are obtained. When the prediction is performed, the evaluation is sequentially performed for each cube whose movement trajectory is at least partially included. If there is a cube that is evaluated as “dangerous”, the operation speed is set to be slow until it passes through the cube. If all the cubes are evaluated as “safe”, or the evaluation is “dangerous”. When the evaluation of all the cubes after passing through the cube “” is “safe”, the operation speed of the robot body 1 up to the predicted position is set to be high. Accordingly, the operation speed can be comprehensively determined to some extent by collectively evaluating the cube intersecting with the box regions B1 and B2 to some extent while the robot body 1 moves to the predicted position.

(Second embodiment)
FIG. 9 shows a second embodiment. The same parts as those in the first embodiment are denoted by the same reference numerals and the description thereof is omitted. Hereinafter, different parts will be described. In the first embodiment, the cube sizes (volumes) are all set equal, but in the second embodiment, as shown in FIG. 9, the volume of the cube located in the vicinity of the robot body 1 is set relatively large. The volume of the cube located far from the robot body 1 is set to be relatively small. That is, when the robot body 1 is installed, since a place where there is no obstacle or the like should generally be selected and installed in the space near the robot body 1, there is no problem even if the volume of the cube is set large.

  On the other hand, in the space far from the robot body 1, the robot body 1 is more likely to come in contact with obstacles and the like, so the volume of the cube is set to be smaller and “safe” and “dangerous” Make the assessment in detail. As described above, according to the second embodiment, the size of the cube is set larger when the cube is located near the robot body 1 and smaller when the cube is located farther from the robot body 1. It is possible to carry out a detailed evaluation on a far-side spatial portion that is relatively likely to occur.

The present invention is not limited to the embodiments described above or shown in the drawings, and can be modified or expanded as follows.
The box area may also be set for the second joint J2.
Further, the box area may be set at least at the hand portion.
The volume ratio between the cube and the box region may be changed as appropriate while maintaining the size relationship.
The low speed setting of the operation speed of the robot body 1 is not limited to 10% of the maximum operation speed, and may be appropriately changed within a range necessary for ensuring safety.

  The determination process when the operation speed of the robot body 1 is switched between high speed and low speed is not limited to FIG. 2 or 3, and the robot body 1 is moved according to the evaluation of the cube to be contacted and crossed next while moving. The operation speed may be switched.

  In the drawings, 1 denotes a robot body, and 11 denotes a control device (unit space setting means, space evaluation means, operation speed setting means).

Claims (10)

The movement area space in which the articulated robot moves is regarded as a set of cubic unit spaces, and the three-dimensional coordinate values defining the outer surface of each unit space are determined.
By setting a box area covering the hand portion of the robot by a space having a size larger than the unit space,
Before starting the operation of the robot, set all the evaluation of each unit space to "danger",
An evaluation control method for a robot, characterized in that, for a unit space that is entirely contained within the box area by the operation of the robot, the evaluation of the unit space is changed to “safe”.   The robot evaluation control method according to claim 1, wherein a box region is set for the joint portion of the robot and the same evaluation is performed.   3. The robot evaluation according to claim 1, wherein the unit space is set to have a large size when it is located near the robot, and is set small when it is located far from the robot. Control method.   When the robot moves, when the robot passes through a unit space that is evaluated as “dangerous”, the robot is set so that its operating speed is slow. When the robot passes through a unit space that is evaluated as “safe”, The robot evaluation control method according to any one of claims 1 to 3, wherein the robot is set so that an operation speed thereof is increased. Predicting the position of the robot after a predetermined time from the reference time point when the robot operates,
When predicting the movement trajectory of the box region from the position of the reference time point to the predicted position after the lapse of the predetermined time, sequentially evaluating each unit space including at least a part of the movement trajectory,
If there is a unit space that is evaluated as “dangerous” among them, the operation speed of the robot is set to be slow until it passes through the unit space,
When the evaluation of all unit spaces is “safe”, or the evaluation of all unit spaces after passing through the unit space whose evaluation is “dangerous” is “safe”, The robot evaluation control method according to any one of claims 1 to 3, wherein the robot is set so that an operation speed thereof is increased. A unit space setting means for determining a three-dimensional coordinate value that defines an outer surface of each unit space, taking an operation region space in which an articulated robot operates as a set of cubic unit spaces;
By setting a box area covering the hand portion of the robot by a space having a size larger than the unit space,
Before starting the operation of the robot, set all the evaluation of each unit space to "danger",
Control of the robot, comprising: a space evaluation unit that changes the evaluation of the unit space to “safe” for the unit space that is entirely contained inside the box area by the operation of the robot. apparatus.   The robot control apparatus according to claim 6, wherein the space evaluation unit sets a box region for the joint portion of the robot and performs similar evaluation.   7. The unit space setting means sets the size of the unit space larger when the unit is located near the robot, and smaller when the unit space is located far from the robot. Or the control apparatus of the robot of 7.   When the robot moves, when the robot passes through a unit space that is evaluated as “dangerous”, the robot is set so that its operating speed is slow. When the robot passes through a unit space that is evaluated as “safe”, 9. The robot control apparatus according to claim 6, further comprising operation speed setting means for setting the operation speed of the robot to be high. A position predicting means for predicting a position of the robot after a predetermined time from a reference time when the robot operates;
The space evaluation means, when predicting the movement trajectory of the box region from the reference time point to the predicted position after the predetermined time has elapsed, sequentially evaluates each unit space including at least a part of the movement trajectory,
If there is a unit space that is evaluated as “dangerous” among them, the operation speed of the robot is set to be slow until it passes through the unit space,
When the evaluation of all unit spaces is “safe”, or the evaluation of all unit spaces after passing through the unit space whose evaluation is “dangerous” is “safe”, 9. The robot control apparatus according to claim 6, further comprising operation speed setting means for setting the operation speed of the robot to be high.

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