JP2016147321A - Robot control apparatus, and control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a robot control apparatus and a control method capable of suppressing the travel speed of an arm sufficiently.SOLUTION: A controller 30 is applied to a robot 10 having an arm and including: a plurality of rotary parts 13 to 18; articulates for connecting the rotary parts rotatably relative to each other; and servomotors for driving the individual rotary parts. The controller 30 comprises: means for calculating the speed of a monitor, as set at the individual rotary parts; means for calculating the angular variations of the individual servomotors for controlling the present position and attitude of the TCP of the arm to the position and attitude after the operation cycle; means for reducing the angular variations of the individual servomotors so that the speeds of the individual monitoring parts may be at or lower than the reference speed; means for updating the position and attitude of the TCP which are obtained by sequentially converting the angles of the individual servomotors after the operation cycle; and means for driving the individual servomotors so that the present position and attitude of the TCP may be controlled to the updated position and attitude.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a robot control device and a control method.

  Conventionally, during manual operation of a robot, when the movement speed of the control point of the robot exceeds the reference speed, there is an apparatus that operates the robot by correcting the operation target position so that the movement speed becomes lower than the reference speed (patent) Reference 1).

Japanese Patent No. 3994487

  However, even if the movement speed of the tip of the arm set as the control point of the robot is controlled to be equal to or lower than the reference speed, the movement speed of the arm may not be sufficiently suppressed. Paid attention.

  The present invention has been made in view of such circumstances, and a main object of the present invention is to provide a robot control device and a control method capable of sufficiently suppressing the moving speed of the arm.

  The first means is applied to a robot including an arm that includes a plurality of rotating parts, a joint that rotatably connects the rotating parts, and a servo motor that drives the rotating parts, and a tip of the arm A control device for a robot that controls the position and orientation of the control point by CP control that sets a movement path when the control point is set as a control point and moves the control point to a target position. Control position calculation means for calculating the position and orientation after the cycle, current monitoring position calculation means for calculating the current position of the monitoring section set in each rotating section, and the control calculated by the control position calculation means Based on the position and orientation of the point after the operation cycle, the next cycle monitoring position calculation means for calculating the position after the operation cycle of each of the monitoring units, and each of the monitoring calculated by the current monitoring position calculation means Speed calculating means for calculating the speed of each monitoring unit based on the current position of the monitoring unit and the position after the operation cycle of each monitoring unit calculated by the next cycle monitoring position calculating means; and Angle change amount calculating means for calculating the angle change amount of each servo motor for controlling the current position and posture to the position and posture after the operation cycle of the control point calculated by the control position calculating means; The angle change amount is set so that the speed of each of the monitoring units is equal to or lower than the reference speed on condition that the maximum speed among the speeds of the monitoring units calculated by the speed calculation unit is higher than a reference speed. A reduction means for reducing the angle change amount of each servo motor calculated by the calculation means, the angle change amount reduced by the reduction means, and the current angle of each servo motor. An angle calculating means for calculating an angle after the operation cycle of each servo motor, and a control point obtained by forward-converting the angle after the operation cycle of each servo motor calculated by the angle calculation means. The update means for updating the position and orientation after the operation cycle of the control point calculated by the control position calculation means with the position and orientation, and the current position and orientation of the control point are updated by the update means. Drive means for driving the servo motors so as to be controlled after the operation cycle up to the position and orientation of the control point.

  In the above configuration, the arm of the robot includes a plurality of rotating units, and the rotating units are connected to each other by joints so as to be rotatable. The tip of the arm is set as a control point, and the current position and posture of the control point are controlled by CP control.

  Here, even if the movement speed of the tip of the arm set as the control point is controlled to be equal to or lower than the reference speed, depending on the posture of the arm (robot), the movement speed of the part other than the control point in the arm may be The inventor of the present application has paid attention to the fact that the speed may be higher than the reference speed.

  Therefore, in the above configuration, a monitoring unit is set for each rotating unit. For example, the portion farthest from the joint that is the center of rotation when rotating each rotating unit is set as the monitoring unit of each rotating unit. Then, the speed of each monitoring unit is calculated based on the current position of each monitoring unit and the position after the operation cycle of each monitoring unit. Then, the angle change amount of each servo motor for controlling the current position and posture of the control point to the position and posture after the operation cycle is reduced so that the calculated speed of each monitoring unit is lower than the reference speed. It is done.

  Then, the angle after the operation cycle of each servo motor is calculated based on the reduced angle change amount of each servo motor and the current angle of each servo motor. Then, the position and orientation of the control point after the operation cycle calculated by the control position calculation means are updated with the position and orientation of the control point obtained by forward conversion of the calculated angle after the operation cycle of each servo motor. Is done. Then, each servo motor is driven so that the current position and orientation of the control point are controlled after the operation cycle up to the updated position and orientation. For this reason, the angle driven per operation cycle of each servo motor is reduced, and the angular velocity at which each servo motor is driven is reduced. Thereby, not only the control point of the robot but also the speed of the monitoring unit set in each rotating unit can be made lower than the reference speed, and the moving speed of the arm can be sufficiently suppressed.

  Further, in the above configuration, the angle change amount of each servo motor is calculated, and the angle change amount of each servo motor is reduced so that the speed of each monitoring unit is equal to or lower than the reference speed. For this reason, the angular velocities of all the servomotors can be accurately reduced, and the effect of suppressing the movement speed of the arm can be enhanced.

  Furthermore, the angle change amount and the moving speed of the arm (specifically, the speed of each monitoring unit) are highly correlated. For this reason, when the amount of angle change is reduced, the moving speed of the arm is surely reduced according to the amount of decrease in the angle change amount. Therefore, despite the fact that the angle change amount of the servo motor is reduced in order to reduce the arm movement speed, the arm movement speed is not reduced to the intended level, and the angle change amount is reduced again. Is suppressed.

  As the speed calculation means, specifically, as in the fifth means, the distance between the current position of each monitoring unit and the position after the operation cycle of each monitoring unit is divided by the operation cycle. Therefore, it is possible to employ a configuration in which the speed of each monitoring unit is calculated.

  Further, as the next cycle monitoring position calculation means, specifically, as in the sixth means, the operation cycle of each servo motor obtained by inversely converting the position and orientation of the control point after the operation cycle. A configuration in which the position of each monitoring unit after the operation cycle is calculated based on the later angle and the size of each rotating unit can be employed.

  Further, as the angle change amount calculation means, specifically, as in the seventh means, after the operation cycle of each servo motor obtained by inversely converting the position and orientation of the control point after the operation cycle. And a difference between the current angle of each servo motor and the current angle of each servo motor can be calculated as the amount of change in angle.

  In the second means, the lowering means lowers the angle change amount of each servo motor based on the value of the ratio between the maximum speed and the reference speed.

  In the above configuration, the angle change amount of each servo motor is reduced based on the value of the ratio between the maximum speed and the reference speed among the calculated speeds of the respective monitoring units. By using the value of the above ratio, it is possible to reduce the amount of angle change reflecting the excess of the maximum speed with respect to the reference speed. The value of the ratio between the maximum speed and the reference speed is a value obtained by dividing the maximum speed by the reference speed (ratio value = maximum speed / reference speed).

  In a third means, the reduction means reduces the angle change amount of each servo motor by dividing the angle change amount of each servo motor by the value of the ratio.

  According to the above configuration, regardless of whether the operation path of CP control is a straight line or a curve, the amount of change in angle can be reduced so that the control point can be maintained on the operation path. Further, according to the above configuration, since the simple calculation of dividing the angle change amount by the ratio value is used, the angle change amount can be easily reduced. Further, according to the above configuration, since the calculation of dividing the angle change amount by the value of the ratio is used, the angle change amount can be reduced at a ratio determined from a certain law, and the operator can predict the decrease in the angle change amount. It becomes easy to do.

  In the fourth means, the portion farthest from the joint that becomes the center of rotation when rotating each rotating unit is set as the monitoring unit of each rotating unit.

  In the above configuration, the portion farthest from the joint serving as the center of rotation when rotating each rotating unit is set as the monitoring unit of each rotating unit. For this reason, in each rotation part, the part with the highest possibility that speed becomes the highest can be set to a monitoring part, and the moving speed of an arm can fully be suppressed.

  The eighth means is applied to a robot including an arm that includes a plurality of rotating parts, a joint that rotatably connects the rotating parts, and a servo motor that drives the rotating parts. A control method for a robot that controls the position and orientation of the control point by CP control that sets a motion trajectory when setting a control point as a control point and moving the control point to a target position, A control position calculating step for calculating a position and orientation after a cycle; a current monitoring position calculating step for calculating a current position of a monitoring unit set in each of the rotating units; and the control calculated by the control position calculating step. Based on the position and orientation after the operation cycle of the point, the next cycle monitoring position calculation step for calculating the position after the operation cycle of each monitoring unit, and the respective monitoring calculated by the current monitoring position calculation step A speed calculation step of calculating the speed of each monitoring unit based on the current position of the monitoring unit and the position after the operation cycle of each monitoring unit calculated by the next cycle monitoring position calculation step; An angle change amount calculating step for calculating an angle change amount of each servo motor for controlling the current position and posture to the position and posture after the operation cycle of the control point calculated by the control position calculating step; The angle change amount is set so that the speed of each monitoring unit is equal to or less than the reference speed on condition that the maximum speed among the speeds of each monitoring unit calculated by the speed calculation step is higher than a reference speed. Based on the reduction step of reducing the angle change amount of each servo motor calculated by the calculation step, the angle change amount reduced by the reduction step, and the current angle of each servo motor. An angle calculation step of calculating an angle after the operation cycle of each servo motor, and the control point obtained by forward-converting the angle after the operation cycle of each servo motor calculated by the angle calculation step. An update step for updating the position and posture after the operation cycle of the control point calculated by the control position calculation step with the position and posture, and the current position and posture of the control point are updated by the update step. And a driving step of driving each servo motor so that the control point is controlled to the position and orientation after the operation cycle.

  According to the said process, there can exist an effect similar to a 1st means.

The figure which shows the outline | summary of a robot, a controller, and a teaching pendant. The front view which shows the specific attitude | position of a robot. The flowchart which shows the process sequence of the speed suppression control of an arm.

  Hereinafter, an embodiment embodied in a control device for a vertical articulated robot will be described with reference to the drawings. The robot of this embodiment is used in an assembly system such as a machine assembly factory as an industrial robot, for example.

  First, an outline of the robot 10 will be described with reference to FIG.

  As shown in the figure, the robot 10 includes a first axis J1, a second axis J2, a third axis J3, a fourth axis J4, a fifth axis J5 as rotation center axes of the joints that connect the rotating units to each other. And a six-axis robot having a sixth axis J6. The operating angle of each part in each axis is adjusted through driving of a driving source composed of a servo motor or the like and deceleration by a speed reducer or the like. Both servomotors can be rotated in both forward and reverse directions, and each rotating unit operates (drives) based on the origin position by driving the servomotor. Each servo motor is provided with an electromagnetic brake that brakes its output shaft and an encoder that outputs a pulse signal corresponding to the rotation angle of the output shaft.

  The robot 10 is installed on the floor, and the first axis J1 extends in the vertical direction. In the robot 10, the base 11 has a fixed portion 12 fixed to the floor or the like, and a rotating portion 13 (first rotating portion) provided above the fixed portion 12. It can be rotated in the horizontal direction around the one axis line J1. That is, the rotating portion 13 extends in the direction of the first axis J1 and is supported by the fixed portion 12 so as to be rotatable about the first axis J1.

  The lower arm 15 (second rotating portion) is coupled to be rotatable in a clockwise direction or a counterclockwise direction about a second axis J2 extending in the horizontal direction as a rotation center. That is, the lower arm 15 extends in a direction away from the second axis J2 included in the plane orthogonal to the first axis J1, and is supported by the rotating unit 13 so as to be rotatable about the second axis J2. The lower arm 15 is provided in a direction extending in the vertical direction as a basic posture.

  The upper arm 16 is coupled to the upper end portion of the lower arm 15 so as to be rotatable clockwise or counterclockwise about a third axis J3 extending in the horizontal direction. That is, the upper arm 16 extends in a direction away from the third axis J3 parallel to the second axis J2, and is supported by the lower arm 15 so as to be rotatable about the third axis J3. The upper arm 16 is provided in a direction extending in the horizontal direction as a basic posture.

  The upper arm 16 is configured to be divided into two arm portions on the base end side (joint side with the third axis J3 as the rotation center during rotation) and the tip end side, and the base end side is the first upper side. The arm 16A (third rotating part), the tip side is a second upper arm 16B (fourth rotating part). The second upper arm 16B is rotatable in the torsional direction with respect to the first upper arm 16A with a fourth axis J4 extending in the longitudinal direction of the upper arm 16 as a rotation center. That is, the second upper arm 16B extends in the direction of the fourth axis J4 included in the plane orthogonal to the third axis J3, and is supported by the first upper arm 16A so as to be rotatable about the fourth axis J4. .

  A wrist portion 17 (fifth rotating portion) is provided at the distal end portion of the upper arm 16 (specifically, the second upper arm 16B). The wrist portion 17 is rotatable with respect to the second upper arm 16B with the fifth axis J5 extending in the horizontal direction as the center of rotation. That is, the wrist 17 extends in a direction away from the fifth axis J5 orthogonal to the fourth axis J4, and is supported by the second upper arm 16B so as to be rotatable about the fifth axis J5.

  A hand portion 18 (sixth rotating portion) for attaching a work, a tool, or the like is provided at the distal end portion of the wrist portion 17. The hand portion 18 is rotatable in the torsional direction around the sixth axis J6 that is the center line thereof. That is, the hand portion 18 extends in the direction of the sixth axis J6 orthogonal to the fifth axis J5, and is supported by the wrist portion 17 so as to be rotatable about the sixth axis J6. As described above, the arm of the robot 10 is configured by the rotating unit 13, the lower arm 15, the upper arm 16, the wrist unit 17, and the hand unit 18.

  The controller 30 (control device) includes a CPU, a ROM, a RAM, a drive circuit, a position detection circuit, and the like. The ROM stores system programs and operation programs for the robot 10. The RAM stores parameter values and the like when executing these programs. Detection signals from the encoders are input to the position detection circuit. The position detection circuit detects the rotation angle of the servo motor provided at each joint based on the detection signal of each encoder.

  The CPU performs CP (Continuous Path) control based on the position information input from the position detection circuit by executing a preset operation program (program). In CP control, when the control point of the arm tip is moved to the target position, the motion trajectory (position and orientation) of the control point is set as a time function. The CPU controls the rotation angle (arm posture) of each joint in the arm by CP control so that the position and posture of the control point follow the motion trajectory. In the present embodiment, a TCP (Tool Center Point) that is the center point 18a of the arm hand portion 18 is set as the control point. Further, the CPU calculates the angle and angle of each joint for realizing the position and posture based on the TCP position and posture, and the position and posture of the TCP based on the angle of each joint. And a function to calculate by forward conversion.

  In the present embodiment, the controller 30 executes speed suppression control that suppresses the moving speed of the arm of the robot 10 to a reference speed or less during teaching of the robot 10 (during manual operation). The reference speed is defined as, for example, 250 mm / s according to standards such as JIS and ISO.

  The teaching pendant 40 (operation device) includes a microcomputer including a CPU, ROM, and RAM, various manual operation keys, a display 42, and the like. The pendant 40 is connected to the controller 30 and can communicate with the controller 30. An operator (user) can manually operate the pendant 40 to create, modify, register, and set various parameters of the operation program of the robot 10. In teaching for correcting an operation program or the like, a teaching point through which a TCP as a control point passes in the work is taught. The operator can operate the robot 10 through the controller 30 based on the teaching operation program. In other words, the controller 30 controls the operation of the arm of the robot 10 based on the preset operation program and the operation of the pendant 40.

  Here, even when the robot 10 is controlled so that the movement speed of the TCP is equal to or less than the reference speed during teaching (manual operation), the movement speed of the part other than the TCP in the arm is the reference depending on the posture of the robot 10. The inventor of the present application has paid attention to the fact that the speed may be higher. For example, when the robot 10 is in the posture shown in FIG. 2, when the rotating unit 13 is rotated, the moving speed of the TCP that is the center point 18a (point C5) of the hand unit 18 is sufficiently smaller than the reference speed. However, the moving speed of the tip end portion (point C2) of the lower arm 15 and one end portion (point C3) of the upper arm 16 may be higher than the reference speed.

  Therefore, the portion farthest from the joint (rotation center axis of each rotation unit) when rotating each rotation unit is set as a monitoring unit (points C1 to C5) of each rotation unit. For example, the point C2 farthest from the joint (the connecting portion between the rotating unit 13 and the lower arm 15) that becomes the center of rotation when the lower arm 15 is rotated is set as the monitoring unit of the lower arm 15. Similarly, the points C3 and C4 that are farthest from the joint (the connecting portion between the lower arm 15 and the upper arm 16) that becomes the center of rotation when the upper arm 16 is rotated are set as monitoring units for the upper arm 16, and so on. I do. When other parts (parts) are attached to the rotating part such as the upper arm 16, the tip part of the part may be set as the monitoring part. Then, the angular speed of each servo motor is suppressed so that the moving speeds of all the monitoring units are equal to or lower than the reference speed.

  FIG. 3 is a flowchart illustrating a processing procedure of speed suppression control that suppresses the moving speed of the arm of the robot 10 to a reference speed or less. This series of processing is repeatedly executed by the controller 30 every operation cycle Tr for operating the arm. The operation cycle Tr (control cycle) is, for example, 8 ms.

  In this series of processing, first, the current position and posture P1 of the TCP that is the control point of the arm is detected (S11). In the CP control for moving the TCP along the teaching motion trajectory, the current position and orientation P1 are calculated.

  Subsequently, the current angle θk1 of each servo motor is detected (S12). Specifically, the current angle θk1 of each servo motor is detected by the position detection circuit based on the detection signal of the encoder provided in each servo motor. Note that k is a number from 1 to 6 corresponding to the first axis J1 to the sixth axis J6, respectively.

  Subsequently, the position and orientation P2 after the TCP operation cycle Tr are calculated (S13). Specifically, first, a change amount ΔP in position and orientation per TCP operation cycle Tr is calculated. Specifically, the change amount ΔP may be calculated based on the motion trajectory taught during teaching. Then, the position and orientation P2 after the TCP operation cycle Tr are calculated by the equation P2 = P1 + ΔP.

  Subsequently, the current position Pi1 of each monitoring unit is calculated based on the current angle θk1 of each servomotor and the size of each rotating unit (S14). i is a number from 1 to 5 corresponding to points C1 to C5, respectively. The calculation method of the current position Pi1 will be described in detail. First, the distance from the rotation center of each rotating unit to the monitoring unit is calculated based on the size of each rotating unit and the set position of each monitoring unit. Then, the positions of the points C1 to C5 are calculated by combining the current angle θk1 of each servo motor, the size of each rotating unit, and the distance.

  Subsequently, the angle θk2 after the operation cycle Tr of each servo motor is calculated by inversely converting the position and orientation P2 after the TCP operation cycle Tr (S15). Then, the position Pi2 after the operation cycle Tr of each monitoring unit is calculated (S16). Specifically, the position Pi2 after the operation cycle Tr of each monitoring unit is calculated based on the angle θk2 after the operation cycle Tr of each servo motor and the size of each rotation unit.

  Subsequently, the speed Vi of each monitoring unit is calculated (S17). Specifically, the speed Vi is calculated by dividing the distance between the current position Pi1 of each monitoring unit and the position Pi2 after the operation cycle Tr by the operation cycle Tr. Note that i is a number from 1 to 5 corresponding to the points C1 to C5, respectively.

  Subsequently, the maximum speed Vmx, which is the maximum speed among the speed Vi of each monitoring unit, is calculated (S18), and it is determined whether or not the maximum speed Vmx is higher than the reference speed Vlm (S19). In this determination, when it is determined that the maximum speed Vmx is higher than the reference speed Vlm (S19: YES), a value α of the ratio between the maximum speed Vmx and the reference speed Vlm is calculated (S20). That is, the ratio value α is calculated according to the equation α = Vmx / Vlm (α> 1).

  Subsequently, the difference between the angle θk2 after the operation cycle Tr of each servo motor and the current angle θk1 is calculated as the angle change amount Δθk of each servo motor (S21). Note that k is a number from 1 to 6 corresponding to the first axis J1 to the sixth axis J6, respectively. Then, the angle change amount Δθk is updated by dividing the angle change amount Δθk of each servo motor by the ratio value α (S22).

  Subsequently, the position and orientation P2 after the TCP operation cycle Tr are updated (S23). Specifically, first, the angle θk2 after the operation cycle Tr of each servomotor is updated with the addition value of the current angle θk1 of each servomotor and the updated angle change amount Δθk of each servomotor. Then, the position and orientation P2 after the TCP operation cycle Tr are updated with the position and orientation obtained by forward-converting the updated angle θk2. And it performs again from the process of S15 using the updated position and attitude | position P2.

  On the other hand, if it is determined in S19 that the maximum speed Vmx is equal to or lower than the reference speed Vlm (S19: NO), the position and posture of the TCP are controlled to the target position and posture P2 by driving each servo motor. (S24). Here, when the process of S23 is performed, the TCP position and attitude are controlled to the position and attitude P2 updated in the process of S23. Then, this series of processing is temporarily ended (END).

  Note that the process of S13 corresponds to the process as the control position calculation means (control position calculation process), the process of S14 corresponds to the process as the current monitoring position calculation means (current monitoring position calculation process), and the process of S15. The processing as the angle calculation means (angle calculation process) corresponds to the processing of S16, the processing as the next cycle monitoring position calculation means (next cycle monitoring position calculation step), and the processing of S17 as the speed calculation means. This corresponds to (speed calculation step). Further, the process of S21 corresponds to the process as the angle change amount calculation means (angle change amount calculation process), the process of S22 corresponds to the process as the decrease means (decrease process), and the process of S23 serves as the update means. The process corresponds to a process (update process), and the process of S24 corresponds to a process (drive process) as a drive unit.

  The embodiment described in detail above has the following advantages.

  The speed Vi of each monitoring unit is calculated based on the current position Pi1 of the monitoring unit (points C1 to C5) set in each rotating unit and the position Pi2 after the operation cycle Tr of each monitoring unit. The angle change amount of each servo motor for controlling the current position and posture P1 of TCP to the position and posture after the operation cycle Tr so that the calculated speed Vi of each monitoring unit is equal to or less than the reference speed Vlm. Δθk is lowered. Then, the angle θk2 after the operation period Tr of each servo motor is calculated based on the reduced angle change amount Δθk of each servo motor and the current angle θk1 of each servo motor. Then, the position and orientation P2 after the TCP operation cycle Tr are updated with the TCP position and orientation obtained by forward-converting the calculated angle θk2. Then, each servo motor is driven so that the current position and orientation P1 of TCP is controlled after the operation cycle Tr to the updated position and orientation P2. As a result, the angular speed at which each servo motor is driven can be reduced, and not only the TCP that is the control point, but also the speed of each monitoring unit can be reduced to the reference speed Vlm or less. Therefore, the moving speed of the arm can be sufficiently suppressed.

  Further, the angle change amount Δθk of each servo motor is calculated, and the angle change amount Δθk of each servo motor is reduced so that the speed Vi of each monitoring unit is equal to or less than the reference speed Vlm. For this reason, the angular velocities of all the servomotors can be accurately reduced, and the effect of suppressing the movement speed of the arm can be enhanced. Thereby, the safety | security of a robot can be improved more.

  Further, the angle change amount Δθk and the moving speed of the arm (specifically, the speed of each monitoring unit) are highly correlated. Therefore, when the angle change amount Δθk is reduced, the moving speed of the arm is surely reduced by an amount proportional to the decrease amount of the angle change amount Δθk. Therefore, even though the angle change amount Δθk is reduced to reduce the arm movement speed, the arm movement speed is not reduced to the intended level, and the angle change amount Δθk is reduced again. Is suppressed. As a result, it is possible to simplify the program for suppressing the arm movement speed, such as suppressing the repetition of the process of reducing the angle change amount Δθk, or simplifying the arm movement speed deceleration confirmation process. it can.

  The angle change amount Δθk of each servo motor is reduced by dividing the angle change amount Δθk of each servo motor by the value α of the ratio between the maximum speed Vmx and the reference speed Vlm. Therefore, regardless of whether the CP control operation trajectory is a straight line or a curve, the angle change amount Δθk can be reduced so that the TCP can be maintained in the operation trajectory.

  Further, since a simple calculation of dividing the angle change amount Δθk by the ratio value α is used, the angle change amount Δθk can be easily reduced. Further, since the calculation of dividing the angle change amount Δθk by the ratio value α is used, the angle change amount Δθk can be reduced at a ratio determined from a certain law, and the decrease in the angle change amount Δθk can be easily predicted by the operator. Become.

  The portion that is farthest from the joint that is the center of rotation when rotating each rotating unit is set as the monitoring unit of each rotating unit. For this reason, in each rotation part, the part with the highest possibility that speed becomes the highest can be set to a monitoring part, and the moving speed of an arm can fully be suppressed.

  Note that the above-described embodiment may be modified as follows.

  In S19 of FIG. 3, it is determined whether or not the maximum speed Vmx is higher than the reference speed Vlm. However, even if it is determined whether or not the maximum speed Vmx is higher than a determination speed set slightly higher than the reference speed Vlm. Good. In this case, the arm speed suppression control can be completed quickly.

  In S22 of FIG. 3, the angle change amount Δθk is divided by the ratio value α to reduce the angle change amount Δθk, but the angle change amount Δθk is divided by a value slightly larger than the ratio value α to obtain the angle change amount Δθk. May be reduced. Also in this case, the arm speed suppression control can be completed quickly.

  -Although 250 mm / s prescribed | regulated by standards, such as JIS and ISO, was used as reference speed Vlm, you may use a slightly lower speed, for example, 230 mm / s as reference speed Vlm. In this case, the moving speed of the arm can be reliably and easily reduced to less than 250 mm / s.

  A horizontal articulated robot or the like may be employed instead of the vertical articulated robot 10.

  DESCRIPTION OF SYMBOLS 10 ... Robot, 13 ... Rotating part, 15 ... Lower arm, 16 ... Upper arm, 16A ... 1st upper arm, 16B ... 2nd upper arm, 17 ... Wrist part, 18 ... Hand part, 30 ... Controller.

Claims (8)

The present invention is applied to a robot including an arm including a plurality of rotating units, a joint that rotatably connects the rotating units to each other, and a servo motor that drives the rotating units, and the tip of the arm is set as a control point. A control device for a robot that controls the position and orientation of the control point by CP control for setting an operation trajectory when the control point is moved to a target position;
Control position calculating means for calculating the position and orientation of the control point after the operation cycle;
Current monitoring position calculating means for calculating the current position of the monitoring unit set in each of the rotating units;
Next cycle monitoring position calculating means for calculating the position after the operation cycle of each monitoring unit based on the position and orientation after the operation cycle of the control point calculated by the control position calculating means;
Based on the current position of each monitoring unit calculated by the current monitoring position calculating unit and the position after the operation cycle of each monitoring unit calculated by the next cycle monitoring position calculating unit, the monitoring units Speed calculating means for calculating the speed of
Angle change amount for calculating the angle change amount of each servo motor for controlling the current position and posture of the control point to the position and posture after the operation cycle of the control point calculated by the control position calculation means A calculation means;
The angle change amount is set so that the speed of each of the monitoring units is equal to or lower than the reference speed on condition that the maximum speed among the speeds of the monitoring units calculated by the speed calculation unit is higher than a reference speed. Reduction means for reducing the angle change amount of each servo motor calculated by the calculation means;
An angle calculation means for calculating an angle after an operation cycle of each servo motor based on the angle change amount reduced by the reduction means and a current angle of each servo motor;
The operation period of the control point calculated by the control position calculation means with the position and orientation of the control point obtained by forward-converting the angle after the operation period of each servo motor calculated by the angle calculation means Updating means for updating the later position and orientation;
Drive means for driving each servo motor so that the current position and orientation of the control point are controlled after the operation cycle to the position and orientation of the control point updated by the update means. A robot control device characterized by the above.   2. The robot control apparatus according to claim 1, wherein the lowering unit lowers an angle change amount of each servo motor based on a value of a ratio between the maximum speed and the reference speed.   The robot control apparatus according to claim 2, wherein the reduction unit reduces the angle change amount of each servo motor by dividing the angle change amount of each servo motor by the value of the ratio.   The robot control device according to any one of claims 1 to 3, wherein a portion farthest from the joint, which is a rotation center when rotating each rotating unit, is set as the monitoring unit of each rotating unit. .   The speed calculation means calculates the speed of each monitoring unit by dividing the distance between the current position of each monitoring unit and the position after the operation cycle of each monitoring unit by the operation cycle. The robot control device according to any one of the above.   The next cycle monitoring position calculation means is based on the angle after the operation cycle of each servo motor obtained by inversely converting the position and posture after the operation cycle of the control point, and the size of each rotation unit. The robot control device according to claim 1, wherein the position of each monitoring unit after the operation cycle is calculated.   The angle change amount calculation means is a difference between an angle after the operation cycle of each servo motor obtained by inversely converting a position and posture after the operation cycle of the control point, and a current angle of each servo motor. The robot control apparatus according to claim 1, wherein the angle change amount is calculated as the angle change amount. The present invention is applied to a robot including an arm including a plurality of rotating units, a joint that rotatably connects the rotating units to each other, and a servo motor that drives the rotating units, and the tip of the arm is set as a control point. A control method for a robot that controls the position and orientation of the control point by CP control for setting an operation trajectory when the control point is moved to a target position,
A control position calculation step of calculating a position and orientation after an operation cycle of the control point;
A current monitoring position calculating step for calculating a current position of the monitoring unit set in each of the rotating units;
A next cycle monitoring position calculation step of calculating a position after the operation cycle of each monitoring unit based on the position and posture after the operation cycle of the control point calculated by the control position calculation step;
Based on the current position of each monitoring unit calculated by the current monitoring position calculation step and the position after the operation cycle of each monitoring unit calculated by the next cycle monitoring position calculation step, each monitoring unit A speed calculating step for calculating the speed of
Angle change amount for calculating the angle change amount of each servo motor for controlling the current position and posture of the control point to the position and posture after the operation cycle of the control point calculated by the control position calculation step A calculation process;
The angle change amount is set so that the speed of each monitoring unit is equal to or less than the reference speed on condition that the maximum speed among the speeds of each monitoring unit calculated by the speed calculation step is higher than a reference speed. A reduction step of reducing the angle change amount of each servo motor calculated by the calculation step;
An angle calculation step of calculating an angle after an operation cycle of each servo motor based on the amount of change in angle reduced by the reduction step and the current angle of each servo motor;
The operation cycle of the control point calculated by the control position calculation step with the position and orientation of the control point obtained by forward-converting the angle after the operation cycle of each servo motor calculated by the angle calculation step An update process for updating the later position and orientation;
A driving step of driving each servo motor so that the current position and orientation of the control point are controlled after the operation cycle to the position and orientation of the control point updated by the updating step. A method for controlling a robot characterized by the above.

Images