JP2015205357A - Robot control system and robot control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a robot control system capable of sophisticating the control without increasing the amount of communication and implementing both miniaturization of a manipulator robot and highly accurate assembling.SOLUTION: A distributedly controlled robot control system comprises a control device and a multi-joint robot, a plurality of joint parts of which includes a control unit, where a target value of the joint angle of a first servomotor and a target value of the joint angle of a second servomotor are sent through multicast communication from the control device to a first control unit. The first control unit drives the joint angle of the first servomotor so as to offset the load applied to the first servomotor by the second servomotor.

Description

  The present invention relates to a control system for an articulated robot.

  Industrial robots are widely used due to factory automation, but there is a demand for faster and more accurate operation. In recent years, multi-joint robots have been widely used for industrial robots, but multi-joint robots have a problem of “interaxial interference”.

  “Other axis interference” will be described with reference to FIG. 6 includes a first joint unit 601, a second joint unit 602, a third joint unit 603, a fourth joint unit 604, a fifth joint 605, and a sixth joint. A part 606 and a hand 607. In order to rotate the third joint portion 603, a third joint torque 608 is applied to the third joint portion 603. At this time, a second joint torque 609 that is a reverse torque proportional to the magnitude of the third joint torque 608 is generated in the second joint portion 602. The generation of rotational torque in the second joint due to the rotational movement of the third joint in this way is called “other-axis interference”.

  As a method of suppressing this “other-axis interference”, Patent Document 1 describes using a motor torque signal and a motor position signal detected from each indirect in a robot composed of a plurality of axes. This method can greatly reduce the amount of calculation.

  Further, in order to operate an articulated robot with high accuracy, high-level control for each joint is required. For this reason, a distributed control type robot control system in which a control unit is provided at each joint of an articulated robot is being studied instead of a centralized control type robot control system that controls all joints at once. (Patent Document 2)

JP 2005-186235 A JP-A-5-38689

  In a distributed control type robot control system, for example, in order to perform advanced control in order to suppress other-axis interference, it is necessary to perform high-speed communication between a robot control device and a joint control unit. When performing high-speed communication, since the amount of information communicated per unit time increases, a shielded line is generally used as the communication line. However, since the shield wire is vulnerable to bending, the bending radius must be increased when it is used in the joint portion of an articulated robot. This needs to be taken and becomes a major obstacle for miniaturization of articulated robots.

  Therefore, an object of the present invention is to improve control without increasing the amount of communication in a distributed control type robot control system, and to achieve miniaturization of the robot and high accuracy of control of the robot.

  A distributed control type robot control system of the present invention is a distributed control type robot control system having a control device and an articulated robot, wherein a plurality of joint parts of the articulated robot are provided with control units. The first control unit that controls the first servo motor from the control device includes the target value of the joint angle of the first servo motor and the target value of the joint angle of the second servo motor. The first control unit drives the joint angle of the first servo motor so as to cancel the load applied to the first servo motor by the second servo motor. It is characterized by making it.

The distributed control type robot control system is a distributed control type robot control method including a control device and an articulated robot, and servo control units are provided at a plurality of joints of the articulated robot. The controller transmits data including the target value of the joint angle of the first servo motor and the target value of the joint angle of the second servo motor to the first control unit by multicast communication. The step of obtaining the motor angle of the second servo motor, and the first control unit, based on the motor angle target value of the second servo motor, joints of the first servo motor A step of calculating a torque, a step of converting the current corresponding to the first joint torque by the first servomotor based on a joint torque of the first servomotor; The control part of The current corresponding to the target value of the joint angle of the first servomotor and the first joint torque so as to cancel the load applied to the first servomotor by the second servomotor And adding the current to energize the first servo motor;
It is characterized by having.

  According to the distributed control type robot control system of the present invention, it is possible to improve the control without increasing the amount of communication, to reduce the size of the robot and to perform advanced distributed control for each joint.

It is the schematic of the robot control system of this invention. It is a figure which shows the control apparatus of 1st Embodiment of this invention. It is a functional block diagram of the control apparatus of 1st Embodiment of this invention. It is a flowchart which shows the other-axis interference control of this invention. It is a figure which shows the control apparatus of 2nd Embodiment of this invention. It is a figure which shows the other-axis interference of an articulated robot.

(First embodiment)
(Robot configuration)
A schematic configuration of an articulated robot used in the distributed control type robot system of the present invention will be described with reference to FIG. The distributed control type robot system of the present invention is a distributed control type robot having a control device and an articulated robot, and having servo control units provided at a plurality of joints of the articulated robot. For example, a distributed control type six-axis articulated robot having servomotors on all six axes can be used.

  In FIG. 1, a robot 100 includes a gantry 117, a first arm 101a, a second arm 101b, a third arm 101c, a fourth arm 101d, a fifth arm 101e, and a sixth arm 101f. Yes. The gantry 117 and the first arm 101a are connected at the first joint portion 102a. The first arm 101a and the second arm 101b are connected at the second joint portion 102b. The second arm 101b and the third arm 101c are connected at the third joint portion 102c. The third arm 101c and the fourth arm 101d are connected at the fourth joint portion 102d. The fourth arm 101d and the fifth arm 101e are connected at the fifth joint portion 102e. The fifth arm 101e and the sixth arm 101f are connected at the sixth joint portion 102f.

  The first arm 101a rotates with respect to the gantry 117 around the rotation shaft 103a in the first joint portion 102a. The second arm 101b rotates around the rotation axis 104b in the second joint portion 102b with respect to the first arm. The third arm 101c rotates about the rotation shaft 103c at the third joint portion 102c with respect to the second arm 101b. The fourth arm 101d rotates about the rotation axis 103d in the fourth joint portion 102d with respect to the third arm 101c. The fifth arm 101e rotates about the rotation axis 103e at the fifth joint portion 102e with respect to the fourth arm 101d. The sixth arm 101f rotates about the rotation shaft 103f at the fifth joint portion 102f with respect to the fifth arm 101e.

  The first joint unit 102a is provided with a first servo motor 104a and a first control unit 105a that controls the first servo motor 104a. The second joint portion 102b is provided with a second servo motor 102b and a second control portion 105b that controls the second servo motor 104b. The third joint unit 102c is provided with a third servo motor 104c and a third control unit 105c that controls the third servo motor 104c. The fourth joint portion 102d is provided with a fourth servo motor 104d and a fourth control portion 105d that controls the fourth servo motor 104d. The fifth joint unit 102e is provided with a fifth servo motor 104e and a fifth control unit 105e that controls the fifth servo motor 104e. The sixth joint portion 102f is provided with a sixth servo motor 104f and a sixth control portion 105f that controls the sixth servo motor 104f. In addition to the servo motors 104a to 104f and the control units 105a to 105f, each joint is provided with a speed reducer, an encoder, a torque detector, and the like.

  The 1st-6th control parts 105a-105f are connected in series by the wiring cable 106 from a control apparatus (not shown). Signal transmission / reception between the control device (not shown) and the first to sixth control units 105 a to 105 f is performed via the wiring cable 106. Further, signals can be transmitted and received between the control units via the wiring cable 106.

(Robot control system)
The robot control system of the present invention will be described with reference to FIG. FIG. 2A is a conceptual diagram showing the configuration of the robot control system. The control device 200 includes a first control unit 105a, a second control unit 105b, a third control unit 105c, a fourth control unit 105d, a fifth control unit 105e, a sixth control unit 105f, and a bus cable 106. Are connected in parallel. The first to sixth servo motors 104a to 104f receive angle target values, rotation speeds, accelerations, torques, and the like of the target values of joint angles from the control device 200, and are driven to rotate accordingly.

  FIG. 2B shows the format of the control signal 200 regarding the angle target value that is the target value of the first to sixth joint angles transmitted from the control device 200 to the first to sixth control units 105a to 105f simultaneously. It is. The format of the first data 200 includes a first ID 210, a first motor angle target value 211, a second motor angle target value 212, a third motor angle target value 213, a fourth motor angle target value 214, A fifth motor angle target value 215 and a sixth motor angle target value 216 are configured. First to sixth motor angle target values 211 to 216 are transmitted to the first to sixth servo control units 105a to 105f, respectively. The first servo control unit 105a to the sixth servo control unit 105f receive the first data 201 from the control device 200 to the first servo control unit 105a to the sixth servo control unit 105f simultaneously by the first ID 210. It can be recognized as data being communicated. In this way. The first control unit 111a to the sixth servo control unit 116a communicate with the target angle values of the motors controlled by the first control unit 111a to the sixth servo control unit 116a. For this communication, it is preferable to use multicast communication capable of communication in a small band.

  Next, the second servo motor for suppressing the other-axis interference exerted on the second joint portion 102b by the third indirect torque generated by driving the third servo motor 104c in the third joint portion 102c. A control method of the second control unit will be described with reference to FIGS.

(Details of second and third control units)
FIG. 3 shows a block diagram of the second control unit 105b and the third control unit 105c. The first data 201 is transmitted from the control device 200 to the third control unit (second control unit) 105c. The third control unit 105c causes the current according to the third motor angle target value 213 (target value of the joint angle of the second servo motor) included in the first data 201 to be supplied to the third servo motor 104c. Control to flow. As the third servo motor 104c rotates, torque is transmitted from the third servo motor 104c to the third joint portion 102c. A load inertia moment is generated in the third joint portion 102c.

  In FIG. 3, the control device 200 transmits the first data 201 to the second control unit 105b (first control unit). The disturbance torque calculator 313 of the second control unit 105b calculates the second joint torque of the disturbance torque from the third servo motor angle target value 213 of the transmitted first data 201 (by the interference of the other axis, the second No.2 servo motor is applied to the first servo motor. The torque current converter 314 converts the second joint torque into a current corresponding to the second joint torque.

  Further, the controller 311 passes a current corresponding to the second motor angle target value 212 in the first data 201 sent from the control device 200. The current amplifier 312 amplifies this current and a current corresponding to the second joint torque and sends the current to the second servo motor. The second servo motor 104b transmits torque to the second joint portion 102b as the motor rotates. The angle 302 of the second motor of the second servo motor 104b measured by an encoder (not shown) or the like is sent to the controller 311. A load inertia moment is generated in the second joint portion (102b). In this way, it is possible to cancel the load applied to the second servo motor (first servo motor) by the third servo motor 104c (second servo motor).

  FIG. 4 shows that the second joint torque generated by driving the third servo motor 104c in the third joint 102c (second joint) is the second joint 102b (first joint). FIG. In step 1 (S1), the second control unit 105b (first control unit) of the robot 100 receives the first data 201 shown in FIG. Data including the motor angle target value 212 and the third data angle target value is acquired. Further, the second control unit 105b acquires data of the angle 302 of the second servomotor by an encoder (not shown) provided in the motor.

  In step 2 (S2), the controller 301 compares the second motor angle target value 212 with the angle of the second motor, performs a PID calculation or the like based on the difference, and calculates a current command value.

  In Step 3 (S3), the disturbance torque calculator 303 generates the second joint torque generated in the second joint portion 102b due to the other-axis interference based on the third motor angle target value 213 of the third servo motor 104c. 609 (first joint torque) is calculated. In this step, the disturbance torque calculator 303 obtains the second joint torque 609 by calculating the third motor angle target value 213. The calculation is performed by forward kinematics calculation and dynamics calculation based on the first data 201 communicated from the control device 200 and the mass information of each link of the manipulator robot. In Step 3, since the first data 201 is composed of target angle values of all the motors including the third target motor angle value 213, the second servo motor 104b performs forward kinematics calculation and dynamics calculation. It is possible.

  In step 4 (S4), the torque current converter 304 converts the current 305 corresponding to the second joint torque based on the joint torque of the second servomotor. In this step, the torque current converter 304 calculates a current 308 corresponding to the second joint torque by dividing the second joint torque 709 by the known torque constant of the second motor 306.

  In step 5 (S5), the current amplifier 302 adds the current command 308 and the current 305 corresponding to the second joint torque, and supplies the current 307 to the motor so as to follow the added value. If the operation has not ended, the operation is repeated from (S1), and if the operation has ended, the end is reached (step 6 (S6)).

  Torque that counteracts the second joint torque while the second joint torque applied to the second joint 102b is applied to the second joint 102b by the step 1 (S1) to the step 6 (S6) by driving the third joint 102c. Occurs in the second servomotor 104b. By canceling the second joint torque, the error between the second motor angle 302 and the second motor angle target value 212 caused by the other-axis interference can be eliminated. In this way, only the first data 201 can be communicated, and other-axis interference can be eliminated without increasing the amount of communication.

  In addition, the first to sixth servo mechanisms can calculate the inertial load applied to the joint attached to the motor controlled by the forward kinematics calculation. Since the optimal gain can be determined by changing the control gain in inverse proportion to the square root of the inertial load, gain scheduling control for setting the optimal gain according to the posture is possible.

  The control of the present invention enables correction of other-axis interference and gain scheduling control without increasing the communication volume, and enables high-precision control of the manipulator robot without a shield on the communication line connecting the servo mechanism and the motor driver. . Therefore, it is possible to reduce the manipulator robot by suppressing other-axis interference without increasing the communication amount.

  Although only the relationship between the second joint portion 102b and the third joint portion 102c has been described above, the first joint portion 102a, the fourth joint portion 102d, and the fifth joint portion 102e with respect to the second joint portion 102b are described. The interference torque of the sixth joint portion 102f can be similarly corrected. Further, correction of interference torque for other joints other than the second joint portion 102b and gain scheduling control are also possible.

(Second Embodiment)
In the second embodiment, unlike the first embodiment, the measured value of the motor is sent to the control device 200 and / or the control units 105a to 105f to suppress other-axis interference.

  A robot control system according to a second embodiment of the present invention will be described with reference to FIG. The control device 200 includes a first control unit 105a, a second control unit 105b, a third control unit 105c, a fourth control unit 105d, a fifth control unit 105e, a sixth control unit 105f, and a bus cable 106. Connected through.

  Similarly to the first embodiment, the second embodiment also describes control when the third joint portion 102c suppresses other-axis interference that affects the second joint portion 102b.

  From the third control unit 105c, the first control unit 105a, the second control unit 105b, the fourth control unit 105d, the fifth control unit 105e, the sixth control unit 105f, and the control unit 200 are connected to the second control unit 105c. Data 501 is communicated. The format of the second data 501 includes a second ID 510 and an actually measured angle value 511 of the third servo motor 104c.

  The control method of the robot control system of the second embodiment is the same as the flowchart of the first embodiment shown in FIG. 4, and only different points will be described.

  In step 1 (S1), the control device 200 transfers the second motor angle target value 212 of the second servo motor 104b (first servo mechanism) to the second control unit 105b (first servo mechanism). Is transmitted by multicast communication. Also, the second data 501 including the actual measured value 511 of the joint angle of the third servo motor (second servo motor) is multicasted to the control unit and the control mechanism 200 including the second control unit 105b. . The second control unit 105b can recognize the data transmitted from the third control unit 105c by the second ID 510.

  In step 3 (S3), the disturbance torque calculator 313 calculates the second joint torque of the second servo motor based on the measured motor angle 511 of the third servo motor 104c.

  There is a slight difference between the third motor angle target value 213 and the third motor angle actual measurement value 511, and the third motor angle actual measurement value 511 more accurately represents the actual movement. Therefore, in the second embodiment, the other-axis interference can be suppressed with high accuracy and gain scheduling control can be performed by using the measured motor angle value.

  The distributed control type robot control system of the present invention can be used to control a robot such as an industrial robot.

DESCRIPTION OF SYMBOLS 100 Robot 101a-101f 1st-6th arm 102a-102f 1st-6th joint part 103a-103f Rotating shaft 104a-104f 1st-6th servomotor 105a-105f 1st-6th control part 200 control unit 201 first data 311 controller 312 current amplifier 313 disturbance torque calculator 314 torque current converter 501 second data 608 third joint torque 609 second joint torque

Claims (5)

A distributed control type robot control system comprising a control device and a multi-joint robot, wherein a plurality of joints of the multi-joint robot are provided with control units,
Multicasting the target value of the joint angle of the first servo motor and the target value of the joint angle of the second servo motor to the first control unit that controls the first servo motor from the control device Send by communication,
The first control unit drives a joint angle of the first servo motor so as to cancel a load applied to the first servo motor by the second servo motor. Distributed control type robot control system.   The first control unit calculates a load applied to the first servomotor by the second servomotor from a target value of a joint angle of the second servomotor that is multicast-communicated. The distributed control type robot control system according to claim 1, wherein:   The first control unit calculates a load applied to the first servo motor by the second servo motor from an actual measurement value of a joint angle of the second servo motor that is multicast-communicated. The distributed control type robot control system according to claim 1, wherein: The articulated robot is a 6-axis articulated robot;
4. The distributed control robot according to claim 1, wherein target values of joint angles of all six axes are transmitted from the control device to all six axis servo motors by multicast communication. Control system. A control method of a distributed control type robot having a control device and an articulated robot, wherein a servo control unit is provided at a plurality of joints of the articulated robot,
Transmitting data including the target value of the joint angle of the first servo motor and the target value of the joint angle of the second servo motor from the control device to the first control unit by multicast communication, Obtaining the motor angle of the second servomotor;
The first control unit calculates a joint torque of the first servomotor based on a motor angle target value of the second servomotor;
The first servomotor converting a current corresponding to the first joint torque based on the joint torque of the first servomotor;
The current corresponding to the target value of the joint angle of the first servomotor so that the first controller cancels the load applied by the second servomotor to the first servomotor. And adding a current corresponding to the first joint torque to energize the first servo motor;
A distributed control type robot control method comprising:

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