JP2003039348A - Control device for remote control robot - Google Patents

Abstract

(57) [Summary] [Problem] Using a joystick or master arm,
Provided is a control device for a remote-controlled robot that can reliably feed back a force sense only at the time of contact and can perform a contact operation efficiently. A remote control robot control device including a master control unit that controls a joystick or a master arm, a robot control unit that controls a robot, and a communication unit that communicates between the master control unit and the robot control unit. The control unit has a motor control unit 12 that detects a joint angle and performs position / speed state feedback control based on an angle command in a joint coordinate system. Flexible control means 1 for restricting
20. A control device for a remotely controlled robot, comprising: a unit 125 for monitoring a deviation of a torque command value before and after a torque limit; and a unit 113 for generating a force feedback signal according to the deviation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a robot or the like, and more particularly to a control device for a remote control robot capable of feeding back a sense of force to an operator without a force sensor.

[0002]

2. Description of the Related Art When it is dangerous for humans to approach a work place, or when the work is physically and mentally burdensome to humans, a robot is placed at the work place to provide a safe and comfortable place. A so-called remote-controlled robot in which an operator performs a work while remotely controlling the robot is sometimes used. In this case, the operator often controls the robot by giving a command to the robot using a joystick or a master arm. At this time, when performing work while the robot arm is in contact with the work target such as assembly work or equipment maintenance work, force control is performed on the robot side, or the operator is not allowed to move the robot arm tip to the work target. The contact force of is fed back, that is, force feedback is performed. By doing so, the work can be performed without destroying the work target, and the burden on the operator can be reduced. Force feedback includes a system using a force sensor and a system without a force sensor. The method using a force sensor allows accurate force feedback, but is often performed without a force sensor in terms of reliability and cost.

FIG. 5 shows an overall configuration of a conventional remote control robot of the force sensorless type. In FIG.
The master control unit 2 generates a command to the robot 5 from the information of the joystick 4 and controls the motor 42 of the joystick 4. The robot control unit 1 controls the robot 5. Normally, proportional-integral control of position and speed is performed for each joint position command. Communication between the master control unit 2 and the robot control unit 1 is performed by the communication unit 3.

A potentiometer 41 is attached to the joystick 4, and the swing angle of the joystick 4 can be detected. A command generation unit 21 generates a position command for the robot 5 according to the detected angle. The generated command is transmitted to the robot control unit 1 via the communication unit 3, the operation command unit 11 reconfigures the command to the motor 51 of each axis of the robot 5, and the command is delivered to the motor control unit 12.

When the robot 5 contacts the work object, the joystick motor 42 is driven by sending a signal corresponding to the contact state to the motor control unit 22 of the master control unit 2, and the operator senses a force. It becomes possible to feel.

FIG. 6 shows a more detailed block diagram of the conventional robot controller 1. The position command of the Cartesian coordinate system from the master control unit 2 in FIG. 5 is input to the joint position command generation unit 111, and inverse kinematics calculation is performed, whereby the robot 5
Each joint position command is generated. The motor control unit 12 uses a normal position-speed proportional-integral control, and outputs a current command from the position-speed control unit 121 to the motor 51 through an amplifier 122. Further, in the coordinate conversion unit 113, a forward kinematics operation is performed from the encoder values of the joint axes obtained from the encoder 52 and the other-axis encoder to generate the position feedback value of the orthogonal coordinate system. Then, the force feedback signal generation unit (position deviation monitoring unit) 112
Then, the deviation between the orthogonal position command value and the feedback value is calculated and sent to the robot communication unit 31. According to this position deviation, the joystick motor 42 is controlled via the master communication section 32 in FIG.

In the method disclosed in Japanese Unexamined Patent Publication No. 8-71960, the load of the motor is detected by the current value of the motor, and the joystick operating force is fed back according to the detected current value.

Although the joystick is used as the operating device here, a master arm may be used instead of the joystick. In particular, in the case of a so-called master arm with the same degree of freedom and the same joint structure as the robot arm, the force on the master arm can be increased by monitoring the position deviation of each corresponding joint without performing forward kinematics calculation on the robot side. Haptic feedback is possible.

[0009]

However, in the above-mentioned conventional control device for the remote control robot, since the position deviation is used, the position deviation increases due to the communication delay, the delay in following the control of the robot arm, and the like. There was a problem that the force sense was erroneously fed back by the motion of the robot even if it was not in contact with an object.

Further, in the method of detecting the current value of the motor in Japanese Patent Laid-Open No. 8-71960, the dynamic characteristics of the robot such as gravity and inertia are added to the current value, so that the rated torque is actually exceeded. However, it is difficult to perform the work while the robot arm is brought into contact with the work object by the joystick and the feeling is fed back.

Therefore, an object of the present invention is to provide a control device for a remote-controlled robot, which uses a joystick or a master arm to reliably feed back a force sensation only at the time of contact and can efficiently perform a contact work. That is.

[0012]

In order to solve the above problems, a control device for a remote-controlled robot according to claim 1 includes a master control unit for controlling a joystick and a master arm, a robot control unit for controlling a robot, In a remote control robot control device having a communication unit for communicating between the master control unit and the robot control unit, the robot control unit detects a joint angle, and based on an angle command in a joint coordinate system, position / speed The motor control means 12 for performing the state feedback control of the above, and the flexible control means 120 for limiting the torque at the subsequent stage of the position / speed control section of the motor control means 12.
And a means 125 for monitoring the deviation of the torque command value before and after the torque limit, and a means 113 for generating a force feedback signal according to the deviation.

According to a second aspect of the present invention, there is provided a control device for a remote-controlled robot, wherein the flexible control means 120 is provided with a constant torque limit value for each joint.

In the control device for a remote-controlled robot according to a third aspect of the present invention, the flexible control means 120 calculates a torque for maintaining the acceleration torque and speed of the motor from the operation command of the motor of each axis, and adds the calculated value. It is characterized in that the torque limit value is used.

According to another aspect of the present invention, there is provided a control device for a remote control robot, wherein a master control unit for controlling a joystick and a master arm, a robot control unit for controlling a robot, and communication between the master control unit and the robot control unit. In a remote control robot controller having a communication unit, the robot control unit has motor control means 12 for detecting a joint angle and performing position / speed state feedback control based on a position command in a work coordinate system. , The motor control means 12
Flexible control means 1 for restricting force downstream of the position / speed controller
20, means 125 for monitoring the deviation of the force command value before and after the force restriction, and means 113 for generating a force feedback signal according to the deviation.

A control device for a remote control robot according to a fifth aspect of the present invention is characterized in that the flexible control means 120 is provided with a constant force limit value for each work coordinate axis.

According to a sixth aspect of the present invention, there is provided a control device for a remote-controlled robot, wherein the flexible control means 120 calculates and adds a torque for maintaining the acceleration torque and speed of the motor from the operation command of the motor for each axis. Is converted into a force of each work coordinate system, and the force of each work coordinate system is set as a force limit value.

According to a seventh aspect of the present invention, there is provided a control device for a remote control robot, wherein the motor control means 12 adds a gravity torque applied to each joint axis to a torque command.
28 is provided.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION A control device for a remote control robot according to a first embodiment of the present invention will be described with reference to FIG. The overall configuration of the control device is the same as that of FIG. 5, and the same components are designated by the same reference numerals and the description thereof is omitted. The same applies to the subsequent drawings. FIG. 1 shows the configuration of a robot control unit 1 according to the present invention. In the conventional position / speed control system, a limit value setting unit 124, a flexible control unit 120 including a torque limiting unit 123, a gravity compensating unit 128, and a deviation monitoring unit. 125 and the force feedback signal generation part 113 are added.

Here, the function of each element will be described. First, the flexible control means 120 including the torque limiting unit 123 and the limit value setting unit 124 will be described.

The flexible control means 120 is a high-order operation command section 1
The torque command generated by the position / speed control unit 121 according to the command from 1 is output to the amplifier after being restricted by the torque limiting unit 123 so that it does not exceed a certain torque limit value set by the limit value setting unit 124. To do. Although not shown, the output of the speed integration of the position / speed control unit 121 is limited to the minimum value necessary for the follow-up operation of the motor.
By doing so, even when a large torque command is generated due to the robot contacting the object and the position deviation and the speed deviation increasing, it is possible to limit the torque command to a small value by this torque restriction. The robot can be operated so as to follow the work target. That is,
It is possible to maintain a stable contact state between the robot and the work target in any part of the robot arm without generating an excessive torque.

Further, the gravity compensating unit 128 calculates the gravity torque of each axis applied by the own weight of the robot arm or the work tool attached to the tip according to the posture of the robot, and the gravity is added to the latter stage of the torque limiting unit. Even if the torque limit value is set small by adding the compensation torque, it is possible to prevent the robot arm from dropping due to its own weight due to insufficient torque. Further, since the gravity balance is always maintained, the torque limit value set by the limit value setting unit 124 does not need to consider the torque for gravity. Therefore, the torque limit value can be set small, and a small contact force can be responded to.

Next, the deviation monitoring unit 125 and the force feedback signal generating unit 113 will be described. When a large torque command that exceeds the torque limit value set by the position / speed control unit 121 is generated due to the robot 5 coming into contact with the work target and the control deviation such as position and speed increasing,
The deviation monitoring unit 125 calculates the deviation between the input torque to the torque limiting unit 123 and the limit value. If the torque generated by the position / speed control system does not exceed the torque limit value, the deviation is zero. This torque deviation is calculated for each joint of the robot and sent to the force feedback signal generation unit 113. The force feedback signal generation unit 113 converts the torque deviation into the force deviation in the work coordinate system by (Equation 1).

[0024]

[Equation 1] Here, J− ^T is a transposed inverse matrix of the Jacobian matrix, and τd is a deviation between the torque command of each joint axis and the torque limit value. Further, Fd is a deviation of force in the work coordinate system. This Fd is used as a contact force with the work object, and after dead zone processing and filter processing are performed, it is used as a force feedback signal to the joystick 4 shown in FIG. It is transmitted to the control unit 2 using the communication means 3. By calculating the contact force in this way, it is not necessary to use a force sensor, and it is possible to feed back the contact state to the operator regardless of which part of the arm is in contact.

FIG. 2A is a diagram showing the operation of the torque limiter 123. Since the torque generated by the position / speed control unit 121 (torque command value) is limited by the torque limit value, even if the robot arm makes contact with the work object, the robot arm operates flexibly and at the same time the torque generated by the position / speed control unit 121 is generated. Since the deviation between the torque limit value and the torque limit value varies depending on the contact state, the operator operating the robot can feel the force according to the contact state, and can perform smooth work. Also, setting the torque limit value as low as possible enables response to a smaller contact force.
Further, since it is possible to change the maximum contact force applied to the object according to the torque limit value, it is possible to deal with various works.

FIG. 4 is a block diagram showing the structure of the master control unit. The command generator 21 converts the output of the potentiometer 41 of the joystick 4 into a velocity and integrates it to generate a position command in a rectangular coordinate system. In addition, the motor control unit 2
In 2, the torque command to the motor 42 is generated from the force feedback signal from the robot 5 and the operation amount of the joystick 4, and is output to the current amplifier to operate the motor.
By performing such control, the spring constant from the neutral point of the joystick 4 can be changed by the motor according to the direction and magnitude of the force calculated by the force feedback signal generation unit 113 of the robot control unit 1. Therefore, it is possible to present a force sensation to the operator according to the contact state of the tip of the robot 5. Moreover, even if the joystick is released from the hand, the robot can be stopped while maintaining a constant contact force.

A remote control robot controller according to the second embodiment of the present invention will be described. The second embodiment is different from the first embodiment in the torque limit value set by the limit value setting unit 124 of the flexible control means shown in FIG. First
In the embodiment, the torque limit value set by the limit value setting unit 124 is a constant value. The second embodiment uses (Equation 2) as the torque limit value.

[0028]

[Equation 2] Here, τlim is the torque limit value, J _L is the inertia value of the robot arm, V is the viscous friction coefficient of the joint, C is the Coulomb friction coefficient, and W is the limit width value. As a method of obtaining the inertia value, (1) a typical value is used, (2)
Calculated by dynamics calculation according to the posture of the robot,
(3) There is a method of using a parameter identification means such as an observer. Further, the viscous friction coefficient and the Coulomb friction coefficient can be obtained in advance from the relationship between speed and friction. A value obtained by adding the torque for the speed due to the Coulomb friction and the viscous friction and the torque for the acceleration due to the inertia becomes a value substantially equal to the torque command in the position / speed control unit. Also,
The limit width value W is set to an appropriate value of about several% of the maximum torque in order to absorb the error in the above calculation.

From the above calculation result, as shown in FIG. 2B, the minimum torque limit value according to the motion command to the robot can be calculated. When the robot moves in normal operation, the torque for the speed and acceleration is generated by the state feedback loop in the position / speed controller, but external force is applied to the robot (or the robot itself contacts the outside). In this case, the robot is pushed or deviates from the trajectory by an external force, so that a large control deviation of the position and the velocity occurs. Therefore, the torque command at that time deviates from the torque limit range calculated by the limit value setting unit. At this time, since the torque limit value is successively set to the minimum with respect to the motion command to the robot, the force feedback can be performed with a smaller contact force. Further, when it is desired to increase the contact force, the limit width value W may be increased.

A control device for a remote-controlled robot according to a third embodiment of the present invention will be described with reference to FIG. While the first and second embodiments are based on the position / speed control system of the joint coordinate system, FIG. 3 is based on the position / speed control system of the working coordinate system. Further, as in the first embodiment, a flexible control means 120 including a force limit value setting unit 124 and a force limit unit 123, a deviation monitoring unit 125, and a force feedback signal generation unit 113 are added.

The position / speed control system of the working coordinate system is constructed as follows. That is, in the forward kinematics calculation unit 127,
From the joint angle feedback measured by the encoder 52 of the motor 51, the solution of the forward kinematics operation for obtaining the position of the end effector of the robot 5 is obtained, and the work is performed based on the solution of the position feedback and the position command of the work coordinate system. A position / speed control system in a coordinate system is configured. The force command value of the position / velocity control unit 121 in the work coordinate system is restricted by the force restriction unit 123 so as not to exceed the force restriction value set by the limit value setting unit 124, and then the force-torque conversion calculation unit. 1
The torque of each axis is converted by 26 and output to the amplifier of each axis. By thus constructing the position / speed control system in the work coordinate system, the flexible control means 1 based on the work coordinate system
20 can be realized. As a result, it is possible to set the flexibility in the work coordinate system, such as soft in the X direction and hard in the Y and Z directions.

In the deviation monitoring unit 125, the position / speed control unit 12
The deviation between the force command value of 1 and the force limit value set by the limit value setting unit 124 is calculated. If the force limit is not exceeded, the deviation is set to zero. In the haptic feedback signal generation unit 113, the deviation is subjected to dead zone processing, filter processing, etc.
As a force feedback signal to the joystick 4,
Send to the master control unit 2 side. By configuring the position / speed control system in the work coordinate system and limiting the force in this way, the force deviation is also output as it is in the work coordinate system.Therefore, the work coordinate is better than force feedback by torque limitation in the joint coordinate system. It enables haptic feedback that is faithful to the system.

Further, as the fourth embodiment of the present invention, the value of (Equation 3) is used as the force limit value of the limit value setting unit of the flexible control means of FIG.

[0034]

[Equation 3] Here, Flim is the torque limit value, J _L is the inertia value of the robot arm, V is the viscous friction coefficient of the joint, C is the Coulomb friction coefficient, and W is the force limit width value. J ^{- T} is a transposed inverse matrix of the Jacobian matrix. As a result, the force limit value can be sequentially set to the minimum with respect to the motion command to the robot, so that the force feedback can be performed even with a smaller contact force. When it is desired to increase the contact force, the force limit value width W may be set large.

In the above description, the joystick is used as the operating device, but force feedback can be similarly performed in a master arm with an actuator. At this time, the force feedback signal sent to the master control unit is distributed as torque to each joint actuator of the master arm by the Jacobian matrix calculated based on the structure of the master arm. Even with the master arm, force feedback can be performed without a force sensor.

[0036]

As described above, according to claims 1 to 7 of the present invention, in the control device for the remote-controlled robot,
Since the force feedback signal is generated according to the magnitude of the difference between the torque command and the torque limit value or the force command and the force limit value, which is not directly related to the position deviation of the position / speed control system, communication delay and control tracking There is no erroneous force feedback due to delay, etc., and force feedback is reliably performed, so work can be performed smoothly.

At the same time, by providing a torque limiting section and a force limiting section, even when the robot arm comes into contact with the work object, the robot arm can flexibly follow the movement, or even if the joystick is released from the hand, the robot arm is stopped with a constant contact force. Therefore, there is an effect that the safety of the robot is improved and the work load on the operator can be reduced.

According to the third and sixth aspects, since the minimum torque limit value or force limit value can be set with respect to the motion command of the robot, it is possible to respond to a smaller contact force.

Further, according to the fourth to sixth aspects, since the deviation of the force command in the work coordinate system is calculated at the time of contact, the force sense feedback more faithful to the work coordinate system can be performed.

According to the seventh aspect, the gravity torque is always compensated for by compensating the gravity torque leaning to each joint axis of the robot, so that the response can be made even for a small contact force.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a first embodiment of the present invention.

FIG. 2 is a diagram showing an operation of the first embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of a second exemplary embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration of a master control unit of the present invention.

FIG. 5 is a block diagram showing the overall configuration of a conventional remote-controlled robot.

FIG. 6 is a block diagram showing a configuration of a conventional robot controller.

[Explanation of symbols]

1: Robot controller 2: Master control unit 3: Communications department 4: Joystick 5: Robot 11: Operation Command 12: Motor control unit 21: Command generation unit 22: Motor control unit 113: Force feedback signal generation unit 120: Flexible control means 123: Torque limiter 124: Limit value setting section 125: Deviation monitoring unit 128: Gravity compensation unit

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hideo Nagata             2-1, Kurosaki Shiroishi, Hachiman Nishi-ku, Kitakyushu City, Fukuoka Prefecture               Yasukawa Electric Co., Ltd. F-term (reference) 3C007 HS27 JT05 KV01 LU07 LV18                       LV23

Claims (7)

[Claims] 1. A control device for a remote-controlled robot, comprising: a master control unit for controlling a joystick or a master arm; a robot control unit for controlling a robot; and a communication unit for communicating between the master control unit and the robot control unit. The robot control unit has a motor control unit 12 that detects a joint angle and performs position / speed state feedback control based on an angle command in the joint coordinate system. The position / speed control unit of the motor control unit 12 And a flexible control means 120 for limiting the torque, a means 125 for monitoring the deviation of the torque command value before and after the torque restriction, and a means 113 for generating a force feedback signal according to the deviation. A control device for a remote control robot characterized by. 2. The control device for a remote-controlled robot according to claim 1, wherein the flexible control means 120 is provided with a constant torque limit value for each joint axis. 3. The flexible control means 120 is configured to calculate a torque for maintaining an acceleration torque and a speed of the motor from an operation command of the motor of each axis and add the calculated value to a torque limit value. The control device for a remote-controlled robot according to claim 1. 4. A remote control robot control device comprising: a master control unit for controlling a joystick or a master arm; a robot control unit for controlling a robot; and a communication unit for communicating between the master control unit and the robot control unit. The robot control unit has a motor control unit 12 that detects a joint angle and performs a position / speed state feedback control based on a position command in a work coordinate system. The position / speed control unit of the motor control unit 12 And a flexible control means 120 for performing force limitation, a means 125 for monitoring a deviation of the force command value before and after the force limitation, and a means 113 for generating a force feedback signal according to the deviation. A control device for a remote control robot characterized by. 5. The control device for a remote-controlled robot according to claim 4, wherein the flexible control means 120 is provided with a constant force limit value for each work coordinate axis. 6. The flexible control means 120 calculates the torque for maintaining the acceleration torque and the speed of the motor from the operation command of the motor of each axis and converts the added value into a force of each work coordinate system, The control device for a remote-controlled robot according to claim 4, wherein the force of each work coordinate system is set as a force limit value. 7. The control of the remote-controlled robot according to claim 1, wherein the motor control means 12 is provided with a gravity compensation means 128 for adding a gravity torque applied to each joint axis to a torque command. apparatus.