JPH0413588A - Control unit for robot - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a control device for a robot having a force control function.

BACKGROUND OF THE INVENTION An example of a conventional robot control device having a force control function will be described with reference to FIGS. 3 and 4.

In FIG. 3, 1 is a force command unit which outputs a force command iFc. 6 is a robot, 11 is a force sensor attached to the tip of the robot, 5 is a motor for driving the robot, and 7 is a position detector attached to the motor 5 for detecting the position of the robot. 8 is a force sensor processing unit that processes the signal of the force F detected from the force sensor 11;
1, the detected minute signal is amplified and a force feedback value Ff corresponding to the force command value Fc is output. Reference numeral 2 denotes a force control calculating section which receives the force command value Fc and the force feedback value Ff, and is composed of a subtracter 10 and a gain calculating section 9.

The subtracter 10 inputs the force command value Fc and the force feedback value Ff and outputs a path difference value ΔF which is a subtracted value between the two. This path difference value ΔF is input to the gain calculation unit 9, and the robot 6
is converted into a position command value Xc (R) in the joint angle coordinate system. Here, (R) indicates a value in the joint angle coordinate system of the robot 6, and the same applies hereafter. 3 is a position control section,
The position command value Xc (R) and the position feedback value XF (R) which is the output of the position detector 7 are used as outputs to perform calculations and output the current command value re(R). 4 is a motor drive unit that drives the motor 5. FIG. 4 shows the configuration of the force correction calculation section 2. 12 is a multiplier that multiplies the path difference value ΔF by a gain Kf and outputs a position error command value ΔXc; 14 is a multiplier that outputs a position error command value ΔXc by an integrator 13, and a value Xc obtained by integrating the position error command value ΔXc from the absolute coordinate system W to the robot This is a coordinate converter that converts the position command value Xc (R) in the joint coordinate system R of No. 6.

The operation of the robot control device described above will be explained below.

The force command unit 1 outputs a force command value Fc in one direction of a specific coordinate system to the tip of the robot 6. The force sensor 11 detects the force acting on the tip of the robot 6. The force F detected by the sensor 11 is input to the force sensor processing section 8. The force sensor processing unit 8 receives this human force F and outputs a force Ff in a specific axial direction of the coordinate system designated by the force command unit 1, and inputs this to the subtracter 10. The subtracter 10 takes the difference ΔF between the force command value Fc and the force feedback value Ff, and applies this to the gain calculation unit 9.
send to The gain calculation unit 9 calculates the following equations (1) and (2), and calculates the integral value Xc obtained from equation (2).
Perform coordinate system transformation for .

ΔXc=Kf・ΔF ・・・・・・・・・・・・・・・
・・・(1)Xc−ΣΔXc ・・・・・・・・・
(2) The position command value Xc (R) obtained by the gain calculation section 9 is sent to the position control section 3. The position control unit 3 uses the position command value Xc (R) and the feedback value Xf (R) from the position detector 7 to calculate the position error value ΔX (R) and generates the speed command value Vc (R). Position control 3 next controls speed command value Vc (R) and position feedback value ΔXf (
A speed feedback value Vf (R) is calculated from R) and sent to the remote drive unit 4, which uses this to generate a current command value Ic (R). The motor drive unit 4 controls the current of the motor 5 so that the current value If flowing through the motor 5 matches the current command value 1c (R). As a result, the motor 5 drives the robot 6 so that the direction difference value ΔF becomes zero, and the force feedback f&Ff matches the force command value Fc in one direction of the specific coordinate system at the tip of the robot 6. The motion of each joint angle will be controlled to do so.

Problems to be Solved by the Invention However, with the above configuration, for example, there is a problem that it takes time to apply a force to an object from a state where no force is acting to reach a target value and balance the object. . In order to reach the target value in a short time, the gain is increased (this makes the robot more likely to vibrate when a force is applied).

Means for Solving the Problems In order to solve the above problems, a robot control device according to a first aspect of the present invention includes means for setting a plurality of sets of condition values and gain values, and a means for setting a plurality of sets of condition values and gain values, and a means for setting a plurality of sets of condition values and gain values. a means for determining whether the commanded condition value has been reached, a means for controlling the force using the commanded gain value, and a gain switching means for switching the commanded condition value and commanded gain value to another set of condition value and gain value when the commanded condition value is reached. It is equipped with The second invention is, in the first invention,
The magnitude of the detected force is used as the condition value.

In a third invention, in the first invention, the amount of change in the detected force is used as the condition value.

Operation This control device switches the gain according to the force detected by the force sensor according to a plurality of sets of condition values and gain values as shown in FIG. First, the gain value G is used until the magnitude or amount of change in the detected force exceeds 01. The operation is controlled as it is. When the means for determining whether the instruction condition value has been reached detects that the magnitude or amount of change in the detected force exceeds C, the gain value is updated to 61 by the gain switching means. The operation is controlled using this gain G until the magnitude or amount of change in the detected force exceeds 02. Similarly, gain value G
. When the magnitude or amount of change in the detected force exceeds Gn while the operation is controlled at -1, the gain value is updated to G.

Multiple sets of condition values and gain values held within the control device are
The operator can set a plurality of sets of condition values and gain values appropriately according to the content of the robot's work.

Embodiment FIG. 1 shows the configuration of a control device in an embodiment of the present invention. The only difference from the configuration of the control device shown in FIG. 3 is that a means 15 for setting a plurality of sets of condition values and gain values is added and the processing contents of the gain calculating section 9. The means for determining whether the instruction condition value has been reached and the gain switching means for switching the instruction condition and instruction gain to another set of condition value and gain value when the instruction condition value is reached are processed by the gain calculation unit 9. is realized within. Therefore, the explanation of other parts will be based on FIG. 3 (the above explanation will be referred to).

In this embodiment, the force command section 1 and the means 15 for setting a plurality of sets of condition values and gain values are constituted by, for example, a microcomputer and program shown in FIG. 5 having a microprocessor, memory, and Ilo, and a control calculation section Or, for example, it is configured by the same microcomputer (having a microprocessor, memory, and Ilo) as shown in FIG. The force control calculation unit 2 and the gain calculation unit 9 input a plurality of sets of condition values and gain values from the keyboard 19 and store them at a predetermined location in the two-port memory 20. Read out the set of condition values and gain values, and use them to produce the position command value according to the processing flow shown in Figure 2.c, H
C8,go is set as the initial value of ΔX, and while the absolute value of the difference ΔF between the target force value and the feedback value is greater than or equal to C, ΔX is calculated without changing the gain g, and the absolute value of ΔF becomes C. When the following is achieved, C and g are updated to the next condition value and gain to produce ΔX.

Next, an example will be described in which the control device of the above embodiment is used to pull an object having a relationship between positional displacement X and tension f as shown in FIG. 8, and to operate the object until it is balanced at the target force value Fc.

CI' as below as multiple sets of condition values and gain values
Set g.

C2〈0c. c gQ > g, > g2 Initially, while a force of less than Fc-〇oC is acting in the area of ■, g. It operates with a gain of

When x=a reaches 1 and a force of Fc-08 or more is detected, the gain is updated to g by the gain switching means and F
It operates at gain g1 until a force equal to or greater than c-c is detected (region ■). Furthermore, when a force equal to or greater than Fc-c is detected, the gain is updated to G2, and the operation continues at gain g2 until the absolute value of the difference between the force and the target force value reaches 02.
Since C2<O, the gain is not switched until the target force is reached. In the above operation, g.

From gl to g2, the gain is decreased (
Therefore, when the object is soft, the gain is high (moves quickly), and as the object becomes harder, it is operated at a low gain that makes it less likely to vibrate.This allows the target force to be reached quickly and stably.

Furthermore, in the embodiment described above, the process for determining whether the instruction condition value has been reached can be configured to compare the detected force change amount and C.

FIG. 9 shows the processing flow of the gain calculation section in this case.

Here, the amount of change in force is expressed as the amount of change ΔFf in the force feedback value with respect to the previous operation position command displacement ΔX, and can be regarded as the compliance of the object on which the force acts at that time. If the amount of change in the detected force is used to determine whether the instruction condition value has been reached, there is an advantage that it can be handled even when there is an offset in the relationship between positional displacement and force.

Effects of the Invention In the robot control device of the present invention, the pair of gain value and condition value is switched in small increments according to the commanded condition value, and since there are no large changes, abnormal vibrations do not occur (in addition, the force quickly stabilizes at the target value). It can also be set to reach .

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a robot control device according to an embodiment of the present invention, FIG. 2 is a processing flow of a gain calculation unit in an embodiment of the present invention, and FIG. 3 is a block diagram of a conventional robot control device. Fig. 4 is a block diagram of a conventional gain calculation unit, Fig. 5 is a block diagram of a microcomputer that implements the means 15 for setting multiple sets of condition values and gain values, and Fig. 6 is a configuration diagram of two examples of the force control calculation unit. Relationship diagram between positional displacement of object and tension, 1st
...force command section, 2...force control calculation section,
3...Position control unit, 4...Motor drive unit, 5...Motor, 6...Robot,
7...Position detector, 8...Force sensor processing unit, 9...-Gain calculation unit, 1o...
Subtractor, 11...Force sensor, 12...
Multiplier, 13... Integrator, 14... Coordinate converter, 15-... Means for setting a plurality of condition values and gain values, 16... CPU, 17...
...Memory, 18...Ilo, 19...
・CRT and keyboard, 20... port memory, 21... CPU, 22... memory,
23...I100 Figure Figure ■-------------=■-■-

Claims (3)

[Claims] (1) A means for setting multiple sets of condition values and gain values, a means for determining whether the instructed condition value has been reached, a means for force control using the instructed gain value, and an instruction when the instructed condition value is reached. A robot control device comprising gain switching means for switching a condition value and instruction gain value to another condition value and gain value set. (2) The robot control device according to claim 1, wherein the condition value is the magnitude of the detected force. (3) The robot control device according to claim 1, wherein the condition value is an amount of change in the detected force.