JPS6250906A - Control device for industrial robot - Google Patents

Abstract

PURPOSE:To improve the safety by storing the electric current value of the servomotor of a time series, and stopping the robot when the difference in the comparing electric current value at the time of the trial operation exceeds the constant value. CONSTITUTION:The electric current value of a servomotor 8 of respective axes from an electric current detecting device 11 stuck to the feeding cable of a sevomotor 8 is A/D-converted. At the time of the completion of the teach ing, the robot is made into a trial operation mode, the robot is operated by the taught channel and a digital electric current value (iab) of respective axes of the motor 8 is stored tos a standard electric current value memory 13 for a constant time clearance DELTAt. Next, at the time of the reproduction work opera tion, an electric current value (ia) of respective axes of the motor 8 is successive ly stored to an electric current value memory 14 for the clearance DELTAt, at a comparing judging part 15, for respective aces, the standard electric current value (iab) and the electric current value (ia) are compared, and when the differ ence exceeds the constant limit, the contact or the collision of the robot are detected and the robot is stopped.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention provides a control device for an industrial robot C2 having a teaching/regeneration function, which has an improved monitoring and protection function during special regeneration operation. It is related to

[Technical background of the invention and its problems] Figure 5 shows a structural diagram of an industrial robot. Figure (a) shows a horizontal articulated robot, with the θl axis and θ
The structure allows the first and second arms to rotate around the z-axis, and by adding the rotation θB-axis of the two-handed light and the vertical Z-axis, positioning can be performed at any position or posture in space. be able to. Figure (b) shows a cylindrical coordinate robot, which has a total of 5 degrees of freedom of motion: the rotation O1 axis of the waist, the vertical Z axis of the arm, the R axis of arm extension and contraction, the 02 axis of arm twisting, and the θB axis of wrist bending. have.

In addition, the same figure (C) shows a Cartesian coordinate robot, with a gate-shaped
A Y-axis arm is mounted on the axis arm, and a two-axis arm is attached to this, and a wrist having a bending ol axis and a torsion O3 axis is attached to the tip C: of the two-axis arm. Same figure (d)
is a vertically articulated robot with 6 degrees of freedom: hip rotation θl axis, shoulder rotation 0z axis, elbow rotation θB axis, wrist twisting O4 axis, wrist bending O8 axis, hand rotation O6 axis, Any point I in space: The workpiece can be moved in any posture.

FIG. 6 shows a block diagram of the control device of the industrial robot, in which the central processing unit IC includes a storage device 2, a point teaching device 3, a program input device 4, an operation panel 5,
An external storage device 6 and a servo drive device 7 are connected via an input/output path.

Further, this servo drive device 7, a servo motor 8 built into the robot interior C1, and a rotation sensor 9 are each connected in parallel.

In order for ζ2 to perform such work on industrial robot C2, it is usually necessary to create a program for the two tasks in advance and store it in the storage device 2C2. and program sequence information, the former is input from the point teaching device 3, and the latter from the program input device 4.When making a general C2 industrial robot automatically operate, the program in memory device #2 is inputted to 1. The contents are taken out one by one, the contents are decoded, and the program sequence C is issued.Accordingly, an operation command for the servo drive device 7C is issued.

As mentioned above, the monitoring and protection function of industrial robots during remanufacturing operations has traditionally been to constantly detect the robot's operating position and detect when the robot's movement deviates from a predefined safe working range. There are functions such as determining that there is an abnormality and stopping the robot.This position monitoring or protection function includes the following 〇 ■ Soft limit monitoring function ° Stage of deciphering the robot's operation commands If it is determined that the robot will move beyond the motion range predefined by software, the motion command will not be executed.In other words, the robot will not move.

■Hard Limit Monitoring Function A limit switch is installed at the end of the robot's operating axis (IJ).If this IJ limit switch operates, the robot's movement will be stopped.

■ Mechanical stopper A mechanical stopper is provided, and in an emergency such as when the robot runs out of control, a part of the robot member collides with this stopper and stops.

The conventional monitoring and protection functions of industrial robots as described above monitor the operating position of the robot, so they cannot effectively protect against collisions with workpieces, peripheral equipment, etc. within the normal operating range. There was a possibility that the device would not be able to perform its function and the device would be damaged.

[Object of the Invention] The present invention is intended to improve the above-mentioned problems, and is intended to solve the problem that collisions between the sea robot and workpieces, peripheral devices, etc. during regeneration operation are normal for industrial robots (industrial robots) having teaching/regeneration functions. It is an object of the present invention to provide a control device for an industrial robot that can promptly exert a protective function even if an occurrence occurs within the range.

[Summary of the Invention] In order to achieve the above objects (2), the present invention detects the current value of a servo motor during one cycle of robot reproducing operation in an industrial robot having a teaching/reproducing function, and Then, proceed to C2 regeneration work operation (automatic operation)
During the operation cycle of the robot, monitor the servo motor current and compare it successively with the current value stored during the trial run, and if the difference in current value exceeds a certain value, It is characterized by having a function to stop.

[Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described in detail. Figure 1? −
In this figure, parts I: that are the same as those in FIG. 5 are designated by the same reference numerals.

A conventional control device (with the addition of a motor current monitoring device 10 and a function of storing and monitoring the current value of the servo motor 8).

FIG. 2 is a block diagram showing details of the motor current monitoring system [10], in which the current value of the servo motor 8 of each axis detected by the current detector Ill2 attached to the servo motor 8 supply cable (unit). is converted into a digital current value by an analog-digital converter 121.

When the teaching is completed, put the robot into the test run mode, operate the robot along the taught path, and set the digital current value tab of each axis of the servo Tanabata 8 to the standard current value ME71J13 for a certain period of time. The gap Δ is memorized for each interval.

Next (-1 during regeneration work operation C;, the digital current value 1a of each axis of the servo motor 8 is sequentially changed to the current value mesori 14 E
- Comparison/judgment section 151 that stores the electric current value Δ for a certain period of time and sequentially compares and judges these current values, compares the f-standard current value jab and the sequential current value 1 for each axis, and calculates the difference l jab.
-ia! If it exceeds a certain limit ε, it is determined that the robot came into contact with or collided with something.

FIG. 3 shows servo motor current values for a certain operating axis during a robot operating cycle. The solid line is the standard 1! If 2 is the current value and 2 is the current difference limit, then when a servo current value exceeding the broken line is detected during regeneration operation, the safety protection function as shown in C below is activated.

■ εl: Outputs a flow value abnormality alarm.

■ εB = Turn off the servo power and turn off the robot (ε8
〉ε2) Always stops.

Figure 4 shows another embodiment of the motor current monitoring device.
What is shown in the figure is the inside of the servo drive device 7 for each axis (with a current monitoring device 10 incorporated therein, and the structure and operation are the same as those in FIG. 2).

[Effects of the Invention] According to the above explanation (2), the current value of the servo motor during one cycle of operation during a test run of the robot is stored in time series (2), and the servo motor during regeneration operation is Detecting contact or collision with the robot by comparing the motor current values and stopping the robot C:
Therefore, it is possible to provide a control device for industrial robots with improved safety.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a control device for an industrial robot according to an embodiment of the present invention, Fig. 2 is a block diagram of a motor current monitoring device shown in Fig. 1, and Fig. 3 is a block diagram of a servo motor current during the operation cycle of the robot. 4 is a block diagram of a motor current monitoring device according to another embodiment of the present invention, FIG. 5 is a structural diagram of an industrial robot, and FIG. 6 is a block diagram of a conventional industrial robot control device. shows. Figure 1 Figure 2

Claims (1)

[Claims] In a control device for an industrial robot that has a teaching/regeneration function, there is a standard current value memory that stores in time series the drive current value of one cycle of regeneration operation during trial operation, and a standard current value memory that stores the drive current value of one cycle of regeneration operation during trial operation, and the value stored in the standard value memory and work operation. 1. A control device for an industrial robot, comprising: a comparison/judgment section that successively compares drive current values at different times; and a robot capable of stopping the robot based on the judgment result of the comparison/judgment section.