JPH04362707A - Teaching/reproduction type robot controller - Google Patents

Abstract

PURPOSE:To prevent the vibrations of a teaching/reproduction type robot by smoothing the command signal which drives a robot arm, etc., and then smoothing the change of acceleration. CONSTITUTION:A teaching/reproduction type robot controller stores the intermittent coordinate data at each interval of the working loci of the robot elements like an arm, a wrist, etc., through a teaching job and then carries out a reproduction job based on the intermittent coordinate data. In such a controller, an interpolator 1 consisting of an LPF is provided at the next stage of the command signal output obtained by giving the correction of the positional deviation to the intermittent coordinate data which are successively taken out in a reproduction state based on the feedback data given from a position detector 7 of a robot driving means 8. In such a constitution, the intermittent command signal is smoothed and inputted to the means 8 which drives the robot elements. Thus the teaching/reproduction type robot is controlled.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a control device for a teaching/reproducing robot that repeatedly performs reproducing work according to coordinate data of a work trajectory obtained by teaching work, and in particular, the present invention relates to a control device for a teaching/reproducing robot that repeatedly performs reproducing work according to coordinate data of a work trajectory obtained by teaching work. The present invention relates to a robot control device that reduces acceleration such as sudden reversals, smoothes changes in acceleration, and controls sudden changes in speed to a minimum.

0002

[Prior Art] In a teaching/reproducing robot, the movement locus of a tool such as a painting gun or a welding torch is taught to the robot through a teaching operation as coordinate data, and during reproduction, these coordinate data are sequentially retrieved and coordinate transformation is performed. It is configured to perform arithmetic processing such as interpolation calculations and repeat playback operations that follow a work trajectory taught in chronological order. Although the output cycle T of such coordinate data depends on the processing speed of the arithmetic device used, it is generally 10 to 30 ms since it requires complex arithmetic processing such as coordinate transformation. If the coordinate data is output intermittently in the output period T, that is, in a stair-like manner, the acceleration and its changes due to sudden acceleration, sudden reversal, etc. when outputting the sequentially output coordinate data are large, and the arm , vibrations of robot elements such as the wrist occur. As a conventional technique for solving the above-mentioned problems, there is a technique disclosed in Japanese Patent Application Laid-open No. 127110/1983. As shown in FIG. 10, this prior art teaching/reproducing robot control method extracts the digital coordinate data stored in the microcomputer 20 during the teaching work into a work operation procedure, and outputs it from a D/A converter or the like. The interpolator 21 converts the signal into an analog value and sends it to the servo driver 22 for driving the robot elements. Servo motor 23 which is the drive source of the robot element
The current position of is detected by a position detector 24 such as a rotary encoder, the current position signal is fed back, the position is corrected so that the difference between the position command signal and the current position signal becomes zero, and the servo driver 22 drives the servo motor 23. is positioned at the work position corresponding to the coordinate data. In this control method, the step-like command signal is smoothed into a ramp shape and given to the robot drive system as a target value, thereby reducing the acceleration during sudden acceleration and sudden reversal, and reducing the change in speed. It is.

0003

[Means for Solving the Problem] However, in the above-mentioned prior art, feedback data, which is a digital quantity from the position detector 24, is inputted to the stage after the interpolator that smoothes the intermittent coordinate data. As a result, the input signal to the servo driver 22 becomes an intermittent signal. This intermittent signal can have a negative impact in the form of vibration on electric robots that have few damping factors such as oil viscosity and cylinder resistance. SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, it is an object of the present invention to provide a control device that controls a robot by smoothing command signals input to a drive system of a robot element.

0004

[Means for Solving the Problems] To achieve the above object, the present invention stores intermittent coordinate data at predetermined intervals of the work position locus of robot elements such as arms and wrists through teaching work, and In a control device for a teaching/reproducing robot that performs reproducing work according to coordinate data, the intermittent coordinate data sequentially retrieved during reproducing is output with position deviation corrected based on feedback data from a position detector provided in the robot driving means. An interpolator configured with a low-pass filter is disposed at a subsequent stage to smooth the intermittent command signal and input it to the drive system to drive the robot element. has been done.

[0005]

[Operation] According to the present invention, in the cycle of periodically outputting coordinate data and driving robot elements in a teaching/reproducing robot, an interpolator consisting of a low-pass filter is installed after correcting the positional deviation of the coordinate data using feedback data. The high-frequency components of the intermittent coordinate data are removed and smoothed, and this output signal is input to the drive system of the robot element to smooth changes in acceleration and eliminate vibration.

[0006]

[Embodiment] Next, an embodiment of the present invention will be described. FIG. 1 is a block diagram of a control device for an electric motor-driven robot to which the present invention is applied, and FIG. 2 is a circuit diagram of a low-pass filter constituting an interpolator in the control device. In the teach/replay type robot, as described above, the coordinate data of the working locus of the robot elements such as the arm is stored in the storage section of the microcomputer 2 according to the order of the working operations through the teaching work. During playback, this stocked digital coordinate data is retrieved in the order of work operations, and after being subjected to arithmetic processing such as coordinate transformation in the arithmetic processing unit 3, feedback is provided from the position detector 7 that detects the current position of the robot element. The position is corrected by the position deviation calculation unit 4 into which the data is input, and the command signal amplified by the proportional gain multiplication unit 9 is input to the robot drive system 8. The signal input to the robot drive system 8 is an intermittent command signal as shown in FIG. , vibrations occur in robot elements such as arms and wrists. Therefore, in this embodiment, as shown in FIG. It is input to the servo driver 5. Therefore, the servo motor 6 driven by the smoothed command signal is smoothly driven without causing vibration or the like. The interpolator 1 is composed of a low-pass filter using an OP amplifier as shown in FIG. 2, and a resistor (R) or a capacitor (
By adding C), a filter with desired characteristics can be constructed. For example, when a circuit configuration is adopted in which the constants of C and R are determined as shown in FIG. 3, a low-pass filter can be formed in which the cut-off frequency f0 of the attenuation characteristic as a filter is determined by the constants of C and R. The command signal passed through the interpolator 1 consisting of a low-pass filter configured in this manner is inputted to the servo driver 5 after being smoothed from a stepwise intermittent signal as shown in FIG. Figures 6 to 9 are actual measurement graphs of torque fluctuations when robot elements are operated. Figures 6 and 7 show the case when the robot element is operated alone, and Figures 8 and 9 show the case when the robot element is operated on a hexagonal trajectory. . 6 and 8 respectively, when there is no interpolator 1, FIG. 7 and FIG. 9
is a case where there is an interpolator 1, and as shown in the figure, the command signal input to the servo driver 5 can be smoothed by going through the interpolator 1, and the spikes caused by torque fluctuations and speed fluctuations of the servo motor 6 can be smoothed. The shaped waveform is cut. By cutting out the spike-like waveforms that cause vibrations, unlike hydraulically driven robots that have large damping factors such as oil viscosity and cylinder resistance, electric motor-driven robots with fewer damping factors can reduce the command signal. The effect of smoothing becomes larger.

[0007]

Effects of the Invention As described above, according to the present invention, in the cycle of periodically outputting coordinate data and driving robot elements in a teaching/reproducing robot, there is a post-stage in which coordinate data is corrected for positional deviation using feedback data. By placing an interpolator consisting of a low-pass filter in the 3D interface to smooth the intermittent coordinate data and inputting this output signal to the drive system of the robot element, changes in the acceleration of the robot element can be smoothed and vibrations can be prevented. It can be eliminated.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of a robot control device according to the present invention.

FIG. 2 is a circuit diagram of an interpolator in the control device.

[Fig. 3] A specific circuit diagram of the interpolator.

FIG. 4: Interpolator input signal graph.

FIG. 5: Interpolator output signal graph.

[Figure 6] Actual measurement graph of torque fluctuation when a single robot element operates (without interpolator).

[Figure 7] Actual measurement graph of torque fluctuation when a single robot element operates (with interpolator).

[Figure 8] Actual measurement graph of torque fluctuation during robot element hexagonal operation (without interpolator).

[Figure 9] Actual measurement graph of torque fluctuation during robot element hexagonal operation (with interpolator).

FIG. 10 is a block diagram of a conventional robot control device.

[Explanation of symbols]

1...Interpolator 7...Position detector 8...Robot drive system

Claims (1)

[Claims] [Claim 1] Control of a teaching/reproduction type robot that stores intermittent coordinate data at predetermined intervals of the work position locus of robot elements such as arms and wrists through teaching work, and performs playback work in accordance with the intermittent coordinate data. In the device,
The intermittent coordinate data sequentially retrieved during playback is corrected for positional deviation based on feedback data from a position detector provided in the robot drive means. A control device for a teaching and reproducing robot, characterized in that the signal is smoothed and input to a drive system to drive the robot element.