JPS62226210A - Compensating device for variance of revolution - Google Patents

Abstract

PURPOSE:To improve the control accuracy of a compensating device for revolution variance by feeding the variance same as that of a revolution transmission system for reduction gear, etc., that causes vibrations back to a control system independently of other types of variance. CONSTITUTION:A motor 1 drives the load of a robot arm, etc., via a harmonic drive reduction gear 2 of a revolution transmission system. A position detector 3 of a rotary encoder, etc., is connected to the drive shaft of the motor 1. The position information (rotational angle information) obtained from the detector 3 is usually counted by a pulse counter 4 with a certain Z pulse defined as a start point. The phase of a signal generator 5 is controlled by a phase controller 6. Then the output signal of an adder 8 is sent to a robot arithmetic unit 9 of a computer which controls the drive of the motor 1. Thus the unit 9 feeds the received signal back to a drive circuit 10 of the motor 1 for automatic control to eliminate the revolving variance of the gear.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is a method for compensating for rotational unevenness that occurs between an input shaft and an output shaft of a rotation transmission system that may cause rotational unevenness in a reduction gear or the like. In particular, the rotation unevenness device generates a rotation unevenness signal according to the known rotational unevenness characteristics of the rotation transmission system and feeds this signal back to the control system of the drive source. ! i (Regarding the M device.

BACKGROUND ART Conventional technology and its problems In industrial robots, NC machines, etc., uneven rotation can cause vibrations. In particular, it is known that vibration appears as a distortion of the tool trajectory in industrial robots (7) and related equipment (work positioners, robot sliders) that obtain tool trajectories by combining multi-jointed, multi-axis systems. .

These rotational irregularities may be affected by poor servo control performance, the resolution of the position detector, angular errors, etc., but rotational irregularities caused by angular transmission errors in rotation transmission mechanisms such as reducers can also occur. make a big impact.

As an example of the above rotation transmission mechanism, transmission unevenness in a harmonic drive reduction gear will be explained with reference to FIG.

As shown in FIG. 3, a position detector 3 is attached to the motor 1, and the output shaft 1' of the motor is connected to the rotation transmission system.
It is connected to an output shaft 12 via a harmonic drive reducer 2, which is an example. The harmonic drive reducer 2 includes a wave generator 13, a circular spline 14. It is composed of a flex spline 15, and the output shaft 12 is connected to a feed screw 17 and the like.

The harmonic drive reducer 2 has an input shaft 1'
The second (f) is between the rotation angle of the output shaft 12 and the rotation angle of the output shaft 12.
The relationship is as shown in the graph below. Figure 2 (f)
The graph shows the rotation angle of the input shaft on the horizontal axis and the rotation angle of the output shaft on the vertical axis, and the 45° dashed line i indicates the rotation of the input shaft and output shaft when there is no uneven rotation transmission. Transmission relationships are shown. However, in reality, it is known that the output shaft rotates with two periods of sinusoidal wave variation per input shaft rotation, as shown by curve j shown in the figure. Therefore, as shown in the figure, the width δ of the curve j indicates the rotation transmission unevenness of the harmonic drive reducer 8.

As described above, the cause of rotation transmission unevenness in the harmonic drive reducer 2 is thought to be due to manufacturing errors of the input shaft and output shaft, or due to the characteristics of the internal drive part. There is a characteristic that two periods of sinusoidal unevenness occur per rotation.

In conventional robots, etc., unevenness caused in the rotation transmission system etc. as described above accumulates and causes uneven rotation of the arm, etc., so a separate position detector is installed at the center of rotation of the arm etc. Control accuracy is improved by feeding back position information to the control system of the drive source, but this conventional method requires an extra expensive position detector, which increases the cost, and also causes various rotational irregularities to accumulate. There was a problem in that the control accuracy was not very good because of the feedback.

OBJECTS OF THE INVENTION Accordingly, an object of the present invention is to provide an inexpensive method capable of compensating for inherent rotational unevenness in a rotational transmission system whose characteristics of rotational unevenness are known without being influenced by other rotational unevenness elements. The purpose is to provide equipment.

Structure of the Invention In order to achieve the above object, the main means adopted by the present invention is to provide a device for compensating for uneven rotation occurring between an input shaft and an output shaft of a rotation transmission system. a pulse encoder with a Z pulse that detects the rotational position of the drive shaft; a signal generator that generates a waveform signal having a predetermined period per revolution of the drive shaft on the drive source side using the Z pulse as a reference; and an increment encoder with the Z pulse. A rotational unevenness compensator comprising: arithmetic processing means for adding position information from a pulse encoder and waveform information from the signal generator and feeding back the added data to a drive source control system. It is.

Next, embodiments embodying the present invention will be explained to provide an understanding of the present invention. Here, FIG. 1 is a block diagram showing the overall control system of a rotational unevenness compensator according to an embodiment of the present invention, and FIG. 2 ta+ is an output signal waveform from an incremental pulse encoder with Z pulse, which is a position detector. Figure, same figure (b
l and fcl are respectively output signal waveform diagrams from the signal generator, and the same figure (dl is an output signal waveform diagram from the pulse counter, and fe in the same figure) is the output signal waveform diagram from the adder that adds the output signals from the signal generator and the pulse counter. The output signal waveform diagram of the same figure (f
1 is a graph showing the rotation angle of the output shaft of the harmonic drive reduction gear.

The following examples are merely specific examples of the present invention, and are not intended to limit the technical scope of the present invention.

In the following embodiments, a case will be described in which a harmonic drive reducer is used as a rotation transmission system, but the present invention is not limited to such a harmonic drive reducer or other reduction gears. The present invention can be applied to any mechanism for compensating rotational unevenness occurring between the input shaft and the output shaft of any rotational transmission system whose characteristics such as the period of unevenness are known.

In FIG. 1, a motor 1 drives a load such as a robot arm (not shown) via a harmonic drive reducer 2, which is an example of a rotation transmission system. A position detector 3 such as a rotary encoder is installed on the drive shaft of the motor 1, which is the drive source.
are connected.

The position detector 3 is constituted in this case by an incremental pulse encoder. Incremental pulse encoders generally have A-phase and B-phase pulses (incremental type) with a 90° position difference as shown in Figure 2 (al), and pulses called Z pulses only once per rotation. There are cases in which the phase and B phase are generated unexpectedly. Such an encoder is referred to as a pulse generator with Z pulses.The present invention uses such a pulse generator with Z pulses.

The position information (rotation angle information) obtained from such an encoder is usually counted by the pulse counter 4 (Fig. 1) starting from one of the Z pulses, and is counted by the pulse counter 4 (Fig. 2) +d
The information has a certain slope with respect to the horizontal axis (time axis) as shown by +.

On the other hand, as shown in FIG. 1, the signal generator 5, which generates a substantially sine wave with two cycles per motor rotation using the Z pulse of the position detector 3 as a starting point, is usually a commercially available function generator. Alternatively, it can be configured by software in a computer.The phase e of the signal generated from the signal generator 5 (FIG. 2(b)) is adjusted by the phase adjuster 6 (FIG. 2 [C1), or In order to match the level of the signal from the signal generator 5 with the level of the rotation angle information from the position detector 3 shown in FIG. send.

The adder 8 adds the sine wave signal from the pulse amplification 37 (which matches the rotational unevenness between the input shaft and the output shaft of the harmonic drive reducer 2) and the rotation angle signal from the pulse counter 4.

The signal thus obtained (FIG. 2(e)) almost coincides with the rotation angle signal of the output shaft of the harmonic drive reducer 2 shown in FIG. 2(fl).

In this embodiment, the output signal of the adder 8 shown in FIG.

The robot arithmetic unit 9 feeds the signal from the pulse adder 8 to the drive circuit 10 of the motor 1 to perform automatic control to eliminate uneven rotation of the speed reducer 2.

Note that a resolver that functions similarly to an encoder, and pulses and Z pulses from its converter may be used.

Effects of the Invention As described above, the present invention provides a Z system for detecting the rotational position of a drive shaft on the drive source side in a device for compensating for uneven rotation occurring between an input shaft and an output shaft of a rotation transmission system. a pulse generator with pulses; a signal generator that generates a waveform signal having a predetermined period per revolution of the drive shaft on the drive source side with reference to the Z pulse; and position information generated by the pulse generator with the Z pulse; and arithmetic processing means for adding the waveform information from the signal generator and feeding back the added data to the drive source control system. # Since it is a compensation device, it is possible to feed back the same unevenness in the rotation transmission system such as a reducer that causes vibration to the control system separately from other unevenness.
Since it is possible to compensate for the unique unevenness of the reduction gear, it is possible to obtain positional braking that is comparable to that of a high-precision reduction gear without using a high-precision reduction gear. In addition, if unevenness due to such a rotation transmission system is the main cause of vibration, etc., conventionally, expensive i! ! Although a detector is provided to perform feedback control, control accuracy can be improved without using such an expensive position detector, which is also advantageous in terms of economy.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the overall control system of a rotational unevenness compensator according to an embodiment of the present invention, and FIG. 2 (al is a waveform diagram of an output signal from an incremental pulse encoder with Z pulse, which is a position detector) , the same figure (tll, (C1 is the output signal waveform diagram from the signal generator, respectively, +d+ in the same figure is the output signal waveform diagram from the pulse counter, and tel in the same figure is the sum of the output signals from the signal generator and pulse counter. An output signal waveform diagram from the adder, a graph showing the angle in the figure, and Fig. 3 is a side sectional view showing the installation state of the conventional harmonic reducer. (Explanation of symbols) 1...Motor 2...・Harmonic drive reducer 3...Position detector 4...Pulse counter 5・
...Signal generator 6...Phase adjuster 7...Pulse amplifier 8...Adder 9...Robot arithmetic unit 10...Drive circuit.

Claims (1)

[Claims] (1) A device for compensating rotational unevenness occurring between an input shaft and an output shaft of a rotation transmission system, which includes a pulse generator with a Z pulse that detects the rotational position of the drive shaft on the drive source side, and the drive source. a signal generator that generates a waveform signal having a predetermined period per rotation of the side drive shaft based on the Z pulse; position information from the pulse generator with the Z pulse; and waveform information from the signal generator. What is claimed is: 1. A rotational unevenness compensating device, comprising: arithmetic processing means for adding up data and feeding back the added data to a drive source control system.