JPH04138088A - motor control device - Google Patents

Abstract

PURPOSE:To maintain constant the abnormality detection sensitivity regardless of the control method to be employed by simulating the transfer function of a control system based on a control system model thereby estimating the current motor speed including a time lag and monitoring the difference between thus estimated speed signal and an actually detected speed signal. CONSTITUTION:A filter circuit 15 is connected between an adder 14 and an absolute value circuit 11. A different filter can be inserted for different control method of a speed amplifier 10. Switching of the filter is implemented similarly to switching of the control method for the speed amplifier 10. According to the constitution, an abnormality detection reference value B can be employed regardless of the control method to be employed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a motor control device for accurately controlling motors that drive a robot, its arms, wrists, etc.

[Prior Art] Conventionally, a motor control device that must accurately control the position and speed of a robot or the like has several functions for checking abnormal movement of the motor. The feature of this function is that it determines whether or not there is an abnormality based on whether the state quantity of the servo system exceeds a certain reference value.

Fig. 3 is a block diagram showing the configuration of this type of conventional motor control device, in which the motor 1 to be controlled has a speed detector 2 such as a generator for a speedometer, and generates a number of pulses according to the rotation angle. A position detector 3 is connected thereto. Of these, the output of the position detector 3 is input to a differential element 4 that calculates the number of pulses per unit time and generates a speed signal. On the other hand, a speed command pattern generating circuit 5 is provided which detects a speed command pattern from the starting position to this target position when the target position of the motor l is input, and furthermore, a speed command pattern generating circuit 5 is provided which detects a speed command pattern from the starting position to this target position. An adder 6 is provided for determining the deviation from the . An integral element 7 is connected to this adder 6, and when a positional deviation signal is output by integrating the speed deviation signal, a position amplifier 8 amplifies this positional deviation signal and outputs a speed command. It has become. Subsequently, this speed command is added to an adder 9, where it is compared with the output of the speed detector 2 and the deviation is output. This speed deviation is amplified by the speed amplifier 10 and applied to the motor 1.

On the other hand, an absolute value conversion circuit 1 which detects the absolute value of the positional deviation is connected to the integral element 7. Further, this absolute position deviation is input to a comparator 12, where it is compared with a reference value A. If the absolute position deviation exceeds the reference value A, an abnormality signal is generated.

The solid line portions in FIGS. 5(a) to 5(c) show these relationships. When the speed command pattern generation circuit 5 generates the speed command pattern shown in FIG. If controlled, there is a time delay during this time, so the output of the speed detector 2, that is, the speed feedback signal, moves to the right side of the drawing.

On the other hand, the output of the position detector 3, that is, the position feedback signal, is manually input to the differential element 4, the adder 6 calculates the deviation between the output and the speed command pattern, and this deviation is input manually to the integral element 7. Fig. 5 (b)
), it is nothing but finding the deviation between the signal indicating the commanded position and the position feedback signal, and as a result, the position deviation signal shown in FIG. 3 is output from the integral element 7. Then, as shown in FIG. 5(a), the comparator 12 compares this positional deviation signal with a reference value A, and when the positional deviation signal exceeds the reference value A, generates an abnormal signal and turns off the power. The circuit was cut off and motor 1 was stopped.

Compared to this method, the inventors have proposed a method for predicting speed using a control model and comparing it with the actual speed, in order to detect abnormal movements more quickly and improve safety.
Suggested by 27444. This method will be briefly explained below.

FIG. 4 is a block diagram showing the configuration of a conventional motor control device. In the figure, the same reference numerals as in FIG. 3 indicate the same elements. A control model 13 that simulates the transfer function of the control system, that is, a transfer function from before the adder 6 to the speed detector 2, is provided before the absolute value conversion circuit 11 for detecting an abnormality, and this control system model An adder 14 is additionally provided to calculate the deviation between the output of the speed detector 13 and the speed feedback signal of the speed detector 2 and add it to the absolute value conversion circuit 11. With this configuration, by simulating the transfer function of the control system, the current motor speed is predicted taking into account the time delay, and the deviation between the predicted speed signal and the detected actual speed signal is smaller than the reference value. The presence or absence of an abnormality was determined by whether or not it exceeded the limit. The dotted line in FIG. 5(c) illustrates this predicted speed.

[M1 problem to be solved by the invention] However, in the invention of patent application No. 2-27444, the control model 13 is the simplest one, KP/(s+Kr)(
(Kp is the position loop gain, S is the Laplace operator), depending on the control method of the speed amplifier IO, e.g., proportional-integral (Pl) control or integral-proportional (1-P) control, the difference in Fig. 5(d) ), PI control 211 time NihaJ! is used as a reference value for abnormality detection. Quasi (1wo, r -P fii
There was a problem that the reference value C used for f-P l!ilJ cannot be made much smaller than the maximum speed of the motor. In the present invention, by inserting a filter circuit I5 between the adder 4 and the absolute value converting circuit 11 according to the speed amplifier IO control method, r
-The purpose is to lower the reference value C during P control and to avoid changing the reference value due to differences in control methods.

[Means for Solving the Problems] In order to achieve the above object, the present invention detects at least a motor position to obtain a position signal of the motor and a speed signal of the motor, and also detects a position signal obtained from a speed command pattern and a position command obtained from a speed command pattern. A motor control device comprising a control system that calculates a speed command based on a deviation from the position signal and controls the motor so that the deviation between the speed command and the speed signal becomes zero, comprising: characteristics of the control system. a control model that predicts the current speed of the motor corresponding to the speed pattern by simulating a speed signal of the predicted current speed and the speed signal obtained from the detected position signal. When the deviation exceeds the reference value, depending on the control method of the comparator that generates a speed abnormality signal and the speed amplifier, it is possible to select whether or not to insert a filter before inputting the deviation from the speed signal to the comparator. It is equipped with a possible circuit.

[Operation] With the above means, the present invention simulates the transfer function of the control system using a control system model, predicts the current motor speed taking into account the time delay, and compares the predicted speed signal with the detected actual speed. By monitoring the deviation from the speed signal of the speed amplifier, safety is improved, and especially when the transfer function of the control system is easily simulated, there is no need to change the sensitivity of abnormality detection due to differences in the control method of the speed amplifier. It becomes constant.

[Example] Hereinafter, specific examples of the present invention will be described.

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. In the figure, the same reference numerals as in FIG. 4 indicate the same elements. A filter circuit 15 is connected between the adder 14 and the absolute value conversion circuit 11.

Moreover, FIG. 2 is a block diagram of the filter circuit 15,
Different filters can be inserted depending on the control method of the speed amplifier 10. This switching is performed using the same means as switching the control method of the speed amplifier 10. Specifically, a signal from a higher-level controller (not shown) that creates the target position is used. If a switching signal cannot be obtained from the host controller, a switch element such as a seat bin can be used.
The specific transfer function of c (s) is, for example, a system in which the position amplifier 8 is composed of a proportional circuit, the proportional gain is Kp, and the speed amplifier 10 is changeable between PI control and IP control. If the speed loop is a quadratic equation, it can be found as follows. First, the transfer function from the speed command pattern to just before the absolute value conversion circuit 11 before connecting the filter circuit 15 is determined by the speed amplifier 10 under PI control. GdHs) = Kps ko / ((S ko + 2
ζω sR+(ω98 +2ζω, Kp)s+KpωJ
)(s+Kp)] Also, when the speed amplifier 10 is operating at t-pHl, Gd2(s)=Kp(s"+2gω,5')/(
(s” +2gal, lS” + 6) @”S
+ K p 6) n” ) (s + Kp)), and the characteristics of the denominators of Gd1 (S) and Gd2 (s) are considered to be almost equal, so the number of transmission lines Gc (s) of the filters to be connected is , Gc(s)=s+2ζω angle.

Therefore, by inserting this filter during IP control, the characteristics from the speed command pattern to the absolute value conversion circuit 11 can be made constant regardless of whether the speed amplifier 10 is under PI control or -P control. The reference value B for abnormality detection can be used regardless of the control method. Furthermore, in the above embodiment, the predicted speed and the speed feedback signal value were compared, but when the present invention is applied by comparing the predicted speed and the speed command, the transfer function of the filter can be obtained using the same calculation below. I can do it.

When the speed amplifier 10 is controlled by PI control, Gd5(
s)=Kp"s"/[(s"+2ζω,s"+
(ω,” +2ζω,Kp)s+Kpω,” )(s+
Kp)] Also, is the speed amplifier 10 T-PIiJ? When carried out at l, Gd4(s)−Kpt(s” +2ζω1ls)/((
s3+2ζ(11,S"10ω,"S+KP(Ill
ll'')(S+KP)1, so it is the same filter as used in the comparison between the predicted speed and the speed feedback signal value, so the filter circuit I
5 can be used as is.

Further, in the above embodiment, the speed detector 2 and the position detector 3 are coupled to the motor l, but the speed signal can be easily converted from the output of the position detector 3, and such conversion is possible. If you add a device, speed detector 2
can be omitted. Furthermore, the speed amplifier 10 is P
Although the explanation has been made assuming that the switching is performed between li control and IpH11, the configuration of the filter circuit 15 may be multi-staged for other control methods, such as when feedforward control is added to the control system or when the speed amplifier 10 includes differentiation. If you allow it to be set to , you can extend it using exactly the same method.

[Effects of the Invention] As described above, according to the present invention, by simulating the transfer function of the control system, the current motor speed is predicted taking into account the time delay, and the detected speed signal is Since abnormalities are detected based on the deviation from the actual detection signal, compared to conventional equipment, the motor does not rotate at higher speeds than necessary, significantly improving the safety of robots, etc. , when the transfer function of the control system is simplified, the abnormality detection sensitivity due to differences in speed amplifier control methods can be made constant.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, FIG. 2 is a block diagram of a filter circuit, FIGS. 3 and 4 are block diagrams showing the configuration of a conventional motor control device, and FIG. (
Figures a), (b), and (c) are time charts of motor position deviation, position, and speed for explaining the operation of the conventional device. l...Motor, 2...Speed detector 3...
Position detector, 4... Differentiator 5... Speed command pattern creation circuit 6.9, ]4... Adder 7... Integral element, 8... Position amplifier 10... Speed amplifier, 11... Absolute value conversion circuit 12... Comparator, 1
3...Control system model 15...Filter circuit patent applicant Yasuyo Electric Manufacturing Co., Ltd. Figure Procedure Amendment (Method) % Formula % Name (662) Yasuyo Electric Manufacturing Co., Ltd. 5. "Brief explanation of drawings" column 6 of the specification to be amended, page 13, lines 1 to 3 F of the specification of contents of the amendment, Figures 5 (a), (b), (
C) is a time chart of motor position deviation, position, and speed for explaining the operation of the conventional device. '', [Figures 5(a), (b), (c), and (d) are time charts of the position deviation, position, speed, and speed deviation of the motor, respectively, to explain the operation of the conventional device. be. ” he corrected. 19μ

Claims (1)

[Scope of Claims] At least the position of a motor is detected to obtain a position signal of the motor and a speed signal of the motor, and a speed command is generated based on a deviation between a position command obtained from a speed command pattern and the position signal. A motor control device having a control system that calculates and controls the motor so that a deviation between the speed command and the speed signal becomes zero, the motor controller comprising: a control system that controls the motor so that a deviation between the speed command and the speed signal becomes zero; a control model that predicts the current speed of the motor; and when a deviation between the speed signal of the predicted current speed and the speed signal obtained from the detected position signal exceeds a reference value, a speed abnormality signal is generated. Whether or not to insert a filter before inputting the deviation between the predicted speed signal and the speed signal obtained from the position signal to the comparator due to the difference in the control method of the comparator that generates the speed signal and the speed amplifier. A motor control device comprising a selectable filter circuit.