JP2959087B2 - Motor control device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor control device for accurately controlling a motor that drives a robot and its arms, wrists, and the like.

2. Description of the Related Art Conventionally, a motor control device that must accurately control the position and speed of a robot or the like has a function of checking for abnormal movement of the motor. The feature of the function is that it is determined 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 a conventional motor control device of this kind. A motor 1 to be controlled generates a speed detector 2 such as a speedometer generator and the number of pulses according to the rotation angle. The position detector 3 is engaged. Among them, the output of the position detector 3 is input to a differential element 4 which calculates the number of pulses per unit time and generates a speed signal. On the other hand, when a target position of the motor 1 is input, a speed command pattern creating circuit 5 for detecting a speed command pattern from the start position to the target position is provided. An adder 6 is provided for obtaining a deviation from the above. An integrating element 7 is connected to the adder 6, and when a position error signal is output by integrating the speed error signal, the position amplifier 8 increases or decreases the position error signal and outputs a speed command. Has become. Subsequently, the speed command is applied to the adder 9, where it is compared with the output of the speed detector 2 to output a deviation. This speed deviation is amplified by the speed amplifier 10 and added to the motor 1.

On the other hand, an absolute value conversion circuit 11 for detecting the absolute value of the position deviation is connected to the integration element 7. The absolute position deviation is input to the comparator 12, where it is compared with the reference value A. If the absolute position deviation exceeds the reference value A, an abnormal signal is generated.

The solid line portions in FIGS. 5A to 5C show these relationships. The motor 1 is generated by the speed command pattern generation circuit 5 generating the speed command pattern shown in FIG.
If the speed is controlled, the output of the speed detector 2, that is, the speed feedback signal has moved to the right side of the drawing because there is a time delay during this time.

On the other hand, the output of the position detector 3, that is, the position feedback signal is input to the differential element 4, the difference between the output and the speed command pattern is obtained by the adder 6, and the difference is input to the integration element 7. 5 and (b), there is no other way than to find the deviation between the signal indicating the command position and the position feedback signal, as shown in FIG. 5 (b).
The position deviation signal shown in FIG. 3 is output from the integration element 7. Then, as shown in FIG. 5 (a), the comparator 12 compares the position deviation signal with the reference value A, and when the position deviation signal exceeds the reference value A, generates an abnormal signal. The circuit was shut off and the motor 1 was stopped.

As a method for detecting abnormal movement more quickly and improving safety as compared with this method, the inventors predict a speed using a control model and compare the speed with an actual speed.
Proposed in -27444. Hereinafter, this method will be briefly described.

FIG. 4 is a block diagram showing the configuration of a conventional motor control device. In the drawing, components denoted by the same reference numerals as those in FIG. 3 indicate the same components. A transfer function of a control system, that is, a control system model 13 for simulating 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. An adder 14 is added to determine the deviation between the output of the model 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 in anticipation of time delay, and the deviation between the predicted speed signal and the detected actual speed signal is used as a reference value. The presence or absence of an abnormality was determined based on whether or not it exceeded. The dotted line in FIG. 5C illustrates the predicted speed.

[Problems to be Solved by the Invention] However, in the invention of Japanese Patent Application No. 2-27444, the control model 1
If one tries to use the simplest one, K _P / (s + K _p ), where K _p is the position loop gain and s is the Laplace operator, the method of controlling the speed amplifier 10, for example, proportional integral (PI)
According to control or integral proportional (IP) control, as shown in FIG. 5 (d), a reference value B is used as a reference value for abnormality detection during PI control, and a reference value C is used during IP control. Thus, there is a problem that the reference value C used in the IP control cannot be made much smaller than the maximum speed of the motor. Therefore, the present invention provides an adder 14 and an absolute value circuit by controlling the speed amplifier 10.
The purpose is to lower the reference value C during the IP control by inserting a filter circuit 15 between 11, and not to change the reference value due to the difference in the control method.

Means for Solving the Problems In order to achieve the above object, the present invention detects the position of a motor and detects the position signal of the motor, or detects the speed of the motor or differentiates the position signal of the motor. Obtaining a detected speed signal of the motor and calculating a speed command based on an integral value of a deviation between a speed command pattern from a speed command pattern creating circuit and a differential value of the position signal, and calculating the speed command and the detected speed. In a motor control device having a control system for controlling the motor so that a deviation from a signal becomes zero, a current speed of the motor corresponding to the speed command pattern is predicted by simulating characteristics of the control system. A control system model, a comparator that generates a speed abnormality signal when a deviation between the speed signal of the predicted current speed and the detected speed signal exceeds a reference value, A filter circuit capable of selecting whether or not to insert a filter before inputting a deviation between the predicted speed signal and the detected speed signal to a comparator due to a difference in a control method of the temperature amplifier. .

[Operation] By the means described above, the present invention predicts the current motor speed in consideration of the time delay by simulating the transfer function of the control system by the control system model, and detects the predicted speed signal as the predicted speed signal. By monitoring the deviation from the actual speed signal,
When improving the safety and simplifying the simulation of the transfer function of the control system in particular, the sensitivity of abnormality detection due to the difference in the control method of the speed amplifier can be kept constant.

EXAMPLES 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 denote the same elements. Then, a filter circuit 15 is connected between the adder 14 and the absolute value conversion circuit 11. FIG. 2 is a block diagram of the filter circuit 15, in which different filters can be inserted depending on the control method of the speed amplifier 10. This switching is performed by the speed amplifier 10
Is executed using the same means as switching the control method. Specifically, a signal from a higher-level controller (not shown) for creating a target position is used. If a switching signal cannot be obtained from the host controller, a switching element such as a short pin may be used. Filter Gc to be connected
The specific transfer function of (s) is, for example, that the position amplifier 8 is constituted by a proportional circuit, the proportional gain is Kp, and the speed amplifier is
Reference numeral 10 denotes a system that can be changed between PI control and IP control. If the speed loop can be approximated by a quadratic equation, it can be obtained as follows. First, the transfer function from the speed command pattern to immediately before the absolute value conversion circuit 11 before connecting the filter circuit 15 is the speed amplifier.
When 10 is performed in the PI ^{control, Gd1 (s) = Kps 3} / [{s 3 + 2ζω n s 2 + (ω n 2 + 2ζω n Kp) s + Kpω n 2} (s + Kp)] The velocity amplifier 10 in the case taking place in I-P control but, Gd2 (s) = Kp ( s 3 + 2ζω n s 2) / (s 3 + 2ζω n s 2 + ω n 2 + ω n 2 + Kpω n 2) (s + Kp)} Since the characteristics of the denominator of Gd1 (s) and Gd2 (s) are considered to be almost equal, the transfer function Gc (s) of the filter to be connected is Becomes

Therefore, if this filter is inserted during the 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 performs the PI control or the IP control. The reference value B for abnormality detection can be used regardless of the control method. In the above embodiment, the predicted speed and the speed feedback signal value are compared. However, when the present invention is applied by comparing the predicted speed with the speed command, the transfer function of the filter may be determined by the following calculation. Can be.

When the speed amplifier 10 is performed in the PI ^{control, Gd3 (s) = Kp 2} s 2 / [{s 3 + 3ζω n s 2 + (ω n 2 + 2ζω n Kp) s + Kpω n 2} (s + Kp)] The speed when the amplifier 10 is performed by I-P control are the ^{Gd4 (s) = Kp 2 (} s 2 + 2ζω n s) / {(s 3 + 2ζω n s 2 + ω n 2 s + Kpω n 2) (s + Kp)} , And the same filter as that used in the comparison between the predicted speed and the speed feedback signal value.
Can be used as is.

In the above embodiment, the motor 1 is combined with the speed detector 2 and the position detector 3. However, the speed signal can be easily converted from the output of the position detector 3. If a device is added, the speed detector 2 can be omitted. Furthermore, the speed amplifier 10
Although the description has been made on the assumption that the control is switched to the IP control, the configuration of the filter circuit 15 is also applicable to other control methods such as a case where the feedforward control is added to the control system and a case where the speed amplifier 10 includes differentiation. Can be set in multiple stages, it can be expanded in exactly the same way.

[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 with a time delay is predicted, and the predicted speed signal and the detected speed signal are estimated. Since the abnormality is detected based on the deviation from the above, the motor is not rotated at a higher speed than necessary compared to the conventional device, so that the safety of the robot and the like can be remarkably improved and the control system can be improved. The abnormality detection sensitivity due to the difference in the control method of the speed amplifier when the simulation of the transfer function is simplified can be made constant.

[Brief description of the drawings]

1 is a block diagram showing a 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 a configuration of a conventional motor control device, and FIG. (A), (b), (c), and (d) are time charts of motor position deviation, position, speed, and speed deviation for explaining the operation of the conventional device. 1 ... motor 2 ... speed detector 3 ... position detector 4 ... differentiator 5 ... speed command pattern creation circuit 6, 9, 14 ... adder 7 ... integral element 8 ... position Amplifier 10 Speed amplifier 11 Absolute value conversion circuit 12 Comparator 13 Control system model 15 Filter circuit

Claims (1)

(57) [Claims] A motor speed signal is detected by detecting a position of the motor, a speed signal of the motor is detected or a position signal of the motor is differentiated to obtain a speed signal of the motor. A speed command is calculated based on an integral value of a difference between a speed command pattern from a creation circuit and a differential value of the position signal, and the motor is controlled such that a difference between the speed command and the detected speed signal becomes zero. A control system model for predicting a current speed of the motor corresponding to the speed command pattern by simulating characteristics of the control system; and a speed of the predicted current speed. A comparator that generates a speed abnormality signal when a deviation between the signal and the detected speed signal exceeds a reference value, and the predicted speed due to a difference in the control method of the speed amplifier. Motor control device is characterized in that a selectable filter circuit whether to insert the filter before entering the No. and the comparison a deviation between the detected speed signal device.