JP2005080333A - Method for calculating load inertia - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To automatically set the servo control gain with which no instability or vibration occurs when driven as it is after calculating an inertia value before a motor is operated. <P>SOLUTION: A servo control unit for driving a servo motor comprises a vibration detecting means which detects the vibration of a control system based on the difference between the estimated speed from the motor and the model of a rod and actual speed, and a vibrating means which applies the vibration of a prescribed level to the control system by adding a pseudo stepwise disturbing torque to a torque command. The magnitude of the pseudo disturbing torque is adjusted by the vibrating means to vibrate the control system and a vibration is detected by the vibration detecting means as a load inertia value is raised, which process is repeated. The load inertia value when the detection result of the vibration detecting means comes to be minimum is acquired. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a servo control apparatus for driving a servo motor, and more particularly to a method for automatically setting a servo control gain by calculating a load inertia before a normal operation of the motor.

  Conventionally, as in Patent Document 1, a motor is operated, and a load inertia is calculated based on a motor acceleration time and a torque obtained by integrating the time. Or the load inertia was estimated using the disturbance torque estimated value and acceleration information which were obtained by the disturbance estimation observer by operating a motor like patent document 2. FIG.

JP2002-153088

JP 11-313495 A

In the conventional method, load inertia cannot be obtained unless the motor is driven to some extent, so the inertia value is undefined at the beginning of driving the motor, and the control system becomes unstable until the inertia value is calculated. There was a problem of vibrating. Further, once it becomes unstable or vibrates, the acceleration is not constant and the acceleration / deceleration is performed. Therefore, there is a problem that the motor operation is not normal and the inertia value cannot be estimated correctly.
Accordingly, an object of the present invention is to automatically set a servo control gain that does not become unstable or vibrate even if the inertia value is calculated as it is before the motor is operated.

  In order to solve the above problem, according to the load inertia calculation method of the present invention, in the servo control device that drives the servo motor, the vibration that detects the vibration of the control system from the difference between the estimated speed from the motor and load model and the actual speed. Detection means and excitation means for applying a predetermined level of vibration to the control system by adding step-like simulated disturbance torque to the torque command, and adjusting the magnitude of the simulated disturbance torque by the excitation means. The process of repeatedly oscillating the control system and detecting the vibration by the vibration detecting means while increasing the load inertia value, and obtaining the load inertia value at the time when the detection result by the vibration detecting means is minimized. I took it.

  According to the present invention, since the load inertia value can be calculated before the motor is normally operated, setting the inertia value does not cause instability or vibration even if the motor is operated as it is. The gain can be set automatically, and the subsequent operation only requires confirmation.

  Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

  In FIG. 1, 1 is a vibration detection means, 2 is a microcomputer, 3 is a current amplifier, 4 is a base drive circuit, 5 is a power transistor module, and 6 is a motor. The operation of the circuit configured as described above will be described with reference to the control block diagram of FIG. 2 and the timing diagram of FIG. First, the microcomputer 2 receives commands such as position and speed from an external controller or the like. For example, in the case of a speed command, speed control is performed, and the motor is controlled by driving the power transistor 5 via the base drive circuit 4 with the output current command or current control output. Here, the vibration detection means 1 detects vibration when the vibration component included in the torque command or the motor speed signal exceeds a predetermined level (detection level). The vibration detection level is determined in advance, for example, or is determined in advance from the amplitude level of vibration when the control system is in a stable state. To detect the inertia value, first, a simulated disturbance torque is added to the torque command at a low gain, and the response is confirmed up to the vibration detection level. If there is no response, the simulated disturbance torque is increased until the response is increased to some extent, or the vibration level is decreased.

  Then, as shown in FIG. 5, the simulated disturbance torque is applied to the torque command of FIG. 2 so that the inertia value is gradually increased and the simulated disturbance is applied, and the vibration is confirmed. Since the simulated disturbance torque is applied with the motor stopped, vibration is confirmed from the estimated speed and the amplitude of the difference between the speeds as shown in FIG. The load inertia and the inertia used in the model are detected as an estimated speed and an inertia value at which the difference between the speeds is minimized as shown in FIG. When the load inertia and the inertia used in the model match, the response of the model speed and the actual speed difference are small because the estimated value is correct, but if the values do not match, the response is as shown in FIG. Since it does not match, the speed difference between the model and the actual speed will increase. Therefore, load inertia can be obtained by calculating a value where the difference between the model speed and the actual speed is small.

A specific procedure for detecting the load inertia value is as follows. First, the vibration level is set as in process 1 of FIG. Next, as in process 2 of FIG. 8, the gain of the control system such as the position loop and the speed loop is set to a low gain, and the simulated disturbance torque is added to the torque command τref in the control block diagram of FIG. Confirm that the response of the difference is above a predetermined level. Here, if there is no response exceeding a predetermined level, it is considered that the applied simulated disturbance torque has not exceeded the mechanical load, and the simulated disturbance torque is increased so that the response is increased to a predetermined level. If the response does not increase even if the simulated disturbance torque is increased, the response detection level is lowered. In this way, the magnitude of the simulated disturbance torque and the detection level of the response are adjusted. After determining the magnitude of the simulated disturbance torque, the inertia value is increased stepwise at the timing shown in FIG. When the inertia value is increased as in processes 4 to 6 in FIG. 8, simulated disturbance torque is added to the torque command, and vibration is detected by the vibration detection means 1. The vibration detection means 1 compares the estimated speed and the amplitude such as the difference between the speed and the vibration detection level, and if it is larger, detects it as vibration. As shown in FIG. 6, after applying the simulated disturbance torque, the minimum value of the speed difference can be detected by detecting a change in which the speed difference becomes large, and the inertia value at the minimum value is stored in the storage means such as the microcomputer. Is stored as a load inertia value. Finally, it is confirmed in process 8 of FIG. 8 that no overshoot or vibration occurs during operation such as acceleration / deceleration as shown in FIG. The processing of the vibration detection unit 1 may be performed by the microcomputer 2.
Further, the difference between the estimated speed and the speed may be performed using an observer as shown in FIG.

  As described above, since the load inertia value can be calculated before the motor is normally operated, the present invention can be applied to a purpose of adjusting the control system quickly and safely.

It is a block diagram of this invention and the conventional concrete Example. It is a control block diagram. It is a detection block diagram of the difference between the estimated speed and the speed of the present invention. It is a detection block diagram of the difference of another estimated speed and speed of the present invention. It is a figure which shows a mode that raise an inertia value, and generate | occur | produce a vibration, and an inertia detection timing. It is a relationship diagram of an inertia value and a speed difference. It is an observation timing diagram of speed overshoot by acceleration / deceleration. It is a schematic flowchart which detects the load inertia value of this invention. It is a block diagram of the conventional Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vibration detection means 2, 21 Microcomputer 3, 22 Current amplifier 4, 23 Base drive circuit 5, 24 Power transistor module 6, 9, 12, 15, 25 Motor 7 Position loop gain 8, 14 Speed control 10, 18 Integration 11 Speed control 13 Motor and load model 16 Observer load inertia 17 Observer speed control gain 19 Observer speed control integration 20 Observer overall

Claims (3)

In the servo control device that drives the servo motor,
Vibration detection means for detecting vibration of the control system, and vibration means for applying a predetermined level of vibration to the control system by applying step-like simulated disturbance torque to the torque command, and the simulation means Adjusting the magnitude of the disturbance torque and oscillating the control system, repeating the process of detecting the vibration by the vibration detecting means while increasing the load inertia value, and at the time when the detection result by the vibration detecting means is minimized A load inertia calculation method for obtaining the load inertia value.   2. The load inertia calculating method according to claim 1, wherein the vibration detecting means detects vibration based on a difference between an estimated speed from a motor and load model of the control system and an actual speed.   The load inertia calculation method according to claim 1, wherein an estimated speed from the motor and load model is calculated by an observer.

Images