JP3385466B2 - Gain Adjustment Method in Mechanical System Operation Control by Negative Feedback Method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the field of automatic control in operation control of a mechanical system by a negative feedback system, which is represented by a servomotor.

[0002]

2. Description of the Related Art As a method for auto-tuning a servo motor or the like, a real-time auto-tuning method for instantaneously detecting an error with respect to a command value and giving a correction signal commensurate with the magnitude of the error to maintain fidelity. However, the control against a sudden disturbance is unstable, and particularly in digital control, the load on the CPU is large and the system tends to be complicated. Also, initial type auto-tuning in which a load parameter is estimated by giving an acceleration / deceleration signal and a gain parameter is set has been generalized, but a perfect one has not been commercialized due to lack of theoretical consideration. Therefore, cumbersome documentation to rely on experience and intuition a lot of gain parameters
It was common to set it by adjusting .

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to easily and surely adjust a gain parameter for determining the fidelity and stability of an operation with respect to a command in the operation control of a mechanical system by the negative feedback method. Another feature is that the system has a simple configuration.

[0004]

The frequency characteristic of the error amplifier is optimized so that the gain is optimized in an unloaded state without changing the frequency and phase characteristics of the error amplifier. The values of the gain parameter to be increased / decreased, the integration frequency (breaking point frequency of the integrating circuit), the differential frequency (breaking point frequency of the differentiating circuit), and the high cutoff frequency are set and arranged as shown in FIG. Here, the resonance frequency f ₀ [Hz] of the mechanical system movable part and the mass M [kg] It is known that It is also known that the phase is greatly delayed in the vicinity of the resonance point (f ₀ ), and it can be seen that the maximum response frequency in closed loop control is limited by the resonance frequency of the mechanical system. In addition, the amplitude response characteristic during open loop is approximately -6 [dB / oct] up to near the resonance point.
(−20 [dB / dec]) first-order delay characteristic (90 °
Phase delay) is also generally known. Na
The electrical time constant of the motor, etc. (armature inductance /
Delay due to armature winding resistance) can be easily compensated for by a separate circuit.
Since it is possible to correct, consider the effect of this .

Here, the values of the load mass and the load inertia moment (load inertia) are twice as large as when there is no load (load mass ratio =
1. Considering the case where the load inertia ratio = 1), the amplitude response characteristic in the open loop is attenuated by 6 dB as compared with that in the case of no load. And the resonance frequency is It can be seen that the intersection point (crossover frequency) can be maintained in the optimum state (phase margin> 45 °).

From the above, as a general theory, the value of the total gain is (value at no load: 0 dB) + 10log {1+ (A or B)} [dB] Integration frequency, differential frequency, high cutoff frequency Is It turns out that it is desirable to (Note) A = Load mass ratio = (Motor side converted load mass value) / (Movable part mass value of linear motor alone) B = Load inertia moment ratio = (Motor shaft converted load inertia value) / (Motor Rotor inertia value)

[0007]

[Effects of the Invention] Based on the above conclusion, after the optimum value of the gain parameter at the time of no load (motor alone) of the servo motor etc. is determined, the above setting is made in accordance with the load mass ratio and the load inertia moment ratio. If the value is adjusted to the optimum value, it automatically becomes the optimum value, so that it becomes possible to easily adjust the gain with one or two parameters. If the step response characteristic is observed and the parameter can be automatically set, it becomes simpler . Also, it has a simple structure as compared with the conventional automatic adjustment from the system.

[Brief description of drawings]

FIG. 1 is an ideal frequency characteristic diagram of an error amplifier.

FIG. 2 is a Bode diagram in the vicinity of a gain intersection when the load mass ratio or the load inertia moment ratio (load inertia ratio) is “1”.

[Explanation of symbols]

I: Overall gain [dB] (0B at no load)
II: integral gain [dB] (20 to 80 [d
B]) III: Differential gain [dB] (6 to 20 [d
B]) IV: Integral frequency [Hz] V: Differential frequency [Hz] VI: High cutoff frequency [Hz] α: Crossover frequency [Hz] in no-load condition (motor alone)

Claims (2)

(57) [Claims] 1. In PID control by a negative feedback method in operation control of a mechanical system, values of an integration frequency, a differential frequency, and a high cutoff frequency, which are control parameters of an error amplifier, are arranged so as to increase in this order, and The value of the total gain of the error amplifier and the value of each of the above frequencies are calculated in accordance with the increase of the load mass ratio or the load inertia moment ratio value.
A method of gain adjustment, characterized in that the value of total gain is large and the value of each of the above frequencies is low. 2. In the PID control by the negative feedback method in the operation control of the mechanical system, the values of the integral frequency, the differential frequency and the high cutoff frequency, which are the control parameters of the error amplifier, are arranged so as to increase in this order, and A method of gain adjustment, characterized in that the value of each frequency is lowered as the value of the load mass ratio or the load inertia moment ratio increases while keeping the ratio of each frequency interval constant.