Method and device for tuning stiffness of servo system and servo system

Patent metadata

Field	Value
Publication number	US-12455544-B2
Application number	US-202217886798-A
Country	US
Kind code	B2
Filing date	Aug 12, 2022
Priority date	Aug 18, 2021
Publication date	Oct 28, 2025
Grant date	Oct 28, 2025

Abstract

Disclosed is a method for tuning stiffness of a servo system, including: reconstructing a characteristic signal of a servo system; calculating a vibration characteristic covariance coefficient of the servo system according to the characteristic signal; and tuning the stiffness of the servo system according to the calculated vibration characteristic covariance coefficient. By reconstructing the characteristic signal of the servo system, relationships between parameters of the system and the characteristic signal of the system are determined, and then, system stiffness tuning is carried out by calculating the vibration characteristic covariance coefficient of the system. In the process of tuning the stiffness of the servo system, a tuning judgment is made according to the system's own parameters without relying on a special locus, thus increasing the compatibility and intelligence degree of an algorithm.

First claim

What is claimed is:

1. A method for tuning stiffness of a servo system, comprising:
reconstructing a characteristic signal of a servo system;
calculating a vibration characteristic covariance coefficient of the servo system according to the characteristic signal; and
tuning the stiffness of the servo system according to the calculated vibration characteristic covariance coefficient;
wherein the vibration characteristic covariance coefficient P IIR (n) of the servo system is calculated according to the following formula:
P IIR ( n )=(1− K IIR ( n )Φ( n )) P IIR ( n− 1)/μ IIR

wherein P IIR (n) is a vibration characteristic covariance coefficient of the servo system in the nth discrete cycle, Φ(n) is a search gradient function for a vibration characteristic frequency of the servo system in the nth discrete cycle, K IIR (n) is a recursive gain of the servo system in the nth discrete cycle, n represents the nth discrete cycle, n is an integer greater than or equal to 1, and μ IIR is a forgetting factor, and
wherein K IIR (n) and Φ(n) are determined according to the characteristic signal.

2. The method of claim 1 , wherein the servo system comprises a speed loop controller and a high-pass filter which are connected in series; and the step of reconstructing a characteristic signal of a servo system comprises:
acquiring a rotational speed command of the speed loop controller and a rotational speed feedback of the speed loop controller,
determining a current command proportional component according to the rotational speed command of the speed loop controller, the rotational speed feedback of the speed loop controller and an equivalent proportional coefficient of the speed loop controller,
obtaining a per-unit value of the current command proportional component with a rated current of the system as a reference; and
passing the current command proportional component as the per-unit value through the high-pass filter to complete the reconstruction of the characteristic signal of the servo system.

3. The method of claim 2 , wherein the current command proportional component is determined according to the following formula:
G k =K sp (ω mRef −ω m )

wherein G k is the current command proportional component, K sp is a proportional gain coefficient of the speed loop controller, ω mRef is the rotational speed command of the speed loop controller, and ω m is the rotational speed feedback of the speed loop controller.

4. The method of claim 3 , wherein the reconstruction of the characteristic signal of the servo system is carried out according to the following formula:

x
IIR

(
s
)

=

G
k

I
N

·

G
t

wherein the above formula is an s domain function expression for a reconstructed characteristic signal of the servo system, s is a differential operator in Laplace transform, x IIR is the reconstructed characteristic signal of the servo system, I N is the rated current of the system, and G t is a function expression for the high-pass filter.

5. The method of claim 1 , wherein the determining K IIR (n) and Φ(n) according to the characteristic signal comprises:
establishing an expected transfer function of vibration y IIR (n) according to the characteristic signal;
establishing a search gradient function Φ(n) for the vibration characteristic frequency according to the expected transfer function of vibration y IIR (n); and
updating a recursive gain K IIR (n) according to the search gradient function Φ(n).

6. The method of claim 1 , wherein the step of tuning the stiffness of the servo system according to the calculated vibration characteristic covariance coefficient comprises:
judging the stability of the servo system;
if the servo system is unstable, reducing the stiffness of the servo system at the end of a cycle, and ending the system tuning process; or
if the servo system is stable, increasing the stiffness of the system at the end of the cycle.

7. The method of claim 6 , wherein the step of judging the stability of the servo system comprises:
judging whether the duration for which the calculated vibration characteristic covariance coefficient P IIR (n) is less than a preset coefficient threshold q IIR1 reaches a set duration q IIR2 ; if so, the servo system being considered unstable; otherwise, the servo system being considered stable.

8. A device for tuning stiffness of a servo system, comprising a processor and a memory storing program instructions, wherein the processor is configured to execute the method for tuning stiffness of a servo system of claim 1 when running the program instructions.

9. A servo system, comprising a speed loop controller and a high-pass filter which are connected in series, wherein the servo system further comprises the device for tuning stiffness of a servo system of claim 8 .

Assignees

• Harbin Inst Technology

Inventors

• Yang Ming
• Chen Yangyang
• Xu Dianguo

Classifications

• G05B2219/34013

  Servocontroller · CPC title

• G05B17/02 Primary

  electric · CPC title

• G05B13/024 Primary

  in which a parameter or coefficient is automatically adjusted to optimise the performance · CPC title

• G05B19/4142 Primary

  characterised by the use of a microprocessor (G05B19/4141 takes precedence) · CPC title