Servo Control Loop Gain Scaling for Delay Compensation
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Solution Overview
Problem
In servomotor velocity control loops, increasing integral gain by the square of proportional gain magnification to enhance responsiveness is limited by delay times, leading to insufficient proportional gain and potential oscillatory overshoot.
Innovation Solution
The integral gain is multiplied by a coefficient that is a value smaller than the square of the proportional gain magnification, with the coefficient determined by the delay time in the velocity control loop, allowing for increased responsiveness without significantly altering the damping characteristic.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the integral gain is increased by the square of the proportional gain magnification to enhance responsiveness, then the responsiveness is improved, but the velocity gain becomes limited at the boundary according to only the integral gain and it is not possible to sufficiently raise the proportional gain due to delay time in the control system
Solution Approach 1:
The patent changes the relationship between integral gain and proportional gain magnification from a square relationship to a power relationship with exponent β (where 0 < β < 2). This parameter change allows the system to achieve higher responsiveness while accounting for delay time in the control system, preventing the velocity gain from being limited at the boundary.
2Speed
If the integral gain is increased by the square of the proportional gain magnification, then the responsiveness is improved, but oscillatory overshoot may occur due to delay time in the control system
Solution Approach 1:
The patent introduces a power relationship with exponent β (0 < β < 2) between integral gain and proportional gain magnification, replacing the square relationship. This parameter adjustment optimizes the balance between responsiveness and damping characteristics, preventing oscillatory overshoot while maintaining improved responsiveness in the presence of control system delay time.
Data Source
AI summary
A servo control device includes a velocity command creation part configured to create a velocity command value for driving a servomotor; a velocity detection part configured to detect velocity of the servomotor; and a torque command creation part configured to create a torque command value using a difference between the velocity command value and the velocity detection value. The torque command creation part has an integral gain part and a proportional gain part, an integral gain and a proportional gain are obtained by multiplying a value calculated by multiplying an initial value by a ratio of load inertia of a machine relative to rotor inertia of the servomotor, by an integral gain magnification and a proportional gain magnification, respectively, and the integral gain magnification is set to a value smaller than the square of the proportional gain magnification according to a delay time of a velocity control loop.