Servo Motor Control Apparatus Resonance Suppression
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Solution Overview
Problem
Existing control apparatuses for servo motors struggle to effectively suppress low-frequency mechanical resonance vibrations, which can lead to reduced precision and performance in machine tools and industrial machines, especially when the resonance frequency overlaps with the control system's frequency band.
Innovation Solution
A control apparatus for servo motors that divides speed commands into filtered and non-filtered parts, using a bandstop filter to selectively suppress resonance frequencies while maintaining dynamic characteristics, and adjusts filtering based on operational parameters like acceleration and deceleration to ensure precise control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a filter is provided to suppress mechanical resonance frequency components in the speed command signal, then vibration due to mechanical resonance is suppressed, but the dynamic characteristics of the control system deteriorate and position control precision falls
Solution Approach 1:
The patent applies dynamics by making the filter characteristics changeable based on operating conditions. The filter cutoff frequency and attenuation characteristics are dynamically adjusted according to the servo motor's speed and acceleration conditions, allowing the system to adapt between resonance suppression and dynamic response requirements at different operating points
Solution Approach 2:
The patent changes filter parameters (cutoff frequency, attenuation level) based on operating conditions such as motor speed and acceleration. By varying these parameters dynamically, the system can suppress resonance when needed while maintaining good dynamic characteristics during high-speed or high-acceleration operations
2Object-affected harmful factors
If the gain of the transfer function is lowered below the mechanical resonance frequency to avoid vibration, then resonance suppression is achieved, but the dynamic characteristics of the mechanical system fall
Solution Approach 1:
The patent makes the filter characteristics dynamic rather than fixed. The cutoff frequency and attenuation level are adjusted based on real-time operating conditions (speed, acceleration), allowing the system to suppress low-frequency resonance during steady-state operation while maintaining good dynamic response during acceleration and deceleration phases
Solution Approach 2:
The patent applies preliminary filtering to the speed command signal before it reaches the motor driver. By pre-filtering the command signal with dynamically adjusted characteristics, the system proactively suppresses resonance excitations while preserving necessary dynamic content for accurate tracking
Data Source
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AI summary
The control apparatus 10 of a servo motor of the present invention has a position control unit 11 controlling the position of a servo motor 33, a speed control unit 12 controlling a speed of the servo motor 33, a distributing unit 13 dividing the speed command output by the position control unit 11 into a filtered part Vf which is filtered to suppress vibration and a nonfiltered part Vnf, a filtering unit 14 receiving as input the filtered part Vf and filtering and outputting the filtered part Vf, and an adder unit 15 adding the filtered part Vf filtered by the filtering unit 14 and the nonfiltered part Vnf and outputting the result to the speed control unit 12.