Servomotor Control Device Vibration Suppression
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Solution Overview
Problem
Machine tools experience vibrations due to aging degradation of the connection mechanism, leading to a decline in machining precision.
Innovation Solution
A servomotor control device that performs dual position feedback control, adjusting the proportion of semi-closed and full-closed feedback control based on the rigidity and resonance frequency of the connection mechanism, using position detection sections and a motor control unit to vary the cut-off frequencies of filters and adapt the control strategy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If full-closed feedback control is used to maintain machining precision, then positioning accuracy is improved, but vibrations occur due to aging degradation of the connection mechanism
Solution Approach 1:
The patent dynamically adjusts the feedback control mode between semi-closed and full-closed based on the detected vibration state. When vibrations are detected in the low-frequency range (10 Hz or below), the system switches to semi-closed feedback control to avoid exciting the resonance. When vibrations are not present, full-closed feedback control is used to maintain high machining precision. This dynamic adaptation resolves the contradiction by selecting the appropriate control mode based on real-time conditions.
Solution Approach 2:
The patent changes the control parameter (feedback control mode proportion) based on the vibration state. By detecting resonance frequency and vibration amplitude, the system adjusts the proportion of semi-closed versus full-closed feedback control. This parameter change allows the system to avoid vibrations caused by aging degradation while maintaining machining precision when conditions permit.
2Object-affected harmful factors
If semi-closed feedback control is used to avoid vibrations, then vibration occurrence is reduced, but positioning accuracy deteriorates
Solution Approach 1:
The system dynamically switches between semi-closed and full-closed feedback control modes based on real-time vibration detection. When vibrations are detected, semi-closed control is used to suppress vibrations. When vibrations are absent, the system transitions to full-closed control to restore high positioning accuracy. This dynamic switching resolves the contradiction by temporarily using semi-closed control only when necessary.
Solution Approach 2:
The patent continuously monitors vibration state and periodically adjusts the feedback control mode. The system detects vibration amplitude and frequency, and based on this periodic detection, switches between control modes. This periodic adjustment ensures that full-closed control (for high precision) is used whenever possible, while semi-closed control (for vibration suppression) is used only when vibrations are detected.
3Manufacturing precision
If dual position feedback control is implemented to balance precision and vibration suppression, then control complexity increases
Solution Approach 1:
The patent implements dual position feedback control where both the servomotor position (first position feedback) and table position (second position feedback) are monitored. The control unit compares both feedback signals with the position command and dynamically adjusts the control mode based on vibration detection from either feedback channel. This comprehensive feedback approach manages the complexity by systematically processing multiple inputs to achieve both precision and vibration suppression.
Solution Approach 2:
The control unit is designed to perform multiple functions: it processes both semi-closed and full-closed feedback signals, detects vibrations, determines resonance frequency, and dynamically adjusts control modes. This multi-functional design manages complexity by consolidating multiple control capabilities into a single integrated control unit rather than requiring separate systems for each function.
Data Source
AI summary
A servomotor control device includes a servomotor, driven body, connection mechanism, first position detection section, second position detection section, and motor control unit. The motor control unit has: a dual position control section that performs semi-closed FB control based on a high-frequency component of a first deviation between a position command value and the position of the servomotor detected by the first position detection section, and full-closed FB control based on a low-frequency component of a second deviation between the position command value and the position of the driven body detected by the second position detection section; an acquisition section that acquires a magnitude of rigidity of the connection mechanism; and a varying section that varies a proportion of the semi-closed FB control to full-closed FB control in the dual position control section, in response to the acquired magnitude of rigidity of the connection mechanism.