Motor Control Device Vibration Damping via Frequency Estimation
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Solution Overview
Problem
Existing motor control devices face challenges in accurately estimating vibration frequencies and attenuation coefficients when multiple frequencies are superimposed, leading to difficulties in setting appropriate pass-frequency bands and achieving effective vibration-damping control.
Innovation Solution
A motor control device with a feedforward control unit, a driving-command computing unit, a vibration-damping-control setting unit, a signal-estimation computing unit, and a resonance-characteristic estimating unit that designates candidate frequencies and sets vibration-damping frequencies to accurately estimate and suppress resonance frequencies and attenuation coefficients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If FFT-based frequency analysis is used to estimate vibration frequencies and attenuation coefficients from superimposed vibrations, then estimation accuracy is improved, but computing load increases and data length requirements increase
Solution Approach 1:
The patent segments the vibration signal analysis by separating the estimation of vibration frequencies and attenuation coefficients into distinct processing stages. The feedforward control unit first identifies vibration frequencies, then the attenuation coefficient calculation unit separately calculates attenuation coefficients based on amplitude ratios at identified frequencies, avoiding the need for complete spectral analysis
Solution Approach 2:
The patent changes the approach from frequency-domain analysis (FFT) to time-domain parameter extraction by calculating amplitude ratios at specific time points. This parameter transformation allows estimation of both vibration frequencies and attenuation coefficients using simpler computational methods that do not require large data sets
2Device complexity
If least squares method is used to estimate vibration characteristics, then computing load is reduced, but estimation accuracy deteriorates when multiple frequencies are superimposed
Solution Approach 1:
The patent introduces an intermediary approach by using amplitude ratio calculations at specific time points as a mediator between the simple least squares method and complex FFT analysis. This intermediary method provides sufficient accuracy for superimposed vibrations while maintaining low computational complexity
Solution Approach 2:
The patent performs preliminary identification of vibration frequencies before calculating attenuation coefficients. This preliminary action allows the system to focus computational resources on extracting relevant parameters at identified frequencies rather than analyzing the entire spectrum
3Manufacturing precision
If vibration-damping control is applied to multiple superimposed frequencies, then positioning precision is improved, but control system complexity increases
Solution Approach 1:
The patent merges the vibration-damping control for multiple frequencies into a unified feedforward control framework. By combining frequency identification and attenuation coefficient calculation into a single integrated process, the system achieves multi-frequency damping without proportionally increasing control complexity
Solution Approach 2:
The patent creates a universal control algorithm that handles both single-frequency and multi-frequency vibrations using the same basic structure. The feedforward control unit and attenuation coefficient calculation unit work together to suppress vibrations regardless of how many frequencies are present, providing multi-functional capability without requiring separate control paths
Data Source
AI summary
A motor control device includes a vibration-damping-control setting unit to designate one of a plurality of candidate frequencies of a vibration-damping frequency, a signal-for-estimation computing unit to output, based on an operation signal related to a controlled object, a signal for estimation in which signal components of the other candidate frequencies excluding the designated one candidate frequency are reduced from a vibration component of a control system, and a resonance-characteristic estimating unit to estimate one resonance frequency from the output signal for estimation. The vibration-damping-control setting unit designates each of the candidate frequencies individually as one candidate frequency and sets, in a feedforward control unit, each of resonance frequencies estimated by the resonance-characteristic estimating unit related to the individually designated each one candidate frequency.