Frequency Identifying Device for Servo Resonance Suppression
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Solution Overview
Problem
Existing servo control systems face challenges in accurately controlling high-frequency signals due to mechanical resonance and interpolation errors, leading to noise and reduced responsiveness, as conventional filters affect phase characteristics in low-frequency bands and are not effective in dynamically changing environments.
Innovation Solution
A frequency identifying device that uses Fourier conversion to identify cyclically changing frequencies and amplitudes in high bands, allowing for the removal of adverse signal components without affecting low-band phase characteristics, using a digital notch filter or signal generation to correct servo motor control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a notch filter is used to remove mechanical resonance frequency, then mechanical resonance is reduced, but the phase characteristic in low band is affected and responsiveness is reduced
Solution Approach 1:
The patent implements dynamic adjustment of the notch filter's center frequency and Q-value based on real-time detection of mechanical resonance frequency. The filter parameters are not fixed but adapt to changing operating conditions, allowing the system to maintain effective resonance suppression while preserving low-frequency phase characteristics for responsiveness.
Solution Approach 2:
The system changes the parameters of the notch filter (center frequency, Q-value) dynamically based on detected resonance conditions. By adjusting these parameters in real-time, the filter can target specific resonance frequencies without broadly affecting the low-frequency band, thus resolving the contradiction between resonance suppression and responsiveness.
2Speed
If servo control responsiveness is enhanced in high band, then control speed is improved, but mechanical resonance and abnormal noise are generated
Solution Approach 1:
The system continuously monitors the output signal for mechanical resonance frequency components and uses this feedback to dynamically adjust the notch filter parameters. This closed-loop control allows the system to maintain high responsiveness while automatically suppressing resonance and noise when they occur.
Solution Approach 2:
The patent extracts and removes only the specific harmful frequency components (mechanical resonance and encoder interpolation error frequencies) from the control signal using a notch filter, while leaving the rest of the high-frequency control signal intact. This selective removal preserves responsiveness while eliminating harmful effects.
3Manufacturing precision
If pre-load is increased to reduce lost motion, then positioning accuracy is improved, but mechanical resonance frequency deviates over time due to abrasion
Solution Approach 1:
The system dynamically tracks and adapts to changes in mechanical resonance frequency caused by pre-load degradation over time. By continuously detecting the resonance frequency and adjusting the notch filter accordingly, the system maintains effective vibration suppression even as the mechanical system's characteristics change due to wear and abrasion.
4Manufacturing precision
If encoder interpolation error is reduced, then positioning precision is improved, but system cost increases significantly
Solution Approach 1:
The patent converts the harmful effect of encoder interpolation error into a detectable signal characteristic. By identifying the specific frequency components generated by interpolation errors and using notch filters to remove them, the system achieves high positioning precision without requiring expensive super-accurate encoders.
Solution Approach 2:
The notch filter acts as an intermediary that compensates for the encoder's limitations. Instead of relying solely on the encoder's inherent accuracy, the system uses signal processing to filter out the periodic errors introduced by interpolation, effectively decoupling positioning precision from encoder cost.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables highly accurate identification and removal of high-frequency noise, improving servo system responsiveness and reducing processing time, thus preventing mechanical oscillation and abnormal noise, while allowing for the use of lower-cost encoders and maintaining low-band phase integrity.
Implementation Method 1
A frequency identifying device that uses Fourier conversion to identify cyclically changing frequencies and amplitudes in high bands
Data Source
AI summary
A window function calculator applies a Hann window function to Vd (n) to obtain a numeric value Vw (n). For twenty successive numeric values Vw(n) for every twenty numeric values (N=20), each of the Fourier calculators to executes Fourier calculation. Further, the SRSS calculators to calculate square root of sum of squares of SIM and COS components of respective orders of the results of Fourier calculation as numeric values A2, A3, A4, A5. A subtractor calculates a numeric value Ci=A3−A5, while a subtractor calculates a numeric value Si=A4−A2. A Frequency calculator calculates a numeric value Fi=(m+1+2*A TAN 2 (Ci, Si)/π)/(NT), which indicates the frequency identified. An amplitude calculator doubles the square root of the sum of squares of the numeric values Ci and Si, and calculates a numeric value Ai that indicates the amplitude of the frequency identified.