Servo Frequency Measurement Around Resonance and Antiresonance

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Solution Overview

Problem

Existing frequency characteristic measurement methods for servo systems fail to achieve high accuracy when resonance or antiresonance frequencies are included in the frequency band of interest, leading to insufficient measurement of these critical components.

Innovation Solution

A frequency characteristic measurement apparatus and method that includes outputting a first excitation signal, calculating initial frequency characteristics, determining resonance or antiresonance frequencies, and then outputting a second excitation signal focused on these frequencies to enhance measurement accuracy, using different excitation signals in distinct frequency ranges.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a single excitation signal covering a broad frequency range is used, then the measurement covers all frequency bands including resonance and antiresonance frequencies, but the measurement accuracy at specific resonance and antiresonance frequencies is insufficient

Engineering Contradiction:
Improvefrequency characteristic measurement accuracyVSAvoidmeasurement efficiency
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The measurement process is divided into multiple stages: first measuring the entire frequency range with a first excitation signal to identify resonance and antiresonance frequencies, then performing targeted measurements at these specific frequencies using a second excitation signal. This segmentation allows comprehensive coverage while achieving high accuracy at critical frequencies through focused measurement.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The first measurement using the first excitation signal serves as a preliminary action to identify the resonance and antiresonance frequencies before the main high-accuracy measurement. This preliminary identification enables the second excitation signal to be optimized for accurate measurement at the specific frequencies of interest.

Inventive Principle:
Principle #10Preliminary action

2Measurement precision

If multiple excitation signals are used to improve measurement accuracy at resonance and antiresonance frequencies, then measurement precision improves, but the device complexity and measurement time increase

Engineering Contradiction:
Improvefrequency characteristic measurement accuracyVSAvoidmeasurement system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The same measurement apparatus performs multiple functions: it generates both the first broad-frequency excitation signal and the second targeted excitation signal, processes both measurement sets, and synthesizes the final frequency characteristics. This multi-functionality avoids the need for separate specialized measurement systems while achieving high accuracy.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The measurement system uses feedback from the first measurement results to determine the resonance and antiresonance frequencies, then adjusts the second excitation signal parameters based on this feedback to optimize the second measurement. This feedback loop ensures high accuracy at critical frequencies while keeping the system adaptable rather than overly complex.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP4425789B1Frequency characteristic measurement apparatus and frequency characteristic measurement method
Publication Date: 2025.11.19 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD
  • EP4425789B1 patent drawingFigure 1
  • EP4425789B1 patent drawingFigure 2A~2E
  • EP4425789B1 patent drawingFigure 3~4

AI summary

Frequency characteristics are measured with high accuracy. Frequency characteristic measurement apparatus (10) includes first output part (11), frequency characteristic calculator (13), resonance frequency calculator (14), and second output part (12). Frequency characteristic calculator (13) calculates a first frequency characteristic of servo system (20) based on a first excitation signal in a first frequency range from first output part (11) and a first state signal acquired from servo system (20) having received the first excitation signal. Resonance frequency calculator (14) calculates a resonance frequency or an antiresonance frequency of servo system (20) based on the first frequency characteristic. Second output part (12) outputs a second excitation signal in a second frequency range including the resonance frequency or the antiresonance frequency. Frequency characteristic calculator (13) calculates a second frequency characteristic of servo system (20) based on a second excitation signal and a second state signal acquired from servo system (20) having received the second excitation signal.