Servo Frequency Response Measurement for Resonance Band Accuracy

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Solution Overview

Problem

Existing methods for measuring the frequency response of servo systems face challenges in achieving high accuracy due to insufficient signal intensity and the risk of device damage, particularly in systems with large inertia, friction, resonance, or anti-resonance.

Innovation Solution

A method involving the output of a first excitation signal in a first frequency range, followed by a second excitation signal in a narrower frequency range with a longer sampling cycle, allowing for accurate frequency response calculation by adjusting signal intensity based on system inertia and friction, and using signals like pseudo-random, multi-sine wave, or sine wave sweep signals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a wide frequency range excitation signal is used for frequency response measurement, then the measurement coverage is improved, but the signal intensity becomes insufficient leading to low measurement accuracy

Engineering Contradiction:

Improvefrequency range coverageVSAvoidfrequency response measurement accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The frequency response measurement is divided into multiple stages: first a wide frequency range measurement is performed to obtain initial frequency response data, then based on this data, specific frequency bands with resonance or anti-resonance characteristics are identified and measured again with higher signal intensity. This segmentation allows both wide coverage and high precision in different measurement phases.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A preliminary frequency response measurement is conducted first using a wide frequency range excitation signal to identify resonance and anti-resonance frequencies. This preliminary action provides the basis for determining the optimal signal intensity and frequency range for subsequent targeted measurements, ensuring high accuracy without excessive signal intensity.

Inventive Principle:

Principle #10Preliminary action

2Measurement precision

If the signal intensity is increased to improve measurement accuracy, then the frequency response measurement precision is improved, but the risk of device damage increases

Engineering Contradiction:

Improvefrequency response measurement accuracyVSAvoiddevice damage risk

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

Instead of applying high signal intensity across the entire frequency range, the method applies increased signal intensity only to specific frequency bands where resonance or anti-resonance occurs. This partial action provides sufficient signal intensity for accurate measurement in critical bands while avoiding excessive signal intensity that could damage the device in other frequency ranges.

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The excitation signal parameters (frequency range and intensity) are dynamically adjusted based on the frequency response data obtained from preliminary measurement. The signal intensity is increased only in frequency bands identified as having resonance or anti-resonance characteristics, while maintaining lower intensity in other bands, thus achieving high measurement accuracy without excessive overall signal intensity.

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If a long sampling cycle is used to improve frequency resolution, then the measurement precision is improved, but the measurement time increases

Engineering Contradiction:

Improvefrequency resolutionVSAvoidmeasurement time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The frequency response measurement is segmented into multiple targeted measurements of specific frequency bands rather than a single long-duration measurement of the entire frequency range. By focusing on identified resonance and anti-resonance frequencies, the method achieves high frequency resolution in critical bands with shorter measurement times.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A preliminary quick measurement is performed to identify critical frequency bands, then targeted measurements are conducted only in these bands with longer sampling cycles for high resolution. This preliminary action approach avoids the need for long sampling cycles across the entire frequency range, reducing total measurement time while maintaining high resolution where needed.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentEP4703811A1Frequency characteristic measurement method and frequency characteristic measurement device

Publication Date: 2026.03.04 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

Figure 1
Figure 2A~2C
Figure 2D~2E

AI summary

A frequency response measurement method includes: outputting, to a servo system (20), a first excitation signal in a first frequency range; calculating a first frequency response of the servo system (20) in the first frequency range based on a first identification input signal and a first identification output signal obtained in a first sampling cycle from the servo system (20) to which the first excitation signal is inputted; outputting, to the servo system (20), a second excitation signal in a second frequency range forming a part of the first frequency range and generated based on the first frequency response; and calculating a second frequency response of the servo system (20) in the second frequency range based on a second identification input signal and a second identification output signal obtained in a second sampling cycle longer than or equal to the first sampling cycle from the servo system (20) to which the second excitation signal is inputted.