Motor Control Device Vibration Amplitude Estimation

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Solution Overview

Problem

Mechanical devices experience vibrations due to increased feedback gain, changes in mechanical resonance frequency, or abnormalities in movable parts, leading to instability and potential damage, with conventional vibration detection methods unable to distinguish between control system degradation and mechanical part abnormalities.

Innovation Solution

A motor control device with an operation determination unit, amplitude estimation units for operating and stopped states, and a state diagnosis unit to separately calculate and output high-frequency vibration amplitudes, allowing differentiation between stability degradation and mechanical part abnormalities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If feedback gain is increased to improve responsiveness, then responsiveness is improved, but high-frequency vibration occurs due to mechanical resonance

Engineering Contradiction:

ImproveresponsivenessVSAvoidhigh-frequency vibration

Core Design Contradiction:

SpeedVSObject-affected harmful factors

Solution Approach 1:

The patent applies dynamics by making the feedback gain adjustable and time-varying rather than fixed. The control device dynamically adapts the feedback gain based on operating conditions, allowing high gain for responsiveness when needed while reducing gain when mechanical resonance occurs, thus resolving the contradiction between responsiveness and vibration suppression

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the feedback gain parameter based on detected vibration levels and operating conditions. By monitoring high-frequency vibration components and adjusting the feedback gain accordingly, the system optimizes responsiveness while preventing mechanical resonance-induced vibrations

Inventive Principle:

Principle #35Parameter changes

2Speed

If feedback gain is set high for responsiveness, then responsiveness is improved, but stability of control system degrades

Engineering Contradiction:

ImproveresponsivenessVSAvoidstability of control system

Core Design Contradiction:

SpeedVSStability of the object's composition

Solution Approach 1:

The patent uses feedback by monitoring the mechanical resonance characteristics and vibration levels in real-time, then adjusting the feedback gain accordingly. This closed-loop approach allows the system to maintain high responsiveness when stable while automatically reducing gain when instability or resonance is detected, resolving the contradiction between responsiveness and stability

Inventive Principle:

Principle #23Feedback

3Reliability

If vibration detection function is provided to detect abnormalities, then abnormality detection capability is improved, but information useful for distinguishing vibration causes cannot be acquired

Engineering Contradiction:

Improveabnormality detection capabilityVSAvoidinformation for distinguishing vibration causes

Core Design Contradiction:

ReliabilityVSLoss of information

Solution Approach 1:

The patent segments vibration analysis into distinct operational phases (acceleration, deceleration, positioning) and separately analyzes vibration characteristics in each phase. This segmentation provides detailed information about vibration causes, enabling distinction between control system issues and mechanical abnormalities while maintaining reliable abnormality detection

Inventive Principle:

Principle #1Segmentation

4Adaptability or versatility

If mechanical resonance frequency is reduced due to change over time, then mechanical characteristics change, but feedback gain setting becomes too high causing vibration

Engineering Contradiction:

Improveadaptation to mechanical characteristic changesVSAvoidhigh-frequency vibration

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The patent makes the feedback gain dynamic and adaptive to changing mechanical characteristics over time. By continuously monitoring vibration levels and mechanical resonance frequency shifts, the system automatically adjusts feedback gain to match current mechanical conditions, preventing vibration caused by outdated gain settings while adapting to aging and wear

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The control device performs self-adjustment by automatically detecting changes in mechanical characteristics and modifying feedback gain without external intervention. This self-service capability ensures the system adapts to mechanical aging and resonance frequency shifts while preventing vibration, eliminating the need for manual recalibration

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS9122258B2Motor control device

Publication Date: 2015.09.01 MITSUBISHI ELECTRIC CORP

AI summary

A motor control device includes an operation determination unit that determines whether a motor is in an operating state or in a stopped state based on an operation command signal or an operation signal and an amplitude estimation unit that, based on a determination result of the operation determination unit, sequentially estimates a vibration amplitude value from a control state quantity of a feedback control unit or a current control unit separately for a case where the motor is operated and a case where the motor is stopped and outputs the vibration amplitude value. A function of outputting an amplitude of a high-frequency vibration that occurs in a mechanical device including a control system as information useful for estimating an occurrence factor of the vibration is provided.