Motor Controller Detecting Power Transmission Abnormality

Solution Overview

Problem

Existing motor controller systems for machine tools require additional sensors like speed sensors and torque meters to detect abnormalities in power transmission units, increasing costs and complexity.

Innovation Solution

A motor controller that uses a single-rotation signal detector and a rotation angle detector to judge abnormalities in the power transmission unit without additional sensors, with adjustable upper and lower limit values for rotation angles based on the speed reduction ratio, and includes an alarm and stop command to prevent defective product production.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If additional sensors like speed sensors or torque meters are added to detect power transmission unit abnormalities, then the detection capability is improved, but the device complexity and cost increase

Engineering Contradiction:

Improveabnormality detection capabilityVSAvoidsensor quantity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The encoder mounted on the motor shaft is made to serve dual purposes: its primary function of measuring motor rotation for control, and a secondary function of detecting power transmission abnormalities by comparing motor rotation with main spindle rotation. This eliminates the need for separate detection sensors while maintaining abnormality detection capability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system uses its own existing components (encoder and control unit) to perform the additional function of power transmission abnormality detection. The control unit compares the encoder-derived main spindle rotation with directly measured main spindle rotation, enabling self-diagnosis without external sensors.

Inventive Principle:

Principle #25Self-service

2Reliability

If additional sensors like speed sensors or torque meters are added to detect power transmission unit abnormalities, then the detection capability is improved, but the cost increases

Engineering Contradiction:

Improveabnormality detection capabilityVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The encoder mounted on the motor shaft is made to serve dual purposes: its primary function of measuring motor rotation for control, and a secondary function of detecting power transmission abnormalities by comparing motor rotation with main spindle rotation. This eliminates the need for separate detection sensors while maintaining abnormality detection capability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system uses its own existing components (encoder and control unit) to perform the additional function of power transmission abnormality detection. The control unit compares the encoder-derived main spindle rotation with directly measured main spindle rotation, enabling self-diagnosis without external sensors.

Inventive Principle:

Principle #25Self-service

3Adaptability or versatility

If the speed reduction ratio of the power transmission unit is changed, then the adaptability is improved, but the measurement precision requirements increase

Engineering Contradiction:

Improvespeed reduction ratio adjustabilityVSAvoidrotation angle measurement precision

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The system dynamically adapts to different speed reduction ratios by receiving input signals representing the current ratio and automatically adjusting the expected rotation angle thresholds. This allows the same detection mechanism to work accurately across multiple speed reduction configurations without requiring precision adjustments.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the parameter of expected rotation angle based on the speed reduction ratio input. When the speed reduction ratio changes, the control unit adjusts the threshold values for abnormality detection accordingly, maintaining measurement precision across different operational configurations.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS10018677B2Motor controller detecting abnormality of power transmission unit between main spindle and motor

Publication Date: 2018.07.10 FANUC LTD

AI summary

A motor controller includes a single-rotation signal detector detecting a single-rotation signal that indicates a single rotation of a main spindle, a rotation angle detector detecting a rotation angle of a motor every predetermined time, and a counter adding up the rotation angle. A value of the counter is reset when the single-rotation signal detector detects the single-rotation signal of the main spindle. The motor controller further includes a judgment unit judging that a power transmission unit has abnormality when a value of the rotation angle of the motor added up in the counter deviates from a predetermined range.