Robot Control Device Rotation Angle Update

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Solution Overview

Problem

Existing robot control devices face challenges in accurately detecting and storing rotation angles exceeding a predetermined range, especially when the device is stopped, due to limitations in encoder configurations and power supply issues, which can lead to loss of rotation data and reduced accuracy in position and posture control.

Innovation Solution

A robot control device equipped with a first and second rotation angle detector, an auxiliary power source for the first detector during stop states, and a control unit that updates and stores rotation angles, allowing for continuous detection and correction of errors when the device is restarted, even without a backup power source for the second detector.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If an absolute encoder is used to detect rotation angle, then the rotation angle can be detected accurately within a predetermined range, but the rotation angle exceeding the predetermined range cannot be detected

Engineering Contradiction:

Improverotation angle detection accuracyVSAvoiddetection range

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The system segments the rotation detection function into two parts: the absolute encoder detects rotation angles within the predetermined range (0-360 degrees), while a separate counter detects the number of full rotations. This segmentation allows the system to handle both precise angular measurement and extended rotation tracking simultaneously.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system transitions from a single-dimensional detection approach to a two-dimensional approach by combining the absolute encoder's angular detection (0-360 degrees) with a counter that tracks the number of full rotations. This dimensional extension enables detection of rotation angles beyond the encoder's inherent range.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Loss of energy

If the robot control device is stopped without backup power source, then power consumption is reduced, but the rotation angle data is lost and cannot be detected after restart

Engineering Contradiction:

Improvepower consumptionVSAvoidrotation angle data

Core Design Contradiction:

Loss of energyVSLoss of information

Solution Approach 1:

The system performs preliminary action by storing the number of rotations in a non-volatile memory or backup register before stopping the device. This ensures that even when power is cut and the main memory is cleared, the rotation count information is preserved and can be used to reconstruct the absolute position after restart.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system creates a copy of the critical rotation data in a non-volatile storage medium. The counter value representing the number of full rotations is copied to a backup storage area that retains data without power, ensuring information preservation while allowing main system power to be reduced during idle periods.

Inventive Principle:

Principle #26Copying

3Measurement precision

If a second encoder is mounted on the output shaft of the reducer to detect rotation angle, then the accuracy of position and posture control is improved, but the device complexity and cost increase

Engineering Contradiction:

Improveposition and posture detection accuracyVSAvoidencoder configuration

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The system introduces an intermediary computational approach instead of adding physical hardware. By using the existing absolute encoder data combined with counter information and mathematical calculations, the system achieves the functional equivalent of a second encoder without the associated complexity and cost.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system replaces the mechanical solution of adding a second physical encoder with an electronic/software-based solution. The rotation angle exceeding the predetermined range is detected through computational methods combining encoder readings with counter data, eliminating the need for additional mechanical sensing components.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Reliability

If backup power source is provided for the second encoder, then the rotation angle detection during stop period is maintained, but the cost and power consumption increase

Engineering Contradiction:

Improvecontinuous detection capabilityVSAvoidpower consumption during stop

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS9636823B2Robot control device for updating rotation angle by plurality of rotation angle detectors

Publication Date: 2017.05.02 FANUC LTD

AI summary

A robot control device, when starting from a stop state, updates a first rotation angle or a second rotation angle based on at least one of the first rotation angle stored in a first rotation angle storage unit and the second rotation angle stored in a second rotation angle storage unit and at least one of the first rotation angle detected by a first rotation angle detector and the second rotation angle detected by the second rotation angle detector.