Robot Control System with Command Interruption for Safety

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Solution Overview

Problem

Existing robot control systems fail to ensure operator safety as they allow slight movements of the robot before complete stoppage, due to interruptions based on servo motor position, leading to potential hazards.

Innovation Solution

A robot control system with an operation command interruption unit that stops the robot by interrupting the operation command and a power interruption unit that disconnects power supply when speed or position deviations exceed threshold values, ensuring immediate cessation of robot operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the robot is stopped based on shaft speed monitoring, then operator safety is improved, but slight movement occurs before actual stoppage

Engineering Contradiction:

Improveoperator safetyVSAvoidslight movement before stop

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The invention applies preliminary action by interrupting the operation command before the servo motor actually stops. When the shaft speed exceeds the threshold, the control device interrupts the operation command to the servo amplifier, preventing further operation commands from being executed. This preliminary interruption stops the robot before any additional movement occurs, eliminating the safety hazard of slight movements during stoppage.

Inventive Principle:

Principle #10Preliminary action

2Measurement precision

If the servo motor is interrupted based on position detection, then control precision is improved, but slight movement of servo motor occurs before shaft stop

Engineering Contradiction:

Improveposition detection accuracyVSAvoidservo motor movement before shaft stop

Core Design Contradiction:

Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The invention replaces the mechanical position-based interruption system with an electronic control-based system. Instead of relying solely on position sensor feedback to interrupt the servo motor, the control device uses electronic monitoring of shaft speed and interrupts the operation command at the electronic control level. This substitution eliminates the delay and slight movement associated with mechanical position-based stopping.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If operation command is continuously outputted, then robot productivity is improved, but safety hazard exists when speed threshold is exceeded

Engineering Contradiction:

Improverobot operation continuityVSAvoidsafety hazard during operation

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The invention implements feedback by continuously monitoring the shaft speed and comparing it against a predetermined threshold. When the shaft speed exceeds the threshold, the control device detects this condition and automatically interrupts the operation command. This feedback mechanism allows the robot to operate continuously at normal speeds while automatically preventing operation when safety thresholds are exceeded, thus maintaining both productivity and safety.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS10105846B2Robot control system having stop function

Publication Date: 2018.10.23 FANUC LTD

AI summary

A robot control system includes an operation command output unit which outputs an operation command of a motor, a position detection unit which is provided on the motor to detect the position of a control shaft, a stop signal output unit which outputs a stop signal to stop the robot when the speed of the control shaft acquired from the position detection unit exceeds a speed threshold value, and an operation command interruption unit which interrupts the operation command outputted from the operation command output unit when the stop signal is outputted.