Relay Failure Detection Circuit for Industrial Robots

Solution Overview

Problem

Existing relay failure detection methods in industrial robots require multiple on/off cycles to detect welding failures, which reduces relay lifespan and is inefficient.

Innovation Solution

A relay failure detection circuit that compares waveforms of AC voltage and inter-terminal voltage signals to determine relay failures, allowing for detection without repeated switching and reducing the number of cycles required.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the relay is turned on and off repeatedly to detect welding failure, then the detection accuracy is improved, but the relay lifespan is reduced

Engineering Contradiction:

Improvewelding failure detection accuracyVSAvoidrelay lifespan

Core Design Contradiction:

Measurement precisionVSDuration of action of stationary object

Solution Approach 1:

The patent performs welding failure detection during the initial power-on state before any relay switching operations. By acquiring the voltage signal across the relay contacts when the relay is in its default closed state and comparing it with the input AC voltage, the system determines whether welding has occurred without requiring any subsequent on/off cycling of the relay. This preliminary detection approach eliminates the need for repeated switching to diagnose welding failures.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent replaces the mechanical relay switching method with an electrical measurement approach. Instead of physically opening and closing the relay to detect welding, the system uses voltage signal acquisition and waveform comparison to identify welding conditions. The determining section analyzes the voltage signal characteristics (such as presence of voltage during expected zero-voltage periods) to detect welding failures, substituting mechanical action with electrical field-based detection.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Duration of action of stationary object

If the relay switching cycles are reduced to extend lifespan, then the relay durability is improved, but the detection efficiency is reduced

Engineering Contradiction:

Improverelay lifespanVSAvoiddetection efficiency

Core Design Contradiction:

Duration of action of stationary objectVSProductivity

Solution Approach 1:

The patent performs welding failure detection during the initial power-on state before any relay switching operations. By acquiring the voltage signal across the relay contacts when the relay is in its default closed state and comparing it with the input AC voltage, the system determines whether welding has occurred without requiring any subsequent on/off cycling of the relay. This preliminary detection approach eliminates the need for repeated switching to diagnose welding failures.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent replaces the mechanical relay switching method with an electrical measurement approach. Instead of physically opening and closing the relay to detect welding, the system uses voltage signal acquisition and waveform comparison to identify welding conditions. The determining section analyzes the voltage signal characteristics (such as presence of voltage during expected zero-voltage periods) to detect welding failures, substituting mechanical action with electrical field-based detection.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS11525860B2Relay failure detection circuit and robot

Publication Date: 2022.12.13 SEIKO EPSON CORP

AI summary

A relay failure detection circuit includes a first voltage acquiring section configured to acquire an AC voltage input to a power supply circuit and output the AC voltage as a first voltage signal, a second voltage acquiring section configured to acquire an inter-terminal voltage of a relay provided in the power supply circuit and output the inter-terminal voltage as a second voltage signal, a comparing section configured to compare a waveform of the first voltage signal and a waveform of the second voltage signal, and a determining section configured to determine a failure of the relay according to a result of the comparison.