Enable Switch Signal Processing for Failure Detection and Safe States
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Solution Overview
Problem
Existing enable switch devices in industrial robots lack a simple configuration to determine the operated state and detect failures in internal two-position switches, leading to potential safety hazards and frequent replacement of electromagnetic relays.
Innovation Solution
An enable switch device with a first and second two-position switch and a first signal processor that determines the operated state and detects failures by analyzing output signals from the switches, allowing for safe transitions and reduced component replacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electromagnetic on-off relays are used to output the state of the switch, then the switch state can be transmitted, but the life of the relay is short and frequent replacement is required
Solution Approach 1:
The patent replaces electromagnetic on-off relays with a field-effect transistor (FET) and diode configuration to output switch states. This solid-state substitution eliminates the mechanical moving parts and electromagnetic components that limited relay life, thereby resolving the contradiction between reliability and ease of manufacture by eliminating the need for frequent component replacement.
Solution Approach 2:
The patent changes the operational parameters by using a FET with gate voltage control instead of electromagnetic actuation. The FET is driven by voltage signals from the switches rather than electromagnetic fields, fundamentally changing how the output stage operates and eliminating the wear mechanisms present in electromagnetic relays.
2Reliability
If a conventional enable switch device configuration is used, then the switch state can be output, but it cannot detect failure in the internal two-position switch
Solution Approach 1:
The patent implements feedback by using the output signals from the FET circuit to monitor the operational state of the switches. The control device receives feedback about switch states and can detect when a switch fails to transition properly, enabling failure detection without significantly increasing overall device complexity.
Solution Approach 2:
The patent introduces a diode as an intermediary component in the FET circuit that enables the detection of switch failures. The diode configuration allows the system to monitor whether switches are properly transitioning between states, acting as a mediator that provides failure information to the control device while maintaining configuration simplicity.
3Reliability
If two three-position switches and two monitor circuits are used, then safety can be secured even when either monitor circuit is short-circuited, but the device complexity increases
Solution Approach 1:
The patent merges the functions of multiple switches and monitor circuits into a single two-position switch with integrated FET-based output circuitry. The FET and diode configuration combines the switching and monitoring functions that were previously distributed across multiple components, maintaining safety while reducing device complexity.
Solution Approach 2:
The patent makes the two-position switch universal by enabling it to perform multiple functions: switching control and failure detection. The FET circuit serves multiple purposes by both outputting the switch state and monitoring for failures, eliminating the need for separate monitor circuits and reducing overall system complexity while maintaining reliability.
Data Source
AI summary
Enable switch device (100) transitions to position 1 when not operated, to position 2 when mid-operated, and to position 3 when full-operated. Enable switch device (100) includes first switch (SW1) and second switch (SW2) each being a two-position switch, and first signal processor (10). First signal processor (10) determines in which one of positions 1 to 3 an operated state of enable switch device (100) is, based on an output signal of first switch (SW1) and an output signal of second switch (SW2). First signal processor (10) detects presence or absence of failure in each of first switch (SW1) and second switch (SW2).