Switch Stuck Open Diagnosis for Multi-Switch Buttons
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Solution Overview
Problem
Current shift-by-wire systems in vehicles lack effective diagnostic methods to detect switch degradation before it interferes with system operation, leading to potential failures and loss of functionality.
Innovation Solution
A method and system that increment counters for button and switch activation events, apply debounce times to signals, and evaluate fault statuses to detect switch failures, including stuck open conditions, allowing for timely reporting of impending or total failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple switches are used per button for redundancy, then system reliability is improved, but device complexity increases
Solution Approach 1:
The system divides each button's switch array into multiple individual switches (e.g., three switches per button). Each switch is independently monitored by the controller, allowing the system to detect failures in individual switches while maintaining overall button functionality through redundancy
Solution Approach 2:
The patent implements localized diagnostic capabilities at each switch level, where the controller monitors the state of each individual switch within a button array. This allows for granular fault detection and reporting, identifying which specific switch failed rather than just the entire button assembly
2Measurement precision
If switch state monitoring is implemented for each button activation, then measurement precision is improved, but use of energy increases
Solution Approach 1:
The controller monitors switch states at periodic intervals triggered by button activation events rather than continuously. Counters are incremented based on switch states during each activation event, and diagnostic evaluations are performed at these discrete moments, reducing energy consumption compared to continuous monitoring
Solution Approach 2:
The system performs preliminary diagnostic actions by incrementing counters during each button activation event. These counters track the number of times each switch is closed or open during activations, building up diagnostic data over time that is evaluated when activation thresholds are reached
3Reliability
If diagnostic evaluation is performed after a threshold number of activations, then reliability is improved, but loss of time occurs before detection
Solution Approach 1:
The system performs preliminary data collection during each button activation by incrementing counters that track switch states. This accumulates diagnostic information over multiple activations, allowing the system to evaluate reliability trends before a complete failure occurs, rather than waiting for a definitive failure state
Solution Approach 2:
The controller provides feedback by monitoring and comparing switch states across multiple activation events. When the number of activations reaches a predetermined threshold, the system evaluates the accumulated counter data to determine if switches are functioning properly, providing ongoing feedback about switch health
Data Source
AI summary
A method for detecting a failure mode in an electronic selector having a button coupled to a first switch, a second switch, and a third switch, the method includes incrementing a button activation counter once for each button activation event and incrementing a first switch-closed counter, a second switch-closed counter, and a third switch-closed counter once for each button activation event if the respective switch is closed at any time during the button activation event. The method further includes incrementing a first switch-opened counter, a second switch-opened counter, and a third switch-opened counter once for each button activation event. The method further includes evaluating a fault status of the first switch, the second switch, or the third switch when the button activation counter reaches or exceeds a predetermined threshold; and reporting the fault status of the first switch, the second switch or the third switch.