Push-Type Shifter Switch Sensing With Sensor Failure Voting
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Solution Overview
Problem
Conventional shift lever position determination devices for vehicles fail to detect failures or avoid erroneous determinations, which is critical in systems requiring functional safety.
Innovation Solution
A switch device with three or more sensors that detect operation positions, a memory, and a processor to determine a switching state through majority decision and failure detection, comparing sensor measurements to identify failed components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional majority decision method is used without failure detection, then device complexity is reduced, but reliability deteriorates due to erroneous determinations from measurement errors
Solution Approach 1:
The system performs preliminary failure detection by comparing measurement values before making the final switching state determination. The processor compares each sensor's measurement value with others to identify failed sensors, then excludes these failed sensors from the majority decision calculation, thereby preventing erroneous determinations while maintaining system reliability
Solution Approach 2:
The system implements a feedback mechanism where the processor continuously monitors measurement values from multiple sensors, compares them to detect failures, and adjusts the determination process by excluding failed sensors. This feedback loop ensures that only reliable sensor data is used in the majority decision, improving determination accuracy without significantly increasing overall system complexity
2Reliability
If three or more sensors are used with failure detection, then reliability is improved, but device complexity increases due to additional comparison operations
Solution Approach 1:
The determination process is segmented into distinct steps: first comparing measurement values to detect sensor failures, then making the switching state determination based on remaining functional sensors. This segmentation allows the system to handle failure detection and determination separately, making the complex process more manageable and implementable
Solution Approach 2:
The system dynamically changes the effective number of sensors used in determination based on failure detection results. When no failures are detected, all three or more sensors are used; when failures are detected, only the functional sensors are used. This parameter change optimizes the balance between reliability and processing complexity
Data Source
AI summary
A switch device includes three or more sensors configured to detect three or more respective measurement values with respect to an operation position of a switch; a memory; and a processor configured to determine a switching state of the switch by making a majority decision based on measurement levels of the three or more measurement values of the three or more sensors, and determine whether a failure has occurred for each of the three or more sensors. The processor compares a measurement value of one sensor among the three or more sensors with measurement values of other sensors other than the one sensor among the three or more sensors, and determines that the one sensor has failed in a case where half or more of the measurement values of the other sensors are not in a predetermined range of the measurement value of the one sensor.