Shift-by-wire Position Diagnostic Test Using Redundant Sensor Validation
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Solution Overview
Problem
Shift-by-wire systems in vehicles face challenges in accurately determining the position of the shift lever due to potential failures in position sensors, which can lead to incorrect transmission range selection, necessitating a redundant and reliable diagnostic testing method to ensure accurate communication.
Innovation Solution
A shift-by-wire system employing two position sensors and a controller that generates position signals with x and y coordinates, performing a rationality test on these coordinates to determine sensor accuracy and reliability, allowing for redundant tracking and fault detection to ensure accurate range selection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple position sensors are used to provide redundancy, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent performs rationality tests on sensor coordinates before using them for transmission range selection. The controller pre-validates the coherence between first and second position sensor readings by checking if their coordinate differences fall within expected ranges, and prepares backup coordination logic in advance to switch to alternative sensors if failures are detected, thereby ensuring reliability without requiring complex real-time decision mechanisms
Solution Approach 2:
The patent implements continuous monitoring and validation feedback loops where the controller constantly compares coordinates from multiple position sensors, detects inconsistencies through rationality tests, and adjusts its operation accordingly. When sensor failures are detected, the system provides feedback to switch to backup sensors or default positions, creating a self-correcting system that maintains reliability without proportionally increasing complexity
2Measurement precision
If rationality tests are performed on coordinate values, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The patent performs rationality tests selectively rather than continuously on all sensor data. The controller checks coordinate coherence from multiple position sensors and performs validation primarily when position changes are detected or at scheduled intervals, rather than validating every single coordinate reading. This partial validation approach ensures measurement precision for critical decisions while minimizing the time loss associated with continuous diagnostic testing
Data Source
AI summary
A position diagnostic test for a shift-by-wire system is provided. The shift-by-wire system includes a shift lever configured to move along a shift path, a first and a second position sensor configured to generate a first and a second position signal, respectively, of the shift lever along the shift path, and a controller configured to receive the first and second position signals. The first position sensor includes a first x-coordinate value and a first y-coordinate value, and the second position sensor includes a second x-coordinate value and a second y-coordinate value. The position diagnostic test includes performing a rationality test on each of the coordinate values. If at least one predetermined condition exists for a particular coordinate value, then it fails the rationality test, and the position signal containing the coordinate value may be disregarded.