Shift-by-wire control device malfunction detection
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Solution Overview
Problem
Existing shift-by-wire systems in automatic transmissions may incorrectly switch to the parking range due to malfunctions in seat belt switches, leading to inconvenient and potentially hazardous situations, such as inhibition of vehicle reversal when the seat belt is fastened but the switch continues to detect an unfastened state.
Innovation Solution
A shift-by-wire control device with a malfunction determining unit that assesses the functionality of seat belt and door switches, ensuring auto parking control only occurs when both switches provide valid detection results, preventing false triggering by identifying and accounting for switch malfunctions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If auto parking control is executed based on seat belt switch detection, then safety is improved by preventing driver departure with vehicle in motion, but reliability deteriorates when seat belt switch malfunctions causing false parking range switching
Solution Approach 1:
The system performs preliminary detection of driver behavior patterns (seat belt fastening, door opening/closing sequences) before executing auto parking control. By analyzing the temporal sequence of driver actions in advance, the system can distinguish between intentional driver departure and situations where the seat belt switch may be malfunctioning, thereby preventing false parking range switching while maintaining safety.
Solution Approach 2:
The control device introduces an intermediary analysis layer that processes detection results from multiple sources (seat belt switch, door switches, shift lever position) before triggering auto parking control. This intermediary processing layer validates the consistency of detection signals and identifies malfunctioning sensors by detecting contradictory patterns, thereby preventing false parking range switching caused by defective seat belt switches.
2Reliability
If multiple detection conditions are required for auto parking control, then false triggering is reduced, but response time increases due to additional validation steps
Solution Approach 1:
The system continuously monitors and pre-processes detection signals from seat belt switches and door switches in real-time, maintaining a ready state for rapid malfunction identification. By performing preliminary validation of detection patterns and storing baseline behavior data, the system can quickly determine whether auto parking control should be executed without time-consuming analysis delays when actual driver departure is detected.
3Measurement precision
If the system continuously monitors detector validity, then measurement precision is improved, but device complexity increases due to additional monitoring functions
Solution Approach 1:
The control device integrates multiple detection functions (seat belt status, door status, shift lever position, malfunction detection) into a single unified control unit. This multi-functional design allows the system to perform various detection tasks using shared processing resources and common control logic, thereby improving measurement precision across all sensors while avoiding the need for separate dedicated monitoring systems that would increase overall device complexity.
Data Source
AI summary
A shift-by-wire control device includes a first detector, a second detector, an auto parking control unit, and a malfunction determining unit. The first and second detectors respectively detect first and second vehicle states attributed to behaviors of a driver. The auto parking control unit executes an auto parking control irrespective of a state of the shift range selected by the shift lever, on conditions that detection results derived from the first and second detectors satisfy respective predetermined conditions. The malfunction determining unit determines that the first detector is malfunctioning, on a condition that the first detector fails to detect a change in the first vehicle state. The auto parking control unit refrains from executing the auto parking control, on a condition that the first detector is determined by the malfunction determining unit as malfunctioning.