Shift Range Control Apparatus Sensor Fault Learning
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Solution Overview
Problem
In shift range control systems, faults in the output shaft sensor can lead to degraded positioning accuracy and a lack of monitoring for control adherence to the target range, making it difficult to execute appropriate fail-safe treatments.
Innovation Solution
A shift range control apparatus that includes a motor, output shaft, and a shift range switching mechanism with a rotation member and engagement member, which uses a motor angle calculator, output shaft signal acquisition, and a fault monitor to learn reference positions when faults occur, ensuring retraction traveling performance by adjusting the target rotation angle based on learned reference positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the target motor rotation angle is set by adopting an angle of an output shaft sensor, then the positioning accuracy is improved, but when a fault occurs in the output shaft sensor, the positioning accuracy degrades and fail-safe treatment becomes difficult
Solution Approach 1:
The system performs preliminary actions by learning and storing reference positions of the rotation member before faults occur. The learning process captures the relationship between motor rotation angles and actual shift ranges under normal conditions, creating a baseline that can be used for fault detection and correction when sensor failures occur later.
Solution Approach 2:
The system implements feedback mechanisms by continuously monitoring whether the actual shift range matches the target shift range. When discrepancies are detected or faults occur in the output shaft sensor, the system uses the pre-learned reference positions to determine the correct shift range and provides feedback to the control unit for appropriate fail-safe treatments.
2Measurement precision
If the system monitors control adherence to target range based on output shaft sensor detection values, then control precision is improved, but when the sensor faults occur, monitoring capability is lost
Solution Approach 1:
The system introduces an intermediary approach by using the learned reference positions as a mediator between the motor rotation angle and the actual shift range determination. When the output shaft sensor fails, the control unit can still determine the shift range by comparing the motor rotation angle against the stored reference positions, effectively mediating the loss of direct sensor feedback.
3Reliability
If the system uses learned reference positions to determine shift range when faults occur, then fail-safe capability is improved, but the complexity of the control system increases
Solution Approach 1:
The learning process is performed preliminarily during normal operation when the output shaft sensor is functioning correctly. This preliminary action stores the reference positions in memory, so that when faults occur later, the system can immediately use these pre-computed reference values without requiring complex real-time calculations or additional hardware.
Data Source
AI summary
A shift range control apparatus acquires a motor rotation angle signal corresponding to a rotation position of a motor, calculates a motor angle based on a motor rotation angle signal, acquires an output shaft signal corresponding to the rotation position of an output shaft, sets a target rotation angle based on a target shift range and the output shaft signal, drives the motor to cause the motor angle to reach the target rotation angle, determines the shift range based on the output shaft signal, monitors a fault in the output shaft signal, and learns a P-side reference position corresponding to the motor angle in a situation where the engagement member abuts against a first wall portion of the shift range switching mechanism, in a condition that the fault occurs in the output shaft signal.