Torque Sensor Failure Detection in Electric Power Steering
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Solution Overview
Problem
Existing electric power steering systems face challenges in accurately determining when only one torque sensor is functioning properly, leading to unreliable torque detection and potential disruption of motor assistance.
Innovation Solution
A failure detection device with a controller that generates continuous torque using a failure detection unit, allowing the system to identify and rely on the functioning torque sensor even if one of the plural torque sensors fails, ensuring continuous motor assistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two torque sensors are provided to accurately determine proper operation, then measurement reliability is improved, but device complexity increases
Solution Approach 1:
The system performs preliminary failure detection by monitoring torque sensor outputs against expected ranges and patterns before critical failure occurs. The controller continuously checks whether detected torque values fall within predetermined ranges and whether changes in torque values follow expected patterns, enabling early identification of sensor degradation or failure.
Solution Approach 2:
The controller acts as an intermediary that processes and validates torque sensor data through multiple checks including range validation and pattern recognition. It compares sensor outputs against predetermined criteria and uses logical reasoning to determine sensor status, serving as a mediator between the physical sensors and the control system.
2Ease of operation
If motor assistance continues after torque sensor failure, then ease of operation is improved, but reliability deteriorates
Solution Approach 1:
The controller implements continuous feedback monitoring of torque sensor outputs, comparing detected values against predetermined ranges and expected change patterns. This feedback mechanism enables the system to automatically detect sensor failures and switch to alternative operation modes, ensuring continuous assistance while maintaining reliability through active monitoring and adaptive response.
Solution Approach 2:
The system dynamically adapts its operation mode based on real-time sensor status. When sensor failure is detected through the feedback mechanism, the controller transitions from normal dual-sensor operation to alternative modes that may include using remaining functional sensors with adjusted parameters or switching to backup detection methods, maintaining ease of operation while compensating for reduced reliability.
Data Source
AI summary
The failure detection device includes: a failure detection unit configured to detect failure of a torque detection unit, the torque detection unit detecting torque applied to a rotary shaft with plural torque sensors; and a controller configured to control drive of a motor such that the motor outputs continuous torque in an event that the failure detection unit detects failure of the torque detection unit, the continuous torque continuously generating torque that is, if at least one of the plural torque sensors is working properly, detectable by the at least one of the plural torque sensors.