Steering Angle Sensor Fail Detection via Motor Current
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Solution Overview
Problem
Conventional electric power steering systems lack an effective method to accurately detect failures in steering angle sensors, relying solely on steering angle signals without considering the motor's rotation direction, which can lead to inaccurate fail-safe logic operations.
Innovation Solution
A system and method that detect the rotation direction of the motor using current and voltage signals, compare it with the steering wheel's rotation direction sensed by the steering angle sensor, and initiate fail-safe logic when a mismatch is found, ensuring accurate detection of steering angle sensor failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional steering angle signal monitoring is used without motor rotation direction detection, then the system complexity is low, but the failure detection accuracy is insufficient
Solution Approach 1:
The system establishes a feedback mechanism by continuously monitoring the relationship between motor rotation direction (derived from current and voltage signals) and steering wheel rotation direction (from steering angle sensor). When a mismatch is detected, the system triggers fail-safe logic, creating a closed-loop verification system that improves detection accuracy without requiring additional hardware sensors.
Solution Approach 2:
The motor's own electrical signals (current and voltage) are utilized to determine its rotation direction, eliminating the need for separate sensing mechanisms. The system uses the motor's operational characteristics to self-verify the steering angle sensor's accuracy, reducing overall system complexity while enhancing failure detection capability.
2Measurement precision
If additional sensors are added to detect motor rotation direction, then the failure detection accuracy improves, but the system complexity and cost increase
Solution Approach 1:
The existing motor serves multiple functions: it provides power steering assistance and simultaneously acts as a rotation direction sensor through its electrical signals. The current and voltage signals originally used for motor control are repurposed to determine motor rotation direction, eliminating the need for dedicated sensing components while improving failure detection accuracy.
Solution Approach 2:
The patent replaces potential mechanical or additional electronic sensing mechanisms with electrical signal analysis. By using the motor's electrical characteristics (current and voltage) to infer rotation direction, the system avoids adding mechanical sensors or complex electronic sensing circuits, thereby maintaining simplicity while achieving accurate failure detection.
Data Source
AI summary
A method and system may detect a fail of a steering angle sensor in an electric power steering apparatus. The system may include: a steering angle sensor for generating and transmitting a steering angle signal measuring a rotation angle of a steering wheel; a motor for generating an assistant power for smooth steering and transmitting a current and a voltage based on rotation of the motor; and an Electronic Control Unit (ECU) for receiving the current and the voltage from the motor, sensing the rotation direction of the motor, receiving the steering angle signal from the steering angle sensor, sensing a first rotation direction of the steering wheel, and then, when the rotation direction of the motor is not equal to the first rotation direction of the steering wheel, determining that the steering angle signal has a fail and starting operation of a fail-safe logic.