Steering Angle Calculation Using Index Sensors for Automated Startup
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Solution Overview
Problem
Current electric power assisted steering systems with 'index' type sensors cannot provide automated steering functions at vehicle startup, as they lack the capability to accurately determine the steering angle, which is essential for functions like automatic parking and angle limitation.
Innovation Solution
The system calculates a first steering angle signal based on assistance torque, a second signal based on the electric assistance motor's angular position, and a convergence signal using an 'index' sensor signal to confirm the steering angle, enabling reliable automated steering functions at startup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an absolute angle sensor is installed to provide steering angle information at startup, then automated steering functions can operate at startup, but the system weight, volume, and cost increase
Solution Approach 1:
The patent introduces an intermediary calculation process that uses the electric assistance motor's angular position (obtained from existing index sensors) as a mediator to derive steering angle information. Instead of directly measuring steering angle with complex sensors, the system calculates it from the motor position through mathematical relationships, thereby avoiding the need for heavy and costly absolute angle sensors while still providing the required steering angle data for automated functions at startup
Solution Approach 2:
The patent replaces the mechanical/physical absolute angle sensor system with an electronic calculation system. By substituting the physical sensing mechanism with computational methods that process signals from existing index sensors and motor position data, the system achieves the same functional outcome (steering angle availability) without the weight, volume, and cost penalties of traditional absolute angle sensors
2Device complexity
If simplified index sensors are used instead of absolute angle sensors, then weight, volume, and cost are reduced, but automated steering functions cannot operate at startup
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing the relationship between motor angular position and steering angle before the vehicle starts. The system prepares the computational models and calibration data in advance, so that when the vehicle starts and automated functions are needed, the steering angle can be immediately determined from the motor position without requiring complex startup procedures or additional hardware
Solution Approach 2:
The patent implements a feedback mechanism where the calculated steering angle is continuously compared with expected values during automated steering operations. The system uses the index sensor signals and motor position feedback to verify and refine the steering angle calculation, ensuring reliability for automated functions at startup while maintaining the simplicity of using only index sensors
Data Source
AI summary
The processing means, which control the power assisted steering motor (8), determine and give consideration to a first steering angle signal (A) determined as a function of the calculation or measurement of the force or torque delivered by the power assisted steering motor (8) and possibly of the steering torque or force applied by the driver to the steering wheel (2), a second steering angle signal (B) determined as a function of the calculation of the measurement of the angular position of the power assisted steering motor (8), a third signal (C) of the “index” type, that is to say of the type emitted for certain angular positions of the steering system (21), a convergence signal (D) indicative of the convergence of the steering angle calculations, and a confirmation signal (E) confirming the calculation of the steering angle, the convergence signal (D) being produced thanks to the signal (C) of “index” type to indicate a confidence level on the estimated steering angle value. The invention can be applied to vehicles that have an automated steering function.