Steering Angle Zero Offset Correction via Yaw Rate Feedback
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Solution Overview
Problem
Existing steering angle measurement systems face challenges in accurately determining the zero offset of the steering angle, which is crucial for vehicle safety systems like ESP, due to initial sensor offset and variability in measurements.
Innovation Solution
A system and method that utilize a sensor arrangement and control unit to measure yaw rate and steering angle, calculate time derivatives, and correct the steering angle based on deviations from calculated values, providing initial and continuously improved zero offset values to vehicle systems with quality metrics like confidence intervals and standard deviations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If inexpensive sensors are used to measure steering wheel angle, then cost is reduced, but measurement precision deteriorates due to zero offset and initial zero values
Solution Approach 1:
The system continuously compares the measured steering angle with the calculated steering angle (derived from yaw rate and steering ratio) and uses this feedback to determine and correct the zero offset. The control unit monitors the difference between measured and calculated values and adjusts the zero offset accordingly, creating a closed-loop correction system that improves measurement precision without requiring expensive sensors.
Solution Approach 2:
The system changes the parameter being measured from the raw sensor value to a corrected value that compensates for zero offset. By dynamically adjusting the zero offset parameter based on the comparison between measured and calculated steering angles, the system transforms inaccurate raw measurements into precise corrected measurements.
2Speed
If the steering angle is determined quickly using simple algorithms, then response time is improved, but measurement precision deteriorates due to inaccuracies in zero offset determination
Solution Approach 1:
The system performs preliminary determination of the zero offset using the relationship between measured steering angle, measured yaw rate, and steering ratio. This preliminary correction is applied immediately to provide a usable steering angle value quickly, while continuous refinement occurs in the background to improve precision over time without delaying the initial response.
Solution Approach 2:
The control unit continuously monitors the difference between measured and calculated steering angles and uses this feedback to iteratively improve the zero offset determination. This allows the system to provide quick initial values while continuously refining precision through feedback-driven correction.
3Measurement precision
If multiple measurements are repeated to improve accuracy, then measurement precision is improved, but productivity deteriorates due to extended determination time
Solution Approach 1:
The system uses feedback to determine when sufficient accuracy has been achieved by monitoring the difference between measured and calculated steering angles. When the difference falls within an acceptable threshold, the determination process stops, avoiding unnecessary repeated measurements and maintaining high productivity while ensuring adequate precision.
Solution Approach 2:
The system replaces repeated mechanical measurements with a calculation-based approach using the relationship between steering angle, yaw rate, and steering ratio. This substitution allows continuous refinement of the zero offset without requiring repeated physical measurements, maintaining determination speed while improving precision.
Data Source
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AI summary
According to an exemplary embodiment of the invention, a steering angle is determined using a single-track model of the vehicle, wherein the steering angle is only corrected when the difference between the derivation of a measured maximum steering angle and the derivation of a calculated maximum steering angle is below a threshold. Otherwise, the measurement is repeated.