Autonomous Vehicle Steering Angle Calibration via Yaw Rate Comparison
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Solution Overview
Problem
Autonomous vehicles face challenges in accurately calibrating their steering angle, leading to potential dangerous deviations in vehicle direction and control due to steering angle offsets caused by mechanical deformations, tire wear, and varying driving conditions, which existing methods struggle to address effectively.
Innovation Solution
The method involves receiving steering angle and yaw rate measurements, estimating a steering angle offset using a wheel base, and employing adaptive filters or Kalman filters to determine an estimated yaw rate, which is then compared to trigger actions such as software calibration or maintenance alerts, while considering operating conditions like speed, road surface, and load to filter out noisy measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If mechanical steering angle alignment is performed by a technician in an auto repair shop, then steering angle calibration accuracy is improved, but operational convenience deteriorates and time loss increases
Solution Approach 1:
The autonomous vehicle performs steering angle calibration autonomously using onboard sensors (steering angle sensor, yaw rate sensor) and processing circuits. The system automatically estimates steering angle offset by comparing measured steering angle with estimated steering angle derived from yaw rate measurements and vehicle dynamics models, eliminating the need for technician intervention while maintaining calibration accuracy
Solution Approach 2:
The patent replaces mechanical alignment procedures with an electronic/software-based calibration system. The processing circuit uses sensor data fusion and computational algorithms (comparing measured vs. estimated steering angles) to perform calibration that previously required physical mechanical adjustment by technicians
2Measurement precision
If mechanical steering angle alignment is performed by a technician, then steering angle calibration accuracy is improved, but time loss increases
Solution Approach 1:
The autonomous vehicle performs steering angle calibration continuously or periodically during normal operation rather than requiring periodic shutdowns for mechanical alignment. The system continuously monitors steering angle sensor data and yaw rate sensor data, automatically updating calibration parameters in real-time as the vehicle operates, thus eliminating time loss while maintaining accuracy
3Speed
If steering angle measurements are used without filtering, then measurement responsiveness is improved, but measurement precision deteriorates due to noise
Solution Approach 1:
The system uses feedback from multiple sensors (steering angle sensor, yaw rate sensor) and compares measured steering angle with estimated steering angle calculated from vehicle dynamics models. This feedback mechanism allows the system to filter out noisy measurements by identifying inconsistencies and correcting them through continuous comparison and adjustment, maintaining both responsiveness and precision
Data Source
AI summary
Among other things, techniques are described for steering angle calibration. An autonomous vehicle receives a steering angle measurement and a yaw rate measurement, and estimates a steering angle offset using the steering angle measurement, the yaw rate measurement, and a wheel base of the autonomous vehicle. An estimated yaw rate is determined based on a yaw rate model, the steering angle measurement and the estimated steering angle offset. The yaw rate measurement and the estimated yaw rate are compared and an action is initiated on the autonomous vehicle in response to the comparing.