Automatic Steering System Sensor Anomaly Handling
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Solution Overview
Problem
Conventional automatic steering systems fail to maintain tracking performance when an anomaly occurs in the acceleration sensor during automatic steering control, leading to potential deviations from the target pass line.
Innovation Solution
An automatic steering system that includes a detection device with an acceleration sensor, vehicle speed sensor, and yaw rate sensor, which calculates a target steering angle using a learning value based on the error between detected and estimated lateral acceleration, switching to a backup value if the acceleration sensor is abnormal, and adjusting control terms to ensure continued accurate steering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If automatic steering control is executed using detected lateral acceleration from the acceleration sensor, then steering accuracy is improved, but if the acceleration sensor becomes abnormal, tracking performance deteriorates and the vehicle may deviate from the target pass line
Solution Approach 1:
The system performs preliminary actions by calculating backup values of lateral acceleration using the relationship between yaw rate and vehicle speed before the acceleration sensor becomes abnormal. This allows the system to switch to pre-calculated backup values when an anomaly is detected, ensuring continuous accurate tracking without deviation from the target pass line.
Solution Approach 2:
The system introduces an intermediary mechanism by using the relationship between yaw rate and vehicle speed as a mediator to calculate backup lateral acceleration values. This intermediary calculation method provides an alternative source of lateral acceleration data when the primary acceleration sensor fails, maintaining steering accuracy and tracking performance.
2Reliability
If the system switches to backup values when the acceleration sensor is abnormal, then reliability is improved, but device complexity increases due to additional calculation mechanisms
Solution Approach 1:
The system applies self-service by using its existing sensors (yaw rate sensor and vehicle speed sensor) to generate backup lateral acceleration values through calculation. Instead of adding independent backup hardware, the system leverages its own existing components to provide redundancy, thereby improving reliability while minimizing the increase in device complexity.
Solution Approach 2:
The system replaces the mechanical/physical redundancy approach with a computational solution. Rather than having duplicate acceleration sensors, the system uses mathematical relationships and algorithms to calculate backup values from existing sensor data, reducing hardware complexity while maintaining reliability.
Data Source
AI summary
An automatic steering system comprises a controller. The controller executes target steering angle calculation processing. The controller further calculates a learning value of lateral acceleration. The learning value is calculated based on an error of a detected value of the lateral acceleration by an acceleration sensor and an estimation value of the lateral acceleration calculated using driving speed and yaw rate. In the target steering angle calculation processing, it is judged whether the acceleration sensor is normal. If it is judged that the acceleration sensor is normal, a target steering angle is calculated by using the detected value. Otherwise, the lateral acceleration used to calculate the target steering angle is switched from the detected value to a backup value of the lateral acceleration. The backup value is calculated using the estimation value and the learning value calculated before a timing at which the acceleration sensor is judged to be abnormal.