Incremental Steering Feedback for Stable Autonomous Lateral Control
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Solution Overview
Problem
Autonomous driving vehicles face inconsistent lateral control behaviors due to varying steering change rates, leading to potential overshoot and oscillation, which existing technologies have not adequately addressed.
Innovation Solution
A computer-implemented method for generating smooth steering commands in autonomous driving vehicles by determining a planning steering command based on a driving trajectory and receiving current steering feedback, applying incremental changes within a predetermined steering change threshold to control the vehicle, thereby reducing overshoot and oscillation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a large steering change rate is applied to quickly adjust vehicle direction, then the vehicle can respond faster to trajectory deviations, but it causes overshoot and oscillation in steering
Solution Approach 1:
The system dynamically adjusts the steering change rate based on real-time feedback from current steering angle sensors and trajectory deviation calculations. The steering command is modified adaptively to maintain optimal response without causing overshoot, resolving the contradiction between fast response and stability.
Solution Approach 2:
The system implements a feedback mechanism where the current steering angle is continuously measured and compared with the target steering angle. The difference is used to adjust the steering change rate, ensuring that steering commands are applied smoothly and consistently without causing oscillation, while still achieving timely correction of trajectory deviations.
2Adaptability or versatility
If different vehicles use varying steering change rate controls, then each vehicle can be optimized for its specific characteristics, but it leads to inconsistent lateral control behaviors amongst different vehicles
Solution Approach 1:
The system provides a universal lateral control solution that works consistently across different vehicle types. By normalizing the steering change rate calculation based on relative trajectory deviation rather than absolute values, the system achieves both vehicle-specific adaptability and cross-vehicle consistency, eliminating the inconsistency problem while preserving optimization capabilities.
3Productivity
If steering commands are applied without incremental limits, then the vehicle can quickly correct large trajectory deviations, but it causes abrupt steering changes and potential oscillation
Solution Approach 1:
The system dynamically determines the appropriate steering change rate based on the magnitude of trajectory deviation. For large deviations, it allows larger incremental changes to maintain correction efficiency, while for smaller deviations it applies finer adjustments to maintain smoothness, thus resolving the contradiction between correction speed and steering smoothness.
Data Source
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AI summary
Embodiments disclose a system and method to generate smooth steering commands for an autonomous driving vehicle (ADV). According to one embodiment, a system determines a planning steering command based on a driving trajectory of an ADV. The system receives a current steering feedback from a sensor of the ADV for a current planning cycle. The system generates one or more smooth steering commands based on the planning steering command and the current steering feedback over one or more planning cycles. The system controls the ADV based on the one or more smooth steering commands so a change in steering applied to the ADV for any planning cycle is within a predetermined steering change threshold for the ADV. That way, the system applies incremental changes for the steering of the ADV.