Static-State Curvature Error Compensation for Autonomous Vehicles
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Solution Overview
Problem
Autonomous vehicles experience stability issues and deviation from planned trajectories due to initial curvature and heading errors when transitioning from a static state to autonomous mode, leading to potential failures in parking maneuvers.
Innovation Solution
A computer-implemented method that calculates and compensates for curvature and heading errors by adjusting the steering command while withholding the throttle command, allowing the vehicle to align with the planned trajectory without acceleration, and issuing the throttle command once errors are within predetermined thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the control module forces the vehicle to make a sharp turn to follow the planned initial curvature, then the vehicle follows the planned trajectory, but the vehicle experiences serious vibrations and loses stability
Solution Approach 1:
The system performs preliminary action by adjusting the steering angle to match the actual vehicle heading before initiating movement. The curvature error compensation control logic calculates the difference between planned and actual curvature, and pre-adjusts the steering command to eliminate heading misalignment, ensuring the vehicle is properly oriented before acceleration begins.
2Manufacturing precision
If the control module forces the vehicle to make a sharp turn to follow the planned initial curvature, then the vehicle follows the planned trajectory, but the vehicle deviates from the initial planned trajectory due to initial heading or curvature error
Solution Approach 1:
The system implements feedback by continuously monitoring the actual steering angle and actual vehicle heading, calculating curvature error based on the difference between planned and actual values, and using this feedback to dynamically adjust the steering command. This closed-loop control ensures the vehicle converges to the planned trajectory while maintaining reliability in parking maneuvers.
3Manufacturing precision
If the control module forces the vehicle to make a sharp turn, then the vehicle follows the planned curvature, but the vehicle needs a relatively long time to converge back to the planned trajectory
Solution Approach 1:
By pre-adjusting the steering angle to compensate for curvature error before the vehicle begins moving, the system eliminates the need for time-consuming convergence corrections during motion. This preliminary alignment ensures the vehicle follows the planned trajectory immediately, reducing convergence time from 3-5 seconds to near-instantaneous correction.
Data Source
AI summary
In one embodiment, static-state curvature error compensation control logic for autonomous driving vehicles (ADV) receives planning and control data associated with the ADV, including a planned steering angle and a planned speed. A steering command is generated based on a current steering angle and the planned steering angle of the ADV. A throttle command is generated based on the planned speed in view of a current speed of the ADV. A curvature error is calculated based on a difference between the current steering angle and the planned steering angle. The steering command is issued to the ADV while withholding the throttle command, in response to determining that the curvature error is greater than a predetermined curvature threshold, such that the steering angle of the ADV is adjusted in view of the planned steering angle without acceleration.