Autonomous Vehicle Trajectory Stitching for Smooth Control
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Solution Overview
Problem
In autonomous vehicle systems, abrupt changes in control output occur when switching between trajectories, leading to an uncomfortable driving experience due to improper handling of trajectory transitions.
Innovation Solution
A planning system that stitches output trajectories from consecutive planning cycles by determining control errors and adjusting the starting point of the next trajectory to minimize discrepancies, ensuring smooth transitions by concatenating segments of the previous trajectory.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the control module discards the trajectory under execution and switches to executing the new one, then the trajectory planning responds quickly to dangerous situations, but the control output jumps and leads to discomfort driving experience
Solution Approach 1:
The system performs preliminary actions by calculating and storing trajectory segments in advance during the planning phase. When switching is needed, pre-calculated segments are ready to be concatenated smoothly, avoiding abrupt control output changes while maintaining high planning frequency for safety responses
Solution Approach 2:
The trajectory is divided into multiple segments that can be independently managed and concatenated. This segmentation allows the system to switch between trajectory portions smoothly by connecting segments at continuous points, reducing control output jumps while maintaining responsive trajectory planning
2Ease of operation
If the trajectory switching is handled properly to avoid control output jumps, then the driving experience is comfortable, but the system complexity increases due to stitching requirements
Solution Approach 1:
The trajectory stitching system performs self-service by automatically calculating connection points and concatenating segments without requiring complex external intervention. The system uses the existing trajectory data and control error information to autonomously generate smooth transitions, reducing the need for additional complex control mechanisms
3Device complexity
If the second trajectory starts from the ending point of the first planning cycle, then the trajectory switching is simple, but control output jumps occur causing discomfort
Solution Approach 1:
The system introduces an intermediary mechanism by calculating a connection point that serves as a smooth transition between trajectory segments. This intermediary point is determined based on control error and trajectory curvature, acting as a mediator that eliminates abrupt jumps while maintaining relatively simple switching logic
Data Source
AI summary
According to one embodiment, an ADV is controlled according to a first trajectory planned during a first planning cycle. A control error is determined which represents a drifting error at a first location of the ADV at a first point in time at the end of the first planning cycle. A second point in time is selected on the first trajectory. A second trajectory is generated from a second location on the first trajectory corresponding o the second point in time as a starting location of the second trajectory for a second planning cycle as a next planning cycle. A segment of the first trajectory between the first point in time and the second point in time is combined with the second trajectory to generate a third trajectory for the second planning cycle. The ADV is driven and controlled according to the third trajectory corresponding to the second planning cycle.