Autonomous Driving Reference Line Smoothing via Truncation
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Solution Overview
Problem
Autonomous driving vehicles face challenges in generating smooth reference lines, especially at high speeds, due to limitations in smoothing algorithms that struggle with high-level derivatives like curvature and curvature derivatives, leading to discontinuous stitch points between reference lines.
Innovation Solution
The system truncates the initial reference line by removing a section to generate a truncated line with stricter constraints at the end point, allowing connection of a new reference line with flexible constraints, ensuring smooth continuity and reducing curvature discontinuity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If smoothing algorithms (e.g., Quadratic Programming) are used to smooth the reference line, then the reference line becomes smoother, but the stitch point between two reference lines becomes discontinuous especially when there is a large gap between two adjacent curvatures
Solution Approach 1:
The patent applies preliminary action by pre-smoothing each reference line segment independently before stitching them together. The smoothing operation is performed on each segment separately using algorithms like Quadratic Programming, ensuring that each segment has smooth curvature properties before connection. This preliminary smoothing prepares the segments for reliable stitching by reducing curvature variations at the boundaries.
Solution Approach 2:
The patent divides the complete reference line into multiple adjacent segments that are smoothed and stitched together. Each segment is processed independently through the smoothing algorithm, allowing local optimization of smoothness while maintaining the ability to handle complex overall paths. The segmentation enables the system to manage large curvature gaps by treating them as boundary conditions between segments rather than global constraints.
2Speed
If the reference line is smoothed separately and stitched together, then the computation time increases exponentially, but the reference line needs to be smoothed for high speed travel
Solution Approach 1:
The patent segments the reference line into multiple smaller sections that can be smoothed and computed independently. This segmentation allows parallel processing of different segments, reducing the overall computation time compared to smoothing the entire reference line as a single continuous path. Each segment's smoothing can be performed separately and then stitched together, making the computation more efficient while still providing smooth reference lines for high-speed travel.
Data Source
AI summary
In one embodiment, a method for generating a reference line for operating an autonomous driving vehicle includes controlling an autonomous driving vehicle to move along a road according to a first reference line, the first reference line having a first set of constraints, and while the autonomous driving vehicle is moving along the road according to the first reference line: truncating the first reference line by removing an end section of the first reference line to generate a truncated first reference line including an end reference point, obtaining a second set of constraints for the end reference point, obtaining a second reference line to be used by the autonomous driving vehicle, the second reference line having the first set of constraints, and connecting the second reference line to the end reference point of the truncated reference line to allow the autonomous driving vehicle to move along the road.