Arc-Based Travel Reference Line for Stable Trajectory
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Solution Overview
Problem
Existing automatic driving systems face challenges in accurately determining vehicle travel trajectories on curved roads, especially under adverse weather conditions or when road surface identification is difficult, due to the limitations of approximating lane lines with quadratic curves and the method of least squares, leading to unstable and inappropriate trajectories.
Innovation Solution
A travel reference line determination system that calculates an arc-shaped travel reference line using an arc defining parameter, minimizing the error between model and estimate values, and incorporating a signal addition parameter to stabilize trajectory determination even under challenging conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the lane line is approximated by a quadratic curve and the model parameter is identified by the method of least squares, then the calculation is simple, but the apex of the quadratic curve cannot be set appropriately and the travel trajectory cannot be calculated appropriately
Solution Approach 1:
The patent changes the mathematical model from a quadratic curve to a cubic curve, introducing an additional parameter (the apex position) that can be independently optimized. This parameter change allows the trajectory to better fit the actual road geometry while maintaining a systematic calculation approach through iterative optimization of the apex position and curve parameters.
2Speed
If the travel trajectory is calculated using the quadratic curve approximation method, then the computation is fast, but the vehicle might travel along an inappropriate and unstable trajectory such as one along which the vehicle should travel rightward once and then turn around to the left
Solution Approach 1:
The patent introduces a dynamic optimization process where the apex position of the cubic curve is iteratively adjusted to minimize the difference between the calculated trajectory and the actual road geometry. This dynamic adjustment ensures that the trajectory remains stable and appropriate under varying conditions, preventing unrealistic path deviations while maintaining computational efficiency through structured iteration.
3Adaptability or versatility
If information representing the track environment is hard to get due to adverse weather conditions, then the quadratic curve method still runs, but the travel trajectory is calculated in an inappropriate state
Solution Approach 1:
The patent implements a feedback mechanism where the calculated trajectory is continuously compared with the available ( albeit limited) track environment information, and the cubic curve parameters are adjusted based on this feedback. This allows the system to adapt to adverse conditions by optimizing the trajectory within the constraints of available data, preventing inappropriate calculations when information is scarce.
Data Source
AI summary
There is provided a travel reference line determination system and an automatic driving system capable of determining a travel reference line of a vehicle appropriately even under conditions where information representing the track environment of the vehicle is hard to get. An ECU of an automatic driving system calculates a model y coordinate value ymw_i using a map in FIG. 4 (Step 12), calculates an estimated y coordinate value y_i using track environment data D_info (Step 11), calculates curvature C so that an error between the model y coordinate value ymw_i and the estimated y coordinate value y_i may be minimized (Step 18), calculates a travel trajectory Xf using the curvature C (Step 4), and executes automatic driving control using the travel trajectory Xf (Steps 31 to 33).