Branch Trajectory Smoothing for Comfortable Vehicle Lane Changes
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Solution Overview
Problem
In situations where a second road branches off from a first road without clear lane boundary lines, the target travel trajectory for a vehicle cannot be accurately generated, leading to potential rapid steering and passenger discomfort during automatic steering based on map information representing lane shapes with nodes and links.
Innovation Solution
A vehicle travel control method that calculates a first trajectory linking a branch point and a point on the second road a predetermined distance away, setting a target travel trajectory to smooth curvature changes and prevent rapid steering, using high-definition map information to guide the vehicle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a target travel trajectory is set based on map information representing a lane shape with a node and a link, then the vehicle can navigate branch sections without clear lane boundary lines, but rapid steering occurs causing passenger discomfort
Solution Approach 1:
The patent applies curvature smoothing to the target travel trajectory by calculating a smoothed trajectory that passes through the branch point and subsequent points on the second road, rather than directly following the sharp angular changes in the map data. This curvature smoothing reduces rapid steering movements while maintaining accurate navigation through branch sections.
Solution Approach 2:
The patent performs preliminary calculation of smoothed trajectory points before generating the final target travel trajectory. By pre-calculating the smoothed path through the branch point and subsequent points, the system prepares a comfortable trajectory in advance, avoiding real-time computational delays and ensuring passenger comfort from the outset.
2Manufacturing precision
If the vehicle follows the lane shape of the second road directly from map information, then the trajectory accurately represents the road geometry, but rapid steering occurs at the branch point
Solution Approach 1:
The patent smooths the curvature of the trajectory by calculating intermediate points that create a gradual transition through the branch point, rather than following the sharp angular changes in the original map data. This maintains geometric accuracy while eliminating abrupt steering movements.
Solution Approach 2:
The patent transforms the trajectory parameters by calculating smoothed coordinate points that maintain the essential geometric features of the road layout while modifying the curvature characteristics. This parameter transformation preserves trajectory precision while reducing steering abruptness.
Data Source
AI summary
A vehicle travel control method including: determining whether or not a target travel route of a vehicle traveling on a first road is a route leading to a second road, the second road branching off from the first road; when the target travel route is a route leading to the second road, calculating a first trajectory linking a branch point at which a second link representing a lane shape of a second lane on the second road, branches off from a first link representing a lane shape of a first lane on the first road, and a point on the second link, the point being located a predetermined distance away from the branch point along the second link, and setting a target travel trajectory, based on the first trajectory; and controlling the vehicle to travel along the target travel trajectory.