Autonomous Vehicle Path Planning at Lane Bifurcations
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Solution Overview
Problem
Existing vehicle control systems struggle to predictably navigate bifurcations, leading to potential lane changes that can confuse occupants and other road users, and may cause the vehicle to exit autonomous mode if lane width exceeds a threshold.
Innovation Solution
A control system that determines the lateral and longitudinal distances to potential lanes at a bifurcation, allowing the vehicle to follow a curve-shaped path into the selected lane, constrained by derivatives of lateral displacement to ensure a smooth maneuver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the host vehicle attempts to remain centred as the first lane widens at a bifurcation, then the vehicle maintains its current lane position, but the lane width may exceed a threshold causing the vehicle to exit autonomous mode
Solution Approach 1:
The control system determines lateral and longitudinal distances to potential lanes before the vehicle reaches the bifurcation point, and plans a curve-shaped path in advance. This preliminary path planning ensures the vehicle transitions smoothly into the selected lane before the lane width exceeds the threshold, maintaining autonomous mode continuity while providing predictable behavior to occupants and road users.
2Stability of the object's composition
If the host vehicle continues straight through the bifurcation without lane selection, then the vehicle maintains its current trajectory, but it may snap into one of the plurality of lanes causing confusion to occupant and other road users
Solution Approach 1:
The control system plans a curve-shaped path (clothoidal or sigmoidal) for the vehicle to follow through the bifurcation. This curved path provides a smooth, predictable transition from the first lane to the selected lane, eliminating sudden snapping movements while maintaining trajectory stability. The curved trajectory is clearly predictable to occupants and road users, resolving the contradiction between stability and predictability.
3Reliability
If the vehicle implements a smooth curve-shaped path through the bifurcation, then the maneuver is predictable and autonomous mode is maintained, but the control system complexity increases due to path planning constraints
Solution Approach 1:
The control system plans a curve-shaped path by defining specific parameters including lateral distance, longitudinal distance, and derivative constraints on lateral displacement. These parameter-based constraints provide a structured mathematical framework for path planning that achieves smooth transitions while maintaining manageable system complexity through standardized computational approaches.
Data Source
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AI summary
The invention relates to control system (200) for a host vehicle (10) operable in an autonomous mode. The control system comprises one or more controllers (202) and is configured to: determine a bifurcation of a first lane into a plurality of lanes; and cause control of the speed and/or direction of the host vehicle as the host vehicle approaches the bifurcation, in dependence on the determined bifurcation.