Autonomous Vehicle Flow Control With Time-Based Position Targets
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Solution Overview
Problem
Existing vehicle control schemes for autonomous vehicles are susceptible to causing traffic jams and collisions due to unpredictable vehicle operations, which negatively affect the efficiency and smooth operation of transportation systems.
Innovation Solution
Implementing a moving position-target vehicle control scheme where vehicles follow virtual position targets defined by functions of time, allowing for closed-loop position control to maintain safe distances and consistent time intervals, and transitioning between different control schemes at junctions and segments to ensure steady-state operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing vehicle control schemes are used, then vehicles can operate autonomously, but traffic jams and collisions occur due to unpredictable vehicle operations
Solution Approach 1:
The patent changes the control parameter from direct distance-based spacing to time-based spacing. By defining the desired distance as a function of time (xd(t) = vt + d0), the system ensures that vehicles maintain predictable intervals while adapting to varying speeds, thereby improving reliability without sacrificing productivity
Solution Approach 2:
The patent implements closed-loop feedback control where each vehicle continuously monitors its position and speed, compares it with the desired trajectory defined by the time-based spacing function, and adjusts its motion accordingly. This feedback mechanism ensures predictable vehicle operations while maintaining efficient traffic flow
2Reliability
If vehicles maintain constant distance spacing, then collision risk is reduced, but traffic flow efficiency decreases due to excessive spacing
Solution Approach 1:
The patent transitions from static distance-based spacing to dynamic time-based spacing. The desired distance xd(t) evolves over time according to the function vt + d0, allowing vehicles to maintain safe spacing while reducing time losses as speeds increase. This dynamic approach optimizes both safety and efficiency
3Device complexity
If vehicles operate with independent control, then system complexity is reduced, but unpredictable operations cause traffic jams
Solution Approach 1:
The patent segments the control function into two independent components: a time-based spacing function xd(t) = vt + d0 that ensures predictability, and a feedback control component that handles individual vehicle adjustments. This segmentation allows simple independent vehicle controllers to achieve coordinated predictable flow
Data Source
AI summary
A method of navigating a plurality of vehicles along a roadway includes, at a first vehicle, navigating along a section of a roadway by following a first moving position-target, the first moving position-target determined in accordance with a first tracking function defining position along the section of the roadway as a function of time, and at a second vehicle, navigating along the section of the roadway by following a second moving position-target, the second moving position-target determined in accordance with a second tracking function defining position along the section of the roadway as a function of time. A distance between the first vehicle and the second vehicle may change as the first vehicle and the second vehicle navigate along the section of the roadway.