Maximizing Safety and Efficiency for Cooperative Lane-Changing: A Minimally Disruptive Approach

Andres S. Chavez Armijos, Anni Li, Christos G. Cassandras,
Boston University
Paper arXiv Code
FxT-OCBF Lane Changing


Cooperative Lane-Changing with Fixed-Time Convergence Optimal Control Barrier Function (Fxt-OCBF) under Disturbance and Uncooperative Vehicles

Abstract

This paper addresses cooperative lane-changing maneuvers in mixed traffic, aiming to minimize traffic flow disruptions while accounting for uncooperative vehicles. The proposed approach adopts controllers combining Optimal control with Control Barrier Functions (OCBF controllers) which guarantee spatio-temporal constraints through the use of fixed-time convergence. Additionally, we introduce robustness to disturbances by deriving a method for handling worst-case disturbances using the dual of a linear programming problem. We present a near-optimal solution that ensures safety, optimality, and robustness to changing behavior of uncooperative vehicles. Simulations demonstrate the effectiveness of the proposed approach in enhancing efficiency and safety.

Problem Setting

Optimal Control Methodology Diagram

Autonomous vehicles that are capable of cooperating with vehicle C are defined as the set S(t) = {1,...,N}. This set contains N vehicles, with vehicles 1 and N being the farthest ahead and behind C, respectively. The vehicles in S(t) can sense the state of the uncooperative vehicles U and F.

When determining the optimal longitudinal maneuver, a subset of vehicles S(tf) in the vicinity of C at the terminal time tf is considered. The goal is to create a minimally disruptive safe gap between a pair of vehicles i* and i*+1 in S(tf) so that C can merge into the fast lane. The optimal i* and i*+1 are determined by solving a mixed integer nonlinear program.

Therefore, the key aspects of the grouping are:

  • S(t) defines the set of all cooperative vehicles near C
  • S(tf) ⊆ S(t) represents the relevant cooperative vehicles at the end of the longitudinal maneuver
  • An optimal pair (i*, i*+1) in S(tf) is chosen for C to merge between

    • The grouping enables coordinated cooperation to create a safe gap for C's lane change while minimizing disruption

Summary

Optimal Control Methodology Diagram

Previous work has focused on selecting optimal cooperative groups and gaps but assumes constant uncooperative vehicle behavior. Other methods using control barrier functions can ensure safety but are overly conservative, losing efficiency.

This paper aims to address the trade-off between safety and efficiency. The key ideas are:

  • Use optimal control with control barrier functions (OCBFs) to get near-optimal, safe lane change trajectories.
  • Incorporate spatio-temporal constraints to ensure the vehicle completes the maneuver in time.
  • Handle disturbances from uncooperative vehicles through duality theory.
  • Extend prior work on minimum disruption cooperative maneuvers to lane-changing scenarios.

The overall contribution is a method to enable cooperative lane changes that are safe despite disturbances while minimizing the disruption to surrounding traffic. This combines optimal and robust control with multi-vehicle coordination.

BibTeX

@article{
      author={Armijos, A. S. C. and Li, A. and Cassandras, C. G.},
      title={Maximizing Safety and Efficiency for Cooperative Lane-Changing: A Minimally Disruptive Approach},
      journal=journal={26th IEEE Conf. on Intelligent Transportation Systems ITSC},
      year={2023},
}