Optimal Control for Connected and Autonomous Vehicles at Signal-Free Intersections

Abstract

Abstract The development of connected and autonomous vehicles (CAVs) is one of the central aspects in the pathway towards future intelligent mobility systems. This paper addresses the problem of coordinating CAVs crossing an uncontrolled intersection so as to maintain safe and efficient traffic flow. The proposed control strategy is based on an optimal control framework that is formulated to minimize a weighted sum of total energy consumption and travel time of all CAVs by finding the optimal velocity trajectory of each vehicle. The design procedure starts with a proper formulation of the autonomous intersection crossing problem for CAVs, with various cases of energy recovery capability by the CAVs considered, to also investigate the influence of powertrain electrification on the intersection crossing problem. This yields an optimal control problem (OCP) with nonlinear and nonconvex dynamics and constraints. In order to ensure a rapid solution search and a unique global optimum, the OCP is reformulated via convex modeling techniques. Numerical results validate the effectiveness of the proposed approaches, while the trade-off between energy consumption and travel time is illustrated by Pareto optimal solutions.