Joint Trajectory Planning for 1-D Snake-like Interruptible Vehicle Platoons in Lane-free Traffic

Abstract

This paper presents a joint trajectory optimization algorithm for connected and automated vehicles forming 1-D snake-like interruptible platoons in a lane-free traffic environment on highways. A double double-integrator model is employed for the longitudinal and lateral movement, respectively, of each vehicle, considering constant and state-dependent bounds on control inputs, including road boundary constraints. An appropriately defined Euclidian distance to track the front vehicle is utilized to establish and operate a 1-D platoon of vehicles at selectable distance from each other. The distance is used as a soft constraint, which allows for platoons to divide, if required to avoid obstacles, and reunite eventually. A joint multi-objective function is formulated and minimized using an efficient feasible direction algorithm. This leads, beyond the flexible platoon operation, to low fuel consumption, passenger convenience, collision avoidance with external obstacles, tracking of desired speed and prevention of infeasible maneuvers. Challenging scenarios are examined on a lane-free straight motorway stretch, producing promising results for further exploration, like forming 2-D interruptible vehicular flocks with flexible shape or implementation of 1-D platoons and flocks in an MPC framework.