Robust optimal control of connected and automated vehicle platoons through improved particle swarm optimization

This paper addresses the robust optimal control problem for connected and automated vehicle platoons subject simultaneously to uncertain parasitic actuation lag and input delays. First, by adopting the constant time headway policy (CTHP) for spacing, the intervehicular spacing error propagation transfer function is derived between adjacent vehicles downstream under a decentralized control law. Second, the Hurwitz stability region for the derived spacing error propagation transfer function is obtained in a unified stability analysis framework for the time headway and controller gains by utilizing the signature conditions for real polynomials. The robust optimal control problem is formulated as a min-max optimization problem, and then an improved multi-agent based particle swarm optimization algorithm is developed to seek the optimal values of the design parameters in the derived stability region such that a weighted objective function is minimized. Finally, simulation experiments are performed on a numerical example to illustrate the effectiveness of the proposed design approach.