Optimal control of connected vehicle systems

In this paper, linear quadratic tracking (LQT) is used to optimize the control gains for connected cruise control (CCC). We consider a vehicle string where the CCC vehicle at the tail receives position and velocity signals through wireless vehicle-to-vehicle (V2V) communication from other vehicles ahead (that are not equipped with CCC). An optimal feedback law is obtained by minimizing a cost function defined by headway and velocity errors and the acceleration of the CCC vehicle on an infinite horizon. We show that the feedback gains can be obtained recursively as signals from vehicles farther ahead become available, and that the gains decay exponentially with the number of cars between the source of the signal and the CCC vehicle. The effects of the cost function on the head-to-tail string stability are investigated and the robustness against variations in human parameters is tested. The analytical results are verified by numerical simulations.