Internal and string stability analyses of longitudinal platoon of vehicles with communication delay and actuator lag under constant spacing policy

 This paper studies the longitudinal control of a group of vehicles following a lead vehicle. A  neighbor based upper level controller is proposed by considering communication delay and actuator lag. Constant spacing policy is used between successive vehicles. Two different approaches based on Lyapunov-Razumikhin and Lyapuniv-Krassovski theorems are presented to stability analysis of closed loop dynamic. By simulation studies, it will be shown that the second approach is less conservatism than the first one. We consider the bidirectional leader following (BDLF) topology for inter-vehicle communication. Based on this structure, some sufficient conditions assuring string stability of platoon is derived. At the end of paper, four different scenarios are presented to study the robustness of algorithm against communication delay, actuator lag, disturbance, heterogeny and communication losses.