Decentralized control of a large platoon of vehicles using non-identical controllers

This paper studies the decentralized control of a platoon of identical vehicles when each control agent is assumed to only have knowledge of the distance between itself and its immediate forward neighbor. In particular, it is desired to solve the decentralized robust servomechanism problem (RSP), so that the vehicles' separation distances are regulated to specified set points, independent of the lead vehicle's velocity and such that the system is string stable. It is shown that for a large class of identical decentralized controllers, namely those decentralized controllers which solve the RSP and which have stable stabilizing compensators, e.g. a 3-term controller, that it is impossible to solve the above problem. This gives motivation to consider nonidentical decentralized controllers for the platoon vehicle problem, and it is shown in this case that it is possible to solve the above problem. A number of examples are included, including examples which have a large number of vehicles in a platoon, i.e. N=2000.