Cooperative adaptive cruise control of heterogeneous vehicle platoons

Road throughput can be increased by cooperative adaptive cruise control (CACC), which allows vehicles to drive at short inter-vehicle distances without compromising string stability by using wireless inter-vehicle communications. Practical application, however, may involve vehicles with different driveline dynamics, thus forming a heterogeneous platoon. This property potentially requires knowledge of other vehicle's driveline dynamics for implementation of CACC, which may not be available. As opposed to robust or adaptive approaches, the heterogeneity problem is solved here by revisiting an existing, widely adopted controller for homogeneous strings using an input-output linearization approach. As a result, a class of controllers is obtained which allows for vehicle strings that are heterogeneous with respect to driveline dynamics, without requiring knowledge of these dynamics. Furthermore, it is shown that the new controller represents a class of controllers that encompasses the original homogeneous controller. To illustrate the performance of the new controller, simulations of a heterogeneous platoon are presented and the string stability properties are assessed. From this analysis, it appears that the new controller performs at least as good as the original one, in terms of minimum string-stable time gap, settling time, and maximum jerk.