The advances in distributed inter-vehicle communication networks have stimulated a fruitful line of research in Cooperative Adaptive Cruise Control (CACC). In CACC, individual vehicles, grouped into platoons, must automatically adjust their own speed using on-board sensors and communication with the preceding vehicle so as to maintain a safe inter-vehicle distance. However, a crucial limitation of CACC is that the string stability of the platoon can be proven only when the vehicles have identical driveline dynamics and perfect engine performance (homogeneous platoon), and possibly an ideal communication channel. This work proposes a novel CACC strategy that overcomes the homogeneity assumption and that is able to adapt its action and achieve string stability even for uncertain heterogeneous platoons. Moreover, in order to handle the inevitable communication losses, we formulate an extended average dwell-time framework and an adaptive switched control strategy which activates an augmented CACC or an augmented Adaptive Cruise Control strategy depending on communication reliability. Stability is proven analytically and simulations are conducted to validate the theoretical analysis.

Grouping individual vehicles into platoons with a defined inter-vehicle spacing policy has been proven to greatly improve road throughput and reduce vehicles’ energy consumption. The emerging interest in distributed intervehicle
communication networks has provided new tools for further improvements of the performance of this platoon-based driving pattern. A leading control strategy of such vehicular cyber-physical systems is Cooperative Adaptive Cruise Control (CACC). However, a crucial limitation of the state-of-the-art is that string stability can be proven only when the vehicles in the platoon have identical driveline dynamics (homogeneous platoons). In this paper, we present a novel CACC strategy that overcomes the homogeneity assumption and that is able to adapt its action and achieve string stability even with uncertain
heterogeneous platoons. Considering a one-vehicle look-ahead topology, we propose a Model Reference Adaptive Control augmentation: the control objective is to augment a baseline CACC, proven to be string stable in the homogeneous scenario, with an adaptive control term that compensates for each vehicle’s unknown driveline dynamics. Asymptotic convergence of the heterogeneous platoon to a string stable platoon is shown analytically for an appropriately designed reference model.
Simulations of the proposed CACC strategy are conducted to validate the theoretical analysis.

Despite the progresses in Cooperative Adaptive Cruise Control (CACC), a crucial limitation of the state-of-the-art of this control scheme is that the string stability of the platoon can be proven only when the vehicles in the platoon have identical driveline dynamics (homogeneous platoons). In this paper, we present a novel control strategy that overcomes the homogeneity assumption and that is able to adapt its action and achieve string stability even with uncertain heterogeneous platoons with unknown engine performance losses and inevitable communication losses. Considering a one-vehicle look-ahead topology, we propose an adaptive switched control strategy: the control objective is to switch from an augmented CACC to an augmented Adaptive Cruise Control strategy when communication is lost based on a dwell time characterized switching law. The simulation of the proposed control strategy is conducted to validate the theoretical analysis.