Adaptive control of interconnected networked systems with application to heterogeneous platooning

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 inter-vehicle 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.