Linearising Longitudinal Vehicle Dynamics through Adaptive Control Techniques for Platooning Applications

Vehicle platooning provides avenues to improve road transportation byreducingenergyconsumptionandpollutantemissionswhileincreasingsafety androadusage.However,tosafelyoperateasequenceofconnectedautonomous vehicles(CAVs)as a platoon, stringent conditions, such as string stability, on the closed-loop platoon dynamics must be guaranteed. To meet such platoon control specifications, linear longitudinal vehicle dynamics are usually assumed for the design of platoon control algorithms, and are imposed to each vehicle in the platoon by using mid-level control systems. However, disturbances and model mismatches can limit the compensation of the nonlinear vehicle dynamics, and thus jeopardise the tracking of the reference linear behaviour. To systematically impose the linear behaviour to the vehicles in a platoon despite model uncertainties and disturbances, in this paper two adaptive solutions are proposed and compared: (i) an adaptive solution for systems in Brunovsky form; and (ii) the Enhanced Model Reference Adaptive Control. Numerical results confirm that both adaptive techniques are effective in imposing the linear dynamics to the longitudinal vehicle motion, also when integrated within a platoon control architecture. The closed-loop platoon performance is assessed via a set of performance indicators for different platoon lengths