Adaptive Interface Design in Lagged Vehicular Platoons: Theory and Autopilot Implementation

Most literature in the field of vehicular platooning considers control-oriented lagged vehicle dynamics where the vehicle acceleration tracks, with some lag, a control command given in terms of desired acceleration/deceleration (hereafter simply referred to as desired acceleration). However, the most typical control command in standard vehicles is the desired throttle/braking (hereafter simply referred to as desired throttle). This work proposes an interface design that allows relating the desired throttle to the desired acceleration, enabling the use of those control-oriented vehicle models in the platooning literature. A challenge in the design of such an interface is that the relation between the desired throttle and the desired acceleration is dynamic and, furthermore, the design must account for the lagged dynamics arising from the time constant of the vehicle powertrain/driveline trying to track the desired command. This challenge adds to the fact that several vehicle parameters, including the powertrain/driveline time constant, are unknown in practice, requiring an adaptive design of the interface able to deal with uncertainties. We initially propose a single-vehicle adaptive design, and then extend it at the platooning level. Theoretical stability analysis is provided, and robustness of the proposed ideas is demonstrated via software-in-the-loop tests using an open-source autopilot suite embedded with the proposed adaptive interface.