Abstract
This study proposes two speed controllers based on a robust adaptive non-singular terminal sliding mode control approach for the cooperative adaptive cruise control problem in a connected and automated vehicular platoon. The delay-based spacing policy is adopted to guarantee that all vehicles in the platoon track the same target velocity profile at the same position while maintaining a predefined time gap. Factors such as nonlinear vehicle longitudinal dynamics, engine dynamics with time delay, undulating road profiles, parameter uncertainties, and external disturbances are considered in the system modeling and controller design. Different control objectives are assigned to the leading and following vehicles. Then, controllers consisting of a sliding mode controller with parameter adaptive laws based on the ego vehicle’s state deviation and linear coupled state errors, and a Smith predictor for time delay compensation are designed. Both inner stability and strong string stability are guaranteed in the case of nonlinear sliding manifolds. Finally, the effectiveness of the proposed controllers and the benefits of 44.73% shorter stabilization time, 11.20% less speed overshoot, and virtually zero steady-state inner vehicle distance deviation are illustrated in a simulation study of a seven-vehicle platoon cooperative adaptive cruise control and comparison experiments with a coupled sliding mode control approach.
Highlights
Significant developments in connected and automated vehicle (CAV) technology have been realized during the last decade
Because the sliding manifold designed for the leading vehicle in Eq (9) with the inner stability derived from Eqs. (18)—(21) cannot guarantee strong string stability, we introduce another non-singular terminal SMC (NTSMC) and its associated parameter adaption laws for the following vehicles in the platoon to ensure strong string stability with a nonlinear sliding manifold based on the modified input error idea. 2.3.1 Control Law Design for Following Vehicles
Two new Cooperative adaptive cruise control (CACC) controllers based on the robust adaptive NTSMC approach were proposed for the leading and following vehicles
Summary
Significant developments in connected and automated vehicle (CAV) technology have been realized during the last decade. Motived by the fact that the slopes, curvatures, speed limits, and other infrastructure information are all position-based, rather than time domain, a D-B space policy that ensures the same velocity and acceleration in the same location for each vehicle is more desirable and reasonable to be chosen as the target profile. Not all of the following vehicles can necessarily achieve speed acceleration owing to the road geometry and limitation of their engine power, the two spacing policies command all vehicles to maneuver synchronously This scenario was recognized in experiments of Ref. Two controllers, for the leading vehicle and following vehicles, are proposed for the different control objectives Factors such as the response process with engine time delay, nonlinearities of the vehicle dynamics, parameter uncertainties, and road vertical profiles are all considered in the CACC controller design.
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