Cooperative adaptive cruise control with enhanced vehicle-following performance for communication and actuator delays of connected vehicle platoons

Cooperative adaptive cruise control (CACC) for connected vehicle platoons is considered an effective solution for reducing vehicle-following distance and energy consumption, as well as increasing road throughput through vehicle-to-everything (V2X) communication. However, communication and actuator delays can significantly diminish its benefits and even cause string instability within the platoon. Therefore, this paper introduces a novel CACC strategy that combines a model predictive control (MPC) approach for the leading vehicle with a robust control strategy for the following vehicles, aiming to optimize string performance and minimize the impact of time delays on the platoon. Unlike the existing results of the hierarchical Eco-CACC strategy framework, the MPC-based controller design for the leading vehicle in the upper layer employs a primal-dual path-tracking method to generate optimal speed profiles, ensuring safety, comfort, and economic efficiency while enhancing computational speed. For the following vehicles in the lower layer, the tracking controller employs a robust control strategy based on a distinct Lyapunov-Krasovskii functional that accounts for time-varying delays to guarantee string and inner stability, achieve minimal time intervals, and effectively prevent spacing disturbances from increasing along the string of vehicles due to delay variations. The feasibility and effectiveness of the proposed strategy are demonstrated through simulations, with results compared to existing studies.