Distributed Sliding Mode Control approach with adaptive spacing policy for vehicle platoons in communication interruption scenario

Communication disruptions in connected and autonomous vehicle (CAV) platoons induce critical stability degradation. This study proposes a dual-layer framework that combines adaptive spacing policy switching and distributed exponential sliding mode control (DESMC). The hybrid policy dynamically switches between constant spacing (CS) and constant time headway (CTH) policies based on real-time metrics, such as packet loss exceeding 5% or RSSI dropping below -90 dBm. This approach reduces emergency braking by 85% compared to pure CS. Additionally, the DESMC controller utilizes an exponential approaching law, resulting in a 1.16% reduction in velocity RMSE and a 21.71% decrease in acceleration oscillations compared to conventional methods. Stability is verified using the Lyapunov theory, and string stability is validated under time delays via infinity-norm analysis. Simulations conducted on six CAVs show that, during failures, the system achieves a safe spacing of 8.7 meters, exceeding ETC standards by 8.75%. Furthermore, platoon synchronization occurs in 35 seconds, 16.7% faster than conventional approaches, with steady-state errors of ±0.15 meters. Finally, the DESMC method proposed here quantitatively demonstrates the superior smoothness and stability compared to the conventional controller. The proposed framework enhances robustness in dynamic communication environments, supporting 5G-V2X-enabled transportation systems.