Robust longitudinal and lateral control for mixed-vehicular platoons with string stability guarantees

Integrating longitudinal and lateral controls for vehicular platoons mixed with Connected and Autonomous Vehicles (CAVs) and Level-2 Automated Vehicles (L2AVs) to guarantee string stability against model uncertainty and external disturbances is essential yet challenging. This paper tackles this challenge by introducing a novel integrated longitudinal and lateral control (ILLC) strategy that guarantees input-to-state string stability (ISSS) for heterogeneous vehicular platoons. The proposed ILLC strategy significantly enhances the robustness of vehicular platoons by maintaining the desired headway and ensuring the ISSS against disturbances. By incorporating a disturbance observer, we directly address the disturbance estimation error within the string stability analysis. We validate the effectiveness of our method through simulations of various traffic scenarios. Compared to conventional cooperative adaptive cruise control (CACC) techniques, the proposed method achieves faster convergence to the desired states and exhibits bounded state fluctuations. Furthermore, our method can effectively attenuate external disturbances and dissipate stop-and-go waves.