Design of a mixed proportional integral - nonlinear model predictive control strategy for automated vehicles: application to mechanically connected convoys

Recent advances in sustainable mobility have accelerated autonomous driving technologies, particularly for public transport convoys of mechanically connected vehicles, improving the mobility and safety of urban mobility. This work develops a control architecture for such convoys, focusing on trajectory tracking and vehicle coordination. Conducted within a UniFi research project on automated electric minibuses, the study evaluates both mechanical coupling and conventional platooning strategies to optimize the reliability of urban transport. A Nonlinear Model Predictive Controller (NMPC) is designed for vehicle lateral and longitudinal control, ensuring precise tracking while considering actuator constraints and vehicle dynamics. The approach is first applied to a single vehicle and then extended to a two-vehicle convoy, where a Proportional-Integral (PI) controller manages the distance between vehicles. The follower replicates the leader’s path while avoiding corner cutting and maintaining a predefined gap. The simulation results demonstrate excellent performance under ideal conditions, achieving precise trajectory tracking with a distance error limited to ±0.05 𝑚. However, Model-In-the-Loop (MIL) tests reveal a larger deviation (up to 0.80 𝑚) due to trajectory characteristics and dynamic constraints. The MATLAB/Simulink ® implementation, validated with GNSS-acquired (Global Navigation Satellite System), confirms the viability of the proposed strategy, paving the way for further optimisations and experimental validations.