Hierarchical Coupling Motion Control of Distributed Vehicle Considering Vehicle Posture

Due to the over-actuated characteristics, the distributed vehicle has more potential for mobility and controllability than the traditional vehicle, making it more suitable for autonomous driving. Motion control of distributed vehicles still faces significant challenges of adjusting longitudinal speed while tracking the reference trajectory and ensuring stability under complex and changeable driving maneuvers. This paper proposes a hierarchical coupling motion control method for the distributed vehicle considering vehicle posture at the handling limit. In the motion-following layer, a coupling motion controller is presented based on variable-time steps discrete linear time-varying model predictive control (VTDLTV-MPC). To improve the predictive model accuracy, the linearization reference point is updated with the predicted state and control sequence of the last moment. While performing coupling motion control, the vehicle posture is coordinated in the heading deviation to enable the reference sideslip angle tracking. By coordinated control of motion and posture, the distributed vehicle can be handled outside the stability region of the traditional vehicle. In the executive layer, a tire parameter online adaptive module (TPOAM) is proposed to update tire parameters online, which does not rely on complex and multi-parameter tire models or look-up tables. Finally, the proposed controller is verified on the hardware-in-the-loop (HIL) platform. The results show that the proposed controller can adaptively adjust the longitudinal speed and control the distributed vehicle at the friction circle boundary to fully utilize the chassis performance, while tracking the reference posture to realize the decoupling of yaw and lateral motions.