Collaborative Control with Nonlinear Observer for the Stability of Electric Vehicles

This paper designs a novel collaborative control approach, including the longitudinal and lateral motion control, to guarantee the vehicle stability by the estimated vehicle states of electric vehicles. A nonlinear observer is developed to observe the lateral velocity and tire-road friction coefficient by a Dugoff's tire model. Moreover, a Lyapunov-based method is utilized to prove that the estimated errors converge to zero. The collaborative control is converted into a tracking problem by establishing a reference model. According to the estimated vehicle states and reference model, a passivity-based control strategy based on the port-Hamiltonian model is adopted to follow the referenced vehicle states and ensure the stable planar motions, and the asymptotic stability of the proposed controller is proved. In addition, a wheel torque distribution considering the transfer of vertical loads is designed to maximize the utilization of tire adhesive forces. Finally, simulation cases demonstrate the effectiveness of the designed nonlinear observer and controller.