Coordinated robust control and energy consumption analysis of active suspension based on bionic reference model and nonlinear extended state observer

This paper proposes a coordinated robust control method for the nonlinear active suspension system based on a bionic reference model and disturbance observer. Inspired by the biological structure of the cheetah's legs and tail, a bionic reference model with nonlinear quasi-zero stiffness characteristics is designed, which has better vibration isolation performance. A new nonlinear function is designed to balance the contradiction between vehicle ride comfort and suspension displacement, in the case of small suspension deflection, the control objective focuses on ride comfort, and with the increase of suspension displacement, the control objective is gradually transformed to avoid suspension displacement exceeding the constraint range of the structure. Then a nonlinear extended state observer is designed to estimate the internal uncertain parameters and external unknown disturbances of the suspension system. Furthermore, a robust tracking controller is designed to ensure that the sprung mass displacement tracks the ideal trajectory, and the asymptotic stability of the system is proved based on Lyapunov theory. The simulation results show that compared with passive suspension, the vertical acceleration under three road excitations is reduced by 78.63 %, 83.07 %, and 76.43 %, respectively. Compared with the ESOT controller, the control energy consumption under three road excitations is reduced by 43.23 %, 51.54 %, and 55.95 %, respectively, and can ensure that the suspension displacement is always within the constraints of the structure. In addition, the problem that the suspension displacement cannot be restored to zero after the tire passes through the steps in the existing control method is solved.