Energy-saving tracking control and experiment of nonlinear active suspension for multi-axle vehicles considering road slope

This article proposes a novel active suspension model of a three-axle heavy vehicle considering road slope and designs an energy-saving backstepping tracking control method based on an ideal reference model and disturbance observer. The motion states of the ideal reference model with sky-hook damping force control are designed as the tracking trajectory of active suspension control. Then the nonlinear extended state observer (NLESO) is designed to estimate the unavoidable internal parameter perturbations and external unknown disturbances in nonlinear suspension systems. In particular, different from the existing control methods, the influence of road slope is considered in the suspension system modeling for the first time, which can reflect the motion states of the car body more accurately. The tracking controller makes full use of the beneficial nonlinear dynamic characteristics of the ideal reference model, which can effectively ensure ride comfort and consume less energy. The complete stability proof of the control system is given, which establishes the theoretical basis for the active suspension to adapt to the new road conditions. The results of simulation and real vehicle tests under various road conditions (especially slope unilateral convex hull road) show that the proposed controller has better shock absorption performance and lower energy consumption compared with passive suspension and the existing controllers.