ESO-Based Terminal Sliding Mode Control for Uncertain Full-Car Active Suspension Systems

In this paper, a fault-tolerant-control (FTC) scheme with finite-time convergence characteristics for vehicle active suspension systems is proposed. A full-car model with unknown dynamics and uncertain parameters is studied. To stabilize the vertical, pitch, and roll displacements into a desired equilibrium in finite time with an uncertain mathematical model and actuator faults, a novel non-singular terminal sliding mode controller (NSTSMC) is designed to control the vertical, pitch, and roll displacements. The control scheme is absolutely continuous and robust. In addition, an improved extended state observer (IESO) with switch terms is employed to compensate for the lumped uncertainty in the suspension systems. Compared with the traditional feedback linearization control based on a linear extended state observer (LESO), this scheme can achieve higher control precision, especially for high-frequency road excitations. Finally, numerical results are shown to verify the merit and effectiveness of the proposed controller, where different types of road excitations are considered to verify the proposed approach in detail.