Chapter 14 - Backstepping controller for nonlinear active suspension system

Abstract

In this chapter, a backstepping controller is presented for a nonlinear active suspension system (ASS) of a quarter car model. The quarter car is a highly uncertain system as the number of occupants may vary. The ride comfort of the passengers can be improved by minimizing the root mean square of the vertical acceleration (RMSVA) of the sprung mass while maintaining hard constraints such as tracking force, road holding, and suspension movement at the same time. The performance of ASS with backstepping controller is compared with the ASS with Fuzzy PD (FPD) and conventional PD controllers wherein FPD controller was realized using seven full terms overlapped triangular membership function for inputs and output variables. The scaling factors of all the three controllers were tuned by Grey Wolf Optimization algorithm for a single bump road surface. In addition to this, the performance of all the three controllers are also evaluated for uncertainty in sprung mass and bump height and also for multiple bumps road profiles. Simulation studies clearly revealed that backstepping controller out-performed FPD and conventional PD controllers and presented far superior comfort ride while maintaining all the hard constraints within prescribed.