Gain-Scheduled Vehicle Handling Stability Control Via Integration of Active Front Steering and Suspension Systems

Abstract

This paper proposes an integrated vehicle dynamics control system that aims to enhance vehicles handling stability and safety performance by coordinating active front steering (AFS) and active suspension systems (ASS). The integrated controller design is based on the lateral stability region described by phase plane approach that is employed to bound the vehicle stability and coordinate AFS and ASS. During normal steering conditions, the vehicle states lie inside the lateral stability region, only the AFS is involved for vehicle steerability enhancement. Whereas, when the vehicle reaches the handling limits and the vehicle states go outside the lateral stability region under extreme steering maneuvers, both AFS and ASS collaborate together to improve vehicle handling stability. The linear parameter-varying (LPV) polytopic vehicle model is built, which depends affinely on the time-varying longitudinal speed that is described by a polytope with finite vertices. The resulting gain-scheduling state-feedback controller is designed and solved utilizing a set of linear matrix inequalities derived from quadratic H∞ performance. Simulation using matlab/simulink-carsim® is carried out to evaluate the performance of the integrated controller. The simulation results show the effectiveness of the proposed controller.