Observer-based multi-actuator vehicle chassis control in critical situations

This paper describes an observer-based control of the vehicle dynamics using a four-wheel active steering system as well as an active suspension system. The objectives of the proposed controller are to improve the vehicle behaviour by forcing the lateral dynamics and the load transfer ration (LTR) to track reference trajectories in critical situations. The Takagi-Sugeno (TS) representation has been used in order to take into account the non-linearities of the lateral forces. Based on the obtained fuzzy model, a TS observer has been designed with unmeasurable premise variables in order to consider the unavailability of the sideslip and the roll angle measurement. The observer and controller design has been formulated in terms of Linear Matrix Inequality (LMI) constraints using H_∞ approach.