Robust feedforward control design for lateral vehicle dynamics

Abstract

In this thesis, robust feedforward controller is designed for active steering which is an alternative vehicle dynamic control method to active braking control. The aim of this study is to increase performance and robustness of active steering using the combination of feedforward and feedback controller instead of using only feedback. A PID feedback controller is designed to stabilize a linear single track vehicle model with optimization of PID controller parameters. Feedforward controller is added to this controlled system to deal with uncertainties such as speed and cornering stiffness. Feedforward controller is designed using linear parameter varying (LPV) control theory and stability analysis results of integral quadratic constraints (IQCs). Both static and dynamic IQCs are used to describe uncertainty of the system and dual IQCs are used for stability analysis because of the nature of feedforward control problem. Linear matrix inequalities (LMIs) are used to define stability conditions. The controllers are designed such that the L2-gain of the closed loop system is minimized. Simulation results of feedback controller, feedforward controller designed with static IQCs and feedforward controller designed with dynamic IQCs are given and compared for different steering angles.