Improving Handling Stability Performance of Four-Wheel Steering Vehicle via μ-Synthesis Robust Control

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> A <formula formulatype="inline"><tex>μ</tex></formula>-synthesis robust controller of a four-wheel steering (4WS) vehicle is designed with the optimized weighting functions to attenuate the external disturbances while the yaw rate is chosen as the only feedback signal. Numerical simulation shows that the 4WS vehicle equipped with the <formula formulatype="inline"><tex>μ</tex></formula>-synthesis robust controller has better maneuverability and a stronger ability to resist disturbances; it is not sensitive to the variations in vehicle parameters. The <formula formulatype="inline"><tex>μ</tex></formula>-synthesis controller has an advantage over the <formula formulatype="inline"><tex>H∞</tex></formula> controller; the latter is thought to be relatively conservative for normal ambient disturbances. </para>