A Time-Varying Lookahead Distance Guidance Law for Path Following

This paper presents a modified version of a well known line-of-sight (LOS) guidance algorithm for path-following. The proposed method employs a time-varying equation for the lookahead distance which depends on the cross-track error. A sliding mode controller is designed in order to stabilize the vehicle heading angle to the desired value specified by the guidance system. The guidance system along with the controller form a cascaded structure which is shown to be globally κ-exponentially stable when the control task is to converge to a straight line. The effectiveness of the proposed strategy is demonstrated by simulations indicating that the variable lookahead distance algorithm can contribute to obtaining a diminished oscillatory behavior around the desired path.