Professional drivers in `drifting' competitions are able to precisely negotiate a specified course at high sideslip angles while operating in an unstable region of state-space. Studying this practice could provide insight into autonomous car control during emergency maneuvers that excurse outside stable handling limits. This paper presents a simple and physically insightful controller for autonomous drifting with simultaneous tracking of a reference path. A feasible reference trajectory is treated as a sequence of unstable drifting equilibrium points, and a basic example is generated from vehicle parameters using a four-wheel model with steady-state weight transfer. Lookahead error and sideslip are chosen as reference states, and a controller for tracking both objectives around an equilibrium point is derived using a simpler single-track model. Experiments on the rear-wheel drive MARTY test vehicle demonstrate good tracking performance of both objectives even at values of sideslip as high as 45 degrees.
Simultaneous Stabilization and Tracking of Basic Automobile Drifting Trajectories