A Synthetic Input Approach to Slip Angle Based Steering Control for Autonomous Vehicles

A new method is presented for low-level steering control of autonomous vehicles. By tracking tire slip angle instead of steering angle, the new controller makes possible a more direct use of force-based high-level control schemes since uncertain, noisy measurements of the vehicle states do not have to be used to convert a desired tire slip angle to a commanded steer angle. Experimental data from a full-size vehicle show that this approach offers some advantages when combined with a force-based path tracking controller. Improved steering control and path tracking performance are demonstrated, particularly at the limits of tire friction, and the reasons for these improvements are briefly discussed.