Automatic Steering of Vehicles Involving Feedforward of the Estimated Track Curvature

Automatic track guiding of vehicles is of increasing interest for Intelligent Vehicle/ Highway Systems 1{3]. Track guided vehicles are used in automated production facilities, ship docks, and for city busses which drive in special narrow lanes. The primary task of such a system is to follow a path as well as possible. Track guiding systems have been designed for various controller structures 4{8]. In the present paper it will be shown how to follow a given path error-free under some idealistic assumptions by feedforward of the estimated curvature of the reference path. For practical use this concept is not directly applicable, mainly due to unknown plant parameters and limited actuator force. However, a modiied control concept based on this result yields good performance under realistic conditions. 1 Model of the Steering Dynamics The 2-wheel single-track model by Riekert-Schunck 9] is used to obtain a mathematical description of the vehicle dynamics. A schematic representation of this model is shown in Figure 1. The front and rear wheels are lumped into one wheel each on the centerline of`r`f f r ~ v CG f r f f Fig. 1: Single-track model for car steering the vehicle. The variables in Figure 1 denote