Global positioning system-based vehicle control for automated parking

This paper addresses control system design for parking of an automated vehicle. The challenge in the control design task for parking arises from the fact that the vehicle constitutes an underactuated non-holonomic system. There are three generalized coordinates to be controlled but only two constrained control inputs. A control system designed to track a two-piece trajectory is developed with only some of the degrees of freedom being controlled in each piece of the trajectory. Constraints on the available parking space, the lateral distance available, and steering limits are taken into consideration in the trajectory design. The trajectory design and control system ensure that the vehicle can reach any desired final point with any desired final orientation. A major portion of the paper concentrates on experimental implementation of the control system. The experimental demonstration is carried out on a truck using a differential global positioning system (GPS) to sense the position of the vehicle. Experimental results show that the truck is able to maintain a spacing accuracy better than 40 cm in tracking the desired trajectory while being driven backwards.