Abstract
This paper describes the development of a trajectory controller applicable to guidance systems for a trailer towed by an agricultural vehicle. The controller was basically a feed-forward type, in which a trajectory was given as a polynomial function in Cartesian coordinates. The objective was to navigate the trailer to a given destination by tracking the designed trajectory. Simulations using a kinematic model of the tractor-trailer system verified that the feed-forward controller could guide the trailer to given destinations in an errorless condition. However, when even a small calculation error existed, it resulted in significant offsets from the given destinations in the case of backing-up motion. Therefore, a feedback controller designed based on locally linearized system equations around a given trajectory was introduced in order to stabilize the system's backing-up motion, therefore reducing the final offsets. The performances of feedback designed based on pole-placement technique and based on optimal control method were compared. Although the simulation results showed that both feedbacks could stabilize the system, the optimal controller showed better trajectory tracking performance than did the pole-placement controller.
