Cartesian control of an advanced tractors rear hitch - geometric solution

Abstract

The movement of a traditional three-point hitch of an agricultural tractor provides one degree of freedom. This limits the use of hitched implements and forces implement manufacturers to build additional hydraulics into the implement. In this research a tractor was instrumented to provide two rotational and two translational degrees of freedom for the rear hitch. The goal was to develop a control system which allows the operator to control the rear hitch in Cartesian coordinates.In this paper a geometric solution for the rear hitch inverse kinematic transform is presented. The transform is tested on the instrumented tractor. The result is a functional control system allowing Cartesian control. The system also provides the rear hitch pose information via virtual terminal (VT) interface. The available workspace is however quite limited due to the mechanical structure.