An experimental study is presented on control of a heavy material handling agricultural manipulator using robust control. The harvesting of heavy vegetables and organic compost fertilization requires hard manual labor. For heavy material handling, an agricultural robot was proposed in the first step. And then a control system using LQ control was designed and high-speed manipulation was realized in the second step. In this paper, we designed a control system to achieve robust performance in the presence of uncertainty. The robotic harvesting experiment was done in the watermelon field and the use of robust gain scheduling and /spl mu/-synthesis was confirmed.

This paper presents a manipulator which is able to handle heavy materials for agricultural applications. The characteristics of agricultural operation are discussed and extracted. As the manipulator for handling heavy materials is analyzed using kinematic indices, the parallel type manipulator is shown to be superior to the other manipulators (i.e. the polar coordinate type, articulated type and cylindrical coordinate type manipulators). A parallel type manipulator has therefore been designed and developed. The robotic harvesting experiment was carried out using the parallel type manipulator in a watermelon field.

For heavy material handling, we first propose an agricultural robot which consists of a 4-DOF underactuated manipulator, a crawler vehicle, and a passive hand in the first step. Then, we discuss the use of LQ control for high speed manipulation. We design a control system based on the characteristics of agricultural operations and the manipulator. The robust stability is analyzed under the structured uncertainty. The robotic harvesting experiment was done in a watermelon field and the effectiveness of LQ control was confirmed.