Control and Task Planning for a Four Finger Dextrous Manipulator

Candidate: Hor,Maw-Kae


Various attempts have been made to build a dextrous hand and to study the control and planning issues involved in dextrous manipulation. However, in many practical situations, the following problems make the real time control and planning of dextrous manipulation very difficult: (1) the discrepancy between the model and reality (for example, imprecise knowledge of inertia, friction, and the geometric dimensions), (2) the inadequacy of the control theory used in controlling a highly non-linear manipulator, (3) the numerous computations required in the dynamic and kinematic calculations, and (4) the lack of abstract level manipulation primitives. This thesis investigates several issues in relation to dextrous manipulation and control. We designed and built a planar manipulator, the Four Finger Manipulator, for studying of the dextrous manipulation. We also developed a prototype software structure for multi-finger manipulators. Models for quasi-static control and real time calculation are presented which make the real time control possible. Heuristics are described for: (a) choosing the finger gripping forces of a force controlled adaptive frictional grasp, (b) estimating the trajectory in compliant motions, and (c) coordinating finger groups to perform tasks that require multiple finger groups. A set of manipulation primitives and algorithms have been developed on the Four Finger Manipulator. Successful performance is demonstrated for various tasks.