Dexterity analysis and design application of articulated robot hands

To increase the ability and flexibility of robots, articulated robot hands have recently become an area of great interest in the field of robotics. These hands are generally called dexterous hands. However, the dexterity of a robot hand could not be quantified as before this study the criterion for determining dexterity was not established.; In this dissertation dexterity of a robot hand has quantitatively been defined. To measure dexterity a measuring sphere has been constructed based on the center of mass of the grasped object and grasped points. The measurement of relative rotation between the object and the measuring sphere results in a criterion called the Rotation-Dexterity Index (RDI). This criterion can be used to evaluate a hand's ability to rotate the grasped object at a position. The distribution of RDIs in the workspace of the hand can be expressed in three ways: (1) Dexterity matrix, a full collection of the RDI over the entire workspace of the hand; (2) Dexterity charts, a graphic expression of a subset of the dexterity matrix; (3) Global dexterity, a definite integral of the RDI taken over the entire workspace of the hand. The three ways provide the same information on dexterity of the hand, differing only in the degree of detail.; Dexterity of a robot hand can be analyzed using the dexterity charts or global dexterity criterion. The effect of selecting different kinematic parameters for a robot hand on the dexterity of the hand can be found by dexterity analysis. Different types of robot hands have been considered in the dissertation. These include planar hands, spatial hands, two-finger hands, multifingered hands, hands with redundant joints, hands with inadequate joints, etc.; In the dissertation a procedure has been developed to design a hand based on the required dexterity as expressed by a set of given dexterity charts. Since it is infeasible to design a hand whose dexterity charts exactly match the given charts, a method to get an approximate design has been developed.; The iterative least-square method has been used to obtain an approximate design. The resulting hand can either have a set of dexterity charts which cover the set of given charts and have minimum deviation from it or have minimum size. Detailed discussions have been presented for planar hands, and have subsequently been extended to spatial hands.