Selecting grasp pattern far multiple robotic manipulators holding a rigid object based on motion-oriented coordinability measure

Abstract

The problem of selecting grasp pattern (SGP) is first stated as a process of optimization based on some performance functions. A performance index, named coordinability measure (CM), is introduced, which describes the flexibility of the motion of the manipulated object in Cartesian space corresponding to the coordinating joint velocities of individual manipulators. Motion-oriented coordinability measure (MOCM) is further developed, which is task dependent and describes the coordinability of the system at some motion direction. Both CM and MOCM are dependent on grasp patterns. The problem of SGP for multiple manipulators is investigated in two cases: firm grasp and non-firm grasp. In the first case, the problem of SGP is solved using MOCM as a performance index to evaluate a finite number of feasible grasp patterns and select one among them. In the second case, the flexibility of grasp on the object is viewed as virtual degrees-of-freedom additional to manipulators.<>