STUDY AND RESOLUTION OF SINGULARITIES FOR A 7-DOF REDUNDANT MANIPULATOR

The singularity problem of a 7-degrees-of-freedom (DOF) redundant mani pulator is analyzed, and a new resolution method is proposed, In this paper, the singularities are decoupled into the position singularities and the orientation singularity by the technique of workspace decompo sition, then all sigularity conditions for both cases are derived, and the new singularity avoidance (NSA) method is proposed. The NSA metho d resolves the escapable singularities which can be reconfigured into a nonsingular posture via self motion. Unlike some existing methods, t he NSA method considers the position singularities and the orientation singularity separately. This method only needs to optimize two order- 3 miners, one for the 3 x 4 Jacobian translational submatrix and the o ther for the 3 x 7 Jacobian rotational submatrix. Therefore, the compu tation for the optimization is greatly reduced, Three examples are pre sented to demonstrate the generality and efficiency of this new method .