Using redundancy to reduce accelerations near kinematic singularities

Solutions of the inverse kinematic problem for redundant manipulators are studied for workspace paths that pass near, but not through, kinematic singularities. Widely-used algorithms such as pseudo-inverse velocity control may compute solution paths that have low joint velocities but very high joint accelerations, which may not be physically desirable or even feasible. In this paper we show the existence of solutions with low joint space acceleration, which use the redundancy of the mechanism to track the workspace trajectory by means of a more natural joint motion. We derive a redundancy resolution algorithm at the velocity level that is computationally undemanding and tracks the desirable low-acceleration solution path. Simulations illustrating the feasibility of the proposed algorithm are presented.