Manipulator control at kinematic singularities: a dynamically consistent strategy

This paper presents a general strategy for manipulator control at kinematic singularities. When a manipulator is an the neighborhood of singular configurations, it is treated as a redundant mechanism in the subspace orthogonal to the singular directions of the end-effector. Control in this subspace is based on operational forces, whale null space joint torques are used to deal with the control an the singular directions. Decoupled behavior is guaranteed b y using the dynamically consistent force/torque relationship. Two dafferent types of kinematic singularities are identified and strategies dealing with these singularities are d e veloped. Experimental results of the implementation of this approach on a PUMA 560 manipulator are presented.