An Efficient Rate Allocation Algorithm in Redundant Kinematic Chains

Abstract

This paper addresses a basic problem which arises in the coordination of serial chain manipulators, namely, that of decomposing a given end effector velocity state into a set of joint rates. Such a problem is indeterminate for manipulators with kinematic redundancy. A novel method of solving the rate distribution problem for the class of fully revolute-jointed, serial manipulators is developed. The technique is an extension of the axial field solution scheme developed initially for solving the force allocation problem in a statically indeterminate parallel chain system. The basis of the solution method lies in the dualities of velocity and force systems between series and parallel mechanisms. The method offers an efficient means of rate coordination and is especially useful in the control of manipulators with high degrees of redundancy. Two examples have been given for illustration. It is shown that the minimum norm solution, obtainable commonly from pseudoinverse, can also be achieved using this new efficient algorithm.