Experimental Analysis of an Optimal Redundancy Resolution Scheme in a Cable-Driven Parallel Robot

This paper addresses the challenge of redundancy resolution in parallel cable robots. Redundancy resolution leads in infinite solutions for tension distribution in cables and hence, force distribution has so far turned into an optimization problem in this class of robots. Therefore, the purpose of this work is to propose a method to optimize the force distribution in cables. In the proposed method, the null space of structure matrix is mapped into the joint space in such a way that all actuators remain in an optimal compromission of actuator forces. Investigation of tension distribution along the cables requires an effective modeling of cables. The proposed algorithm is evaluated within an experimental study on the RoboCab, a cable-driven parallel robot. Results demonstrate the ability of the algorithm to keep the tensions within the desired interval while maintaining the optimality. It is derived that this algorithm can be applied as a force estimator in similar applications.