Study of effect of cable yielding in cable-driven robotic system

This paper presents a method for characterizing the performance limitations imposed by the yielding of the cables in a planar robotic mechanism with a cable-driven transmission. The method involves developing a model for the cable tensions based on a rigid-body model of the system, where the tensions are considered as reaction forces. The kinematic coupling between links in the mechanism due to the cable-drives is also studied. The model allows for analysis of the tensions in a manner similar to that of a recently developed characterization called the Dynamic Capability Hypersurface. In effect the limitations on dynamic performance caused by cable yielding are added to the limitations caused by the bounds on actuator torque capacity, in order to give a more comprehensive description of the capabilities of the cable-driven system. A two degree-of-freedom mechanism is analyzed in order to illustrate the methodology.