Configuration design method for cable-driven parallel robot considering force control errors and external uncertain wrenches

This study presents a configuration design method for a redundantly cable-driven parallel robot under hybrid control, where the selected redundant cables are force-controlled, whereas the other cables perform length control in the joint space. The general wrench-feasibility for the hybrid joint-space control strategy was analyzed based on a space with cable tension vectors as bases. A novel performance index, general force-determined cable adjustable force, which considers not only the external interfering forces and moments but also the cable force control errors for the controllers, is explained in this study. A configuration design methodology, combining collision-free and wrench-feasible detection, is developed to obtain the optimal parameters. A trajectory with external disturbance forces and moments is considered in the experimental case study, in which the center of mass of the end effector remains unknown, and force control errors are also considered under the hybrid joint-space control strategy. We found that the hybrid joint-space control has the ability to explicitly control the cable force and cable length, and it can be applied for carrying loads with high accuracy under uncertain external interfering forces and moments by means of an appropriate configuration design.