Hybrid Joint-space Control Strategies Analysis for One-redundant Cable Suspended Parallel Robots

Hybrid joint-space control strategy, where some redundant cables are force control, while other cables perform the length control, has the ability to control the robots with small pose errors, and maintain all cables tensioned at the same time. In the cable-driven parallel robots with redundant drives, all the cable tensions have a predicable range, we called cable adjustable force (CAF) in this study. This work aims at investigating the relationships between the CAF of target force-controlled cables, and the pose errors under the hybrid joint-space control strategy. A simulation framework, considering interfering cable length and cable forces, is developed to analysis the characters of hybrid-input control strategy, based on a cable suspended with one redundant layout. We found that the CAF is related to the pose control error of the end-effector, and can be regard as a selection criteria for the target cable for the force control in the hybrid joint-space control strategy.