Implementation and control for an MDOF cable-suspended parallel robot

In this work, a multi-degrees-of-freedom (MDOF) cable-suspended robot that can perform pick-up-and-place tasks in large workspaces with weighty loads is designed. The proposed cable-suspended parallel robot comprises a rigid frame and an end-effector that is suspended from eight cables — four upper cables and four lower cables. The lengths of the cables are computed from the given positions of the suspended end-effector using a kinematic model. However, most multicable-driven robots struggle with interference among the cables, requiring a complicated control methodology to find a target goal. Owing to this issue with cable-driven parallel robots, the whole control structure decomposes positioning control missions and allocates them into upper- and lower- level. The upper-control is responsible for tracking the suspended endeffector to the target region. The lower-level control makes fine positional modifications. Experimental results demonstrate that the hybrid control mode significantly improves positioning performance. The broad variety of issues that are presented in this work apply to aerostats, towing cranes, locomotion interfaces, and large-scale manufacturing that require cable- suspended parallel robots.