Dynamic modeling and active control of a cable-suspended parallel robot

Cable-suspended parallel robot (CPR), in which cables are utilized to replace links to manipulate objects, is developed from parallel and serial cable-driven robot. Compared with the parallel robot, this kind of robot has more advantages. The cooperative variation of lengths of six cables pulls the feed cabin to track radio source with six degrees of freedom (DOFs). Similar to a parallel robot, the cable-cabin mechanism for 500-m aperture spherical radio telescope (FAST) can be viewed as a CPR. According to its 5-m scaled model, based on the inverse kinematics analysis the inverse dynamic formulation of CPR with non-negligible cable mass is established using Lagrangian dynamic formulation. Then, considering random wind forces acted on the cabin are simulated based on the characters of the mechanism, a fuzzy plus proportional–integral control (FPPIC) method, which can enhance the control performance for steady-state errors, is utilized to control the wind-induced vibration of the trajectory tracking of the feed cabin. Finally, we provide the examples of simulation and experiment to justify the dynamic modeling for control and to test the proposed method.