Dynamic Point-to-Point Trajectory Planning of a Three-DOF Cable-Suspended Parallel Robot

This paper proposes a dynamic trajectory planning method for point-to-point motion of three-degree-of-freedom (three-DOF) cable-suspended parallel robots. Natural frequencies as well as associated periodic trajectories that can be obtained from the integration of the dynamic model of an equivalent passive mechanical system are used to design point-to-point trajectories. The trajectories can be used to connect consecutive points in sequence that may lie beyond the static workspace of the robot. The technique ensures zero velocity at each of the target points and continuity of the accelerations. Based on the cable tension constraints, attainable regions can be determined to search for the next target point, while feasible regions of intermediate points are generated in cases for which a given point cannot be directly attained. An example trajectory is performed to illustrate the approach. An experimental implementation is also presented using a three-DOF prototype, and video extensions are provided to demonstrate the results.