Kinematics and Trajectory Planning of 3-PSS/7R Spatial Hybrid Re-dundantly Driven Mechanism

       A novel 3-PSS/7R spatial hybrid redundantly driven mechanism (HRDM) is proposed. The mechanism is driven by constant velocity (CV) motor and servo motor at the same time. The CV motor provides the main power for the system, and the servo motor plays the role of motion regulation. This system not only has the advantages of the traditional mechanical system, such as stable operation, large bearing capacity, but also can output controllable and adjustable flexible trajectory. The degrees of freedom of the mechanism are determined by the middle limb, which is called hybrid redundantly driven limb, which is driven by both CV motor and servo motor. Based on closed vector method, the position equation of the mechanism is established, and the velocity mapping matrix and acceleration change law of the mechanism are obtained. Further, the necessary and sufficient conditions for the mechanism to realize continuous trajectory and the relationship of rod constraints are obtained. The correctness of the kinematics equation and the smooth and controllable operation of the mechanism are verified by examples. The research results of this paper lay a foundation for the in-depth research and application expansion of spatial hybrid redundantly driven mechanism.