A New Four-Degrees-of-Freedom Parallel Manipulator

This work reports on the kinematic analyses of a novel robot manipulator composed of a three-degrees-of-freedom parallel manipulator endowed with a central kinematic chain whose function is to provide a yaw freedom to the end-effector platform. Semi-closed form solutions to solve the displacement analysis are easily obtained owing the decoupled motions of the robot. After, the input-output equations of velocity and acceleration are obtained by resorting to the theory of screws. A numerical example is provided in order to show the application of the method. As far as the authors are aware, the combination of an inversion of a zero-torsion mechanism with the architecture of the central kinematic chain here proposed has not been considered in previous works.