Dynamics analysis of a novel over-constrained three-DOF parallel manipulator

In this paper, a novel over-constrained three degree-of-freedom (DOF) spatial parallel manipulator (SPM) is proposed. The architecture of the SPM is comprised of a moving platform attached to a base through two revolute- prismatic-universal jointed serial linkages and one spherical-prismatic-revolute jointed serial linkage. The prismatic joints are considered to be actively actuated. Kinematics and dynamics of the SPM are studied systematically. Firstly, both of the inverse and forward displacements are derived by analytic formulae. Then, the velocities and the accelerations of the moving platform and each limb are obtained. Finally, dynamics of the mechanism is derived based on the principal of the virtual work. The results are illustrated by numerical examples.