Analyses of kinematics,statics,and workspace of a 3-RR P RR parallel manipulator and its three isomeric mechanisms

A novel 3-RRPRR parallel manipulator with three pure translational movements and a relative larger workspace is proposed. Its three isomeric mechanisms 3-RR PU, 3-R PRU, and 3-U PU with three pure translational movements are constructed by varying dimensions of some links. Their common kinematic characteristics, workspace, and singularity are analysed, the active force and the constrained torque are solved. First, a simulation mechanism of the 3-RR PRR manipulator is created, and its kinematics, singularity, and workspace are analysed by using an analytical approach and a computer-aided design (CAD) variation geometry approach. Second, the common analytical formulae for solving the displacement, velocity, and acceleration of the four manipulators are derived. Third, the formulae for solving the active forces and constrained torques of the 3-RR PRR manipulator are derived. The analytic-solved results are verified by their simulation mechanisms.