Parallel manipulator POLMAN with isotropic properties dedicated for fast manipulation

This paper is introducing a prototype of a novel 6 DOF parallel robot POLMAN-3x2 dedicated for fast manipulation. In the manipulator design the special motion transmission mechanisms was applied bringing a dynamic decoupling. Robot has an unique kinematics structure. Adequate selection of link lengths and design of mass distribution resulted in good kinematic properties (e.g. large workspace) and high dynamic manipulability appropriately. All six heavy motors are located in the manipulator base, this needed an elaboration of a special solution concerning the motion transmission. POLMAN-3x2 consist of three identical parallel chains, with two active and six passive degrees of freedom each. Special chain geometry allows to obtain the linear displacements of the moving platform (attached to the manipulator end-effector) being independent on joints motion. The special orientation chosen for each motion transmitting mechanisms results in that, that the performance of moving platform is similar to such exhibited by Cartesian robots. Manipulator has good isotropic kinematics and dynamic manipulability. In the design of the moving platform attached to the end-effector special multi spherical joint was applied. The mechanical structure of the manipulator was designed using UNIGRAPHICS system. In optimization of the robot links size the virtual prototyping methods were used (many variants were tested, analyzed model was parameterized). We are discussing shortly the performed tests concerning the basic properties of the prototype. Prototype was build and the simple control system developed.