Transition of Output Error Distribution caused by Joint Clearances around 3-DOF Planar Parallel Manipulator

Planar parallel manipulators with three degrees of freedom are instruments adequate enough to complete planar microstage mechanisms. Because the planar parallel manipulators have high enough structural stiffness and whole of their actuators are allowed to be arranged on a base with ease. In this paper, 3-DOF planar parallel mechanisms with revolute joints and strict output errors are analyzed theoretically and experimentally in consideration of joint clearances. In the case where large joint clearances are found, for example, as a result of the above analysis, in the joint clearances in the mechanisms constructed by surface micromachining techniques, a magnification of output error areas produced by transition from a direct kinematic solution to the other one is liable to occur and output errors are made greater in the areas where transmission index (TI) remains small.