Classification and general kinematic models of 3-DOF planar parallel manipulators

This paper presents a new classification for 3-DOF planar parallel manipulators (PPM) with symmetrical configurations and workspace, and the resulted general forms of kinematic model. Under the proposed scheme, 3-DOF PPMs can be classified into two categories. Following this classification, the forward kinematics of category 1 and category 2 are derived and presented in this study, which are featured with a sixth order polynomial and a second order polynomial, respectively. The presented forward kinematic models are ready to be computerized and implemented unlike the classifications and models derived by other researchers requiring much more derivation before they could be implemented