Kinematics Analysis of an Asymmetrical 3-DOF Spatial Parallel Manipulator

A novel asymmetrical spatial parallel robotic manipulator with three degrees of freedom (DOF) is proposed. The moving platform of the mechanism has two-translational and one-rotational DOF with respect to the fixed base. Motion output characteristics and the mobility of the manipulator are analyzed based on the screw theory. Solutions of position and velocity for both direct and inverse kinematics are derived. Furthermore, the singularity and the dexterity are discussed. The Jacobian matrix, mapping the input velocity vector space of the actuated joints into the output velocity vector space of the moving platform, is an identical 3×3 matrix, so the parallel mechanism is a free-singularity fully-isotropic one. Thus, this mechanism performs very well with regard to motion and force transmission and has potential applications in the field of industrial robots and medical devices.