Stiffness Analysis of a 3-DOF Parallel Manipulator with Variable Geometry Platforms

In this work, stiffness characteristics of a planar 3-DOF parallel manipulator with variable geometry platforms are investigated. Firstly, the stiffness model is established based on the Jacobian matrix, with consideration of the geometry variables of both the base and mobile platforms. Then, by means of singular value decomposition, the dimensionally inhomogeneous stiffness matrix is transformed into two homogeneous submatrices. Upon which, two kinds of performance indices are derived to evaluate the manipulator’s stiffness behaviors, one for translation and the other for rotation. Finally, a comparative study of the considered parallel manipulator with different geometry platforms is carried out with regard to the proposed stiffness performance indices.