Abstract: Research on compliant mechanisms and fully compliant mechanisms has been a hot issue in recent years. The kinematics analysis of fully compliant mechanisms is discussed. Because of spherical joint in this mechanism, the method of pseudo-rigid-body model which has been extensively used in the analysis and design of the compliant mechanisms with only revolute flexure joints is limited in analyzing its kinematics. In addition, the method of finite element analysis is also very complicated. So an expanded pseudo-rigid-body model method is presented. To specify it, the stiffness models of the flexible joint by using the displacement matrix method in structural analysis are established firstly. The close-loop displacement equations of mechanism are derived through the transformations of a series of coordinate systems. Thus both the forward and inverse displacement solutions of the mechanism are presented.

Key words: Compliant mechanism, Flexure hinge, Fully compliant mechanism, Kinematics, Pseudo-rigid-body model