Due to their redundant links and redundant restriction forces,it has been a different problem for dynamic modeling and analysis of over-constrained parallel mechanism.A planar 2-DOF over-constrained parallel mechanism is discussed as an example.On the basis of kinematics analysis,the equilibrium equations for the force and moment of this mechanism are established by using Newton Euler method and D'Alembert principle.The model cannot be solved because the number of equations is less than that of unknown vari...