Kinematics, dynamics and stiffness analysis of a novel 3-DOF kinematically/actuation redundant planar parallel mechanism

Abstract

A novel 5-degree-of-freedom (DOF) hybrid serial-parallel manipulator is introduced, and the prototype of its parallel part has been manufactured for pratical testing purpose. The parallel part is a 3-DOF metamorphic planar parallel mechanism (PM) with two different types of configuration: actuation redundancy and kinematic redundancy. First, to establish the inverse dynamic model of the 3-DOF planar PM, its kinematics are studied systematically, including mobility, position, velocity, acceleration, singularity and workspace analysis. Second, an inverse dynamic model of the kinematically redundant planar PM is established by using the virtual work principle method. The actuation forces of the kinematically redundant planar PM are obtained, and the internal forces acting on revolute joints are also obtained by means of separated model blocks. Then, the stiffness matrix is obtained easily by means of the same method used in the dynamics modeling. Finally, kinematics, dynamic numerical simulations considering actuation forces and joint force trends are performed, and the stiffness distributions with contour atlases are also given. The results show the correct of the theoretical kinematic and dynamic models and give reference to know the stiffness performances. A systematic and comprehensive analysis of mentioned planar PM shows that the kinematics of this manipulator with a high degree of modularity are quite simple. And the metamorphic characteristics of kinematic redundancy and actuation redundancy are believed to be able to enhance the research applications of the robot. This research will lay good theoretical foundations for application of this novel manipulator.