Analysis and modeling of the equivalent system dynamics of 7R-III degree mechanism

The general equivalent dynamics model for 7R-III degree mechanism was established on the basis of EFEM (equivalent finite element method). The fundamental principle is that equivalent should be combined with FEM(finite element method). Quality and inertia are equivalent to the centroid or on the two ends of the bar for any form of component by the type of statical and dynamical condensation. Every element was built through the FEM. The system motive differential equation for any kind of constraint was derived. The key point of building dynamic model is to set up 2 steps tensor T_ia and 3 steps tenser T_ibc and assemble the equivalent mass matrix. The process to establish dynamics model was simple, rapid, standard, unification and programmed and the function is easy to be assembled.