Dynamic Modeling of Multibody Constrained Mechanisms With Rigid Links

An approach for dynamic modeling of spatial closed loop robots with rigid bodies is proposed. The method is based on the computation of the dynamic equations of a collection of free rigid links, in the term of maximum generalized coordinates and then assembling the system by taking into account the joints holonomic constraints. The model is obtained in its reduced form, expressed in the term of only the controlled variables. The method can deal with closed loop or open loop structures by a unified approach. Some difficulties usually presented in classical methods are dealT with, such as: taking out of the non-working constraints forces and moments in the Newton-Euler method, the tedious calculation of derivatives in the Lagrange formalism. For illustration, a reduced model for the spatial closed-loop robot of LASEM is developed and compared through numerical simulation to another model obtained with Lagrange constrained formalism