DYNAMIC MODELING OF CONSTRAINED FLEXIBLE ROBOT ARMS FOR CONTROLLER-DESIGN

The modeling for controller design of a constrained rigid-flexible rob ot arm is considered. The mathematical model is obtained as a set of n onlinear hybrid ordinary-partial differential equations and an algebra ic constraint equation. Galerkin's method is employed to discretize th e partial differential equations. Because of the constrained environme nt of the robot arm, the choice of approximating functions in the spat ial discretization is crucial for obtaining accurate simulation result s from a low order model. Several candidate approximating functions ar e evaluated through convergence and accuracy studies. This work also i nvestigates the effects of coupling between rigid- and flexible-body m otion, and the effects of axial force (due to the contact force) on be nding vibrations through axial shortening. It is shown that the use of inappropriate spatial approximating functions with a low order model can result in faulty predictions of the dynamic response, especially, the axial force effects due to the contact force.