Modeling Of Multibody Systems For Controls Using General Purpose Simulation Languages

Abstract

This paper demonstrates how to use an interpretive-type simulation language, such as MATRIXx or SIMULINK, in the simulation of multibody systems. Functional blocks that contain details of the dynamics of a rigid body and of the equations of several joints were created by using the graphical user interface of MATRIXx. Models of complex multibody systems are built by graphically selecting, duplicating, and connecting appropriate blocks of rigid bodies and joints. This modularity is afforded because joints are formulated using the explicit singularly perturbed formulation. The singularly perturbed formulation, originally developed in bond graph language, is based on modeling infinitesimal defonnation in joints, a characteristic of realistic multibody joints. Bond graphs are graphical models of multi-energy doinain dynamic systems that depict and account for the power structure in the system. In this paper, block diagrams that were obtained from an algorithmic translation of joint bond graphs are coded using the simulation language graphical interface. The methodology is demonstrated by modeling the dynamic behavior of a complex multibody system; namely, a Stewart platform. Because this formulation is explicit, it sets the stage for the simulation of very large- scale multibody systems by exploiting parallelisin of novel computer architectures.