Dynamics and control of flexible multibody systems: an application to orbiting platforms

The paper focuses on an approach to the study of the dynamics and control of large flexible space structures which comprise of sub-assemblies. To begin with, a relatively general Lagrangian formulation of the problem is developed. The governing equations are nonlinear, nonautonomous, coupled and extremely lengthy even in matrix notation. Next, an efficient computer code is developed and the versatility of the program illustrated through a dynamical study of the first element launch (FEL) configuration of the Space Station Freedom, now superseded by the International Space Station. Finally, robust control of the rigid body motion of the FEL configuration using both the LQG/LTR and H_∞, procedures is demonstrated. The controllers designed using the simplified linear models, prove to be effective in regulating librational disturbances. Such a global approach-formulation, numerical code, dynamics and control- can serve as a powerful tool to gain comprehensive understanding of dynamical interactions and thus aid in the development of an effective and efficient control system