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UBC Theses and Dissertations

An approach to dynamics and control of flexible space structure Chen, Yuan


A relatively general formulation for studying dynamics and control of a large class of systems, characterized by interconnected rigid bodies, beam and plate type structural members forming a tree topology with two levels of branching, is developed using the Lagrangian procedure. The governing equations are discretized using two fundamentally different approaches of system and component modes synthesis. Versatility of the formulation is demonstrated, through its application to two systems of contemporary interest,in the presence of nonlinear control: (i) Space station based, two-arm mobile, flexible manipulator; (ii) NASA proposed configuration involving a flexible slewing arm abode a flexible truss with a rigid antenna. Relative merit of the two discretization procedures is assessed over a range of system parameters through comparison of the controlled and uncontrolled responses. Results suggest that the component mode synthesis, though relatively easy to implement, can lead to inaccurate response unless the boundary con-ditions are modeled precisely. Unfortunately, this is seldom possible, particularly with complex systems of current interest. On the other hand, discretization through system modes, though precise, would require frequent updating leading to an increase in the computational time. The investigation represents an original contribution of far-reaching consequence to the field. Such a planned approach to assess discretization methodologies with reference to space based system has not been reported in open literature.

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