THE VIBRATION CONTROL OF LARGE FLEXIBLE STRUCTURE BY EIGENSTRUCTURE ASSIGNMENT METHOD
大型柔性构件振动控制的特征结构配置

The eigenstructure assignment for large flexible structure is studied in the paper basedon the fact that vibration control of large flexible structure has the characteristics of possessingmuch more degrees of freedom at nodes, being not appropriate to directly measure the globalstructure parameters, taking too much computation time for its feedback and having need to redesigning the global controller if a component is partially modified. In order to reduce the amount ofcalculation, to facilitate modification, and to manufacture in differeds places, the author assumesthat the features of global control system can be obtained by assigning eigenstructure to eachindividual substructure respectively. Starting from eigenstructure and its decomposition features,the impacts of left and right eigenvectors at each stage on controllability and observability of thesystem are analyzed and "the output features of the mode is decided by both observable matrix andright eigenvector while the controlling features of the mode is determined by the left eigenvector,controlling matrix and also feedback matrix" are pointed out. Furthermore, the assignment ofpartial eigenstructures and the relevant protective algorithm is put forward is accordance withthe feature that only some eigenstructures of the actual substrcture need to be reassigned whileothers remain unchangeable. The algorithm makes those unnecessarily assigned left and righteigenvectors orthogonal with the newly decomposed sub-controller and sub--observer maines, andthus they become uncontrollable and unobservable parts. Moreover, a joint decoupling controlmethod is suggested to avoid disrupting the results of the original assignment of each individualsubstructures in the process of assembling each substructure controller into a global one. Byinstalling controllers at the interface of each individual substructure, the convey of vibration energyamong all substructures is severed. So the global structure features are equal to the characteristicsof each individual substructure. Finally, the proposed method is proved by a two-substructuremass-spring-damper system.