Determination of Critical Parameters in Large Flexible Space Structures With Uncertain Modal Data

Abstract

This paper addresses the problem of control design for large flexible space structures with uncertain modal data. The concepts of modal cost analysis are applied to flexible space structures with these uncertain parameters: modal damping, modal frequencies, and mode shapes at actuator (sensor) locations. A quadratic function of displacements and displacement rates is used as a performance metric. In this case it is possible to obtain explicit formulas for the cost contributions labeled “modal costs” and “parameter costs.” This type of cost decomposition analysis by which one can determine the significant modes and parameters can be useful in model reduction, parameter estimation, and structure redesign. The proposed technique is applied to the “Purdue Model,” a generic model for a two dimensional flexible structure.