PARAMETER-IDENTIFICATION IN DISTRIBUTED SPACECRAFT STRUCTURES

Space structures can be regarded as distributed-parameter systems characterized by mass, damping and stiffness distributions. A technique for the identification of the mass, damping and stiffness distributions is presented which is based on the finite element method. The technique has the advantage that it identifies physical properties instead of matrices, where the latter are abstract quantities, not unique for a given structure. The identification process consists in exciting the structure by means of known nodal forces and measuring the response at each nodal degree of freedom. Because the excitation and response are known, the equations of motion can be regarded as a set of simultaneous algebraic equations in the system parameters, and can be solved by a least-squares technique. The method is stable in the presence of noise. The effect of the noise can be reduced by increasing the number of samplings.