STRUCTURAL CONTROL SYSTEM OPTIMIZATION WITH VARIABLE ACTUATOR MASSES/

A method is presented to integrate the design space for structural/con trol system optimization problems in the case of linear state feedback control. Nonstructural lumped masses and control system design variab les as well as structural sizing variables are all treated equally as independent design variables in the optimization process. Structural a nd control design variable linking schemes are used in order to avoid a prohibitively large increase in the total number of independent desi gn variables, when actuator masses are treated as nonstructural lumped mass design variables, special consideration is given to the relation between the transient peak responses and the required actuator masses that is formulated as a behavior constraint form. A method to prevent instability of uncontrolled higher modes by modifying the feedback ga in matrix without information about higher modes is also presented. Th e original nonlinear mathematical programming problem based on a finit e element formulation and linear state feedback is replaced by a seque nce of explicit approximate problems exploiting various approximation concepts such as design variable linkings, temporary constraint deleti on, and first-order Taylor series expansion of nonlinear behavior cons traints in terms of intermediate design variables. Examples which invo lve a variety of dynamic behavior constraints (including constraints o n closed-loop eigenvalues, peak transient displacements, peak actuator forces, and relations between the peak responses and the actuator mas ses) are effectively solved by using the method presented.