Research On Dynamic Modeling And Vibration Control Of Solar Array With ACLD Treatments

Active vibration control of Large Flexible Solar Array (LFSA) is a challenging subject in the domain of spacecraft dynamics and control. LFSA has structural characters of large span, light mass, low rigidity, which lead to the dynamics characters of low frequency, light damping, dense modes. The vibration of LFSA can be intrigued by orbit or attitude maneuver of the spacecraft, as well as by environment disturbances from the space. Because of the light structural damping of LFSA and absence of atmosphere damping, the harmful vibration doesn't attenuate. The harmful vibration has bad effect on the attitude stability and pointing accuracy of the spacecraft. Conventional control methods and classical control theories are not suited to the control problem of the large flexible system again. Based on the background, this dissertation brings forward the active constrained layer damping control method and multi-objective robust controller design theory and method in the LMI framework, which have been deeply studied and discussed, the main contents and results in the dissertation are as follows:(1) According to the mechanics characteristics of the LFSA, they are simplified as five kinds of models: one piece of plate, one piece of frame plate, joint multi-plate, joint multi-frame plate and rigid flexible model of the flexible spacecraft. The dynamics model of the above five simplified model with ACLD treatments are developed. The finite element analysis programs are coded in Matlab. The dynamics model are verified through the comparison of eigenvalues and frequency response curves between the model above and one set up by the Msc.Nastran software.(2) The effect of the ACLD position on the modal damping factors was analyzed from the view of shear deformation of viscoelastic layer, a simple method of the ACLD disposition is given hereby.(3) Dynamics model reduction is studied for the structures bonded with ACLD treatments. Both the balance reduction method and dynamic reduction method which are widely used, are inapplicable to the model with viscoelastic materials. A new compound model reduction method based on the Krylov subspace method and the balance reduction method is proposed. It demonstrates that the reduced model holds the main dynamics characteristics of the original model including the eigenvalues, the frequency responses, the impulse responses and the sine responses. The lower model available to design the control system is obtained through model reduction using the compound method.(4) In the multichannel spirit, the multi-objective synthesis of vibration control of the grid solar arrays is discussed. The observer-based states feedback controller is designed in the LMI framework. The model uncertainties are dealt with by introducing an internal feedback loop. The input saturation constraint is addressed by the peak-peak gain and the invariant ellipsoid shaped by the Lyapunov function. A sufficient condition is derived for disturbance rejection performance, and the control input constraints. Taking the rigid solar array as the research object, the controller method is shown to be feasible and effective through the numerical simulation.(5) Validating vibration control experiment of the imitational foldaway solar array with ACLD treatments is done. The experiment results show that the ACLD control strategy and the robust controller can suppress the vibration of the solar array effectively.