M. Wagner, A. Grillenbeck, A. Abou-El-Ela

Within the scope of the frame contract between Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR) and IABG mbH, an applicable control methodology for active vibration suppression on a flexible spacecraft structure was designed, implemented, and experimentally verified. The main objective of active vibration suppression is to reduce the structural vibrations due to unknown, external perturbations. A practical application is the stabilization of on-board science payload of earth observation satellites. According to this application, four piezo-electric actuators were attached to a flexible structure at dedicated positions to introduce the artificial attenuation. The objective was not to design a new control strategy but to provide a practicable design guide for existing control methods which may efficiently be realized in a straight forward manner. In order to find the most suitable control strategy to be used in representative, low damped structure applications, several control algorithms, in particular. Modal Filtering Techniques (Spatio-Temporal-Filtering) and the LQG (Linear-Quadratic-Gaussian) were investigated with respect to performance and robustness. The control design methodology was based on a high fidelity mathematical model of an existing spacecraft experimental structure, obtained by finite element modelling and applying model order reduction methods in the modal space. This model was supplemented by appropriate actuator and sensor models, and validated experimentally utilizing modal analysis techniques. Prior to the implementation and experimental validation, numerical simulations of open and closed loop behaviour using MATLAB/Simulink™ were performed. The model-based LQG control approach in conjunction with a Kalman filter turned out to be most suitable with respect to controller- performance, applicability, and stability. In several iterative steps, the controller design was adapted to the dynamic properties of the spacecraft truss structure CEM-3, which was provided by NASA Langley Research Center. Finally, the applicability of the control system was verified in a real world experiment on the CEM-3 test bed by using piezo-electric actuators and a configurable dSPACE™ controller hardware. As a major result of this experimental verification step, attenuations of up to -30 dB for the main target modes in the frequency range of 20 Hz - 70 Hz were achieved. This paper gives a brief overview on the methodology which was used to develop and to implement a controller for an active structural damping. Further on, the difficulties occurred during control loop synthesis and the results achieved are addressed.

International Forum on Aeroelasticity and Structural Dynamics, 2005, München

Conference Paper

englisch

21,0 x 29,7 cm, 14 Seiten

DGLR-Bericht, 2005, 2005-04, International Forum on Aeroelasticity and Structural Dynamics 2005; S.1-14; 2005; Deutsche Gesellschaft für Luft- und Raumfahrt - Lilienthal-Oberth e.V., Bonn

NA

in getr. Zählung;

vibrations, structures

Bibliothek

2005