Speaker
Dr
David McKeown
(University College Dublin)
Description
ABSTRACT
The dynamics of a typical launch vehicle are non-linear, non-uniform and time variant. In addition, liquid fuel systems introduce sloshing dynamics which can be difficult or impossible to model, especially if required for real time control. It is a difficult problem, with consequences for the stability, trajectory tracking and efficiency of the launcher. Wave based control has been developed to deal with such difficulties in a natural way and has been shown to cope well with under actuated flexible space systems.
The key concept is that the motion of a flexible body can be separated into two notional components, one travelling from the actuator, for example a TVC engine, into the system, the other leaving the system through the actuator. The actuator, simultaneously launches mechanical waves into a system while it absorbs returning waves. When the launching and absorbing is finished, vibrations launcher have been damped and the desired reference motion is left behind.
A wave-based controller is designed for a launcher similar to the European launcher Vega, where the input data to build the launcher model has been taken from publicly available information. In numerical simulations the controller successfully suppresses the disturbance of the launcher body due to structural flexibility and fuel sloshing motion. A major advantage of the strategy is that no direct measurement of the sloshing motion is required. Only measurements of launcher attitude and actuator torque are needed.
The work has been carried out as part of ESA Future Launchers Preparatory Programme (FLPP)
Keywords: Spacecraft Dynamics, Launchers, Attitude Control, Flexible Systems, Sloshing, Mechanical Waves
REFERENCES
[1] M. Reyhanoglu. Modeling and Control of Space Vehicles with Fuel Slosh Dynamics. 2004.
[2] William J O Connor. Excellent control of flexible systems. Control, pages 6181–6186, 2005.
[3] Edouard Perez. Vega User’s Manual, Issue 3, Revision 0. (3):188, 2006.
| Applicant type | First author |
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Primary author
Dr
David McKeown
(University College Dublin)
Co-authors
Mr
Joseph Thompson
(University College Dublin)
Dr
William O'Connor
(University College Dublin)
