Active gust load alleviation is seen as one of many promising technologies that should make it possible to design aircraft to be more energy-efficient in the future and thus reduce the climate impact of aviation. Active gust load alleviation refers to control systems that control actuators on the basis of measured gust loads in order to reduce the loads. By significantly reducing the maximum loads that occur, airplane structures could be designed to be lighter in future, which would result in fuel savings. There are various concepts for active gust load alleviation, depending on the sensors and actuators provided. Furthermore, various control methods are available. The main contribution of this work lies in the analysis of the strongest possible gust load alleviation of future, flexible commercial airplanes with sensors and actuators distributed along the wing. The control method used is incremental nonlinear dynamic inversion, which has gained popularity in recent years due to its properties of strong disturbance rejection and high robustness against uncertainties, among others, and therefore seems suitable for this task. The vertical acceleration of the aircraft and the deflection of the first and second symmetrical wing bending mode are used as control variables. It is assumed that the speed and acceleration of the wing bending modes are also available as measured variables. It is shown that the performance of the active gust load alleviation system depends significantly on the reaction time of the system and that an almost complete reduction of the gust loads is possible with a sufficiently short reaction time. In addition, a simple but effective method is presented with which the reaction time of the actuators can be artificially reduced. Fast-moving trailing-edge flaps are used as actuators in this work. While these appear to be suitable for providing the negative lift required for load reduction, the undesirable pitching moment has led to control reversal -- the wing would therefore have to be designed to be more torsionally stiff or an actuator concept with a lower pitching moment would have to be used. For the design and testing of gust load alleviation systems, simulation models are required that can predict gust loads efficiently and with high precision, taking into account the flexible structure and unsteady aerodynamics. However, such aeroelastic simulation models are not freely available. Therefore, another contribution of this thesis is the publication of an aeroelastic flight dynamics model, mainly written in MATLAB/Simulink, in open source. A special feature of the model is the consideration of dynamic stall. The analysis of the influence of dynamic stall on the gust loads with and without active load alleviation is another contribution of this work.
Active Gust Load Alleviation with Boosted Incremental Nonlinear Dynamic Inversion: Modeling, Control, and Simulation of a Flexible Airplane
Aktive Böenlastabminderung mit verstärkter Inkrementeller Nichtlinear Dynamischer Inversion: Modellierung, Regelung und Simulation eines flexiblen Flächenflugzeugs
2024
Forschungsbericht Niedersächsisches Forschungszentrum für Luftfahrt, vol. 2024-19
Miscellaneous
Electronic Resource
English
DDC: | 629.1 |
British Library Conference Proceedings | 2018
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