Flight Controls
Aeroservoelastic Control:
Modern aircraft designers are adopting light-weight, high aspect ratio wings to take advantage of wing flexibility for increased manoeuvrability. Those modifications can lead to improved performance and reduced operating cost. However, the high flexibility and significant deformation in flight exhibited by these aircraft increase the interaction between the rigid body and structural dynamics modes, resulting in Body Freedom Flutter. This phenomenon occurs as the aircraft short period mode frequency increases with airspeed and comes close to a wing vibration mode, typically the wing bending mode. This leads to poor handling qualities and may even lead to dynamic instability. Hence, an integrated active approach to flight control, flutter suppression and structural mode attenuation is required to meet the desired handling quality performance for modern flexible aircraft.
Publications
- Theis J. Pfifer H. and Seiler P., "Robust Modal Damping Control For Active Flutter Suppression", Journal of Guidance, Control, and Dynamics 43 (6), 1056-1068, 2020.
doi.org/10.2514/1.G004846
Autolanding Control:
Automatic control systems play a fundamental role in modern civil aviation and are by now capable of assisting the pilot in all flight segments. In fact, today’s autopilots can perform challenging maneuvers such as to land the aircraft in poor visibility. To safely land the aircraft, the autopilot must achieve a very high level of precision in a variety of different scenarios. Crosswind poses one of the most severe dangers to landing air-
craft. The autolanding system of the A320, e. g., is certified to perform safe landings in crosswind up to 20 knots. For comparison, the demonstrated crosswind in manual flight operation (that requires clear sight of the runway) on the A320 is 35 knots. Improving the ability to handle adverse wind conditions is thus important to increase performance and availability of future autolanding systems.
Publications
- Biertümpfel F. and Pfifer H., "Finite Horizon Touchdown Analysis of Autolanded Aircraft under Crosswind", IFAC PapersOnLine 54-8 (2021), 124–129, 2021. doi.org/10.1016/j.ifacol.2021.08.591
- Theis J., Ossmann D., Thieleke F., and Pfifer H., "Robust Autopilot Design for Landing a Large Civil Aircraft in Crosswind", Control Engineering Practice, 2018.
doi.org/10.1016/j.conengprac.2018.04.010 - Theis J., Ossmann D., and Pfifer H., "Robust Autopilot Design for Crosswind Landing", IFAC World Congress, 2017. doi.org/10.1016/j.ifacol.2017.08.770