Vorausschauende Flugbahnregelung für Kippflügelflugzeuge
- Predictive Flight Path Control for Tilt-Wing Aircraft
Hartmann, Philipp; Moormann, Dieter (Thesis advisor); Abel, Dirk (Thesis advisor)
Dissertation / PhD Thesis
Dissertation, RWTH Aachen University, 2017
This thesis presents a novel method of flight path control for highly automated convertible aircraft. The method is implemented and evaluated for a tilt-wing demonstrator aircraft. Convertible aircraft configurations are of particular interest in the future-oriented fields of civil unmanned aircraft systems and on-demand air mobility. They offer both, good flight performance and the ability to land and take-off vertically, which allows them to be operated away from airport infrastructures. However, their wide range of possible flight speeds comes with significant variations in flight mechanics characteristics. Automation of convertible aircraft hence poses a challenging problem.Known approaches to flight control of convertible aircraft allow for fully automated flight operation, but flight path control is limited with regard to flight path geometry and with regard to the utilised range of flight speeds. The flight path controller presented in this thesis allows for flights along arbitrarily shaped flight paths and is able to make use of the entire flight speed range. Extensive flight state adjustments, which are necessary to follow the flight path, are planned ahead by this controller during operation. The planning takes into account the current and changing wind situation, all flight mechanics limitations and the flight path ahead of the aircraft.In this thesis the flight path control system is implemented for a tilt-wing aircraft in the form of a cascade control system. An inner flight state controller addresses the problem of controlling the state of motion relative to the air and an outer flight path controller addresses the problem of controlling the inertial state of motion. A non-linear plant model is developed to describe the special flight mechanics characteristics of the tilt-wing aircraft. To perform the flight state planning, a computationally efficient, specialised algorithm is designed. The control system is evaluated by means of simulation experiments. These experiments include flights along simple flight paths to investigate the general behaviour of the control system as well as flights along an example mission flight path under disturbances to analyse the control performance in a quantitative way. Results show that convenient flight state adjustments are determined at all times and that the control system is able to guide the aircraft along complex flight paths precisely, even under the influence of disturbances.