Flugzustandsregler für Kippflügel-Fluggeräte mit hohen Flugleistungen
- State controller for flight performance oriented tilt-wing aircraft
Schütt, Marten; Moormann, Dieter (Thesis advisor); Alles, Wolfgang (Thesis advisor)
Dissertation / PhD Thesis
Dissertation, Rheinisch-Westfälische Technische Hochschule Aachen, 2019
The wide flight envelope of tilt-wing aircraft includes VTOL and high flight speeds, making them attractive for various applications such as inspection, air delivery and air taxi. The different flight states -from thrustborne to liftborne- place high demands on the design of aircraft and control system. Thanks to current technologies, tilt-wing aircraft can be designed unstable to achieve high flight performance. Nevertheless, stabilization is a mandatory criterion which must always be fulfilled. The required flight controller must therefore ensure stabilization throughout the entire flight envelope while enabling high flight performance. In this work, a flight state controller is designed and evaluated which finds a compromise to achieve high flight performance while maintaining the required flying qualities for tilt-wing aircraft. This supports the ability to shift the design objectives of tilt-wing aircraft to good flight performance. The contradictory goals of high flight performance and good flying qualities on the one hand and the conflicting requirements for high flight performance in different flight conditions on the other are discussed. The designed flight state controller enables an optimal compromise between these contradictory goals based on the consideration of predefined criteria. Feedforwarding a trim control vector allows stationary flight in the entire flight envelope. For the usually large number of manipulated variables, a suitable trim control vector is selected on the basis of different criteria of flight performance and flying qualities. A control allocation preserves the control reserves required for stabilization and generates a compensated control deflection by applying the pseudoinverse. The reserve of the manipulated variable is taken into account implicitly by an artificial reduction of the control effectiveness. The designed approach of the flight state controller is applied to an example aircraft with high flight performance and a large number of control variables. The functionality of the approach is proven by means of a nonlinear simulation and final flight tests.