Gütekriterien zur Bewertung der Eigenschaften von Tiltwingflugzeugen zur Auslegung ihrer Basisregelung

  • Criteria for Assessment of Tilt-Wing Aircraft Characteristics for Flight Control Law Design

Holsten, Johanna; Moormann, Dieter (Thesis advisor); Alles, Wolfgang (Thesis advisor)

Aachen (2017)
Dissertation / PhD Thesis

Dissertation, RWTH Aachen University, 2017


Design criteria are essential for qualitative and quantitative assessment, analysis and optimization of control systems. Flight control law design for conventional aircraft uses dedicated criteria in time and frequency domain. For tilt-wing aircraft in particular, criteria used for conventional aircraft cannot be directly adapted. Tilt-wing aircraft rotate their wings together with the propulsion system around the aircraft lateral axis. The resulting significant change in configuration influences the flight dynamics and aerodynamic characteristics. In order to enable seamless operation throughout the entire flight envelope from hover flight to energy efficient fast forward flight, an optimization based approach can significantly speed up tilt-wing system design.The main topic of this thesis is the derivation and systematic application of design criteria depending on specific flight dynamics and variable operating points for control law design and flight dynamics assessment of a tilt-wing aircraft configuration. To achieve this, the flight dynamics of an exemplary tilt-wing configuration is modeled in time and frequency domain to enable evaluation of criteria throughout the entire flight envelope. The criteria are analyzed systematically with regard to their suitability to assess and optimize a control system of tilt-wing aircraft. Furthermore, an optimization based approach is applied to validate and adapt the selected criteria and flight states.In a concluding verification step, a benchmark control system is enhanced by applying multi-objective optimization using selected criteria. Variations regarding performance, control and disturbance responses as well as stability are analyzed. Results show that the determined criteria are suitable for optimization of a tilt-wing flight control system. As the criteria are dependent on mission and configuration, it is shown how they can be adapted using a systematic approach for varying requirements, flight states and configurations of tilt-wing aircraft.