This paper describes the design, implementation and flight testing of flight control laws based on Incremental Nonlinear Dynamic Inversion (INDI). The method compares commanded and measured accelerations to compute increments on the current control deflections. This results in highly robust control solutions with respect to model uncertainties as well as changes in aircraft dynamic characteristics of failure cases during flight. At the same time, the complexity of the algorithms is similar to classical ones. The key for practical implementation is in ensuring synchronization between angular acceleration and control deflection measurements or estimates. The underlying theory and practical design methods of INDI are very well understood, but implementation and testing has remained limited to sub-scale UAVs. The main contribution of this paper is to present the design and validation of manual attitude control functions for a Cessna Citation II experimental aircraft, covering control structure design, application of INDI, design optimization, robustness analyses, software implementation, ground and flight testing. For comparison, also control laws based on classical Nonlinear Dynamic Inversion were implemented and flown. The flight tests were highly successful and marked the first successful demonstration of INDI on a CS-25 certified aircraft. The flight test results proved that INDI clearly outperforms NDI and provided valuable lessons-learnt for future applications. Nomenclature A x , A y , A z Specific forces along body X/Y/Z axis, g C Dimensionless coefficient F Force, N J Inertia matrix, kg•m 2 J Moment of Inertia, kg•m 2 K Gain M Moment, Nm M Mach number N 1 Fan speed, s −1 S Wing surface area, m 2 V Velocity vector, m/s V Airspeed, m/s a x , a y , a z Linear accelerations along body X/Y/Z axis, m/s 2 b Wing span, m 2 c Mean aerodynamic chord, m

No abstract

No abstract

No abstract

To improve performance and efficiency of future aircraft generations, multi-objective control design problems considering effects such as over-actuation and lowly damped flexible modes arise from new materials in the wing design. A candidate method, which delivers a solution to this problem for the whole flight envelope is linear parameter varying (LPV) control synthesis. It already incorporates the controller scheduling in the synthesis process, guaranteeing stability and robustness over the entire scheduling envelope, and enables intuitive multi-objective, multiple-input multiple-output (MIMO) controller designs. To prove the concept of LPV controllers in a realistic environment, the flight test campaign results of LPV inner loop control laws on a Cessna Citation II (550) aircraft are presented in this paper. The implemented inner loop controllers are inspired by classical flight controllers used on state-of-the-art fly-by-wire airliners. The longitudinal motion is augmented with load-factor command and the lateral motion controller, which is inherently of MIMO type, features a roll rate command with attitude hold behavior. The control laws are validated in flight by the pilot with respect to functionality, flying and handling qualities. Furthermore, auto generated input signals are used to excite the aircraft without pilot in the loop to allow for a comparability with simulation results.