Session 4: Control Systems

This talk presents the current research & development of wing shaping control technologies for high-aspect ratio wing aircraft funded by NASA Advanced Air Transport Technology (AATT) project. The development of the Variable Camber Continuous Trailing Edge Flap (VCCTEF) provides new capabilities for in-flight aerodynamic optimization to improve aircraft efficiency. An overview of wing shaping flight control technologies will be presented. These include: real-time drag optimization, maneuver and gust load alleviation, multi-objective flight control, and Hamiltonian distributed-parameter control. Wind tunnel experiments of these control technologies have been conducted at University of Washington Kirsten wind tunnel and in addition will take place in NASA Langley Transonic Dynamic Tunnel. Lessons learned from the wind tunnel experiments will be discussed.

The presentation provides a brief review of the relevant certification rules and the impact on the design process concerning a flexible aircraft. It addresses necessity to use an integrated model, to take into account the interaction between rigid and flexible dynamics. It shows the Impact of flexibility on pilot handling quality, and the use of real-time simulation model for test with pilot in the loop as a controlled environment for test, earlier in the design. In the end, some results about handling quality analysis in a full motion simulator with pilot in the loop are presented.

A control design framework for gust load alleviation systems is presented. Potentially higher flexibility is addressed by considering geometrical nonlinearities that become apparent at large deformations and may lead to more complex dynamics. The proposed framework includes a linearization method around nonlinear aeroelastic equilibrium to obtain a linear full-order model and Krylov-based subspace methods for a reduced-order model used for control synthesis. Linearization and reduction methods are demonstrated on a very flexible configuration, and an initial LQG controller is designed and tested using a linear full-order model in a closed-loop system. A UDP interface finally enables control testing on the nonlinear system for which, however, substantial design adjustments needed to be made to account for the different behaviour of aeroelastic models due to nonlinearities in GLA system designs.

This talk will explore some key challenges involved in the control of high-aspect ratio aircraft. We introduce a modelling framework that can create nonlinear reduced-order aeroelastic models of sufficiently low order to enable real-time model predictive control (MPC). Natural extensions of this approach to state-estimation and fault detection will be introduced. The developed nonlinear control algorithms will be applied to both the flexible Pazy wing and full aircraft models. Closed-loop performance issues related to use of linear internal aerodynamic models will be shown, and it will argued that data-driven nonlinear aerodynamic ROMs have the potential to partially alleviate these issues.