Hugh HT Liu

Professor, Institute for Aerospace Studies
University of Toronto
Director, Centre for Aerial Robotics Research and Education

Speech Title: Tiltrotor VTOL aircraft modelling and transition control: Recent Progress

Abstract: Tilt-rotor and transitional VTOL aircraft combine vertical takeoff and landing capability with efficient fixed-wing cruise, but transition flight remains challenging because lift, propulsion, and control authority vary continuously between rotor-borne and wing-borne regimes. This presentation introduces our recent research work on that front of hybrid modelling and control. It shows a reduced-order, control-oriented framework for modelling and trajectory generation of transitional VTOL aircraft. A six-degree-of-freedom rigid-body model is derived integrated with flight modes representation. The model includes tilting rotors with thrust lag, tilt-rate limits, induced-velocity effects, rotor reaction torque, and ground effect, together with quasi-steady fixed-wing aerodynamics modified by prop wash and transition-flow effects. Several control methods are investigated, including nonlinear model predictive control (NMPC), nonlinear dynamics inversion (NDI), as well as latest learning-based control approaches. The focus places upon a smooth transition. The resulting framework is promising, enabling computationally efficient simulation and closed-loop control development for hover-to-cruise and cruise-to-hover transition maneuvers.

Bio

Hugh H.T. Liu is a Professor of the University of Toronto Institute for Aerospace Studies, where he has been on the faculty since 2000. His research interests in the area of aircraft systems and control include autonomous unmanned systems, cooperative and formation control, fault tolerant control, active control on advanced aircraft systems, as well as integrated modeling and simulations. He currently serves as the Associate Editor of AIAA Journal of Guidance, Control and Dynamics. He is also an Associate Editor of the Canadian Aeronautics and Space Journal. Dr. Liu is a fellow of Canadian Academy of Engineering, a fellow of Engineering Institute of Canada, an Associate Fellow of AIAA The Canadian Aeronautics and Space Institute (CASI), and a Fellow of Canadian Society of Mechanical Engineers, and a registered Professional Engineer in Ontario, Canada. In 2021, Professor Hugh H.T. Liu was awarded the CASI McCurdy Award, presented for his outstanding achievement in the science and creative aspects of engineering relating to aeronautics and space research. ucation (CARRE)