Control effectiveness investigation of a ducted-fan aerial vehicle using model predictive controller

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Abstract
Special attention is given to vertical takeoff and landing air vehicles due to their unique capabilities and versatile missions. The main problem here is control effectiveness at low flight speeds and transition maneuvers because of the inherent instability. RMIT is a small sized tail-sitter ducted fan air vehicle with a particular configuration layout, multiple control surfaces, low weight, and high-speed flight capability. In the current study, a comprehensive nonlinear model is firstly developed for RMIT, followed by a validation process. This model consists of all parts including aerodynamic forces and moments, control surfaces term together with the gravity and driving fan forces. Subsequently, linear and model predictive controllers are designed in vertical flight. Based on the simulation results, it is shown that the linear controller is not able to eliminate the inherent instability of the vehicle in hover, while the model predictive controller is tuned to stabilize the attitude and provide an acceptable closed-loop performance over a wide range of external disturbances.