Back-Transition Control With Large Deceleration for a Dual Propulsion VTOL UAV Based on Its Maneuverability

This letter analyzes the maneuverability of a fixed-wing hybrid Vertical Take-Off and Landing (VTOL) Unmanned Aerial Vehicle (UAV), and proposes a control strategy for back-transitions from fixed-wing mode to rotary-wing mode based on it. Longitudinal aerodynamic forces and moment are modeled to derive a dynamic model of the UAV, and the translational and rotational accelerations that can be generated for the UAV are examined based on the model. To achieve a back-transition with the largest deceleration while maintaining level flight, we search for the best choice of pitch angle and thrust forces for each forward speed by numerical optimization. Flight experiments demonstrate that it is possible to perform a horizontal back-transition while generating a large deceleration with the chosen pitch angles.