Dynamics and control design of a blended wing-body transitioning UAV

In this paper, dynamic modeling of a new transitioning unmanned aerial vehicle (UAV) is presented. This UAV is capable of VTOL, hovering, efficient (fixed-wing type) forward flight, and online transition between these states. The overall configuration of this UAV comprises a blended-wing-body (BWB), with two rotor arms mounted on the two wing tips using span-wise shafts; the arms can rotate about the span-wise axis, and each arm contains two propellers at its two ends (four propellers in total). Owing to the BWB structure and the novel transitioning mechanism, the dynamic behavior and the required control strategies differ significantly from typical fixed-wing or quadcopter UAVs. The fundamental equations of translational, rotational, and state transition dynamics of this transitioning UAV are thus derived in this paper. Simulation of flight dynamics includes computation and consideration of aerodynamic lift and drag forces as well as weight/inertia estimations, performed through previously developed models. Non-linear control strategies (based on the Lyapunov method) are then developed and implemented, particularly for attitude control and altitude control under the hovering state. A set of numerical experiments are conducted to test the performance of the controllers in responding to disruptions in the attitude angles, performing an altitude maneuver and altitude trajectory tracking, and doing a combination of altitude trajectory tracking and attitude stabilization. Successful stabilization was accomplished in each case with an observed 10-15 second target attainment/settling time. Ongoing research is further expanding these promising developments towards designing the comprehensive control system for this UAV, which includes forward flight and state transition control.