Optimization on the Distributed Propulsion UAV's Leap Take-off Trajectory

In the field of take-off research for distributed propulsion unmanned aerial vehicles (UAVs), the trajectory research of leap take-off lacks attention. This paper designs three optimal leap take-off trajectories for different missions to improve the take-off rapidity and energy efficiency of such UAVs. First, to better take advantage of the distributed propulsion, a tandem-wing-configuration UAV with 8 distributed propellers is taken as the research object, and a nonlinear dynamic model is established. Notably, the model specifically considers the significant slipstream uplift effect during take-off, expanding the take-off envelope. Based on the UAV's dynamic model, the leap take-off flight envelope is drawn. From this envelope, the UAV's take-off angle, transition speed, and take-off boundary constraints are summarized. Under the take-off boundary constraints, the optimal leap take-off trajectory is designed using the Gaussian Pseudospectral Method. Taking the minimum time, minimum energy consumption, and a weighted sum of time and energy consumption as objective functions, the article obtained three optimal leap take-off trajectories: the time-optimal leap take-off trajectory, energy-optimal leap take-off trajectory, and time-energy-optimal leap take-off trajectory. The UAV's flight trajectory control loop and attitude control loop are built to verify the three leap take-off trajectories through simulation and semi-physical experiments. The results show that the three optimal leap take-off trajectories designed in this paper can guide the UAV to complete the take-off task rapidly, energy-efficiently, and safely, proving strong effectiveness and feasibility.