Lift+Cruise Small Uncrewed Aircraft System Trajectory Optimization with Flexible Mode Waypoints

This paper applies an optimal control path planner to a Lift+Cruise electric Vertical Takeoff and Landing (eVTOL) small Uncrewed Aircraft System (sUAS) based on a QuadPlane dynamic model derived from experimental data. Spline-based paths developed in previous work are simulated in closed-loop control to initialize each optimal control problem. Optimal control adjusts initial spline-based solutions to reduce total energy use subject to flight envelope constraints in each mode. Impacts of optimal control efficiency gains and extra closed-loop control effort are assessed in accelerated hover-to-hover waypoint transit and then in three-waypoint fly-by, fly-over, and fly-coverage reference trajectories. Choice of intermediate flight mode / waypoint type is evaluated with respect to total energy consumption and overflown area coverage. Results indicate optimal control can appreciably reduce energy used for fly-by and fly-over waypoint transits, but optimal control has difficulty converging to improved solutions for fly-coverage or Lift (Quad mode) cases. Lessons from this study will inform future work in hybrid trajectory optimization with spline-based solutions for coverage and Lift mode segments integrated with optimal control transit segments for fly-over and fly-by waypoints.