Autonomous aerial refueling based on the tanker reference frame

An aircraft formation autopilot is designed for flight test to demonstrate autonomous aerial refueling. The controller requirements are stated, and models for the lead and wing aircraft are outlined and stabilized. Control laws are developed for the model, and four frames of reference are investigated for optimal control. Next, a simulation is constructed with modeled disturbances to produce the real-time inputs that will be available to the controller. Results from simulations of the controller are presented and assessed, including an exploration of sensitivity and robustness. Finally, results are presented from a limited flight test investigation conducted with a formation of an Air Force C-12 and a variable stability Learjet LJ-25, flown by the controller. Fully autonomous aerial refueling maneuvers were successfully demonstrated in both level and turning flight. Finally, conclusions and lessons learned from the flight test and the controller development are presented.