Control System Development for Autonomous Aerobatic Maneuvering with a Fixed-Wing Aircraft

Abstract

The increasing popularity of unmanned aircraft today has led to the development of more sophisticated vehicles with greater operating capabilities. The multirole nature of many civil and military unmanned aircraft along with the desire to increase the amount of automation requires the capability of the onboard control systems to handle a wide range of flight maneuvers. With the expanding flight envelope of unmanned aircraft, it is desirable to be able to quickly tune control gains for both conventional maneuvers as well as maneuvers involving unusual attitudes and airspeeds below stall speed.

The focus of this research is on designing and simulating an autopilot system capable of executing aerobatic maneuvers in addition to conventional unmanned aircraft control. Aerobatic maneuvering is used to gauge the autopilot's effectiveness in handling unusual attitudes as well as airspeeds close to and below stall speed. Modern control theory is applied to the development of a pilot-inspired control strategy based on linearized models of multiple flight conditions. A comparison between using linear aircraft models based on stability derivatives from a linear vortex lattice method and using linear models based on linearized wind tunnel data to determine the control gains is performed. The effects of sensor noise and control actuators on the performance of the autopilot is explored. Testing is also performed to determine control improvement when the control gains are scheduled based on airspeed.

Simulation shows that the pilot-inspired control strategy, together with the developed gain tuning method, can control the aircraft during both normal flight and while performing aerobatic maneuvers. While the developed autopilot is intended for use on unmanned aircraft, the same control method could also be applied to manned aircraft which could benefit from a lightweight control system capable of autonomous stall and spin recovery.