Attitude command attitude hold and stability augmentation systems for a small-scale helicopter UAV

Helicopters are inherently unstable flying machines. to provide adequate handling qualities to small-scale remotely-piloted unmanned helicopters mechanical dampers are utilized. This mechanical damper, or flybar, greatly increases the mechanical complexity of the overall rotor system. It also increases the drag profile of the vehicle. The advent of miniaturized computer and sensor technologies enables the elimination of the flybar from small-scale UAV helicopters. This paper from small-scale UAV helicopters. This paper describes two flight control methods to assist an external pilot in flying a small-scale helicopter. The first method is designed around a lagged-rate feedback system. The second is a more complex attitude command attitude hold (ACAH) system based on adaptive neural-network, model inversion control. Control system architecture and hardware will be presented. Flight test and simulation results will also be included. The U.S. Naval Research Laboratory's test helicopter will be described.