Autonomous flight control design for a small-scale unmanned helicopter

Abstract

An autonomous flight control (AFC) law is designed for a small-scale unmanned helicopter with the hierarchical dynamic inversion (HDI). HDI is based on the hierarchical structural properties of a nonlinear system to partition the nonlinear system into a number of subsystems so that the dynamic inversion based methods are easily applicable to control design of these subsystems. The recursive control (RC) technique is applied in the AFC design because the attitude subsystem is non-affine nonlinear in the control variables. RC is one of the dynamic inversion based methods and is applicable to control design of a class of non-affine nonlinear systems so that there is no iterative numerical computation needed. There is no gain scheduling based technique needed in the AFC design with HDI. The designed AFC laws for the small-scale unmanned helicopter are verified in simulation on the basic 6-DOF nonlinear model of the helicopter. The simulation results demonstrate that the resulting closed-loop system from the AFC law designed with HDI can achieve better flight performances than the closed-loop system resulting from that designed with the linear quadratic regulator in a wide range of flight conditions. The simulation results also show that the closed-loop system resulting from the AFC law designed with HDI is capable of carrying out autonomous flight. © 2011 by the american institute of aeronautics and astronautics Inc. All rights reserved.