Control of a Helicopter During Autorotation

Abstract

This paper demonstrates an autonomous autorotation controller, which is developed and implemented to a real-time high-fidelity mathematical model of a full-scale light utility helicopter. For developing the autonomous autorotation controller that consists of a standard inner-outer loop architecture, full linear and reduced order linear models, which are obtained around different trim points, are utilized. Inner loops are used for stabilizing the helicopter as well as for holding attitude, heading and speed of the helicopter. While designing the outermost loop, autorotation maneuver is divided into five different phases (steady state descent, preflare, flare, landing and touchdown) and different controllers are developed for each of these phases. Collective commands generated from these controllers are blended using fuzzy transitions. Comparison results of non-linear and linearized models are presented together with details of control law formation. For assessing performance of the autorotation controller, real-time simulation results of integrated high-fidelity model are provided. Results demonstrate the capability of the proposed controller for achieving safe power-off landings. © 2019 The Vertical Flight Society. All rights reserved.