A Real Time Expert Control System for Helicopter Autorotation

A control algorithm for autonomous helicopter autorotation is proposed and evaluated. The algorithm consists of a multi-phase control law with fuzzily-defined transitions, and provides outputs in the form of collective commands, desired forward speed, and maximum pitch and roll angle limits. The algorithm is designed to be used in conjunction with an inner loop velocity tracking controller. A unique feature of the proposed control law is its use of estimated time to ground impact to compute near-optimal flare trajectories from a wide range of initial conditions. Performance of the proposed expert control system is evaluated through six-degree-of-freedom simulation of both a full-size helicopter and a small hobby-size helicopter, and Monte Carlo examples demonstrate robustness to various initial flight conditions. Limited flight test results are presented demonstrating suitable performance of the algorithm in realistic disturbance environments.