Abstract
This paper proposes improved estimation methods of dead zones of control inputs used for yaw rate regulation when disturbances are applied to helicopters which lose tail rotors and conduct auto-rotation flights. The proposed method is based on the nonlinear extended Kalman filter which enables simultaneous estimation of dead zones and a yaw moment external disturbance by using a rotational speed of a main rotor in addition to a yaw rate for measurement updates of the estimator. In this paper, the newly developed main rotor brake unit is introduced, algorithms and design methods of the improved dead-zone estimator are described, and then the proposed method is validated by several simulation results.
