Environmental adaptive yaw control autonomous unmannedhelicopter and bifurcation of maneuvering in turning

Adaptation to the environmental changes, such as wind, has very important role to improve the reliability of an autonomous unmanned helicopter. In this paper, we propose an adaptive yaw (heading) control for an autonomous helicopter. The control structure is based on a hierarchal scheme utilizing an inner yaw feedback control loop plus an outer feedback loop, which estimates the direction of the airspeed using roll angle and roll angular rate. Stable coupling in yaw and roll motion is induced by the proposed controller to improve the stabitity of the helicopter´ flight. Turning utilizing the proposed adaptive control system is discussed in particular. Results of flight experiments showed bifurcation of the helicopter´s maneuvering in turning occurs depending on the airspeed.