In this paper we present a globally convergent and ultimately exponentially convergent tracking controller for an X4 Flyer rotor craft. The desired or reference trajectory is restricted in one way: its scalar thrust must be uni signed and bounded away from zero. The proposed controller is a two phase one. Phase I converges the attitude (orientation) error and thrust error to zero globally and ultimately exponentially. Phase II is a position tracking and relative yaw angle tracking controller, which is not globally convergent by itself. By carefully postponing a switch from Phase I to Phase II, we are able to assure that Phase II will ultimately drive the position error and relative yaw angle error to zero exponentially. In problem-statement/theorem/proof format, we define the system, the control objective, the proposed controller, and a rigorous proof that the controller maintains boundedness of all closed loop signals and provides global convergence of the tracking error to zero and also ultimately exponential convergence of the tracking error to zero.
