In this paper we propose an alternative approach to estimate the UAV translational velocity and position applying an onboard optical flow sensor. This, is a appropriated sensor to be used in a mini UAV due to its lightness and smallness. With this approach we are able to perform real-time autonomous outdoor and indoor flight without using the GPS information, which in some case is blocked, denied or jammed. Additionally, a PD controller is robustly tuned in order to compensate the uncertain velocity measurements provided by the optical flow sensor. The experimental results obtained by using this approach shown the feasibility of the proposed sensor-controller scheme.