This chapter explains a fast and low-cost state localization estimation method for small-sized UAVs, that uses an IMU, a smart camera and an infrared time-of-flight range sensor that act as an odometer providing absolute attitude, velocity, orientation, angular rate and acceleration at a rate higher than 100Hz. This allows estimating almost continuously the localization of the aerial robot, when GPS or other methods can at most reach 5Hz. This technique does not require creating a map for localization.