An Attitude Estimation Method for RPRVs Using Angular Rate Sensors with Drifts.

The authors have developed a method for the estimation of the pitch and roll angles of small aircraft such as RPRVs (Remotely-Piloted Research Vehicles) and UAVs (Unmanned Aerial Vehicles) which are too small to carry vertical gyros. The method uses three angular rate sensors with drifts, two accelerometers and air-data sensors. The attitude data obtained from the outputs of the accelerometers, which are corrected for translational and centripetal accelerations, contain high frequency errors due to the correction error for centripetal accelerations using body-axis angular rates. Similarly, the attitude data obtained from the integration of the outputs of the angular rate sensors contain low frequency errors due to sensor drifts and integration errors. Correct pitch and roll angles can be estimated by filtering out and combining the meaningful frequency regions of the two.