Low-cost attitude estimation with MIMU and two-antenna GPS for Satcom-on-the-move

We detail a low-cost method to estimate vehicle attitude for Satcom-on-the-move (SOTM) using micro inertial measurement unit and two-antenna global positioning system (GPS). The attitude is calculated by integrating gyros, while accelerometers and GPS are used as an aiding system to calibrate the gyro biases. In order to accurately eliminate the accelerometer errors induced by maneuvering accelerations, a sideslip compensation is proposed to calibrate the acceleration estimation derived from the GPS-measured velocity. An adaptive unscented Kalman filter is then developed to deal with the failure of the two-antenna GPS to provide the yaw and sideslip angles. When the yaw angle is unavailable and the vehicle is in straight motion, the yaw angle observation is substituted by velocity heading. During turning, the yaw angle observation is turned off and the yaw angle estimates are obtained from integrating gyros only. Meanwhile, the sideslip angle is estimated by differencing the yaw angle estimate and the velocity heading. The performance of the proposed method is demonstrated with driving tests, suggesting that this technique is a viable candidate for low-cost SOTM.