MAV Attitude Determination From Observations of Earth’s Magnetic and Gravity Field Vectors

In this paper, a method for attitude determination from vector observation suitable for Micro Aerial Vehicle application is proposed. The attitude determination algorithm is an estimator which uses a measurement equation derived from the linearization of the non-linear function which maps vectors from one coordinate frame to the other. The physical realization of the system uses Earth’s magnetic and gravity field vectors as observations from which attitude is deduced. While Earth’s magnetic field vector is easily measured using a magnetometer triad, measuring the gravity field vector requires a novel sensor fusion scheme which blends the outputs from a triad of accelerometers and WAAS corrected GPS velocity measurments. Two linearization and estimator design schemes are presented. The trade-off involved with these linearization and estimator design schemes are discussed. The attitude determination algorithm and system are validated by both simulation studies as well as experimental flight testing. These results show that the system proposed in this paper can generate an attitude solution with errors (expressed in terms of a 3-2-1 Euler angle sequence) of approximately 5 degree (1 σ) in yaw and approximately 1 degree (1 σ) in roll and pitch.