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Aircraft Attitude Determination Algorithms Employing Gravity Vector Estimations and Velocity Measurements

Precision on Navigation, Guidance and Control of aircraft is dependent on the precision of the measurement system both for position and attitude. It is well known in aerospace engineering that the rotation of an aircraft or space vehicle can be determined measuring two vectors in two different reference systems. Velocity vector in an aerospace vehicle can be determined in an inertial reference frame directly from a GNSS-based sensor. Also this velocity vector can be determined by integrating the acceleration measurements in an aircraft body fixed reference frame. By estimating gravity vector in an inertial reference frame, which currently is perfectly tabulated, and in a body reference frame, and combining these measurements with the velocity vector, rotation of the body can be determined. Application of these concepts is especially interesting in order to substitute high-precision attitude determination devices, which are usually expensive as they are forced to bear high solicitations as for instance G forces.