Autonomous inertial-magnetometric device for defining aircraft attitude angles
Аuthors1*, 2**, 3***, 1****
1. Company Avionica, 7, Obraztsova str., Moscow, 127055, Russia
2. Moscow Aviation Institute (National Research University), 4, Volokolamskoe shosse, Moscow, А-80, GSP-3, 125993, Russia
Attitude solution for fixed-wing aircrafts using a magnetometer remains relevant due to its well-known advantages. Taking this fact into account inertial-magnetometric method is proposed for computing roll, pitch and magnetic heading angles in static position of an aircraft as well as in motion, but with some restrictions depending on included sensors and algorithmic support.
There exists a well-known problem of ambiguity of spatial attitude defining in case of measuring geomagnetic field by a single three-axis magnetometer. In proposed inertial-magnetometric device the problem is solved by applying two magnetometers set horizontally and rotated 180 degrees about vertical body axis. Complementing the system by block of triaxial gyroscope allows to connect multiple measurements of geomagnetic field in time, filter measurement errors and increase the accuracy of attitude computation.
The research was conducted for three cases: case of fully eliminated deviation of magnetometers and absence of angular misalignment error between them, case of angular misalignment error of 0.5 degrees and 1 degree with the flight above magnetic anomaly. The research justified the application of two magnetometers for solving aircraft attitude defining problem. The research also resulted that estimated attitude angles maintain acceptable accuracy at increase of angular misalignment error between two magnetometers. Along with this the influence of magnetic anomaly almost doesn’t reduce the accuracy of estimation.
Thus, three angles are defined. Along with this the estimation of angles is provided without accumulation of error and with following accuracy: pitch and roll of about 0.2 degrees rms, magnetic heading of about 0.6 degrees rms.
The device is fully autonomous and allows usage of microelectromechanical gyroscopes with drift of about 300 degrees per second, and has an ability of self-recovery and readiness time of 10 seconds.
Keywords:autonomous device, inertial-magnetometric, magnetometer, geomagnetic field, attitude computation algorithm
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