UAV Navigation in Depth: Use of magnetometers in fixed wing platforms
UAV Navigation is aware of the possible challenges that an unmanned vehicle faces during a flight, so it works to develop a reliable system that is easy to operate and capable of overcoming all the situations.
As it was explained in the previous blog articles, an accurate estimation of heading in a UAS can be critical to completing the mission safely, so a reliable and accurate system should be used.
UAV Navigation families POLAR AHRS and VECTOR autopilots include internal magnetometers. However, as magnetometers use magnetic fields to calculate the vehicle heading, the autopilot position inside the platform - close to the center of gravity - with ferromagnetic components (avionics bays…) may create electromagnetic disturbances which affect the heading calculation, producing an inaccurate navigation. For that reason, the use of external magnetometers is very common in fixed-wing platforms with an MTOW bigger than 10 kilograms.
Our external magnetometer MG01 has been designed to be integrated into aircraft structures and can cope with the possible surrounding electronics magnetization. The MG01 offers the possibility to install the device in more appropriate zones far from interferences, like wingtips or the aircraft tail.
Although these devices require a previous soft iron and hard iron calibration and provide a lower static precision against other technologies GNSS-based as the Dual GNSS Compass, they provide great advantages at a very low cost. Also, single GNSS systems are affected by outside conditions and may affect the precision of the calculations on windy days with the aircraft drifting (“crab angle”). The use of our external magnetometer creates a physical redundancy in the system that ensures flight safety in case of entering fly zones with potential jamming or spoofing of GNSS signal, hence flying in a denied GNSS scenario and in case of sensor failures during the flight. In this sense, the use of magnetometers is critical for dead reckoning operations in order to provide an accurate and autonomous heading estimation in situations where internal algorithms can not use the GNSS source, and hence, precise and clear data from magnetometers become critical to estimate heading. In the same way, these devices are also very useful in VTOL platforms where the aircraft’s heading may be critical in their vertical takeoff and landing stages of the flight.
UAV Navigation autopilots and AHRS have faced many different and demanding scenarios and have worked in every part of the world through the years. The company uses that experience to recommend the best subsystems and components to their projects, acting as a consultant to their clients and helping them maximize the success of their projects.