A Novel Positioning Method for UAV in GNSS-Denied Environments Based on Mechanical Antenna

As the application of unmanned aerial vehicle (UAV) become increasingly widespread in various industries, its positioning in Global Navigation Satellite System (GNSS) denied environments plays an indispensable role in certain scenarios such as dense woods and enclosed underground environment. However, there are several existing defects of the conventional positioning method for UAV in GNSS-denied environments, such as the error accumulation and poor long-term accuracy in Inertial Navigation Systems and requirement for sufficient light and high computing power in vision-based localization. Therefore, a novel positioning method for UAV in GNSS-denied environments based on mechanical antenna (MA) is proposed in this work, which consists of MA installed on UAV to generated low-frequency (LF) magnetic signal, the three-dimensional magnetic field sensor in ground base station to receive signal, and the corresponding positioning algorithm based on particle swarm optimization. EM signals in LF bands is applied in positioning, therefore, this method has high propagation stability and anti-interference due to the characteristics of LF bands. Furthermore, because MA technology can greatly reduce the size and power consumption of the LF transmitting system, the LF signal used for positioning can be generated by a portable MA installed on UAV. Theoretical analysis and positioning experiments based on this method are carried out in detail. According to the results, the positioning method proposed in this work is of great feasibility with a mean error < 0.45 m in measurement, which will provide an alternative instrumentation for the positioning of UAV in GNSS-denied environments and can be used in a variety of industrial scenarios with complex electromagnetic environments in the future.