基于小型无人机的航磁测量系统研发及试验应用

Development and experimental application of an aeromagnetic measurement system based on small unmanned aerial vehicles

高精度磁力仪是观测地磁场的基本仪器,也是开展高精度磁法测量的核心装备,广泛应用于放射性矿产勘查、多金属矿产勘查以及基础地质调查等领域。为实现在无人机平台上搭载高精度磁力仪开展航空磁测,满足铀资源及多金属等综合矿产勘查的需求,提高空白区和低工作程度区铀资源勘查效率,提出了一种基于FPGA芯片和STM32单片机的高精度磁数据采集系统设计方案,突破了高精度测频和数据采集系统小型化等关键技术,实现了设备小型化和低功耗。通过设计整形电路和FPGA内部基于多通道时间内插法的测频算法,实现了拉莫尔频率的高精度测量,进而得到了高精度的磁场数据;通过设计信号分压电路和24位A/D转换电路实现了磁通门三分量数据的高精度采集。基于STM32单片机实现对磁总场、三分量及辅助测量数据的采集和存储。经测试,该数据采集系统可实现15000~105000 nT磁总场数据和-100000~100000 nT三分量数据的采集。设计了小型集成化的磁数据采集系统机箱,对数据采集板、电源板和数据接口进行了系统集成,该系统和国外商业化产品相比,体积减小了45%,重量减小了71%,功耗降低了51%。在黑龙江某地区开展了试验飞行,磁静态噪声为0.004 nT,航磁动态噪声一级资料占比95.88%,数据质量可靠,满足基于小载荷无人机平台开展高精度磁测的需求,可为今后开展高精度磁测提供技术装备。

High precision magnetometers are the basic instruments for observing the geomagnetic field and the core equipment for conducting high-precision magnetic measurements.They are widely used in the fields of radioactive mineral exploration,polymetallic mineral exploration,and basic geological surveys.In order to carry out aviation magnetic surveys on Unmanned Aerial Vehicle(UAV)platforms with high-precision magnetometers,meet the needs of comprehensive mineral exploration such as uranium resources and multi metals,and improve the efficiency of uranium resource exploration in blank areas and low work degree areas,a high-precision magnetic data acquisition system design scheme based on FPGA chips and STM32 microcontrollers was proposed,which breaks through the key technology of high-precision frequency measurement and data acquisition system miniaturization,Implemented device miniaturization and low power consumption.By designing a shaping circuit and a frequency measurement algorithm based on multi-channel time interpolation inside the FPGA,high-precision measurement of the Lamar frequency was achieved,resulting in high-precision magnetic field data.The high-precision acquisition of three component data of the flux gate was achieved by designing a signal divider circuit and a 24 bit A/D conversion circuit.The STM32 microcontroller realized the collection and storage of magnetic total field data,three component data,and auxiliary measurement data.After testing,the data acquisition system can achieve the collection of 15000~105000 nT magnetic total field data and-100000~100000 nT three component data.A small integrated magnetic data acquisition system chassis has been designed,which integrates the data acquisition board,power board,and data interface.Compared with foreign commercial products,the system has reduced its volume by 45%,weight by 71%,and power consumption by 51%.A test flight was conducted in a certain area of Heilongjiang province,with a magnetic static noise of 0.004 nT and a first level aeromagnetic dynamic noise data accounting for 95.88%.The data quality is reliable and meets the needs of high-precision magnetic measurement based on small payload unmanned aerial vehicle platforms.It can provide technical equipment for future high-precision magnetic measurement.