Design Of Small Marine Aeromagnetic Measurement System Based On Multi-rotor UAV

Ocean magnetic measurement technology is an important way to understand and develop the ocean.Obtaining marine magnetic field information not only helps to clarify regional geological features and survey marine resources in scientific investigations,but also plays a pivotal role in the military field.At present,the main method of ocean magnetic measurement is still shipborne magnetic measurement.This method can obtain high-precision magnetic field information.However,it has certain advantages when facing several large and small uninhabited islands and complex areas such as shallows,reefs,and breeding areas.The limitations of these special areas make it difficult for the survey ship to enter,resulting in missing magnetic data in some areas.Therefore,it is necessary to develop a magnetic measurement system that can operate in complex sea areas and has high precision and high resolution.Compared with conventional ocean magnetic detection systems,UAV aeromagnetic survey has outstanding advantages such as fast speed,large amount of information,high safety,and convenient implementation.It is especially suitable for magnetic detection of beaches,shallow seas,islands and polar ice regions.Therefore,this paper designs a small and convenient ocean magnetic measurement system.The system uses a small multi-rotor UAV equipped with related magnetic detection equipment,and uses a low-altitude flight method for ocean magnetic measurement.The realization of the UAV aeromagnetic system in this paper is mainly based on three parts: the construction of the UAV flight platform,the design of the aeromagnetic suspension towing system and the processing of aeromagnetic data.The main work done in this article is to first compare and build a flight platform through selection,the UAV flight platform is based on the multi-rotor UAV as the core combined with the A3-pro flight control system to realize the UAV heading lock,automatic flight and other functions.Secondly,considering factors such as the size of the unmanned aerial vehicle body's load space and the influence of magnetic interference,an aeromagnetic suspension towing system was designed.The aeromagnetic suspension towing system is suspended under the body of the drone through a sling and keeps a certain distance from the drone to reduce magnetic interference.In addition,a set of portable,high-precision aeromagnetic data acquisition system is designed based on the realization of the entire aeromagnetic system in this paper,and an equal-precision frequency measurement method is used to realize high-accuracy surveying and acquisition of magnetic signals.By integrating the aeromagnetic data acquisition system,cesium optical pump magnetometer,GPS,attitude sensor and other related magnetic detection equipment in the aeromagnetic suspension towing system,the real-time magnetic data,positioning data and attitude data of the UAV during flight are realized Collection and storage.Finally,the preprocessing of aeromagnetic data is written by Matlab.When the aeromagnetic task is over,the collected data will be optimized first,effective data will be extracted,and then the optimized data will be drawn and observed through the Surfer software.The small multi-rotor UAV ocean magnetic measurement system designed in this paper breaks through the limitations of the traditional survey area based on survey ships or some medium and large UAVs.It can be combined with the ship-borne magnetic measurement method to achieve multi-directional and full-area coverage of ocean magnetic measurement.It is a brand-new ocean magnetic measurement method.Through the actual field test,the system can be unaffected by factors such as surface terrain.It can perform high-precision magnetic measurement in some complex and special sea areas,which verifies its feasibility.Through the comparative analysis of the test results,it is found that the magnetic interference inside the aeromagnetic system is greatly affected by the suspension distance of the pod and the acceleration of the drone,and the system will continue to be improved in the future.These tests also accumulate valuable experience for the future research of UAV aeromagnetic survey.