| Magnetic detection is an important non-sound detection method for underwater targets.The magnetic detecting technology of unmanned aerial vehicle(UAV)are developing vigorously all over the world.When the magnetic detection equipment is mounted on the UAV,the interference magnetic field generated by the ferromagnetic materials and electrical equipment on the UAV would affect the accuracy of the measurement of geomagnetic field and the submarine’s magnetic anomaly of the.Therefore,it is necessary to deeply analyze the magnetic field characteristics of the UAV to provide guidance and basis for suppressing the disturbing magnetic field.In this paper,the simulation and experimental research on the magnetic interference problem of the UAV in the magnetic detection system of the rotorcraft are carried out.The variation characteristics of the induced magnetic field,eddy current magnetic field and motor magnetic field of the rotary wing UAV are studied and verified by experiments.The main contents are as follows:Firstly,the finite element method is used to model and simulate the induced magnetic field and eddy current magnetic field in the interference magnetic field of the rotorcraft.Aiming at the ferromagnetic material in the UAV,the induction magnetic field simulation model is established,and the size and distribution of the induced magnetic field and the matrix of the induction coefficient are obtained.By changing the attitude of the UAV,the variation law of the induced magnetic field with the attitude is obtained.A eddy current magnetic field simulation model is established for the metal material mounting bracket of the magnetic sensor.The strength and variation law of the eddy current magnetic field on the mounting frame under different speeds,different motion modes and different background magnetic fields are analyzed.Secondly,according to the structure and winding characteristics of the UAV permanent magnet synchronous motor,the static and dynamic simulation model of the UAV motor magnetic field are established.When the motor is stationary,since the six motors are spatially symmetrically distributed,the magnetic field has a canceling effect in space,and the leakage magnetic field at the sensor is small.When the motor is working,the phase space characteristics of the leakage magnetic field are studied.The attenuation characteristics of the leakage magnetic field in the vertical section are studied,and the curve fitting is performed.Considering the influence of the position sensor on the magnetic field of the motor,the time-frequency characteristics of the magnetic field are analyzed.Finally,an experimental evaluation of the magnetic field of the drone is performed.In the experimental field,the static magnetic field of the six-rotor UAV was measured,and the magnetic field distribution characteristics of the UAV under the action of theearth’s magnetic field were verified.The experimental test of the leakage magnetic field of the motor is carried out to verify the relationship between the frequency of the leakage magnetic field and the speed of the motor during the actual rotation process,and reveals the law of the attenuation of the leakage magnetic field of the motor with distance.The results show that the simulation results of the induced magnetic field,eddy current magnetic field and motor magnetic field of the rotorcraft UAV are basically consistent with the experimental results.The simulation method and model of the magnetic characteristics of the UAV established by the thesis can provide guidance and basis for understanding and suppressing the disturbance magnetic field of the UAV. |
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