Research On The Positioning System Of Radiation Resistant Underwater Vehicle Based On Three-dimensional Electromagnetic Coils

Nuclear power pools bear the heavy responsibility of handling nuclear fuel in nuclear power plants,which will easily lead to nuclear accidents in case of nuclear leakage.There are drawbacks such as low efficiency and health hazards to operators when handling by manual means.Therefore,it is of great practical importance to carry out research on underwater robots that can replace manual work.Underwater robots working in nuclear power pools usually need to know their position for detection and data return.The traditional hydroacoustic positioning technology,underwater laser positioning technology and underwater electromagnetic positioning technology have disadvantages such as low bandwidth,intolerance to radiation and small working range,which are difficult to meet the practical applications in nuclear power pools.Underwater wireless magnetic induction localization technology,as a new technical means,can better realize the operation of nuclear power pool robots.In this thesis,the theory and methods related to underwater wireless magnetic induction localization communication are studied for the needs of underwater robot positioning and communication,and the coil magnetic dipole model and magnetic induction communication system model are built.The transmission characteristics of underwater magnetic induction signals are also studied,and the eddy current loss and path loss are simulated and analyzed.For the situation that the position and direction of the receiving and transmitting coils may be shifted leading to the degradation of positioning ability,the thesis analyzes the positioning reliability of one-way and three-dimensional coils,and proves that the positioning reliability of three-dimensional coils is higher.At the same time,a mathematical relationship model based on the receiving voltage of the 3D coil and the position and angle of the receiving coil is proposed,and the position and angle of the receiving coil can be calculated based on the magnitude of the receiving voltage.After that,a nonlinear optimization algorithm is used to process the positioning data,which reduces the position and angle deviation and improves the positioning accuracy.In view of the limited localization range of a single 3D coil underwater,the thesis investigates an underwater multi-base station wireless magnetic induction localization system and analyzes the effect of different numbers of base stations on the magnetic induction intensity distribution in space.At the same time,a new base station layout is designed to achieve full coverage of the positioning range,and an energy-optimized underwater multi-base station control strategy is proposed to switch the base stations through the control strategy to complete the positioning of the underwater robot while reducing energy waste.Finally,this thesis builds an experimental platform for underwater magnetic induction localization and communication,designs and fabricates the transceiver coil and hardware circuit of the system,and conducts wireless magnetic induction localization tests and communication tests in air and water respectively to verify the theoretical analysis.The experiments on the transceiver coil in the nuclear radiation environment verified that the system can work normally in the nuclear radiation environment.