Research On Underwater Target Detection Based On Magnetic Induction Communication

The prelude to competition for marine resources has begun in the 21 st century.All countries are strengthening the development of marine resources.Underwater target detection technology based on wireless sensor networks has become a hot research direction in the field of marine communications.Traditional underwater communication technologies mainly include microwave communication,visible light communication,underwater acoustic communication,etc.However,these traditional underwater communication technologies all have the defect of high latency and cannot meet the real-time application requirements of underwater detection.As an emerging information transmission technology,wireless magnetic induction communication technology has a low-latency feature that provides a new solution for real-time underwater target detection in underwater wireless sensor network scenarios.By using Autonomous Underwater Vehicle(AUV),this thesis uses wireless magnetic induction communication technology to study target positioning and attitude estimation methods in underwater target detection.First of all,this thesis introduces the research background and significance of the subject,and explains the current situation in which countries are paying increasing attention to the development of marine resources.It shows that the development of marine research technology has become our country's primary strategic work.At the same time,the thesis introduces the current development status and application goals of underwater sensor networks and summarizes the characteristics of current underwater wireless communication technology.What's more,we focuse on the advantages of underwater wireless magnetic induction communication technology and the development status of underwater target detection technology.Secondly,this thesis has carried on the theoretical analysis to the magnetic induction communication technology used.We deduce the magnetic dipole model according to the radiation principle of the electromagnetic fieldandanalyze the magnetic field strength in the near field and the far field,and calculated the field strength.The basic magnetic induction communication model is introduced,the point-to-point magnetic induction communication model and the magnetic induction waveguide relay communication model under the coaxial parallel state are given,and the transmission path loss is analyzed.In addition weintroduce the compressed sensing method used in the subsequent chapters of this thesis,and summariz its basic solving principle.Then,for the problem of underwater target positioning,wireless sensor network nodes are used to form clusters.The nodes in the cluster use magnetic induction communication technology for time synchronization.The clusters and remote base stations use underwater acoustic communication technology for information transmission,thus forming an acoustic-magnetic heterogeneous wireless sensor networks.Through the analysis of the time synchronization error between the nodes in the cluster,we get the conclusion that the time synchronization method based on the magnetic induction communication in the cluster can effectively improve the positioning accuracy.Finally,this thesis introduces the AUV attitude estimation model for the underwater target attitude estimation problem,combined with actual application scenarios.By deploying a wireless magnetic induction sensor node using a single-coil array on the AUV recovery platform,and deploying a three-way receiving magnetic induction coil inside the AUV,this thesis derives the mathematical relationship model between the voltage and the attitude angle of the three-way receiving magnetic induction coil,and proposes a model based on compression Perceptual attitude estimation method.The theoretical analysis of the influence of different numbers of transmitting coil arrays on the target attitude estimation shows that increasing the number of transmitting coil arrays can effectively improve the target attitude estimation accuracyand hardware experimental measurement verifies the target attitude.The final experimental results also verify the feasibility of the proposed pose estimation method.Multiple measurement analysis can effectively improve the accuracy of the target attitude error.The thesis has 33 pictures,4 tables,and 72 references in the thesis.