Research On Contactless Information Transmission Technology For Autonomous Underwater Vehicles

In recent years, the marine exploration and the marine resources exploitation are expanding to larger and deeper sea, so the underwater operating equipment also has got a higher demand. Small deep-sea mobile workstation equipped with Autonomous Underwater Vehicles (AUV) has got a great deal of attention by marine researchers. Subsequently,some key technical problems need to be solved, one of which is how to provide a stable contactless information transmission platform for the AUV and mobile station during the docking process under the sea.Through summarizing the domestic and international research on underwater information transmission technology, with the comprehensive analysis of underwater acoustic communications, underwater blue and green laser communication and underwater electromagnetic communication , in this paper, we developed a system of underwater contactless information transmission based on electromagnetic coupling, which can work in the volatile sea water environment with high water pressure, strong signal interference, strong corrosion. The main research work of this paper are as follows:Firstly, we studied the theory of electromagnetic coupling, and the original mode of the electromagnetic coupling communication was put forward; we studied the characteristics of the electromagnetic transmission in the sea water, which provides theoretical support for the scheme design.Secondly, the scheme design of the system is carried out, and the pressure water sealing of the data exchange equipment and the loop antenna is made. The carrier frequency is selected base on the characteristics of electromagnetic transmission under the sea and combined with the system's requirements for the communication rate and the communication distance. The parameters of the antenna are designed through the analysis of the dimension parameters of the coupled loop antenna and the experimental comparison. The binary ASK digital modulation demodulation scheme was used in the system and the hardware platform was developed based on FPGA.Thirdly, the hardware platform and software program ware designed in detail, which contained data transmitting module, data receiving module and other peripheral circuit module design. The hardware module is built with Cyclone IV as the core chip, and the FPGA development platform is formed by combining the peripheral circuit interface and on-chip memory. In the software program design, the logic circuit is designed base on hierarchical,modular design method.Finally, the feasibility and reliability of the system ware verified by the ground test and water test and final sea test, which can meet the project requirements.