| China has a continental coastline of 18,000 kilometers long,which is of great practical significance for the investigation of underwater topography and landforms in offshore areas.At present,the main survey method for offshore is the manual operation method,and the staff use long poles to collect operations by boating,This method not only consumes a lot of manpower,material resources,and financial resources,but also has very low survey accuracy and coverage,and cannot achieve full coverage detection.Based on ultrasonic detection technology and intelligent control technology,building an intelligent collaborative detection system can effectively solve the above problems.To complete the coverage survey of the offshore area,multiple unmanned ships are required to coordinate and work together,which puts higher requirements on the wireless network interconnection between multiple ships and the shore-based control center.Based on the small unmanned ship system independently developed by the National Mobile Ultrasonic Detection Engineering Technology Center,this paper designs the communication network in the offshore area in response to the needs of multi-vessel cooperative formation detection,and gives a heterogeneous network solution.The solution provides low-latency data transmission,flexible ad hoc network structure,and automatic switching and fast response capabilities of heterogeneous networks.The main research work and innovations of this article are as follows:(1)Detailed analysis of the characteristics and application scenarios of the existing wireless communication technology.For the application of cooperative detection of multiple unmanned ships,three different targeted wireless interconnection technologies(Wi-Fi,Lo Ra,Bluetooth)were selected to meet the needs of multiple wireless transmission channels,and a comprehensive application-oriented heterogeneous network construction scheme was given.(2)Based on the Wi-Fi communication mechanism,a data transmission network between multiple ships and the shore-based main control center is designed,and the high-speed gateway is connected through Wi-Fi to realize the interconnection between the control commands and detection data of each ship and the cloud background.Based on the spread spectrum radio technology,a master-slave wireless command control network was developed,which was applied to a low-latency multi-unmanned ship formation remote control system.Based on the Bluetooth communication mechanism,a high-speed data mutual transmission and sharing system of the self-organizing network structure between the handheld terminal and the unmanned ship’s end was developed,which was applied to the transmission of large amounts of data at close range.(3)Based on FPGA processor,the architecture of parallel processing multiple data transmission channels is designed.The above data links are efficiently integrated,and the advantages and characteristics of the self-organizing heterogeneous network are fully utilized.Based on the heterogeneous network vertical switching technology and RSS characteristics of wireless signals,a dedicated heterogeneous network automatic switching scheme for dedicated USV data transmission applications is designed.(4)Based on the previous theory and practice,I participated in the physical development of the unmanned ship system and conducted related experiments on the system’s heterogeneous network communication scheme.In the experiment,the concurrent transmission throughput rate of the three ships based on the Wi-Fi network can reach 2.79Mbps;.Reliability rate of point-to-point and broadcast communication based on spread spectrum radio network reaches 97%;The average switching time of the wireless remote control network based on spread spectrum radio and Wi-Fi is 0.95 s,which can meet the uninterrupted communication and control in the mobile state.Prove the feasibility and reliability of the heterogeneous network. |
