| China’s water transport is very convenient, which leads the rapid development of inland water transport and a strong impetus to the development of national economy. With the increasing amount of inland water transport, inland vessels ultra-draft violations is also increasing, which make a serious thread on the inland waterways navigation safety and navigation efficiency, hindering the healthy development of the economy. Relevant law enforcement departments, however, still take the only way on board to make the detection of ship waterline to measurement the ship ultra-draft, which is both time-consuming and affects the normal navigation of the ship. At present, no effective techniques for rapid ship draft measurement.Measurement of ship’s3D draft can gain not only the ship’s largest draft value, but also a lot of information of ship bottom model, which is the base of testing the deformation of ship’s bottom and detecting the ship overload. According to the requirements of navigation ship’s3D draft detection, we developed the navigation ship’s3D draft dynamic measurement system based on single beam ultrasonic sensor array, ensure the premise of navigation efficiency, realize the parallel navigation ships3D draft dynamic test, and for the ultra-draft warning. At present the system has set up in the Yangtze three gorges shiplock and operates well.The ultrasonic sensor array of measurement system is installed on the detection stent, using the detection trestle synchronous automatic lift subsystems putting down the trestle synchronously, smoothly to the measuring position underwater, avoid affecting the normal navigation. Ship’s3D data acquisition and processing subsystem gains ship’s3D draft data by sensor array, eliminate the abnormal data, make segmentation of the ship draft data and modification processing of3D draft data model. The draft data processed will be displayed in3D way on a computer, and every ship be measured will be calculated the deepest ship draft correspondingly. By a wireless network the result will be sent to the central management information system for the ultra-draft warning.Use navigation ship’s3D draft dynamic measurement system, we obtain the original ship’s3D draft data model, which is with so much abnormal data in it and mix several ship’s3D draft data together. For the original3D draft data model, use the point cloud data median filtering algorithm to eliminate the "similar random noise" and the least square method linear regression forecast method to eliminate "ship wake turbulence noise". For the preprocessed ship’s3D draft data, this paper analyzes the features of hull in different parts of the draft data, and based on the inspection system dynamic measurement requirements, put forward the point cloud data segmentation algorithm based on the data features extraction to realize the3D draft data model dynamic segmentation, and use the actual measurement system data to verify the whole algorithm. At the same time, this paper introduces the dynamic3D display technology of ship draft data based on OpenGL, and uses the system measured data to verify the function.In order to further enhance the system precision, the paper puts forward using the model matching technology realize ship bottom deformation testing and ship’s3D draft revised. This paper introduces the important part of ship model matching technology, including standard database established, the deformation detection algorithm and3D model ship draft correction algorithm, and demonstrates the algorithm simulation test.The system experiment result is given to determine the accuracy ratio. The results show that the precision of the system is±0.048meters, better than the requirement of design, which is0.1meters, meet the design requirements. The algorithm of the system is practical and effective. |
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