Research On Multi-Frequency Ultrasonic Array Side Sweep Draft Inspection System

With the strong support from the state in recent years and the increasing demand for the economic development in inland waterways,the volume of shipments in ships shows a sharp increase.However,more and more ships carry cargo,making the surge in the depth of draft of the ship.If the draft is serious,it will threaten waterway safety.In order to solve these problems,it is necessary to conduct draft detection on navigable ships.When it is detected that the vessel in violation of regulations is over-draft,stop them in time to avoid accidents.So,it will effectively improve navigation efficiency.At present,there are some drawbacks in the draft test at home and abroad,such as the inability to disembark from the ship and poor accuracy.Therefore,this paper presents a multi-frequency ultrasonic array side sweep draft detection system.First of all,this paper analyzes the multipath effect and the principle of diffraction effect of ultrasonic waves in water.According to these principles,the short time-sharing control method and the design of amplitude subdivision technology are completed.Then,the characteristics of the ultrasonic transducer are studied,which provide the basis for the subsequent selection of the ultrasonic transducer.According to the requirements of the multi-frequency ultrasonic array side sweep draft detection system,this paper designs DSP multi-frequency data acquisition module to send and receive ultrasonic waves of different frequencies and analyzes the amplitude of the ultrasonic signal corresponding to each frequency of the spectrum by using spectrum analysis technique,and inter-channel interference is eliminated.The ARM data fusion module is designed and the dual-core real-time acquisition structure with DSP multi-frequency data acquisition module is completed.The functions of extraction and fusion of ultrasonic data and water level meter data,noise processing and so on are completed,and the data are transmitted to the host computer system.The developed PC software system uses the median filter method to solve the existing random noise problem.The transducer data characteristic standardization method is adopted to solve the problem of different parameters of the ultrasonic transducer caused by different factors,and the amplitude subdivision technique is used to improve the detection accuracy of the system.After the experiment at Dalian Maritime University Fishing Museum and the commissioning of the Three Gorges Ship Lift,it is proved that the side-sweep draft detection system developed in this paper can meet the actual engineering requirements and the technical scheme is feasible.The system has been accredited by the Chinese Academy of Metrology.When the width of the waterway is 30m,the measurement accuracy reaches 2.0cm.When the width of the waterway is 50m,the measurement accuracy reaches 2.8cm.