A Multi-channel Inland Ship's Draft Depth Detection System Based On The Sonar Ranging

With the rapid development of shipping industry in Zhejiang Province,the shipping trade becomes more and more busy,which leads to the ship grounding and other canal traffic accidents occur frequently.When overload cargoboat passing through shallow and dangerous reach,it will seriously block the shipping trade of other ships once the ship is grounded.Traditional ship draft depth detection method is low-efficiency and poor in measurement accuracy,which reduces the management efficiency of canal management department.So,it is urgent to propose a new type of ship draft depth detection system to assist the management carry out an effective management of shipping trade,which can automatically detect the draft depth of vessels voyaging in waterway and improve the precision of the measurement system.At present,Industrial sounder is mostly dual-channel sounder,it will cause the phenomenon of echo interference when different sounders work at the same time and then lead to the wrong measurement results and the failure of measurement if the multi-channel ship's draft depth detection system is constructed by using the way of integrating many dual-channel sounder.The paper presents a multi-channel inland ship's draft depth detection system based on the sonar ranging to solve the above problems.The multi-channel detecting system can detect the ship's draft depth with the principle of sonar ranging.It can reduce the effect of human factor by using the method of underwater installation because we put the sonar probes in the riverbed of the measured water.The problem of echo interference when many sonar detection channels work together can be eliminated by using polling detection in the principle of time-division multiplexing in the detection system.The multi-channel detecting system writes the control interface of upper computer with LabVIEW,from which we can view the measurement result intuitively.The multi-channel detecting system consists of hardware equipment and the upper computer control system.The hardware includes sonar signal transmitting and receiving circuit board and NI sbRIO-9637 embedded computer.The sonar signal transmitting and receiving circuit board has four components: power amplification circuit,transceiver conversion circuit,bandpass filtering circuit,post amplifier circuit,whose function is to amplify the power of sonar signal and amplification and filter the echo signal.The NI sbRIO-9637 embedded computer is connected with the PC host computer through Ethernet,The upper computer software can drive the eight digital output pin and eight analog input pin on the embedded computer,through which achieve the time sharing transmission between eight sonar signal transmission channel and the time sharing receiving between eight echo signal receiving channel.The upper computer software consists of three modules,which including the time sharing transmission algorithm of sonar signal,the time division receiving algorithm of echo signal and ship draft depth calculation unit.The time sharing transmission algorithm of sonar signal is used to alternately generate 200 KHz square wave signal through eight digital ports on the embedded computer.The time-share receive algorithm of echo signal is used to take turns in receiving corresponding channel's echo signal through eight channel analog ports on the embedded computer.The ship draft depth detection and calculation unit is used to combine the primary echo signal in echo signal and time of flight,calculating the maximum draft depth of ship.Finally,we realize the experimental study of the multi-channel detecting system's ranging accuracy,echo signal disturbing problem and the system detection time by associated debugging the hardware and the upper computer software.The experimental result shows that when the canal depth is less than 3.5m,the ranging error of multi channel detection system is less than 4%.The minimum measurement distance of the system is less than 35 cm.The scheme is practical and feasible,which has a certain application value.