A method and device for three-dimensional measurement of the shape of the mouth of a marine fishing trawl

Abstract

The invention discloses a method and device for three-dimensionally measuring the shape of a trawl net mouth of a marine fishery, relates to the field of marine fishery trawl fishing, solves the drawback that the traditional trawl net mouth measurement cannot obtain the shape of the entire net mouth, which affects the fishing efficiency. The key points of the technical solution are that it includes a plurality of positioning array elements evenly spaced and arranged on the trawl net mouth for positioning, a main control machine that controls the positioning array elements and receives and processes the position information detected by the positioning, and a data transmission cable that transmits data signals between the main control machine and each positioning array element; the main control machine obtains the position information of each positioning array element, and determines the shape of the trawl net mouth according to the relative position of each positioning array element. The method and device for three-dimensionally measuring the shape of a trawl net mouth of a marine fishery fishing can accurately determine the precise three-dimensional shape of the trawl net mouth, and are convenient for adjusting the net mouth to improve the trawl fishing efficiency.

Description

Technical Field

[0001] The invention relates to the field of marine fishery trawling, and in particular to a method and a device for three-dimensionally measuring the shape of a marine fishery trawling net mouth. Background Art

[0002] Trawl fishing is one of the main operating methods of marine fisheries. Due to its advantages of wide range of fishing targets, high fishing efficiency, active and flexible production, and wide operating range, trawl still occupies a very important position in modern fishery production. In the process of fishing operations, in order to achieve higher fishing efficiency, trawlers use trawls with a total length ranging from tens to hundreds of meters. When the current state of the net mouth is known, the net mouth can be opened as wide as possible under different operating environments by adjusting the depth and direction of the fishing boat and the length of the trawl rope, so as to improve the trawl fishing efficiency.

[0003] The traditional method of measuring the current state of the net mouth is to install acoustic long-distance devices, commonly known as net position meters, at both ends of the net mouth to measure the distance between two ropes near the net mouth. The shape of the entire net mouth cannot be obtained, and it is difficult to accurately obtain the shape of the trawl net mouth, and thus the size of the net mouth cannot be adjusted in time for fishing, affecting the trawl fishing efficiency. Summary of the invention

[0004] The purpose of the present invention is to provide a method and device for three-dimensionally measuring the shape of a trawl net mouth for marine fishing, which can accurately determine the precise three-dimensional shape of the trawl net mouth and facilitate the adjustment of the mouth to improve the trawl fishing efficiency.

[0005] The above technical objectives of the present invention are achieved through the following technical solutions:

[0006] A method for three-dimensionally measuring the shape of a trawl net mouth in a marine fishery comprises the following steps:

[0007] The main control machine sends a self-check command to several positioning array elements installed on the trawl network port to determine that each array element is in working condition;

[0008] Each positioning array element enters a working state, and the positioning array elements are divided into a first group of array elements and a second group of array elements according to their positions on the trawl net mouth;

[0009] The main control machine sends a positioning command, and each positioning array element of the first group of array elements and the second group of array elements receives the positioning command, and transmits and receives the position signal alternately according to a set period;

[0010] The positioning array elements obtain relative position information between each other and transmit it to the main control machine;

[0011] The main control machine receives and processes the relative position information of each positioning array element, calculates and obtains the relative position between each positioning array element, and determines the shape of the trawl net mouth according to the relative position of the positioning array element.

[0012] Preferably, the specific steps of alternating the transmitting and receiving states of each positioning array element are:

[0013] Each positioning array element is provided with a one-to-one corresponding array element number;

[0014] The master computer sends a positioning command with an array element number;

[0015] Each array element receives the positioning command and compares it. When it is determined that the positioning command contains the array element number corresponding to itself, the positioning array element enters the transmitting state; otherwise, it enters the receiving state.

[0016] Preferably, the step of each positioning array element of the first group of array elements and the second group of array elements obtaining relative position information between each other is specifically:

[0017] The positioning array elements of the first array element group and the second array element group alternately enter the receiving state and the transmitting state;

[0018] Each positioning array element in the transmitting state obtains its own depth information, and measures the relative distance between itself and each positioning array element in the receiving state through underwater acoustic ranging;

[0019] Each positioning array element in the receiving state obtains its own depth information, and receives and obtains the relative distance information with the positioning array element in the transmitting state;

[0020] The same positioning array element in the receiving state calculates and determines the relative positions between the positioning array elements according to the relative distance and depth information between the positioning array elements in the transmitting state.

[0021] Preferably, the specific steps of positioning each positioning element are:

[0022] Positioning element initialization parameters, including the corresponding element number;

[0023] The positioning array element receives the transmitted self-test command, and each array element performs clock synchronization and enters a waiting state, waiting to receive the positioning command to set the working state, which includes transmitting and receiving;

[0024] When the positioning array element enters the transmitting state, the transmitting subroutine is called to enable the positioning array element to transmit the positioning signal;

[0025] When the positioning array element enters the receiving state, the acoustic receiving subroutine, the pressure receiving subroutine, the angle subroutine, the data packaging subroutine and the data transmission subroutine are called to receive and package the relative position information for transmission;

[0026] Each positioning array element receives and transmits the positioning signal alternately according to a set period to complete the positioning of each positioning array element relative to each other.

[0027] A three-dimensional measuring device for the shape of a trawl net mouth of a marine fishery, comprising a plurality of positioning array elements evenly spaced and arranged at the trawl net mouth for positioning, a main control computer for controlling the positioning array elements and receiving and processing the position information detected by the positioning, and a data transmission cable for transmitting data signals between the main control computer and each positioning array element;

[0028] The main control machine obtains the position information of each positioning array element, and determines the shape of the trawl net opening according to the relative position of each positioning array element.

[0029] Preferably, the plurality of positioning array elements are symmetrically divided into a first group of array elements and a second group of array elements according to their positions on the network port, which transmit and receive position information alternately at a set period; each of the positioning array elements includes a pressure sensor for measuring the depth position, a compass for measuring the deviation angle, and an acoustic sensor for measuring the relative distance between the positioning array elements and other positioning array elements.

[0030] Preferably, the positioning array element includes a main control DSP, an underwater acoustic transmitter and receiver, a communication circuit, a pressure sensor, an acoustic transducer, a magnetic compass, a power module, and a peripheral circuit connected via communication.

[0031] Preferably, each of the positioning array elements is provided with an array element number corresponding thereto, and the main control machine sends a positioning instruction corresponding to the array element number to control the operation of the positioning array element.

[0032] In summary, the present invention has the following beneficial effects:

[0033] By setting a number of positioning array elements at the trawl net mouth, the shape of the net mouth can be determined according to the relative positions between the positioning array elements. Through the mutual positioning between the positioning array elements, as well as the control and calculation processing of the main control computer, the relative positions between the positioning array elements can be obtained, and then the precise three-dimensional shape of the trawl net mouth can be determined, and then the depth and direction of the fishing boat's heading, and the length of the trawl rope can be conveniently adjusted to make the net mouth as wide as possible in different operating environments, thereby improving the trawl fishing efficiency and making it more accurate and efficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 A schematic diagram of a three-dimensional measurement device for the shape of a trawl net mouth in marine fisheries;

[0035] Figure 2 A main flow chart of positioning operations for each positioning array element;

[0036] Figure 3is a schematic diagram of the first group of array elements entering the transmitting state;

[0037] Figure 4 is a schematic diagram of the second array element entering a transmitting state;

[0038] Figure 5 It is a flowchart of the initialization module;

[0039] Figure 6 A flowchart of a subroutine for receiving instructions;

[0040] Figure 7 It is a flowchart of the launch subroutine;

[0041] Figure 8 It is a flowchart of the underwater acoustic receiving subroutine;

[0042] Fig. 9 It is a flowchart of the pressure receiving subroutine;

[0043] Fig.10 This is a flowchart of the angle receiving subroutine;

[0044] Fig.11 It is a flowchart of the data packaging subroutine and the data transmission subroutine;

[0045] Fig.12 This is a schematic diagram of the underwater network port shape measurement principle;

[0046] Fig.13 This is the hardware block diagram of the positioning array element;

[0047] Fig.14 This is a schematic diagram of the internal structure of the positioning array element;

[0048] Fig.15 This is the system block diagram of BF533;

[0049] Fig.16 The internal logic block diagram of the main control board FPGA

[0050] Fig.17 This is the structural block diagram of the underwater acoustic receiver;

[0051] Fig.18 This is the structural block diagram of the underwater acoustic transmitter;

[0052] Fig.19 This is the power management block diagram. DETAILED DESCRIPTION

[0053] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0054] According to one or more embodiments, a method for three-dimensionally measuring the shape of a trawl net mouth in a marine fishery is disclosed, such as Figure 1As shown, it includes a fishing boat trawl, a plurality of positioning array elements installed on the trawl net port of the fishing boat, a main control computer for control and processing, and a data transmission cable for data transmission, and specifically the following steps are performed:

[0055] The main control machine sends a self-check command to several positioning array elements installed on the trawl network port to determine that each array element is in working condition;

[0056] Each positioning array element enters a working state, and the positioning array elements are divided into a first group of array elements and a second group of array elements according to their positions on the trawl net mouth;

[0057] The main control machine sends a positioning command, and each positioning array element of the first group of array elements and the second group of array elements receives the positioning command, and transmits and receives the position signal alternately according to a set period;

[0058] The positioning array elements obtain relative position information between each other and transmit it to the main control machine;

[0059] The main control machine receives and processes the relative position information of each positioning array element, calculates and obtains the relative position between each positioning array element, and determines the shape of the trawl net mouth according to the relative position of the positioning array element.

[0060] Specifically, the specific steps of alternating the transmitting and receiving states of each positioning array element are as follows:

[0061] Each positioning array element is provided with a one-to-one corresponding array element number;

[0062] The master computer sends a positioning command with an array element number;

[0063] Each array element receives the positioning command and compares it. When it is determined that the positioning command contains the array element number corresponding to itself, the positioning array element enters the transmitting state; otherwise, it enters the receiving state.

[0064] Specifically, the steps of obtaining relative position information between each positioning array element of the first array element group and the second array element group are as follows:

[0065] The positioning array elements of the first array element group and the second array element group alternately enter the receiving state and the transmitting state;

[0066] Each positioning array element in the transmitting state obtains its own depth information, and measures the relative distance between itself and each positioning array element in the receiving state through underwater acoustic ranging;

[0067] Each positioning array element in the receiving state obtains its own depth information, and receives and obtains the relative distance information with the positioning array element in the transmitting state;

[0068] The same positioning array element in the receiving state calculates and determines the relative positions between the positioning array elements according to the relative distance and depth information between the positioning array elements in the transmitting state.

[0069] Further, such as Figure 2 As shown, the specific steps of positioning each positioning element are:

[0070] Positioning element initialization parameters, including the corresponding element number;

[0071] The positioning array element calls the receiving command subroutine to receive the transmitted self-test command, and each array element performs clock synchronization and enters a waiting state, waiting to receive the positioning command from the master control machine to set the working state, which includes transmitting and receiving;

[0072] When the positioning array element enters the transmitting state, the transmitting subroutine is called to enable the positioning array element to transmit the positioning signal;

[0073] When the positioning array element enters the receiving state, the acoustic receiving subroutine, pressure receiving subroutine, angle subroutine, data packaging subroutine and data transmission subroutine are called; the acoustic receiving subroutine is called to collect, save, filter and calculate the delay value of each channel of underwater sound; the pressure receiving subroutine is called to collect, smooth and calculate the pressure value and convert it into depth; the angle receiving subroutine is called to receive the north angle value measured by the compass. These measured data are packaged and sent to the data packet through the agreed transmission protocol, and the main control computer receives it to calculate the relative position;

[0074] Each positioning array element receives and transmits the positioning signal alternately according to a set period to complete the positioning of each positioning array element relative to each other.

[0075] like Figure 3 and Figure 4 As shown, if eight positioning array elements are provided, the corresponding array elements are numbered 1# to 8#, preferably symmetrically divided into two groups, and the main control machine sends a positioning instruction, and this positioning instruction contains 1#, 2#, 3#, and 4#, then the 1#, 2#, 3#, and 4# positioning array elements enter the transmitting state, and the remaining positioning array elements enter the receiving state. The main control machine receives the data and preliminarily solves the position of each positioning array element. After the set delay time, the main control machine sends a positioning instruction with numbers 5#, 6#, 7#, and 8#, then the positioning array elements corresponding to the numbers 5#, 6#, 7#, and 8# enter the transmitting state, and the remaining positioning array elements enter the receiving state. The main control machine receives the data and preliminarily solves the position of each positioning array element, and performs periodic alternation according to the time interval period.

[0076] The positioning array element initialization parameters are processed by the initialization module. After the system is powered on, it must first be initialized, such as Figure 5As shown, the initialization module performs not only array element parameter initialization, but also system initialization, on-chip peripheral initialization, and some variable initialization.

[0077] System initialization includes internal initialization that affects CPU operation and peripheral initialization that affects the operation of each on-chip peripheral. Since on-chip peripherals are only started when needed, the initialization of peripherals does not need to be included in the system initialization. Here, only the stack and interrupt are initialized. When the program calls an interrupt service program or subroutine, the PC value of the program counter and some important register values ​​are pushed onto the stack for protection so that the program can continue to execute normally from the interruption point when it returns. On-chip peripheral initialization includes initialization of clock generators, serial ports, UART ports, PF, general timers, external bus interface components, etc. Variable initialization includes initialization of some variables. Parameter initialization sets different array element numbers, transmission frequencies, etc.

[0078] like Figure 6 The figure shows the flow chart of the receiving command subroutine. After the master sends all the self-checking commands, it receives the returned data to determine that the positioning array element is in working state. The master command transmitted via the data packet is received through the serial port. When a frame of data is received, an interrupt is generated to synchronize the positioning array element. The array element number in the command is identified and compared with the array element number of the current array element. If the array element number in the command is the same as the array element number of the current array element, the positioning array element enters the transmitting state. If they are different, the positioning array element enters the receiving state.

[0079] like Figure 7 The figure shows the flow chart of the transmitting subroutine. The prototype transmitter uses a Class D power amplifier. When the array element enters the transmitting state, a square wave signal with specified parameters is sent through the DSP SPORT port. The frequency of the transmitting signal depends on the cable where the array element is located: 65KHz for cable 1#; 68KHz for cable 2#; 71KHz for cable 3#; and 74KHz for cable 4#.

[0080] When the array element enters the receiving state, the DSP collects the underwater acoustic signal through the SPORT0 port, such as Figure 8 As shown in the figure, it is a flow chart of the underwater acoustic receiving subroutine. The signal acquisition length is 0.5 seconds, and the data is saved through DMA. After that, the data is repeatedly retrieved and filtered at different frequencies to calculate the delay. Here, the AD sampling rate is 500KHz, the NOTCH filter center f1 is 65KHz, f2 is 68KHz, f3 is 71KHz, and f4 is 74KHz.

[0081] When the array element enters the receiving state, the DSP collects the pressure signal through the SPORT1 port, such as Fig. 9The figure shows the flow chart of the pressure receiving subroutine, which specifically collects 10 sets of data, averages them, converts the pressure value into the depth value and saves it. Here, the AD sampling rate is selected as 500KHz.

[0082] When the array element enters the receiving state, the DSP receives the angle data through the SPI port, such as Fig.10 The figure shows the flow chart of the angle receiving subroutine. The compass module sends the measurement data through the RS232 port, and the data is received into the DSP by converting the SPI port to RS232. 10 sets of data are collected, averaged and saved. The AD sampling rate is temporarily set to 500KHz.

[0083] like Fig.11 As shown in the flowchart of the data packaging subroutine and the data transmission subroutine, after the array element obtains all the required depth, angle, and delay data through measurement and calculation, it packages these data according to the communication protocol and sends them.

[0084] In the measurement of the shape of the trawl net mouth, more positioning devices can be used, which provides the possibility for high-precision positioning of the underwater tow cable. The positioning of each section of the net mouth should fully consider the characteristics of multi-sensor positioning, give full play to the advantages of multiple positioning methods to improve the positioning accuracy of the underwater net mouth, and solve the problem based on the multi-sensor fusion array element positioning principle of the underwater multi-cable positioning system with a long baseline. Fig.12 As shown in the figure, the depth information of the positioning array element is directly obtained through the pressure sensor. By combining the depth information, the hydroacoustic positioning system solves the X-coordinate and Y-coordinate of each section of the towline symmetrically from both ends to the middle. In addition, since the longitudinal positioning error of the array element on the towline is greater than the lateral positioning error, and this phenomenon becomes more obvious with the increase of the order, the compass data is introduced here to re-determine the longitudinal position of the towline, which can improve the positioning accuracy of the system to a certain extent and improve the reliability of the system.

[0085] According to one or more embodiments, a three-dimensional measurement device for the shape of a trawl mouth of a marine fishery is disclosed, comprising a trawl, such as Figure 1 As shown, it includes several positioning array elements, a main control machine and a data transmission cable. Each positioning array element is evenly installed at the trawl net mouth to perform positioning operations to obtain position information; the main control machine is installed on the trawler to control each positioning array element, receive and calculate the position information of the positioning array element, calculate and obtain the relative position information between each positioning array element, and obtain the three-dimensional shape of the trawl net mouth according to the relative position relationship of the positioning array elements on the trawl net mouth; the main control machine and each positioning array element transmit signal data through the data transmission cable.

[0086] A number of positioning array elements are symmetrically divided into a first group of array elements and a second group of array elements according to their positions on the trawl net mouth. Each positioning array element is correspondingly provided with a uniquely identifiable array element number. The main control machine sends a positioning instruction corresponding to the array element number to control the positioning array element to perform positioning operations. Figure 3 to Figure 4 As shown, if eight positioning array elements are provided, the corresponding array elements are numbered 1# to 8#, preferably symmetrically divided into two groups, and the main control machine sends a positioning instruction, and this positioning instruction contains 1#, 2#, 3#, and 4#, then the 1#, 2#, 3#, and 4# positioning array elements enter the transmitting state, and the remaining positioning array elements enter the receiving state. The main control machine receives the data and preliminarily solves the position of each positioning array element. After the set delay time, the main control machine sends a positioning instruction with numbers 5#, 6#, 7#, and 8#, then the positioning array elements corresponding to the numbers 5#, 6#, 7#, and 8# enter the transmitting state, and the remaining positioning array elements enter the receiving state. The main control machine receives the data and preliminarily solves the position of each positioning array element, and thus periodically alternates according to the time interval period to complete the mutual positioning between the positioning array elements.

[0087] The positioning array elements are all of the same model, such as Fig.13 As shown, each includes a pressure sensor for measuring the depth position, a compass for measuring the deviation angle, and an underwater acoustic sensor for measuring the relative distance between other positioning array elements. The underwater acoustic sensor includes an underwater acoustic transmitter and a receiver; it also includes a main control DSP, a communication circuit, an acoustic transducer, a power module, and a peripheral circuit connected through communication. Fig.14 As shown, it is a schematic diagram of the internal structure of each positioning array element.

[0088] The preferred compass model is HMR3000, which has a small structure and can achieve a heading measurement accuracy of 0.50. The HMR3000 compass uses the RS232 serial interface to output data. The UART port of the DSP has been used for data transmission, so the SPI port to RS232 port method is used to receive compass data. The signal received by the pressure sensor is amplified and converted by ADC and sent to the DSP SPORT1 port; at the same time, the system also has the ability to monitor battery voltage, and the output voltage of the battery is sent to the analog-to-digital converter ADC for sampling after voltage division, and then sent to the DSP SPORT1 port after ADC conversion. The preferred ADC model for the battery voltage and pressure data measurement device is ADS8320EB.

[0089] The DSP processor is the core part of the array element, completing functions such as real-time analysis of received data, transmitting acoustic pulse signals and power supply monitoring. At the same time, the system requires the DSP processor to be low-power, have PWM signal output, can directly drive the power amplifier, and have rich interfaces. The DSP processor uses Blackfin533. Blackfin533 (hereinafter referred to as BF533) is one of the three new products of enhanced Blackfin DSP that are fully pin-compatible, ADSP-BF533, ADSP-BF532 and ADSP-BF531, based on the BlackfinDSP series. They have the fastest speed and lowest power consumption among similar products. Among them, ADSP-BF533 has a clock frequency of 600MHZ and an operating speed of 1.2GMACS. This processor series integrates an on-chip switching regulator, which can generate a settable core operating voltage of 0.7V-1.2V using a 2.25V-3.6V external power supply voltage, realizing enhanced dynamic power management functions, thereby reducing overall costs and saving external power supply components. Such as Fig.15 As shown, it is the system block diagram of BF533.

[0090] The main features of BF533 are as follows:

[0091] 1) 16-bit fixed-point DSP core, capable of continuous operation up to 600MHz;

[0092] 2) Two 16-bit multiplier-accumulator (MAC) and two 40-bit arithmetic logic units (ALU), which can achieve an operating speed of 1.2GMACS at 600MHz;

[0093] 3) Flexible software-controlled dynamic power management, supporting 4 operating modes;

[0094] 4) L1 instruction memory includes 80KB SRAM, of which 16KB can be configured as a 4-way set-associative cache;

[0095] 5) L1 data memory includes two 32KB SRAM banks, each bank consists of two 16KB;

[0096] 6) SRAM consists of 16KB which can be configured as Cache;

[0097] 7) Support off-chip synchronous or asynchronous memory (including PCI33 SDRAM);

[0098] 8) Flexible boot mode (SPI or external storage resources);

[0099] 9) The memory management unit provides memory protection;

[0100] 10) Level 2 interrupt event processing;

[0101] 11) With RTC module;

[0102] 12) With WatchDog timer;

[0103] 13) It has two 32-bit calculators;

[0104] 14) 16 GPIOs;

[0105] 15) 1 universal serial port supporting IrDA;

[0106] 16) Parallel peripheral interface (PPI), which can be seamlessly connected with parallel AD and DA;

[0107] 17) 1 SPI compatible port (supports 7 channels);

[0108] 18) 2 dual-channel full-duplex synchronous serial interfaces (SPORT);

[0109] 19) 12-channel DMA, including peripheral DMA and memory DMA.

[0110] A miniaturized main control DSP module is designed for the array element structure, such as Fig.13 , which is composed of core processor DSP, FLASH memory, SDRAM, etc., is convenient for debugging and can save costs.

[0111] FLASH memory (flash memory) is a non-volatile memory that is electrically erasable and rewritable. Even if the system loses power, it can ensure that the stored data will not be lost. Due to its large capacity, non-volatility, and fast access speed, FLASH memory is particularly suitable as a storage medium for large-capacity data acquisition systems. SST39V160 is preferred. Its capacity is 16Mbit (1M×16bit), and only 2.7V voltage is required to complete read, write and erase operations. It only takes 14μs to write a word (16bit), and it only takes 70ms to erase the entire memory.

[0112] SDRAM is used as a buffer for data and to cache applications when the internal SRAM space is insufficient. It has the advantages of large storage capacity per unit space and low price, and has been widely used in various embedded systems. The synchronous memory control in the EBIU of BF533 provides a seamless interface with standard SDRAM. The EBIU uses the system clock (SCLK) as the clock of the SDRAM, and the SCLK can be obtained by programming the MMR of the DSP internal PLL system. Therefore, the speed of accessing the external SDRAM can be set according to the requirements of different systems for cache speed, thereby improving the flexibility of the embedded system in controlling power consumption. HY57V561620C (32MBytes) is preferably used.

[0113] The specific allocation of the peripheral interface of the master DSP is as follows Fig.13 As shown, it specifically includes: connecting the input and output with the communication circuit through the UART interface to realize data communication; the SPI interface is converted to two RS232s, one for receiving compass data and the other for standby; the input interface of SPORT0 receives the underwater acoustic related information obtained by the underwater acoustic receiver, and the output interface is connected to the underwater acoustic transmitter for signal transmission; the input interface of SPORT1 is connected to receive the voltage signal output by the pressure sensor; and the EBIU interface is connected to the FLASH memory and SDRAM to realize the storage of programs and data.

[0114] For the underwater acoustic related information obtained by the underwater acoustic receiver, the data collection and related operations are completed through FPGA to send the related result data to DSP. FPGA preferably uses Cyclone III, which is a low-cost and low-power device. It is manufactured using TSMC's 65nm low-power device and has optimized software features to minimize power consumption. Fig.16 As shown in the figure, it is the internal logic block diagram of the array element mainboard FPGA, which is implemented by VHDL. Fig.17 As shown, the transducer converts the underwater acoustic signal into a weak electrical signal, which needs to be amplified and filtered by the receiver and then sent to the FPGA for processing after single-bit quantization. The operating frequency band of the underwater acoustic receiver is 60kHz to 80kHz; the analog output voltage range is -3.0V to +3.0V; the output signal is in the form of analog signal and zero-crossing detection digital pulse; the adjustable amplification gain range is 20dB; the working power supply is 5V; the working temperature is -10℃ to +55℃.

[0115] like Fig.18 As shown, the underwater acoustic transmitter preferably adopts a Class D power amplifier structure, with a center frequency of 70kHz and a frequency band of 20kHz; the transmission signal form is a single-frequency filling pulse; the transmission source level is 180dB; the pulse width is less than 2ms; the duty cycle is less than 1:3000, and the power supply voltage is 14.4V. The input signal form: reverse dual digital level (minimum 3.0V)

[0116] The hardware system is powered by batteries, preferably a switching power supply with high conversion efficiency.

[0117] The power requirements of the system are as follows:

[0118] 1) Power amplifier power supply: 3.6V*4 cells=14.2V;

[0119] 2) DSP processor: +3.3V;

[0120] 3) FPGA and peripheral circuits: +3.3V, +2.5V, +1.2V;

[0121] 4) Receiver power supply: +5V;

[0122] 5) Communication circuit power supply: +5V, -5V;

[0123] 6) Magnetic compass power supply: +5V.

[0124] All the above power sources (except the power amplifier) ​​are converted by the battery pack. Fig.19 As shown, the switching power supply 1 converts the +14.2V output of the battery into +3.8V and +3.0V respectively, of which 3.8V is provided to LDO1 and LDO2, and +3V is provided to LDO3. The switching power supply 2 converts the +14.2V output of the battery into +1.6V and +5.5V respectively, of which +1.6V is provided to LDO4, and +5.5V is provided to LDO5 and LDO6. LDO7 converts +5V to -5V. The switching power supply preferably adopts the model LT1940EFE. The low voltage difference linear power supply LDO1, LDO2, LDO3, LDO4, LDO5, and LDO6 preferably adopts the model LT1763IS8; LDO7 preferably adopts the model LT1054lL; in order to reduce the average power consumption of the prototype system, LDO2, LDO3, LDO4, and LDO5 are controlled by DSP. When the system is in a long waiting state, LDO2, LDO3, LDO4, and LDO5 are powered off and the corresponding circuits are turned off.

[0125] This specific embodiment is merely an explanation of the present invention and is not a limitation of the present invention. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed. However, as long as they are within the scope of the claims of the present invention, they are protected by the patent law.

Claims

1. A method for three-dimensional measurement of the shape of a trawl net mouth in marine fisheries, characterized in that: The following steps are included: The main control machine sends a self-checking command to a plurality of positioning array elements installed on the trawl net mouth to determine that each array element is in a working state, each of the positioning array elements includes a pressure sensor for measuring the depth position, a compass for measuring the deviation angle, and a hydroacoustic sensor for measuring the relative distance between other positioning array elements; Each positioning array element enters a working state, and the positioning array elements are divided into a first group of array elements and a second group of array elements according to their positions on the trawl net mouth; The main control machine sends a positioning command, and each positioning array element of the first group of array elements and the second group of array elements receives the positioning command, and transmits and receives the position signal alternately according to a set period; The positioning array elements obtain relative position information between each other and transmit it to the main control machine; The main control machine receives and processes the relative position information of each positioning array element, calculates and obtains the relative position between each positioning array element, and determines the shape of the trawl net mouth according to the relative position of the positioning array element; The steps of obtaining relative position information between each positioning array element of the first array element group and the second array element group are specifically as follows: The positioning array elements of the first array element group and the second array element group alternately enter the receiving state and the transmitting state; Each positioning array element in the transmitting state obtains its own depth information, and measures the relative distance between itself and each positioning array element in the receiving state through the hydroacoustic sensor; Each positioning array element in the receiving state obtains its own depth information, and receives and obtains the relative distance information with the positioning array element in the transmitting state; The same positioning array element in the receiving state calculates and determines the relative positions between the positioning array elements according to the relative distance and depth information between the positioning array elements in the transmitting state.

2. The method for three-dimensional measurement of the shape of the mouth of a marine fishing trawl according to claim 1, characterized in that: The specific steps for alternating the transmitting and receiving states of each positioning array element are as follows: Each positioning array element is provided with a one-to-one corresponding array element number; The master computer sends a positioning command with an array element number; Each array element receives the positioning command and compares it. When it is determined that the positioning command contains the array element number corresponding to itself, the positioning array element enters the transmitting state; otherwise, it enters the receiving state.

3. The method for three-dimensional measurement of the shape of the mouth of a marine fishing trawl according to claim 1, characterized in that: The specific steps of positioning each positioning element are as follows: Positioning element initialization parameters, including the corresponding element number; The positioning array element receives the transmitted self-test command, and each array element performs clock synchronization and enters a waiting state, waiting to receive the positioning command to set the working state, which includes transmitting and receiving; When the positioning array element enters the transmitting state, the transmitting subroutine is called to enable the positioning array element to transmit the positioning signal; When the positioning array element enters the receiving state, the acoustic receiving subroutine, the pressure receiving subroutine, the angle subroutine, the data packaging subroutine and the data transmission subroutine are called to receive and package the relative position information for transmission; Each positioning array element receives and transmits the positioning signal alternately according to a set period to complete the positioning of each positioning array element relative to each other.

4. A three-dimensional measurement device for the shape of a marine fishery trawl net mouth, based on the three-dimensional measurement method for the shape of a marine fishery trawl net mouth according to any one of claims 1 to 3, characterized in that: It includes a plurality of positioning array elements evenly spaced and arranged at the mouth of the trawl net for positioning, a main control machine for controlling the positioning array elements and receiving and processing the position information detected by the positioning, and a data transmission cable for transmitting data signals between the main control machine and each positioning array element; The main control machine obtains the position information of each positioning array element, and determines the shape of the trawl net opening according to the relative position of each positioning array element.

5. The three-dimensional measuring device for the shape of the mouth of a marine fishing trawl according to claim 4 is characterized by: The positioning array element includes a main control DSP, an underwater acoustic transmitter and receiver, a communication circuit, a pressure sensor, an acoustic transducer, a magnetic compass, a power module, and a peripheral circuit connected through communication.

6. The three-dimensional measuring device for the shape of the mouth of a marine fishing trawl according to claim 5 is characterized by: The positioning array elements are all provided with array element numbers corresponding thereto one by one, and the main control machine sends positioning instructions corresponding to the array element numbers to control the transmission / reception of the positioning array elements; the main control machine is provided with a sending cycle for sending positioning instructions.

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