Method for long-term automatic measurement of wide-area wave making of model in large towing tank

Abstract

A method capable of automatically measuring wide-area wave making of a model in a large towing tank for a long time adopts a distributed test scheme in which a cRIO system and an industrial personal computer are matched, zero is automatically collected according to time intervals, two optoelectronic switches are installed on a ship model trigger switch base on the tank wall and used in cooperation with a reflector on the bow of a ship model, and the ship model trigger switch base is connected with the reflector. The trigger signal is used for activating the cRIO system to perform data acquisition; the photoelectric switches with different heights can adapt to model tests under different draught conditions; eight wave height meters are transversely arranged on the base on the pool wall at equal intervals and are used for measuring wave-making distribution at different transverse positions of the ship model; the base can move transversely, the laser displacement sensor is arranged at the far end, the reflecting plate at the bow of the ship model is combined, wave-making distribution on one side of the ship model can be measured at extremely high density, the high-standard requirements of a large towing tank for time efficiency, surrounding safety protection and the like are effectively met, the overall working reliability is good, and the long-term service capacity is good.

Description

Technical Field

[0001] The present invention relates to the technical field of ship hydrodynamics tests, and in particular to a method for long-term automatic measurement of the wide-area wave-making of a model in a large towing tank. Background Art

[0002] Wave-making resistance is an important part of ship resistance, and its precise measurement is an important task for evaluating and optimizing ship forms.

[0003] Regarding ship wave-making measurement methods, classified by the measurement surface, there are mainly the following three types:

[0004] (1) Transverse cutting method: Take two or more transverse sections behind the ship model to measure the transverse wave pattern.

[0005] (2) Longitudinal cutting method: On one side of the ship model, take one or more longitudinal sections to measure the wave pattern.

[0006] (3) Matrix method: Set multiple points along a certain direction or at a certain distance on one side of the ship to measure the wave pattern.

[0007] The matrix method has complex installation conditions, requires a large distance between the measurement position and the ship model, and the distance between intervals becomes farther as the test speed is higher, requiring the pool to have sufficient width. At the same time, it is difficult to guarantee the calculation accuracy, so this method is often rarely used.

[0008] The transverse cutting method makes measurements within a limited range and does not need to introduce corrections. However, the measurement technology is relatively complex. It requires a transverse support far enough behind the ship model, and the measuring needle can move horizontally on it. The measurement accuracy is also affected by factors such as uneven tracks and wake behind the ship tail. In addition, due to the need for calculation, it is necessary to measure the wave patterns of multiple different sections.

[0009] The main advantage of the longitudinal cutting method is that only one or more wave height gauges need to be placed on one side of the center plane of the ship pool. By measuring one or more wave patterns, the wave pattern resistance can be obtained. The measurement method is also relatively simple and can be carried out simultaneously with the usual towing resistance test, which is advocated by the ITTC.

[0010] For the vertical cutting method, most of them adopt a scheme where one or more ultrasonic / servo wave gauges are arranged on the pool wall. The lateral distance between the wave gauge and the ship model is obtained through conversion by other objects rather than direct measurement. The positional relationship between the photoelectric switch used for triggering and the trigger point on the ship model is poorly defined. A combination of a conventional industrial control computer and a display is used as the acquisition and display scheme and arranged beside the track. The above measures are not suitable for large towing tanks. Large towing tanks have extremely high requirements for wave pattern measurement by the vertical cutting method in terms of safety protection beside the track, the complexity of the trailer structure, and the scale of the physical space of the pool. Moreover, researchers are increasingly interested in the wide-area wave-making distribution with large-scale continuity around the ship. Ordinary single-channel / multi-channel discrete wave-making data lacks relevance and cannot provide sufficient support for the research work on the ship wave-making distribution. Summary of the Invention

[0011] In view of the above-mentioned disadvantages in the existing production technology, the applicant provides a method for long-term automatic measurement of the wide-area wave-making of a model in a large towing tank, effectively solving the high-standard requirements of large towing tanks for time efficiency and surrounding safety protection, as well as the conflict between the implementation of the conventional vertical cutting method and the complex spatial distribution of large test facilities. The overall work has good reliability and has good long-term service ability.

[0012] The technical solution adopted by the present invention is as follows:

[0013] A method for long-term automatic measurement of the wide-area wave-making of a model in a large towing tank, including the following operation processes:

[0014] S1. Adopt a distributed test scheme with a combination of a cRIO system and an industrial control computer. The cRIO system is responsible for data acquisition and manages business logic with high-precision clock resolution. The industrial control computer is responsible for data display, data processing, and data local storage tasks. Data interaction between the cRIO system and the industrial control computer is carried out through a network.

[0015] S2. The FPGA module on the cRIO system is specifically responsible for implementing the operation of logical functions and collecting physical signals of relevant channels on the acquisition card. The RT system is responsible for monitoring the operation status of the FPGA module, reading the digital quantity signals sampled and converted by the FPGA module, judging the validity of the sampled data, and sending valid sampled data to the remote industrial control computer.

[0016] S3. Arrange two photoelectric switches at intervals beside the pool. The trigger signals are introduced into the cRIO system. The movement direction and speed of the trailer are automatically judged according to the order of triggering, and the state can be automatically restored according to the strategy after being triggered under abnormal conditions.

[0017] S4. Automatically zero the sampling at time intervals, and automatically accept / reject the automatically zeroed data according to relevant statistical methods.

[0018] S5. On the trigger switch base on the pool wall, there are two photoelectric switches installed, which are used in conjunction with the reflector on the bow of the model ship. The trigger signal is used to activate the cRIO system for data acquisition. Photoelectric switches at different heights can adapt to model tests with different draft conditions;

[0019] S6. On the base on the pool wall, eight wave gauges are installed at equal intervals horizontally to measure the wave-making distribution at different lateral positions of the model ship. The base can move horizontally. At the far end, a laser displacement sensor is equipped. Combined with the reflector on the bow of the model ship, the wave-making distribution on one side of the model ship can be measured with extremely high density.

[0020] Its further technical solution lies in:

[0021] The structure of the wave-making measurement device includes: a model ship arranged inside the pool, and a base installed on the pool wall. On the base, there is a sub-board that can move up and down along the base. At equal intervals at the bottom of the sub-board, eight wave gauges are installed, and a laser displacement sensor is installed at the end of the sub-board. On the pool wall, there is also a trigger switch base for the model ship, and multiple photoelectric switches for triggering the model ship are installed at the lower part of the trigger switch base for the model ship. Above the pool, there is a track, and a trailer drags the model ship along the track. A reflector is installed at the bow of the model ship, and a #1 photoelectric switch and a #2 photoelectric switch are arranged at intervals on the shore. Beside the track, there is a cRIO system. The cRIO system directly collects analog signals or digital signals from the wave gauges, laser displacement sensors, photoelectric switches for triggering the model ship, #1 photoelectric switch, and #2 photoelectric switch, and transmits the sampled data to the industrial control computer at the far end through a network cable.

[0022] Each wave gauge can obtain the time history wave-making data of a certain longitudinal section when the model ship 2 passes by.

[0023] The distance between the #1 photoelectric switch and the #2 photoelectric switch is greater than the length of the trailer.

[0024] The #1 photoelectric switch and the #2 photoelectric switch detect obstacles above the height of the track. Once the trailer passes by, the two photoelectric switches can generate trigger signals.

[0025] The photoelectric switches for triggering the model ship are used to adapt to the test conditions of model ships with different drafts. Once the model ship passes by and the light source of any one of the two photoelectric switches for triggering the model ship is blocked by the reflector of the model ship, a trigger signal will be generated.

[0026] The cRIO system continuously obtains the signals of the wave gauges, photoelectric trigger switches, and laser displacement sensors through relevant acquisition boards, and transmits them to the FPGA module through a bus. The FPGA sends the received sampled signals to the RT system at intervals of 20 - 50 ms; relevant logical operations are also run on the FPGA module to meet user requirements such as automatic trigger acquisition and automatic restoration of monitoring state variables.

[0027] The industrial control computer only sends and collects two relevant setting parameters to the RT system of cRIO when the program runs for the first time, including: automatic sampling duration and sampling rate. Operations such as starting / stopping and restarting the FPGA module can be performed on the program user interface of the RT system.

[0028] It involves starting / stopping / restarting the FPGA module and obtaining the sampling data of the FPGA; when the RT system starts / restarts the FPGA module, it also writes the two sampling-related setting parameters received from the industrial control computer into the FPGA; after receiving the data sent by the FPGA, it processes the data and transfers it to the industrial control computer according to two different extraction strategies (latest data and complete data stream).

[0029] After receiving the latest data, the industrial control computer will display the sampling data of each channel's wave height meter, and can use this data for manual zero sampling and automatic zero sampling operations; display the lateral distance between the wave height meter and the ship model; it can automatically perform special processing on events introduced by the mouse such as starting / stopping zero sampling, channel coefficient update, and display channels on the user interface, as well as dynamic events caused by automatic zero sampling and receiving data sent by the RT system, so as to operate stably for a long time without human intervention.

[0030] The beneficial effects of the present invention are as follows:

[0031] The present invention adopts a distributed test scheme with a cRIO system and a conventional industrial control computer, which has the characteristics of small volume, low power consumption, and strong environmental adaptability. It is sensitive to activation signals under the premise of meeting the extremely high requirements for safety protection in a large towing tank, clearly decouples the coupling problem between unexpected working conditions and monitored state variables, strictly controls the data transmission path at the software layer, effectively reduces the memory fragmentation during program operation, and has the stability for long-term measurement. Two photoelectric switches are arranged at a certain interval by the pool, and the trigger signals are introduced into the cRIO system. The movement direction and speed of the trailer are automatically judged according to the order of triggering, and the state can be automatically restored according to the strategy after being triggered under abnormal conditions; zero sampling is automatically performed at time intervals, and automatic zero sampling data is automatically accepted / rejected according to relevant statistical methods; two photoelectric switches are installed on the trigger switch base of the ship model on the pool wall and are used in cooperation with the reflector on the bow of the ship model, and the trigger signals are used to activate the cRIO system for data acquisition; photoelectric switches at different heights can adapt to model tests with different draft conditions; eight wave height meters are installed at equal lateral intervals on the base of the wave-making measurement device on the pool wall, which can measure the wave-making distribution at different lateral positions of the ship model; the base can move laterally, and a laser displacement sensor is installed at the far end. Combined with the reflector on the bow of the ship model, a wide-area wave-making distribution on one side of the ship model can be measured with extremely high density.

[0032] Through the distributed working scheme of the NI cRIO system and a conventional industrial control computer, the cRIO system, which is the core device with characteristics such as small volume, low power consumption, and strong environmental adaptability, can be arranged near the towing tank track, without posing any hidden danger to on-site safe operation and not occupying a large area near the trailer operation route. Moreover, it can realize real-time monitoring of the on-site wave-making motion at a remote end through the network.

[0033] The present invention introduces multi-channel wave height gauges and laser displacement sensors, enabling rich wide-area wave-making data to be obtained with fewer towing times by using the longitudinal cutting method, improving the commercial service ability of large towing tanks and reducing the operation cost.

[0034] The present invention deploys both the acquisition of analog / digital signals and the transaction logic function on the FPGA module of the cRIO system, making full use of the physical parallel operation ability of the FPGA module. And the real-time performance of the RT system running on the cRIO system, compared with the task execution mode relying on the CPU of a conventional PCI / PXI industrial control computer, the present invention has higher stability, more accurate response characteristics for instructions and transaction logic running depending on time cycles, and can be deployed as a conventional test device to run automatically by the pool, with good long-term service ability. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is the overall test diagram of wave-making measurement of the present invention.

[0036] Figure 2 It is the layout diagram of the trigger switch base of the ship model of the present invention.

[0037] Figure 3 It is the layout diagram of the base of the wave-making measurement device of the present invention.

[0038] Figure 4 It is the data flow and core function design scheme of the present invention.

[0039] Figure 5a It is the FPGA function design scheme (cycle 1) of the present invention.

[0040] Figure 5b It is the FPGA function design scheme (cycle 2) of the present invention.

[0041] Figure 6 It is the design scheme of the FPGA function - variable monitoring and restoration module of the present invention.

[0042] Figure 7 It is the design scheme of the FPGA function - end automatic acquisition judgment module of the present invention.

[0043] Figure 8 It is the design scheme of the FPGA function - automatic acquisition interruption cause judgment module of the present invention.

[0044] Figure 9a This is the functional design scheme of the RT system of the present invention (Loop 1).

[0045] Figure 9b This is the functional design scheme of the RT system of the present invention (Loop 2).

[0046] Figure 10a This is the functional design scheme of the industrial control computer of the present invention (Loop 1).

[0047] Figure 10b This is the functional design scheme of the industrial control computer of the present invention (Loop 2).

[0048] Figure 10c This is the functional design scheme of the industrial control computer of the present invention (Loop 3).

[0049] Figure 10d This is the functional design scheme of the industrial control computer of the present invention (Loop 4).

[0050] Among them: 1. Rail; 2. Ship model; 3. Wave height gauge; 4. Laser displacement sensor; 5. Base; 6. Ship model trigger switch base; 7. Ship model trigger photoelectric switch; 8. Trailer; 9. No. 1 photoelectric switch; 10. No. 2 photoelectric switch; 11. Reflective plate; 12. Industrial control computer; 13. cRIO system;

[0051] 501. Sub-board. Specific embodiments

[0052] The following combines the accompanying drawings to illustrate the specific embodiments of the present invention.

[0053] Figure 1 It is the overall test diagram for wave-making measurement. The trailer 8 drags the ship model 2 along the rail 1. A reflective plate 11 is installed at a position with known three-dimensional coordinate information at the bow of the ship model 2; The No. 1 photoelectric switch 9 and the No. 2 photoelectric switch 10 are arranged successively on the shore, and the distance between the two is slightly greater than the length of the trailer 8. The above two photoelectric switches rely on the base to detect obstacles at a height higher than the rail 1. Once the trailer 8 passes by, the above two photoelectric switches can generate trigger signals.

[0054] Figure 2 It is the layout diagram of the ship model trigger switch base. The ship model trigger switch base 6 is installed on the pool wall, and two ship model trigger photoelectric switches 7 are respectively installed at different positions along the Z direction at the bottom, which are used to adapt to the test conditions of ship models with different drafts. Once the ship model 2 passes by and the light source of any one of the two ship model trigger photoelectric switches 7 is blocked by the ship model reflective plate 11, a trigger signal will be generated.

[0055] Figure 3The figure shows the layout of the base of the wave-making measurement device. The base 5 of the wave-making measurement device is installed on the pool wall and has a lifting function to adjust the height of the auxiliary plate 501. Eight wave gauges 3 that can sample simultaneously are evenly installed on the auxiliary plate 501. Each wave gauge 3 can obtain the time-history wave-making data of a certain longitudinal section when the ship model 2 passes by. A laser displacement sensor 4 is installed at the end of the auxiliary plate 501. When the ship model 2 passes near the base 5 of the wave-making measurement device, the light source of the laser displacement sensor 4 is reflected by the reflector 11 to measure the Y-direction distance between the laser displacement sensor 4 and the ship model 2. The auxiliary plate 501 can move precisely along the Y-direction (transverse direction) on the base 5 of the wave-making measurement device, so that the time-history wave-making data of eight different longitudinal sections beside the ship model 2 can be collected simultaneously during each ship model towing, and the wide-area wave-making data distribution around the ship model 2 can be obtained through fewer towing tests.

[0056] The cRIO system 13 is arranged beside the track 1, directly collects the analog / digital signals of devices such as the wave gauges 3, the laser displacement sensor 4, the ship model trigger photoelectric switch 7, the 1# photoelectric switch 9, and the 2# photoelectric switch 10, and transmits the sampled data to the industrial control computer 12 at the remote end through the network cable.

[0057] The industrial control computer running the Windows system, the RT system on the cRIO controller, and the FPGA all run the relevant programs developed with Labview. The working process is described as follows.

[0058] Figure 4 The figure shows the data flow and the core function design scheme. The cRIO system continuously obtains the signals of devices such as wave gauges, photoelectric trigger switches, and laser displacement sensors through relevant acquisition boards, and transmits them to the FPGA module through the bus. The FPGA sends the received sampled signals to the RT system at intervals of 20 - 50 ms; relevant logical operations are also run on the FPGA module to meet user requirements such as automatic trigger acquisition and automatic restoration of monitoring state variables.

[0059] The industrial control computer only sends and collects two relevant setting parameters to the RT system of the cRIO when the program runs for the first time, including: the automatic sampling duration and the sampling rate. The operation of starting / stopping and restarting the FPGA module can be performed on the program user interface running on the RT system. The RT system interacts with the FPGA through a dedicated FPGA communication method, which involves starting / stopping / restarting the FPGA module and obtaining the sampled data of the FPGA. When starting / restarting the FPGA module, the RT system also writes the two sampling-related setting parameters received from the industrial control computer into the FPGA; after receiving the data sent by the FPGA, it performs data processing and transfers it to the industrial control computer according to two different extraction strategies (the latest data and the complete data stream).

[0060] After receiving the latest data, the industrial control computer will display the sampling data of the wave height meters of each channel, and these data can be used for manual zero sampling and automatic zero sampling operations; display the lateral distance between the wave height meter 3 and the ship model 2; and can automatically perform special processing on events introduced by the mouse such as start / stop zero sampling, channel coefficient update, and display channel on the user interface, as well as dynamic events caused by automatic zero sampling and receiving data sent by the RT system, so as to operate stably for a long time without human intervention.

[0061] Figure 5a and Figure 5b The FPGA functional design scheme is shown as follows, and two loops are used to realize the acquisition of multiple signals.

[0062] Among them, loop 1 is only responsible for acquiring the analog signal of the single-channel laser displacement sensor 4. Each loop only obtains the data once and assigns it to the relevant display control. The loop time of loop 1 can be set relatively large, and the reference value is 500 ms.

[0063] Loop 2 acquires the analog signal of the wave height meter 3 and the digital signals of multiple photoelectric switches. Among them, the loop time is determined by the sampling rate transmitted by the RT system. Only 8 analog signal points (corresponding to 8 wave height meters respectively) and 4 digital signals (corresponding to 4 photoelectric switches respectively) are obtained in each loop. Since the data acquired by the acquisition card is transmitted to the FPGA through the PCI bus, it will occupy a large amount of resources. In order to ensure that the FPGA module can strictly execute the transaction logic part according to the time node and avoid the loop execution time jitter caused by insufficient performance, resulting in the time when the cRIO system recognizes the automatic acquisition hardware trigger signal lagging behind the time when the photoelectric switch on the trigger pool wall of the ship model is triggered, and finally causing a deviation between the wave generated by the automatic trigger acquisition and the real-time wave information around the ship model 2 in the time stamp, so we adopt the pipeline working mode in loop 2, that is, the FPGA module acquires the sampling signal on the acquisition card and sends the sampling signal to the RT system in parallel. The latest 8 data are stored by means of a shift register, and the 8 data stored in the shift register in the previous loop are sent to the RT system by using the DMA technology. In the specific implementation process, the function of sending the sampling signal to the RT system is embedded in the state machine for execution. There are 3 states in the state machine: "idle", "automatic acquisition", and "restoration waiting". Each state will provide an identification data to define the attributes of the 8 data sent to the DMA buffer this time. 1: represents the sampling data automatically triggered by the hardware, 0: represents others. This identification data is written into the DMA buffer transmitted to the RT system as the 9th number in sequence.

[0064] If the state entered in this cycle is "idle", the key variable monitoring and state quantity automatic recovery functions are executed. The automatic acquisition branch can be entered according to the state of the photoelectric switch. For the relevant state quantities activated due to unexpected situations, such as the state latch value of the 1# photoelectric switch 9 and the cycle count value changed by the activation addition count function, a method is provided to achieve timed reset. For details, see Figure 6 The FPGA function shown in the figure - variable monitoring and recovery module design scheme monitors 1# photoelectric switch 9, 2# photoelectric switch 10 and 2-way ship model triggering photoelectric switch 7, wherein the states of 1# photoelectric switch 9 and 2# photoelectric switch 10 are latched by logical "or" operation. Once the real-time signal or latched state of 1# photoelectric switch 9 is detected to be TRUE, the real-time signal or latched state of 2# photoelectric switch 10 is TRUE and at least one of the 2-way ship model triggering photoelectric switches 7 has a real-time signal of TRUE, the state machine state is assigned to "automatic acquisition", otherwise the state machine state is assigned to "idle", and the state machine will enter the corresponding branch according to the state value when loop 2 is executed next time. The function of this part corresponds to the trailer 8 passing through 1# photoelectric switch 9 and 2# photoelectric switch 10 in turn during the physical model test, until the ship model 2 passes through the ship model triggering photoelectric switch 7, and the above photoelectric switches are triggered in turn (the value is TRUE), which can make the The wave data collected by the system at the beginning is marked as the automatic data collection attribute; once the latch state of the 1# photoelectric switch 9 is TRUE, the addition (plus 1) operation will be started. If the latch state of the 2# photoelectric switch 10 is FALSE, the addition operation will be stopped. The time that the trailer 8 passes through the 1# photoelectric switch 9 and the 2# photoelectric switch 10 = the count value * the cycle interval time of loop 2. The speed of the trailer 8 can be obtained by the layout spacing of the above two photoelectric switches; in addition, once the 1# photoelectric switch 9 is triggered, the calculation of the remaining execution times of the loop will be started. Each time loop 2 is executed, a subtraction (minus 1) operation is performed, and then compared with 0. If the remaining execution times of the loop are less than 0, the relevant variables are reset, that is, the latch states of the 1# photoelectric switch 9 and the 2# photoelectric switch 10 are set to FALSE, the cumulative running times of the loop used to calculate the trailer speed is set to 0, and the remaining execution times of the loop used for countdown are set to a larger value.

[0065] If the state entered in this cycle is "automatic collection", the automatic collection judgment function will be executed. If the full rated amount of data is collected or the 1# photoelectric switch 9 is triggered and activated, this branch will be ended. For details, see Figure 7The design scheme of the FPGA function - end automatic acquisition judgment module is shown. Among them, the initial value / default value of the remaining sampling number = sampling frequency * sampling time. Each time this branch is executed, a subtraction (subtract 1) operation is performed on the remaining sampling number, and the resulting value is compared with 0. The comparison result is "OR" - operated with the real - time state of the 1# photoelectric switch 9. If the result is TRUE, the state of the state machine is assigned as "restore waiting", otherwise the state of the state machine is assigned as "automatic acquisition". When the loop 2 is executed next time, the state machine will enter the corresponding branch according to the state value.

[0066] If the state entered in this loop is "restore waiting", the function of judging the reason for the automatic acquisition interruption is executed, and different implementation paths are executed according to different interruption factors. See specifically Figure 8 The design scheme of the FPGA function - automatic acquisition interruption reason judgment module is shown. The remaining sampling number is judged. If it is not less than 0, it means that the trailer 8 reverses under unexpected circumstances and triggers the 1# photoelectric switch 9, resulting in the interruption of "automatic acquisition", and the state of the state machine is assigned as "idle"; otherwise, it is considered that the "automatic acquisition" is normally interrupted because the rated number of sample data is collected as expected. The state of the 1# photoelectric switch 9 needs to be checked. If it is TRUE, the state of the state machine is assigned as "idle", otherwise it is "restore waiting".

[0067] Figure 9 shows the function design scheme of the RT system, which uses two - way loops to realize the distribution and parsing judgment of data.

[0068] In order to reduce the resource utilization rate of the RT system, the loop interval time of loop 1 is defaulted to 50 ms (much larger than the loop interval time of loop 2 in the FPGA module). Loop 1 reads a specified number (a multiple of 9) of data from the DMA buffer, stores all the data in the queue, and at the same time extracts the latest 1 sampling data of each wave height meter from the read data, and sends 8 data points to the industrial control computer 12 through the network; reads the data of the laser displacement sensor 4 collected by the FPGA and sends it to the industrial control computer 12 through the network; reads the real - time status quantities of the 4 - way photoelectric switches collected by the FPGA and displays them on the interface.

[0069] The loop interval time of Loop 2 is defaulted to 500 ms. It reads the data stored in the queue in Loop 1 at one time, and searches for the data values at the 9th, 18th, 27th... 9*nth positions (i.e., the marked data shown in Figure 5). If the data value is 1, it indicates that the 8 data in this time belong to the automatically collected data triggered by hardware. These 8 data are stored in the specified memory block in sequence, the automatic sampling count (with an initial value of 0) is incremented by 1 per channel, and the automatic collection flag is set to TRUE. If the data value is 0, first judge the value of the automatic collection flag. If it is FALSE, it means that the attribute of the previous group of 8 data is not the automatically collected data triggered by hardware, and no other operations need to be performed. Otherwise, it means that the attribute of the previous group of 8 data is the automatically collected data triggered by hardware. Then compare the automatic sampling count and the rated sampling count. If they are the same, it means that the rated sampling data volume has been obtained, and the wave height meter sampling data stored in the specified memory needs to be sent to the industrial control computer 12 through the network. If the automatic sampling count and the rated sampling count are different, it means that the data collected by this automatic trigger is not complete data, and the automatic collection flag needs to be reset to FALSE and the automatic sampling count needs to be reset to 0.

[0070] Figure 10a - Figure 10d The following shows the functional design scheme of the industrial control computer, which uses four loops to realize the sending, receiving and processing of data.

[0071] The loop interval time of Loop 1 is defaulted to 50 ms (the same as the loop time of Loop 1 on the RT system). It receives the latest data of each wave height meter sent by the RT system through the network and stores it in the queue.

[0072] Curve display is required for Loop 2, and it should not be refreshed too fast or too slow. Therefore, the loop interval time is defaulted to 250 ms. It receives the sampling data of the laser displacement sensor 4 sent by the RT system through the network. Generally, it is voltage (V) / current signal (mA), which needs to be linearly converted into distance (m) and displayed on the interface. It obtains the wave height meter data stored in Loop 1 from the queue, calculates the sampling data volume of each wave height meter, and performs zero deduction and multiplication by the amplification factor on the data of each wave height meter. The wave height of the excited wave (mm) is continuously displayed on the interface as the object. In order to display the time history data of each wave height meter in a larger space, only the data of the first 4 wave height meters are displayed on the display page at a time. Switching the channel number can display the data of the last 4 wave height meters, and the amplification factor can be set separately for each wave height meter.

[0073] In Loop 2, the state machine tasks are also executed in parallel. There are 5 states: "Update Parameters", "Manual Zeroing Start", "Manual Zeroing End", "Display", and "Automatic Zeroing". If entering the "Update Parameters" branch, the channel number, zero point, and channel coefficient displayed on the interface are updated. Then, it is judged whether the branch state value executed last time is "Update Parameters". If so, the state is assigned as "Display", otherwise it is assigned as the state executed last time. If entering the "Manual Zeroing Start" branch, the data read from the queue in this loop is stored in the dedicated memory, and the state is assigned as "Manual Zeroing Start". If entering the "Manual Zeroing End" branch, a dynamic user event is generated: post-processing of zeroing data, and the state is assigned as "Display". If entering the "Display" branch, a countdown counting function needs to be executed to automatically transfer to the "Automatic Zeroing" branch. The specific method is to perform a subtraction (subtract 1) operation on the count value (the initial value is a relatively large value). If the count value is less than 0, the state is assigned as "Automatic Zeroing", otherwise it is assigned as "Display". If entering the "Automatic Zeroing" branch, the data read from the queue in this loop is stored in the dedicated memory. It is judged whether the amount of zeroing data reaches the set value. If it reaches, the state is assigned as "Display", and a dynamic user event is generated: validity judgment of automatic zeroing data. If it does not reach, the state is continuously assigned as "Automatic Zeroing".

[0074] Loop 3 is specifically for event handling. For two types of events, namely button operations on the graphical user interface and events dynamically registered during the program running process, the loop interval time is defaulted to 50 ms.

[0075] For the event source triggered by the interface button, if the "Stop" button is clicked, the program executes according to the stop instruction logic. If the "Start Zeroing" button is clicked, the state is assigned as "Manual Zeroing Start". If the "Stop Zeroing" button is clicked, the state is assigned as "Manual Zeroing End". If the "Coefficient Update" button is clicked, the current state value is first extracted, and then the state is assigned as "Update Coefficient". If the "Channel Switch" button is clicked, the current state value is first extracted, and then the state is assigned as "Update Coefficient".

[0076] For the dynamically registered user event source, if it is "automatic zero data validity judgment", perform a statistical 3-sigma check on the zero data stored in the dedicated memory block. The rule is: the number of data points of a certain wave height meter within the range of [the sample average of this wave height meter - 3 standard deviations, the sample average of this wave height meter + 3 standard deviations] ≥ 95% of the sample number of this wave height meter, and all wave height meters meet the above rules, then the automatically collected zero data is considered valid, and a dynamic user event is generated: post-processing of zero data. Otherwise, assign the status as "automatic zero collection", and re-automatically capture the zero sample data; if it is "post-processing of zero data", calculate the zero average value of each wave height meter and save it on the local hard disk, then extract the current status value, and then assign the status as "update coefficient"; if it is "post-processing of automatically triggered waveform acquisition", perform zero-point subtraction processing on the time history data of the wave height meter automatically triggered for acquisition, then calculate the average value, and store the wave height meter average value, the time history value after zero-point subtraction, and the trailer speed information on the local hard disk.

[0077] The default loop interval time of loop 4 is 2s. Obtain the complete time history data of the wave height meter automatically triggered for acquisition sent by the RT system through the network, and then generate a dynamic user event: post-processing of automatically triggered waveform acquisition.

[0078] The above description is an explanation of the present invention, not a limitation of the invention. For the scope defined by the present invention, refer to the claims. Any form of modification can be made within the protection scope of the present invention.

Claims

1. A method for long-term automatic measurement of wide-area wave generation of a model in a large towing tank, characterized in that: The operation process includes the following: S1. Adopt a distributed test scheme with a cRIO system (13) and an industrial control computer (12). The cRIO system (13) is responsible for data acquisition and manages business logic with high-precision clock resolution. The industrial control computer (12) is responsible for data display, data processing, and data local storage tasks. Data interaction between the cRIO system (13) and the industrial control computer (12) is carried out through a network. S2. The FPGA module on the cRIO system (13) is specifically responsible for implementing the operation of logical functions and collecting physical signals of relevant channels on the acquisition card. The RT system is responsible for monitoring the operating status of the FPGA module, reading the digital quantity signals sampled and converted by the FPGA module, judging the validity of the sampled data, and sending valid sampled data to the remote industrial control computer (12). S3. Two photoelectric switches are arranged at intervals by the pool, and the trigger signals are introduced into the cRIO system (13). The moving direction and speed of the trailer (8) are automatically judged according to the order of triggering, and the state can be automatically restored according to the strategy after being triggered under abnormal conditions. S4. Automatically zero the sample at time intervals, and automatically accept / reject the automatically zeroed data according to relevant statistical methods. S5. Two photoelectric switches are installed on the trigger switch base (6) of the ship model on the pool wall and are used in cooperation with the reflector (11) at the bow of the ship model (2). The trigger signals are used to activate the cRIO system (13) for data acquisition. Photoelectric switches at different heights can adapt to model tests with different draft conditions. S6. Eight wave gauges (3) are installed horizontally and equidistantly on the base (5) on the pool wall to measure the wave-making distribution at different lateral positions of the ship model. The base can be moved laterally, and a laser displacement sensor (4) is installed at the far end. Combined with the reflector (11) at the bow of the ship model, the wave-making distribution on one side of the ship model can be measured with extremely high density.

2. A method for long-term automatic measurement of wide-area wave generation of a model in a large towing tank according to claim 1, characterized in that: The structure of the wave-making measurement device is as follows: It includes a ship model (2) arranged inside the pool and a base (5) installed on the pool wall. A secondary plate (501) that can be lifted along the base (5) is installed on the base (5). Eight wave gauges (3) are installed at equal intervals at the bottom of the secondary plate (501), and a laser displacement sensor (4) is installed at the end of the secondary plate (501). A ship model trigger switch base (6) is also installed on the pool wall, and multiple ship model trigger photoelectric switches (7) are installed at the lower part of the ship model trigger switch base (6). A track (1) is installed above the pool, and a trailer (8) drags the ship model (2) along the track (1). A reflector (11) is installed at the bow of the ship model (2), and a spaced 1# photoelectric switch (9) and 2# photoelectric switch (10) are arranged on the shore. A cRIO system (13) is arranged beside the track (1). The cRIO system (13) directly collects analog signals or digital quantity signals of the wave gauges (3), laser displacement sensor (4), ship model trigger photoelectric switches (7), 1# photoelectric switch (9), and 2# photoelectric switch (10), and transmits the sampled data to the remote industrial control computer (12) through a network cable.

3. A method for long-term automatic measurement of wide-area wave generation of a model in a large towing tank as described in claim 2, characterized in that: Each wave gauge (3) can obtain the time history wave-making data of a certain longitudinal section when the ship model 2 passes by.

4. A method for long-term automatic measurement of wide-area wave generation of a model in a large towing tank as described in claim 2, characterized in that: The distance between the 1# photoelectric switch (9) and the 2# photoelectric switch (10) is greater than the length of the trailer (8).

5. A method for long-term automatic measurement of wide-area wave generation of a model in a large towing tank as described in claim 2, characterized in that: The 1# photoelectric switch (9) and the 2# photoelectric switch (10) detect obstacles above the height of the track (1). Once the trailer (8) passes by, the two photoelectric switches can generate trigger signals.

6. The method for long-term automatic measurement of wide-area wave generation of a model in a large towing tank according to claim 2, characterized in that: The ship model trigger photoelectric switch (7) is used to adapt to the test conditions of ship models with different drafts. Once the ship model (2) passes by, if the light source of any one of the two-way ship model trigger photoelectric switches (7) is blocked by the ship model reflector (11), a trigger signal will be generated.

7. A method for long-term automatic measurement of wide-area wave generation of a model in a large towing tank as described in claim 1, characterized in that: The cRIO system (13) continuously obtains the signals of the wave height meter (3), the photoelectric trigger switch, and the laser displacement sensor (4) through relevant acquisition boards, and transmits them to the FPGA module through the bus. The FPGA sends the received sampling signals to the RT system at intervals of 20 - 50 ms; relevant logical operations are also run on the FPGA module to meet user requirements such as automatic trigger acquisition and automatic restoration of monitoring state variables.

8. A method for long-term automatic measurement of wide-area wave generation of a model in a large towing tank as claimed in claim 1, characterized in that: The industrial control computer (12) only sends and acquires two relevant setting parameters to the RT system of the cRIO when the program runs for the first time, including: the automatic sampling duration and the sampling rate. Operations such as starting / stopping and restarting the FPGA module can be performed on the program user interface of the RT system. The RT system interacts with the FPGA through a dedicated FPGA communication method, involving starting / stopping / restarting the FPGA module and obtaining the sampling data of the FPGA; When starting / restarting the FPGA module, the RT system also writes the two sampling-related setting parameters received from the industrial control computer (12) into the FPGA; after receiving the data sent by the FPGA, it performs data processing and transfers it to the industrial control computer (12) according to two different extraction strategies (the latest data and the complete data stream).

9. A method for long-term automatic measurement of wide-area wave generation of a model in a large towing tank as described in claim 1, characterized in that: After receiving the latest data, the industrial control computer (12) will display the sampling data of each channel of the wave height meter (3), and can use these data for manual zero-point sampling and automatic zero-point sampling operations; display the lateral distance between the wave height meter (3) and the ship model (2); it can automatically perform special processing for events introduced by the mouse such as start / stop zero-point sampling, channel coefficient update, and display channel on the user interface, as well as dynamic events caused by automatic zero-point sampling and receiving data sent by the RT system, so as to run stably for a long time without human intervention.

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