Geotechnical centrifuge data acquisition multi-channel selection device and operation method

Abstract

The present invention discloses a geotechnical centrifuge data acquisition multi-channel selection device and an operation method. The device includes a multi-channel selection device and a wireless remote control box. The multi-channel selection device is arranged between a data acquisition interface and a sensor. The multi-channel selection device is controlled by the wireless remote control box to realize the selection of a designated channel. The present invention realizes the signal acquisition, storage and display of different sensors without stopping the geotechnical centrifuge, avoids the influence of the stress release and reloading of the model structure on the test due to the shutdown and restart of the geotechnical centrifuge, shortens the test cycle, and reduces the cost of a single group test.

Description

Technical Field

[0001] The invention belongs to the field of geotechnical technology and relates to a geotechnical centrifuge data acquisition multi-channel selection device and an operating method. Background Art

[0002] Geotechnical engineering centrifuge simulation testing methods are currently a hot topic of research in various countries. Their basic principle is to place the test model in a high-gravity field generated by a centrifuge. This method has the advantage of achieving equal stress and strain, similar deformation, and the same failure mechanism as the prototype, facilitating intuitive study of the stress-deformation characteristics and failure process of geotechnical engineering under the same stress conditions as the prototype. Due to the special operating conditions of geotechnical centrifuges, in order to achieve test data in a certain high-stress field, they must be operated at a specified rotational speed (without stopping the machine).

[0003] As an instrument for conducting dynamic model tests, a centrifuge is usually equipped with a complete data acquisition system for sensors of different signal types (voltage, current, and strain). It consists of a data acquisition server, a data acquisition card, and a certain number of voltage / current / strain data acquisition interfaces. Currently, the number of test data acquisition channels equipped on various centrifuges at home and abroad is usually 100 to 200. When the number of sensors required for the centrifuge model test design exceeds the number of corresponding data acquisition channels on the centrifuge, data acquisition becomes very difficult. To obtain test data from all sensors, the existing solutions are as follows:

[0004] 1. Conduct multiple or multiple sets of centrifuge model tests

[0005] Geotechnical centrifuge model tests are usually divided into two types of tests, one is non-destructive test and the other is destructive test. Non-destructive test means that the centrifuge model material is in the elastic range during the centrifuge test and can be restored to the initial test state after stopping and unloading; while destructive test means that the centrifuge model material is in the elastic-plastic and plastic range during the centrifuge test and cannot be restored to the initial state after stopping and unloading. (1) For non-destructive centrifuge model test, all designed sensors can be embedded in a centrifuge model at one time, and some sensors can be connected at one time. After completing a set of test data using the existing data acquisition system, the centrifuge is shut down, the sensors are manually replaced, and then the centrifuge is restarted to collect the next set of centrifuge model test data. The test data of all sensors are collected multiple times. There are some problems: ① The shutdown and startup time of the centrifuge is long, which makes the total time of the entire centrifuge model test long and the test cost increases; ② The centrifuge is shut down and started, and the test model is repeatedly unloaded and loaded. There is a certain difference between its stress state and the initial state of the model, which has a certain impact on the subsequent test data. (2) For destructive centrifuge model test. Since the centrifuge model cannot be restored to its initial state after a single test, the only way to obtain test data for all sensors designed for the model test is to create multiple centrifuge test models, conduct multiple centrifuge model tests, and utilize the existing data acquisition system to collect multiple data. However, there are also some problems: ① Generally, it takes 1 to 2 months or even longer to complete the production of a single centrifuge model, and the production of multiple centrifuge test models requires several times that time, resulting in a long test cycle; ② When the centrifuge models are produced and sensors are embedded at different times and under different personnel conditions, there are certain differences in the quality of the test model molding and the location of the sensor embedment, which has a significant impact on the test data.

[0006] 2. Add data acquisition equipment

[0007] When the geotechnical centrifuge was first designed and built, considering the future upgrade of centrifugal test functions, some space was reserved inside for the installation of other equipment, such as signal amplifiers for testing various sensors, new acquisition technologies in the centrifugal field (image acquisition technology, three-dimensional laser measurement technology), etc. The impact of multiple or multiple centrifugal model tests on the test data is obviously greater than that of a single centrifugal model test. Therefore, the test data of all sensors can be obtained in a single centrifugal test by the following methods: (1) Add multiple sets of acquisition boards and channel interfaces that are the same as the existing data acquisition system; Based on the existing data acquisition system, add the same acquisition boards and matching channel interfaces. This method can perfectly keep consistent with the existing system. However, there are also several problems: ① The installation position of the acquisition boards and channel interfaces. Although space is reserved inside the centrifuge, whether the remaining space can match the space for adding equipment. Taking the 64-channel dynamic and static acquisition system as an example, the acquisition equipment size is 1600mm×800mm×500mm (length×width×height), and the channel interface panel size is 800mm×800mm (length×width). ② The problem of acquisition system software: whether the existing acquisition software can be expanded, the restrictions of expansion, and whether its restrictions can meet the requirements of this and future tests. (2) Adding other data acquisition equipment: With the development of science and technology, there are various wired / wireless acquisition equipment on the market, such as voltage / strain acquisition instruments, fiber optic modems and other wired acquisition equipment, and equipped with wireless transmission devices such as WIFI, Bluetooth, 4G network, etc., which are convenient and fast, and expansion is not restricted. However, in addition to facing the same installation space problem as adding boards, the use of other acquisition equipment also faces the question of whether to use the existing acquisition system. If not used, it will cause waste and loss of existing acquisition system equipment; if used, there will be problems such as compatibility, consistency, and complexity of acquisition operations of different acquisition systems. For example, the DH5929N dynamic stress and strain test and analysis system has a maximum of 32 or 64 measurement points per device. The dimensions of a single device (32 channels) are 800mm × 700mm × 500mm (length × width × height). It can be directly installed in a standard cabinet to form an unlimited multi-channel dynamic strain test system. Through Gigabit Ethernet communication and network technology, unlimited channel expansion and parallel sampling can be achieved, and multiple instruments are synchronized using a synchronous clock box.

[0008] Furthermore, in addition to numerical accuracy, dynamic testing requires greater attention to data synchronization when collecting data from centrifugal tests. This is especially true in centrifugal fields, where the test frequency is multiplied by several times. The issue of synchronization between different devices is crucial. Furthermore, whether adding acquisition boards and channel interfaces consistent with existing acquisition equipment or using other acquisition equipment, the equipment selection, bidding, procurement, installation, and commissioning require significant capital costs and a long timeframe.

[0009] At the same time, during the centrifugal test, whether it is wired collection or wireless transmission, the collector must be installed in the centrifuge and rotate with the model. Whether the collector can work normally in complex environments such as supergravity centrifugal field and dynamic vibration test interference. Summary of the Invention

[0010] In order to solve the above problems, the present invention provides a multi-channel selection device for data acquisition of a geotechnical centrifuge, which realizes the signal acquisition, storage and display of different sensors without stopping the geotechnical centrifuge, avoiding the influence of stress release and reloading of the model structure on the test due to the shutdown and restart of the geotechnical centrifuge, shortening the test cycle, reducing the cost of a single group test, and solving the problems existing in the prior art.

[0011] Another object of the present invention is to provide an operating method for a geotechnical centrifuge data acquisition multi-channel selection device.

[0012] The technical solution adopted by the present invention is a multi-channel selection device for geotechnical centrifuge data acquisition, which includes a multi-channel selection device and a wireless remote control box. The multi-channel selection device is arranged between the data acquisition interface and the sensor, and the multi-channel selection device is controlled by the wireless remote control box to realize the specified channel selection.

[0013] Furthermore, the multi-channel selection device is internally provided with a plurality of multi-channel selection controllers, each of which includes a single-chip microcomputer for wirelessly receiving instructions sent by the wireless remote control box and converting them into binary signal instructions, and sending binary signal instructions to the analog switch; each pin of the analog switch is connected to the parallel node of multiple two-open and two-closed analog switches, and the input side of the two-open and two-closed analog switch connected to the same pin of the analog switch is connected one-to-one with a group of sensors, which are used to collect different parameters at the same time, and the output side of the two-open and two-closed analog switch is connected to the data acquisition interface.

[0014] Furthermore, each multi-channel selection controller has n channels, each channel has m two-open, two-closed analog switches, one two-open, two-closed analog switch in each channel is connected in parallel to a pin of the analog switch, and the inlet side of the two-open, two-closed analog switch connected to the same pin of the analog switch is connected to a group of sensors in a one-to-one correspondence; the total number of channels n is less than or equal to the total number of channels of the data acquisition system provided with the centrifuge.

[0015] Furthermore, the m two-open and two-close analog switches of each channel are connected in parallel on the output side and then connected to an output plug, and all the output plugs are connected to the data acquisition interface.

[0016] Furthermore, the total number of output plugs on all the multi-channel selection controllers is less than or equal to the total number of channels of the data acquisition system of the centrifuge, and the output plugs match the data acquisition interface of the centrifuge.

[0017] Furthermore, a light emitting diode is provided between each of the two-open and two-close analog switches and the corresponding group of sensors.

[0018] Furthermore, each of the sensors is connected to the control angle of the corresponding double-closed analog switch through an input plug.

[0019] Furthermore, the on-resistance of each of the two-open and two-close analog switches is less than 50 mΩ.

[0020] Furthermore, the wireless remote control box is wirelessly connected to the single-chip microcomputer in the multi-channel selection device through a wireless data transmission radio. The wireless remote control box includes a control module selection switch and a measurement channel selection switch. The number of control module selection switches is the same as the number of multi-channel selection controllers, which are used to control the opening and closing of the corresponding multi-channel selection controllers; the number of measurement channel selection switches is the same as the number of two-open and two-close analog switches of each channel.

[0021] An operating method of a geotechnical centrifuge data acquisition multi-channel selection device is specifically performed according to the following steps:

[0022] S1, the output end of each multi-channel selection controller is connected to the data acquisition interface of the centrifuge;

[0023] S2, turning on at least one control module selection switch, turning on only one measurement channel selection switch, completing the signal connection of the corresponding sensor through the multi-channel selection device, and recording the sensor's acquisition time and acquisition data;

[0024] S3, turn on the remaining required measurement channel selection switches in sequence, complete the signal connection of the corresponding sensors through the multi-channel selection device, and record the sensor's acquisition time and acquisition data.

[0025] The beneficial effects of the present invention are:

[0026] 1. The data signal acquisition and transmission of the present invention still adopts the data acquisition system provided by the centrifuge, and a non-stop data acquisition signal multi-channel selection device is added between the sensor and the data acquisition interface to establish a connection between the existing data acquisition system and multiple groups of voltage-type, current-type, and strain-type sensors. The wired transmission of the data acquisition signal is stable and reliable, effectively preventing data interference and loss, accurately acquiring data, ensuring data storage, and low cost. The data acquisition signal multi-channel selection device is switched and controlled by a wireless remote control box, and the sensor data signal is wired to the optical terminal and converted into an optical signal, which is transmitted to the data acquisition system in the central control room using an optical ring, and the data signal is not interfered with.

[0027] 2. During the centrifugal test, the real-time signals of all sensors can be displayed in batches on the data acquisition system in the central control room to ensure that the signals of all sensors can be collected. In a complete centrifugal test, a total of 200 to 300 sets of test data from sensors of different types and quantities can be obtained. Only one set of non-stop data acquisition signal multi-channel selection device and wireless remote control box is added, and the cost is only 40,000 to 50,000 yuan.

[0028] 3. The present invention fully utilizes the existing data acquisition system of the centrifuge, without the need for new acquisition software and acquisition equipment, and effectively solves the problems of different acquisition software, offline data extraction and analysis, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0030] Figure 1 It is a basic principle diagram of an embodiment of the present invention.

[0031] Figure 2 It is a front view of the multi-channel selection device in an embodiment of the present invention.

[0032] Figure 3 It is a rear view of the multi-channel selection device in an embodiment of the present invention.

[0033] Figure 4 2 is a side view of a multi-channel selection device according to an embodiment of the present invention.

[0034] Figure 5 1 is a top view of a multi-channel selection device in an embodiment of the present invention.

[0035] Figure 6 This is the component layout diagram of the multi-channel selection controller

[0036] Figure 7 This is the multi-channel selection controller circuit board design diagram.

[0037] Figure 8 This is the working principle diagram of the multi-channel selection controller.

[0038] Figure 9 This is the schematic diagram of single-group switching of a multi-channel selection controller.

[0039] Figure 10 This is the design drawing of the wireless remote control box.

[0040] Figure 11 This is the schematic diagram of the signal sending and receiving principle of the wireless remote control box.

[0041] In the figure, 1. Data acquisition server, 2. Data acquisition interface, 3. Sensor, 4. Multi-channel selection device, 4-1. Switching power supply, 4-2. Communication plug, 5. Wireless remote control box, 7. Multi-channel selection controller, 8. Output plug, 9. Input plug, 10. Light-emitting diode, 11. Two-open and two-close analog switch, 12. Analog switch, 13. Microcontroller. DETAILED DESCRIPTION

[0042] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0043] The present invention establishes a data acquisition system connected with 200-300 groups of voltage-type, current-type and strain-type sensors, and can realize the acquisition, storage and display of 200-300 groups of voltage-type, current-type and strain-type sensors during geotechnical centrifuge testing (without stopping the machine).

[0044] The embodiment of the present invention is a geotechnical centrifuge data acquisition multi-channel selection device, such as Figure 1 As shown, it includes a multi-channel selection device 4 and a wireless remote control box 5, based on the data acquisition server 1 and data acquisition interface 2 of the existing data acquisition system, the data acquisition interface 2 is of voltage / current / strain type, etc., and a multi-channel selection device 4 is set between the data acquisition interface 2 and the sensor 3. The multi-channel selection device 4 is controlled by the wireless remote control box 5 to realize the specified channel selection, changing from "one to one" to "one to many", thereby realizing the signal collection, storage and display of all sensors without stopping the geotechnical centrifuge.

[0045] like Figure 2-5 As shown, the multi-channel selection device 4 has an overall dimension of 358mm × 291mm × 102mm (length × width × height). It is constructed from 1mm thick steel plate cut and welded together. A 102mm × 30mm × 2mm (length × width × thickness) angle steel with two screw holes is welded to the bottom of each of the left and right sides of the box. Six multi-channel selection controllers 7 (M1 to M6) are provided on the multi-channel selection device 4.

[0046] like Figure 6-9As shown, a multi-channel selection controller 7 has 8 channels, each channel has 6 two-open and two-closed analog switches 11, and one two-open and two-closed analog switch 11 of each channel is connected in parallel to a pin of the analog switch 12. The two-open and two-closed analog switches 11 connected to the same pin of the analog switch 12 are connected on the input side to a group of sensors 3 in a one-to-one correspondence. The group of sensors 3 is used to simultaneously collect different parameters, and the output side of the two-open and two-closed analog switches 11 is connected to the data acquisition interface 2; specifically, the sensors 3 are divided into 6 groups, each group has 8 sensors 3, and the first group of 8 sensors 3 are respectively connected to the input side control angle of the first two-open and two-closed analog switch K1 of the first group of 8 two-open and two-closed analog switches 11, and so on. The 8 sensors 3 of the sixth group are respectively connected to the input side control angle of the sixth two-open and two-closed analog switch K6 of the sixth group of 8 two-open and two-closed analog switches 11. The first two-open-two-closed analog switch K1 of the eight groups of two-open-two-closed analog switches 11 is connected in parallel to the first pin of the analog switch 12. Similarly, the sixth two-open-two-closed analog switch K6 of the eight groups of two-open-two-closed analog switches 11 is connected in parallel to the sixth pin of the analog switch 12. A single-chip microcomputer 13 is installed in the multi-channel selection device 4. The wireless remote control box 5 is communicatively connected to the single-chip microcomputer 13. The single-chip microcomputer 13 is circuit-connected to the analog switch 12. The wireless remote control box 5 cyclically sends six binary signal instructions to the analog switch 12 through the single-chip microcomputer 13. Each binary signal instruction controls one pin of the analog switch 12 to be energized, so that the control angle of the corresponding two-open-two-closed analog switch 11 is turned on. One two-open-two-closed analog switch 11 of each channel is energized, and the remaining two-open-two-closed analog switches 11 are not energized, thereby realizing simultaneous signal connection of a group of eight sensors 3.

[0047] A multi-channel selection controller 7 has 48 two-open two-close analog switches 11. When a group of 8 sensors 3 are connected, one two-open two-close analog switch 11 of each channel is energized, and the other 5 two-open two-close analog switches 11 are not energized to avoid mutual influence. The two-open two-close analog switches 11 of different channels (such as Figure 9 When K1 and K7 are energized at the same time, they will not affect each other, thus improving the monitoring accuracy.

[0048] The six two-open, two-close analog switches 11 on each channel are connected in parallel on the output side to an output plug 8, and all output plugs 8 are connected to the data acquisition interface 2. The total number of output plugs 8 on all multi-channel selection controllers 7 is less than or equal to the total number of channels in the centrifuge's built-in data acquisition system, and the output plugs 8 match the centrifuge's data acquisition interface 2. The volume of each multi-channel selection controller 7 is primarily limited by the number of two-open, two-close analog switches 11, which is the same as the number of sensors 3. Reducing the number of multi-channel selection controllers 7 can also reduce the number of analog switches 12 and single-chip microcomputers 13. The number of multi-channel selection controllers 7 in the present invention is not limited; the appropriate number of multi-channel selection controllers 7 is determined based on the installation volume and weight capacity of the geotechnical centrifuge. Six multi-channel selection controllers 7 are installed in the multi-channel selection device 4 of this embodiment.

[0049] In this embodiment, each multi-channel selector controller 7 is equipped with 48 two-open, two-close analog switches 11 (divided into eight groups of six each), for a total of 288 two-open, two-close analog switches 11 in the multi-channel selector device 4. Each multi-channel selector controller 7 is flanked by a set of 16-pin output plugs 8, eight sets of 12-pin input plugs 9, a row of LEDs 10, an analog switch 12, a single-chip microcomputer 13, a dip switch, and a set of 485 signals. The two-open, two-close analog switches 11 are model HRS2H-S-DC12V-N, the analog switch 12 is a ULN2803 8-to-1 analog switch, the single-chip microcomputer 13 is model STC12C5604-35I-SOP20, and the dip switch is model SW DIP-3. An LED 10 is located between each two-open, two-close analog switch 11 and the corresponding sensor group 3. Different multi-channel selector controllers 7 are distinguished by the different dial numbers of the dip switches.

[0050] The total number of channels of the data acquisition system of the centrifuge is 64 channels, which are grouped into 8 channels, and each channel is transmitted by a "+" and "-" 2-core cable. The system can be combined into a group with any number of channels, in order to facilitate the connection and combination with the data acquisition system; the embodiment of the present invention proposes that each multi-channel selection controller 7 is connected to 8 channels, so the output plug 8 is 16 cores, consisting of 8 KF2EDGK-3.81-2P plugs (numbered A to H), and each KF2EDGK-3.81-2P plug is connected to the data acquisition interface 2; similarly, an output signal can be realized with any number of input signals. The present invention selects the number of sensors / number of channels = 6 as the control requirement, so the input plug 9 is a 12-core device. The input plug 9 is divided into 6 groups. Each group of input plugs 9 consists of 6 KF2EDGK-3.81-2P plugs (A1 to A6, ..., H1 to H6). Each KF2EDGK-3.81-2P plug of the input plug 9 is hardware-connected to the data signal line "+" and "-" of a sensor 3. In addition, the input plug 9 and the output plug 8 are disconnected and connected by opening and closing two open and two closed analog switches 11, thereby realizing the connection of the data signal of the sensor 3 to the data acquisition interface 2 of the centrifuge for data acquisition.

[0051] Each sensor 3 is connected to the control angle of a corresponding double-close analog switch 11 via an input plug 9. Each KF2EDGK-3.81-2P plug on the input plug 9 is connected to only one sensor 3 signal. If all are fully connected, each multi-channel selector controller 7 can connect 48 sensor signals, and six multi-channel selector controllers 7 can connect a maximum of 288 signals. The data acquisition system is powered by 15V, and collects voltage signals of -5V to 5V, current signals of 4 to 20mA, and strain gauge resistances of 120Ω or 350Ω. Testing has shown that the on-resistance of each double-open, double-close analog switch 11 is less than 50mΩ, indicating no impact on the signals of voltage-type, current-type, or strain gauge sensors.

[0052] like Figure 10 、 11 The wireless remote control box 5 includes control module selection switches and measurement channel selection switches. The number of control module selection switches is the same as the number of multi-channel selection controllers 7, and they are used to control the opening and closing of the corresponding multi-channel selection controllers 7. The number of measurement channel selection switches is the same as the number of two-open-two-close analog switches 11, and they are used to control the opening and closing of the corresponding two-open-two-close analog switches 11. The wireless remote control box 5 of the present invention transmits the signals collected by the required sensors by sending and receiving wireless data transmission radio signals, and receives the signals fed back after the multi-channel selection device 4 is operated, thereby completing the wireless control of the multi-channel selection device 4, realizing remote operation of the multi-channel selection device 4 during the centrifugal test (without stopping the machine).

[0053] The wireless data transmission radio in the wireless remote control box 5 wirelessly communicates with the single-chip microcomputer 13 in the multi-channel selection device 4 (unaffected by the centrifuge's steel structure, centrifuge test rotation, or other electromagnetic signals outside the laboratory). The wireless data transmission radio model is JZX878 or E32-DTU 433L30. The COM1 single-chip microcomputer transmits the target operating state transfer instruction to the multi-channel selection device 4 via the wireless data transmission radio, causing its corresponding multi-channel selection controller 7 to operate; the switching power supply IRS-50-12 powers the COM1 single-chip microcomputer. Figure 8 SN65LBC184D is used to write program to MCU 13 using RS485 signal line, L7805CD2T is a voltage regulator, Figure 9 X1-X14 represent the input and output KF2EDGK-3.81-2P plugs.

[0054] The working process of the non-stop data acquisition signal multi-channel selection device for a geotechnical centrifuge according to an embodiment of the present invention is as follows:

[0055] The signal selection process of the multi-channel selection controller 7 is described by taking the signal selection of the channel number A in a certain output plug 8 as an example. The engineering process of other channel numbers (B to H) is the same as that of the channel number A.

[0056] Signal cable connection:

[0057] (1) The signals of the six sensors 3 are connected to the first group of input plugs 9 (six KF2EDGK-3.81-2P plugs, numbered A1 to A6) corresponding to channel number A;

[0058] (2) The KF2EDGK-3.81-2P plug of channel number A of the output plug 8 is connected to an aviation plug (voltage / current / strain data acquisition interface) in the data acquisition interface 2 of the centrifuge;

[0059] (3) The multi-channel selection controller 7 is developed by the self-developed circuit board (such as Figure 4 As shown, the first set of input plugs 9 (12-pin plugs) are connected to the input terminals of the first set of six HRS2H-S-DC12V-N two-open, two-close analog switches 11 (K1 to K6) according to the specified "+" and "-" (i.e., left +, right -). The "+" and "-" terminals on the output terminals of the two-open, two-close analog switches 11 are connected in parallel to the KF2EDGK-3.81-2P output plug 8, channel number A. The internal circuitry of the independently developed circuit board for the multi-channel selector controller 7 connects the microcontroller 13 and the 8-to-1 analog switch 12 to the control angles of the six two-open, two-close analog switches 11 (K1 to K6). At this point, only the signal cable hardware connection from the sensor to the data acquisition system is completed.

[0060] Device connection:

[0061] 1. The switching power supply 4-1 and communication plug 4-2 of the multi-channel selector 4 are located on the side of the box. The communication plug connections are: 1: Power +; 2: Power -; 3: RS485 +; 4: RS485 -; 5: No pin. The communication plug is internally connected to the RS485 communication plug of the multi-channel selector controller 7 and externally connected to a wireless data transmission radio.

[0062] 2. The sensor input terminals of the multi-channel selection device M1 to M6 modules are A1 to A6, B1 to B6, C1 to C6, D1 to D6, E1 to E6, F1 to F6, G1 to G6, and H1 to H6, and the corresponding output terminals are A, B, C, D, E, F, G, and H. For the sensors to be measured in the same time, the sensor input terminals with the same number should be selected, such as A2, B2, C2, D2, E2, F2, G2, and H2.

[0063] Wireless remote control box 5 controls:

[0064] Since the centrifuge test process always rotates around the central axis (without stopping), and the existing centrifuge cable channels have been fully used and there are no reserved channels, it is impossible to control the multi-channel selection device 4 by wired methods, and only wireless methods can be selected for control signal transmission and reception. The present invention independently developed a wireless remote control box 5, such as Figure 10 As shown, it features a "control module select" switch, a "measurement channel select" switch, a "power" indicator light, a "transmit" indicator light, and a "start switching" button. The control module selector switches M1 through M6 can be multi-selectable: "up" selects, "down" switches off. The measurement channel selector switch is a mechanical switch, capable of single-selection. To avoid misoperation during testing, where two or more switches are facing upward, potentially disrupting the internal program and causing a crash in the multi-channel selector 4, preventing signal acquisition, the larger number is used when setting multiple selections: "up" selects, "down" switches off. All sensors connected to the multi-channel selector are disconnected from the acquisition system, creating a circuit break and no signal feedback. Sensor signals can only be collected by the acquisition system when "measurement channel selection" is activated and the corresponding channels are connected. The "transmit" indicator flashes when a switching command is being transmitted and remains on when a transmission failure occurs.

[0065] 1. Turn on the power of the multi-channel selection device 4. All channels of the selection device are in the disconnected state and the power light flashes.

[0066] 2. Turn on the power of the wireless remote control box 5 and the green power light will flash.

[0067] 3. Select control module M1 to M6 (can be multiple options), and select one of measurement channels 1-6;

[0068] 4. Press "Start Switching" and the "Transmit" indicator light will flash. When the "Transmit" indicator light goes out completely, the switching operation is completed.

[0069] 5. If the "Transmit" indicator light is always on, it means that the transmission is faulty. You can press the "Start Switch" button again to operate it once.

[0070] 6. For unselected modules, all channels of the module are in the closed state after the switching operation.

[0071] Table 1 Operation instructions

[0072] Serial number Sending Commands return Remark 1 XX 10 0064 0001 02 0000 CRC XX 10 0064 0001 CRC Close all channels 2 XX 10 0064 0001 02 0001 CRC XX 10 0064 0001 CRC Open 1 channel 3 XX 10 0064 0001 02 0002 CRC 001 XX 10 0064 0001 CRC Open 2 channels 4 XX 10 0064 0001 02 0003 CRC XX 10 0064 0001 CRC Open 3 channels 5 XX 10 0064 0001 02 0004 CRC XX 10 0064 0001 CRC Open 4 channels 6 XX 10 0064 0001 02 0005 CRC XX 10 0064 0001 CRC Open 5 channels 7 XX 10 0064 0001 02 0006 CRC XX 10 0064 0001 CRC Open 6 channels 8 XX 90 YY CRC Instruction error

[0073] Note: 1. XX is the conversion unit ID address (M1 to M6);

[0074] 2. CRC communication data check code;

[0075] 3. YY is the exception code (01 to 04) in Article 8.

[0076] For example, when measuring strain gauges, different resistors are connected to H1 through H6 on the same module. The resistance data on H1 through H6 is collected and recorded in advance. In actual measurement, the data on H1 through H6 can be used to verify the channel selection procedure.

[0077] Signal control and acquisition:

[0078] The single-chip microcomputer 13 receives the control command from the wireless remote control box 5, converts the control command into a binary signal instruction, and sends the binary signal instruction to the analog switch 12. The corresponding pin of the analog switch 12 is energized, thereby instructing the corresponding two-open-two-close analog switch 11 to connect the control angle, causing the corresponding two-open-two-close analog switch 11 to close, thereby connecting the signal of a certain sensor 3. Then, the existing data acquisition server 1 realizes the signal collection, storage, and display of the sensor 3. The single-chip microcomputer 13 then sends the remaining five instructions in sequence to complete the signal connection of the corresponding sensor 3, thereby realizing the signal collection, storage, and display of the first group of six sensors. The details are as follows:

[0079] For example, if the wireless remote control box 5 sends a command "XX 10 0064 0001 02 0001 CRC", the single-chip microcomputer 13 converts "XX 100064 0001 02 0001 CRC" into a binary signal instruction "000". The single-chip microcomputer 13 sends a binary signal instruction "000" to represent that A1 is connected. At this time, the 1# pin of the 8-to-1 analog switch 12 is energized, and the control angle of the K1 switch of the two-open and two-close analog switch 11 is powered. The closure of the K1 switch enables the A1 plug in the input plug 9 to be physically connected to the A plug in the output plug 8, while the remaining switches (K2 to K6) connected to the A plug in the output plug 8 are not powered and are all in the disconnected state, which has no effect on the signal of the A plug of the output plug 8, so that the data acquisition server 1 can realize the signal acquisition, storage and display of the sensor connected to the A1 plug. The remaining measurement channels are selected in sequence, and the single-chip microcomputer 13 sends binary signal instructions 001, 010, 011, 100, and 101 in sequence to represent the connection of the A2, A3, A4, A5, and A6 sensors plugged into the input plug 9. The 8-to-1 analog switch 12 sequentially supplies power to the control angles of K2, K3, K4, K5, and K6 of the two-open and two-close analog switch 11, so that the K2, K3, K4, K5, and K6 switches are closed, thereby realizing the signal connection between the A2, A3, A4, A5, and A6 sensors plugged into the input plug 9 and the A plug of the output plug 8 respectively. Using the existing data acquisition server 1, the signals of all sensors connected to the A2, A3, A4, A5, and A6 plugs can be collected, stored, and displayed in sequence.

[0080] The 1st to 6th switches in each multi-channel selection controller 7 are switched synchronously. Each signal instruction can connect 8 sensors 3. For example, the A1 to A6, B1 to B6, C1 to C6, D1 to D6, E1 to E6, F1 to F6, G1 to G6 and H1 to H6 terminals of the input plug 9 are respectively connected to the corresponding sensors 3. If the "000" instruction is issued, it means that the 1st sensor is selected for collection. The A1, B1, C1, D1, E1, F1, G1 and H1 terminals of the input plug 9 are powered by the K1 switch control angle of the two-open and two-close analog switch 11, and are respectively connected to the A, B, C, D, E, F, G and H plugs of the output plug 8. In order to clearly observe the working status of the multi-channel selection controller 7, the No. 1 light of the light-emitting diode 10 is always on. By analogy, if the "001" instruction is issued, it means that the second sensor is selected for collection. The A2, B2, C2, D2, E2, F2, G2, and H2 terminals of the input plug 9 are powered by the K2 switch control angle of the two-open and two-close analog switch 11, and are respectively connected to the A, B, C, D, E, F, G, and H plugs of the output plug 8. At this time, the No. 2 light of the light-emitting diode 10 on the multi-channel selection controller 7 is always on.

[0081] The data signal acquisition and transmission of the present invention still adopts the data acquisition system provided by the centrifuge, and a multi-channel selection device is added between the sensor and the acquisition end, and the connection between the existing data acquisition system and multiple groups of voltage-type, current-type, and strain-type sensors is established through shielded cables.

[0082] An operating method of a geotechnical centrifuge data acquisition multi-channel selection device is specifically performed according to the following steps:

[0083] S1, the output plug 8 of each multi-channel selection controller 7 is connected to the data acquisition interface 2 of the centrifuge; the two open and two closed analog switches 11 connected to the same pin of the analog switch 12 in each multi-channel selection controller 7 are connected to a group of sensors 3 on a one-to-one basis. The group of sensors 3 is used to simultaneously collect different parameters to provide effective data for geotechnical testing;

[0084] S2, turn on at least one control module selection switch, turn on only one measurement channel selection switch, complete the signal connection of the corresponding sensor 3 through the multi-channel selection device 4, and record the acquisition time and data of the sensor 3;

[0085] S3, turn on the remaining required measurement channel selection switches in sequence, complete the signal connection of the corresponding sensor 3 through the multi-channel selection device 4, and record the collection time and collection data of the sensor 3.

[0086] Advantages of the present invention:

[0087] (1) The equipment size of this structure is small

[0088] Taking the embodiment that can achieve 288-channel switching as an example, the structural device has an external dimension of 358mm×291mm×102mm (length×width×height), which is comparable to the small chassis of an everyday desktop computer, and much smaller than an existing 64-channel acquisition device (1600mm×800mm×500mm) and a single 32-channel DN5929N acquisition device (800mm×700mm×500mm), with a volume of only 1% to 3% of theirs.

[0089] (2) Minor changes to existing equipment

[0090] The present invention fully utilizes the existing data acquisition system of the centrifuge. It is only installed between the data acquisition system and the sensor. It is fixed in the reserved space of the centrifuge with four M8 screws, and the data acquisition system and the sensor are connected via a shielded cable. The upgrade and transformation cost is only 40,000 to 50,000 yuan. No new acquisition equipment is required, which greatly saves the use of the reserved space of the centrifuge and avoids the upgrade and transformation cost investment of millions of yuan for data acquisition equipment. At the same time, it utilizes existing data acquisition software, without the need for upgrading. There is no need to learn different data extraction and analysis methods due to the different acquisition software used by the new acquisition equipment, which shortens the learning time investment.

[0091] (3) No impact on the collected signal

[0092] The present invention adopts shielded cable to transmit sensor signal to data acquisition system through wired transmission, the signal is stable and reliable, and the signal is effectively prevented from being interfered with and lost, the data acquisition is accurate, the data storage is guaranteed, and the cost is low.

[0093] (4) Able to work normally in centrifugal field and vibration environment

[0094] In this embodiment, the equipment is installed at a position 0.5m away from the rotation center of the centrifugal machine, which can effectively reduce the overweight effect caused by centrifugal rotation and reduce the vibration impact of the dynamic test. The equipment has been used to complete multiple tests under different centrifugal accelerations (50g, 70g, 100g) and different dynamic test conditions (sine wave: frequency 1Hz~50Hz, vibration amplitude 1g~20g, seismic wave: Wenchuan wave, EL wave, Kobe wave, Taft wave, custom). Each test was carried out continuously for more than 6 hours, and the total working time has exceeded 100 hours. The equipment is currently in good condition.

[0095] (5) Reduce the cost and impact of centrifugal testing

[0096] By utilizing the present invention, test data of all sensors can be obtained in one centrifugal test, thus reducing repeated shutdown and startup processes, effectively shortening the entire test time, and reducing the impact of repeated unloading and loading of model materials on test data.

[0097] The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention are included in the scope of protection of the present invention.

Claims

1. A geotechnical centrifuge data acquisition device, characterized in that: It comprises a multi-channel selection device (4) and a wireless remote control box (5), wherein the multi-channel selection device (4) is arranged between the data acquisition interface (2) and the sensor (3), and the multi-channel selection device (4) is controlled by the wireless remote control box (5) to realize the selection of a designated channel; The multi-channel selection device (4) is provided with a plurality of multi-channel selection controllers (7) inside. Each multi-channel selection controller (7) includes a single chip microcomputer (13) for wirelessly receiving instructions sent by the wireless remote control box (5) and converting them into binary signal instructions, and sending the binary signal instructions to the analog switch (12); each pin of the analog switch (12) is connected to a parallel connection point of a plurality of two-open and two-close analog switches (11); the input side of the two-open and two-close analog switches (11) connected to the same pin of the analog switch (12) is connected to a group of sensors (3) in a one-to-one correspondence. The group of sensors (3) is used to collect different parameters at the same time. The output side of the two-open and two-close analog switches (11) is connected to the data acquisition interface (2).

2. A geotechnical centrifuge data acquisition device according to claim 1, characterized in that: Each multi-channel selection controller (7) has n channels, each channel has m two-open and two-closed analog switches (11), one two-open and two-closed analog switch (11) of each channel is connected in parallel to a pin of the analog switch (12), and the inlet side of the two-open and two-closed analog switch (11) connected to the same pin of the analog switch (12) is connected to a group of sensors (3) in a one-to-one correspondence; the total number of channels of all multi-channel selection controllers (7) is less than or equal to the total number of channels of the data acquisition system provided by the centrifuge.

3. A geotechnical centrifuge data acquisition device according to claim 2, characterized in that: The m two-open and two-close analog switches (11) of each channel are connected in parallel on the output side and connected to an output plug (8), and all the output plugs (8) are connected to the data acquisition interface (2).

4. The geotechnical centrifuge data acquisition device according to claim 1, characterized in that: The total number of output plugs (8) on all the multi-channel selection controllers (7) is less than or equal to the total number of channels of the data acquisition system provided by the centrifuge, and the output plugs (8) match the data acquisition interface (2) of the centrifuge.

5. The geotechnical centrifuge data acquisition device according to claim 1, characterized in that: A light emitting diode (10) is provided between each of the two-open and two-close analog switches (11) and the corresponding group of sensors (3).

6. The geotechnical centrifuge data acquisition device according to claim 1, characterized in that: Each of the sensors (3) is connected to a control pin of a corresponding two-open and two-close analog switch (11) via an input plug (9).

7. The geotechnical centrifuge data acquisition device according to claim 1, characterized in that: The on-resistance of each of the two-open and two-close analog switches (11) is less than 50 mΩ.

8. The geotechnical centrifuge data acquisition device according to claim 2, characterized in that: The wireless remote control box (5) is wirelessly connected to the single-chip microcomputer (13) in the multi-channel selection device (4) via a wireless data transmission radio. The wireless remote control box (5) comprises a control module selection switch and a measurement channel selection switch. The number of the control module selection switches is the same as the number of the multi-channel selection controllers (7) and is used to control the opening and closing of the corresponding multi-channel selection controllers (7). The number of the measurement channel selection switches is the same as the number of the two-open and two-close analog switches (11) of each channel.

9. The method for operating a geotechnical centrifuge data acquisition device according to claim 8 is specifically carried out according to the following steps: S1, the output end of each multi-channel selection controller (7) is connected to the data acquisition interface (2) of the centrifuge; S2, turning on at least one control module selection switch, turning on only one measurement channel selection switch, completing the signal connection of the corresponding sensor (3) through the multi-channel selection device (4), and recording the acquisition time and acquisition data of the sensor (3); S3, turning on the remaining required measurement channel selection switches in sequence, completing the signal connection of the corresponding sensor (3) through the multi-channel selection device (4), and recording the acquisition time and acquisition data of the sensor (3).

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