Passive millimeter wave imaging information acquisition system design method based on cRIO platform

Abstract

The invention discloses a passive millimeter wave imaging information acquisition system design method based on a cRIO platform, and relates to a passive millimeter wave imaging information acquisition system design method. The invention aims to solve the problems that radiometer sensors in a millimeter wave imaging system are expensive, and area array imaging needs a large number of sensors. A linear array passive millimeter wave sensor is used for scanning to form an area array millimeter wave image under the driving of a mechanical structure, the number of the sensor is reduced, the equipment cost is further reduced, a passive millimeter wave imaging information acquisition system is designed on the basis, a scanning angle is obtained through an angle encoder, and multiple times of linear array sampling are performed at equal intervals to splice the area array image. The problems of synchronous acquisition precision and transmission stability of multiple sensors in the data acquisition process are solved, meanwhile, the invention further designs a calibration method of the multiple sensors, the inconsistency of the multiple millimeter wave sensors in a linear array is calibrated, and the imaging quality is improved. The invention belongs to the technical field of passive millimeter wave imaging.

Description

Technical Field

[0001] This invention relates to a design method for a passive millimeter-wave imaging information acquisition system, belonging to the field of passive millimeter-wave imaging technology. Background Technology

[0002] Passive millimeter-wave imaging systems utilize millimeter-wave radiometers to receive millimeter-wave radiation from targets and backgrounds, converting it into voltage signals to ultimately provide an intuitive millimeter-wave image. This image reflects the difference in radiation capabilities between the background and the target, enabling target identification and detection. It can be used in fields such as airport security to achieve radiation-free, non-contact, and rapid detection. While passive millimeter-wave imaging systems offer many advantages, the millimeter-wave signals emitted by objects themselves are very weak, requiring high-sensitivity millimeter-wave radiometers for reception. These radiometers are expensive, and uniformly distributing sensors across the entire imaging array would be too costly. Therefore, this invention designs an acquisition system that uses linear millimeter-wave sensors to form an area array image through scanning. The data acquisition system is a crucial subsystem of the passive millimeter-wave imaging system. NI's Compact RIO is a high-performance embedded controller that integrates an embedded real-time controller and an FPGA chip as its core, featuring expandable interfaces and making it ideal for data acquisition and industrial control. The information acquisition platform built on the NI cRIO embedded controller has strong computing performance, good flexibility and high versatility. It is programmed using the LabVIEW graphical language, which greatly simplifies the time required to develop FPGAs using traditional hardware description languages ​​and reduces the development difficulty of FPGAs. Therefore, data acquisition systems based on the NI cRIO platform are widely used in building inspection, energy applications, power monitoring and control and other fields. Summary of the Invention

[0003] To address the issue of high cost of radiometer sensors for acquiring millimeter-wave signals in passive millimeter-wave imaging systems, this invention proposes a method for using a linear array passive millimeter-wave sensor to achieve area array imaging effects through scanning. Furthermore, it proposes a design method for a passive millimeter-wave imaging information acquisition system based on the cRIO platform.

[0004] The technical solution adopted by the present invention to solve the above problems is as follows: The steps of the present invention include: Step 1: Design the data acquisition system architecture, using 64 channels to simultaneously acquire data from a linear array passive millimeter-wave sensor, and then stitching the data into a planar array millimeter-wave image after multiple acquisitions at equal intervals through scanning. Step 2: Design the data acquisition system software; Step 3: Design a multi-channel millimeter-wave sensor calibration method to solve the imbalance problem between the sensors.

[0005] Furthermore, step 1 specifically includes: Step 101: Analyze the requirements of the passive millimeter-wave imaging information acquisition system, and design the data acquisition system implementation scheme and performance indicators; Step 102: Select a hardware platform and development software for synchronous acquisition of 64-channel passive millimeter-wave sensors; Step 103: Complete the overall architecture design of the data acquisition system. Use FPGA as the data acquisition processor, and implement instruction control, information processing and network uploading on the embedded real-time controller. Use FIFO temporary memory as the data transmission channel between the embedded real-time controller and FPGA.

[0006] Furthermore, in step 101, based on the requirements of the passive millimeter-wave imaging information acquisition system, a method is proposed to use a linear array passive millimeter-wave sensor to present a planar array imaging effect through scanning. Based on this, a data acquisition system is designed to acquire equally spaced linear array information triggered by an angle encoder. After being uploaded via the network, the linear array information is stitched together into planar array information on a host computer to obtain a millimeter-wave imaging image. Multiple data acquisitions are performed each time the reflector rotation angle output by the angle encoder reaches the trigger angle, and the average value is taken as the result of one linear array acquisition, reducing interference during the acquisition process.

[0007] Furthermore, in step 102, the NI cRIO-9039 is selected as the embedded real-time controller, four NI cRIO-9220 acquisition cards are selected as the acquisition module, the NI cRIO-9401 is selected as the digital I / O control interface, and LabVIEW is selected as the development software.

[0008] Furthermore, step 2, designing the data acquisition system software, includes: Step 201: Design system functions; Step 202: Design the FPGA-side data acquisition program, including the design of the scanning angle acquisition program, the angle control acquisition program, and the multi-channel data acquisition program. Step 203: Design the embedded real-time controller program, including the data acquisition engine and the communication engine.

[0009] Furthermore, step 3 of the procedure verifies the data acquisition system, including: Step 301: Design and implementation of a multi-channel passive millimeter-wave sensor calibration method; Step 302: Data collection and verification.

[0010] The beneficial effects of this invention are: 1. Based on the requirements of the passive millimeter-wave imaging information acquisition system, a method is proposed to use a linear array passive millimeter-wave sensor to present the area array imaging effect through scanning. Based on this, a data acquisition system is designed to collect equally spaced linear array information according to the trigger of the angle encoder. After being uploaded to the network, the linear array information is stitched into area array information on the host computer to obtain the millimeter-wave imaging image.

[0011] 2. When the reflector rotation angle output by the angle encoder reaches the trigger angle each time, multiple data acquisitions are performed and the average value is taken as the result of one linear array acquisition, thereby reducing interference during the acquisition process.

[0012] 3. A multi-channel radiometer sensor calibration method was designed to ensure the consistency of multi-channel data acquisition.

[0013] 4. This invention, through performance index analysis of the data acquisition system, clarifies the performance requirements of the hardware modules and development software of the data acquisition system, selects cRIO as the development platform, and LabVIEW as the development software; the embedded real-time controller adopts NI cRIO-9039 from NI, the C-series data acquisition module is selected from NI cRIO-9220, and the digital I / O module is selected from NI cRIO-9401; the data acquisition system achieves 16-bit acquisition accuracy and a sampling rate of 100kS / s; 5. This invention completes the detailed flowchart design and writing of the data acquisition system program. Based on the LabVIEW development environment, the program of the NI cRIO data acquisition system was designed. The FPGA data acquisition program running on the backplane of the NI cRIO chassis was developed using LabVIEW FPGA, realizing the configuration of the acquisition module and data acquisition. The RT real-time controller program running on the NI cRIO embedded controller was developed using LabVIEW Real-Time, realizing functions such as parameter passing to the FPGA program and transmitting acquired data to the host computer. 6. This invention verifies the functionality of the NI cRIO data acquisition system. Using a standard voltage source as the input signal, the acquired data from each channel is compared and analyzed. The data error is less than 0.4%, meeting the design requirements. Connecting 64 radiometers to the data acquisition system, and collecting data with a palm and with a book blocking the palm, the radiometer voltage values ​​acquired by the data acquisition system decrease when the palm is blocked, with the largest voltage drop reaching 0.042V. In Planck's blackbody radiation theory, the brightness of the blackbody radiation spectrum of an obstructed object decreases, and electromagnetic and thermal radiation decreases, thus reducing the output voltage value of the radiometer. In summary, this invention verifies the functionality of the NI cRIO data acquisition system. Attached Figure Description

[0014] Figure 1 This is a block diagram of the data acquisition system of the present invention; Figure 2 This is a flowchart of the program functions of the present invention; Figure 3 This is a flowchart of the FPGA-side data acquisition program; Figure 4 This is a flowchart of the RT-side data acquisition engine workflow; Figure 5 This is a flowchart of the RT-side communication engine workflow. Detailed Implementation

[0015] Specific implementation method one: as follows Figure 1 The diagram shows the hardware and software architecture of a passive millimeter-wave imaging information acquisition system based on the cRIO platform. Figure 2 The main program module block diagram shows the specific steps the system takes to operate: Step 1: Before the system starts working, first configure the IP address; Step 2: After setting the IP address, the cRIO device will start first, and then the host computer will open the software interface and wait for the cRIO device to connect. Step 3: After the computer detects the connection request, it establishes a connection with the NI cRIO. After the connection is established, the computer sends acquisition commands to the NI cRIO and the motor. Step 4: The NI cRIO acquisition device configures the parameters according to the acquisition command. At the same time, the motor drives the reflector to rotate and scan. The motor rotates within the pre-set maximum and minimum angles to acquire data. The millimeter wave is reflected to the ellipsoidal focusing antenna for electromagnetic signal focusing, and then the voltage signal is output by the radiometer. Step 5: The angle encoder is connected to the NI cRIO acquisition device via the SSI serial port. The data acquisition program in the FPGA reads the angle encoder information from the SSI serial port to obtain the reflector scanning position in real time. Step 6: The 64-channel radiometer has been connected to four 16-channel acquisition cards via shielded cables. The radiometer sensor converts the millimeter-wave signal of the target object into 64 analog voltage signals, which are then connected to the NI cRIO acquisition card to be converted into digital signals that can be acquired by the FPGA. Step 7: The FPGA data acquisition program in NI cRIO acquires angle encoder data and 64-channel radiometer data, and acquires radiometer voltage data according to the preset angle interval. Step 8: The FPGA data acquisition program writes the acquired data into the FIFO, and the acquisition engine program of the RT real-time controller obtains the data acquired by the FPGA by reading the FIFO. Step 9: The communication engine of the RT terminal real-time controller program completes the data packaging and sends the collected data to the host computer through the connection-oriented TCP protocol. Step 10: Calibrate the multi-channel radiometer sensor. Under the calibration command, align the radiometer with a specific target, collect data from the specific target, and upload it. Correct the normally collected data.

[0016] Step 11: The host computer completes image processing and grayscale image display based on the collected target data and calibration data.

[0017] The radiometer is a direct-detection millimeter-wave radiometer, designed to detect brightness temperatures ranging from 263K to 343K, with a center frequency of 35GHz and an operating bandwidth of 4GHz. The radiometer array is arranged linearly in four groups, totaling 64 channels. The radiometer receives electromagnetic thermal radiation from the target and background, focused by the ellipsoidal antenna, and performs millimeter-wave low-noise amplification, detection, integration, and other processing to convert the brightness temperature at the receiving point into a corresponding voltage signal. The data acquisition system then collects these voltage signals.

[0018] The radiometer has a maximum output differential voltage of 2.5V, a minimum rate of change of 10mV / K, and a raw millimeter-wave image resolution of V231×H64 (231 rows and 64 columns). The motor accelerates from 0 to its maximum speed. After a period of uniform motion, the speed is reduced to 0, with acceleration and braking times of 0.1s and effective scan time of 0.3s. The time taken for one frame is 0.5s, and the frame rate is 2Hz. The allowable error range of the data acquisition system output is ±1%, and the A / D conversion accuracy of the data acquisition system is required to reach 0.1mV, or 0.0001V. 14-bit quantization acquisition is required, so this paper selects a 16-bit data acquisition system. The acquisition system continuously acquires data 5 times within a sampling point, with each acquisition interval of 10μs. Therefore, the selected system sampling frequency is 100kHz. The system performance indicators are shown in Table 1.

[0019]

[0020] During sampling, the instantaneous sampling data rate for the 64 channels is:

[0021] The amount of data output per second by the data acquisition system is: .

[0022] The cRIO data acquisition system consists of an embedded hardware platform and software components. The hardware platform includes a C-series voltage acquisition module, a resettable high-performance FPGA chip, an embedded real-time controller, and hardware interfaces, providing stable and reliable hardware support for upper-level acquisition applications. The real-time application software includes an FPGA acquisition program and an RT real-time controller program. The FPGA program runs on the backplane of the cRIO chassis and is responsible for high-speed data acquisition. The RT real-time controller program runs within the embedded real-time controller and is responsible for online data analysis and processing, transmission, and communication with the host computer.

[0023] The NI cRIO-9039 real-time controller was selected. The NI cRIO-9039 features a 1.91GHz quad-core CPU, 2GB of DRAM, and 16GB of storage. It runs on a Kintex-7 325T FPGA mounted on the backplane of the chassis, and the operating system is NI Linux Real-Time. The NI cRIO-9039 is an 8-slot controller, allowing for the connection of different modules to meet varying user needs, ensuring future scalability.

[0024] Four NI cRIO-9220 acquisition modules with 16 channels and 16-bit synchronous differential analog inputs were selected. The NI cRIO-9220 module has a voltage range of -10 to +10V, a maximum sampling rate of 100 kS / s, and 16-bit A / D isolation, which ensures the high speed and integrity of the acquired data. This acquisition card can generate 3.2 MB / s of data per channel under high sampling rate.

[0025] The NI cRIO-9401 is selected as the digital I / O interface, featuring 4-bit incremental inputs or outputs. The NI cRIO-9401 has configurable I / O capabilities; it can be configured using LabVIEW FPGA programming to achieve customizable high / low level outputs and pulse generation.

[0026] In step 1, before the system starts working, the IP address is set first. The IP settings for the host computer and the CRIO device are shown in Table 2.

[0027]

[0028] In step 2, after the computer and the CRIO acquisition device are powered on, they establish a network connection. The CRIO is in a silent state, waiting for the computer to send acquisition instructions. When operating on the computer software interface, the computer sends corresponding instructions to the CRIO device through the network port. To ensure the reliability of instruction transmission, each instruction is sent three times consecutively.

[0029] In step 3, the commands are single acquisition command, continuous acquisition command, calibration command, and stop command. The detailed functions of the commands are as follows: (1) Single acquisition: The computer sends a single acquisition command to the CRIO acquisition device. After receiving the command, it judges the encoder status. When it judges that the encoder value increases and is ≥2069, it starts acquisition. For every 2 increments of the encoder angle step, it continuously acquires 5 frames of data with an acquisition interval of 10µs. The 5 frames of data are averaged to form one frame of data (64-channel radiometer data). Then, it is combined with the encoder data to form one frame of data and uploaded immediately. The above process is repeated. When the angle encoder value reaches 2519, acquisition stops. After the angle value is greater than 2519, it pauses for a certain period of time. When it judges that the encoder value decreases and is ≤2519, it starts acquisition. It judges based on the encoder angle change value. For every 2 increments of the step, it continuously acquires 5 frames of data with an acquisition interval of 10µs. The 5 frames of data are averaged to form one frame of data (64-channel radiometer data). Then, it is combined with the encoder data to form one frame of data and uploaded. The above process is repeated. When the angle encoder value reaches 2069, acquisition stops. After acquisition is completed, it enters standby mode. During the acquisition process, it only responds to the stop command.

[0030] (2) Continuous Acquisition: The computer sends a continuous acquisition command to the CRIO acquisition device. After receiving the command, the continuous acquisition mode is started. The continuous acquisition mode is to continuously repeat the single acquisition process. The acquisition triggering method and the upload method are the same as the single acquisition. The continuous acquisition mode keeps data acquisition going until a stop command is received. During the continuous acquisition process, only the stop command is responded to (single acquisition, continuous acquisition, and calibration are not responded to). After receiving the stop command, the acquisition stops and the device enters standby mode.

[0031] (3) Calibration: The passive millimeter-wave system equipment is calibrated using a standard temperature source. A calibration command is sent from the computer to the cRIO acquisition device. Upon receiving the command, the cRIO device outputs the calibration command through its digital I / O ports. The calibration operation is completed by controlling two external relay switches via two DIO ports. When the cRIO acquisition device receives the calibration command in standby mode, it outputs a high level on DIO5 and a low level on DIO6. After 3 seconds, it acquires and uploads data (5 frames of data are acquired consecutively at 10µs intervals, and the average of the 5 frames forms one calibration data frame). Then, it outputs a low level on DIO5 and a high level on DIO6. After 5 seconds, it outputs a low level on DIO5 and a low level on DIO6 again, entering standby mode. No other commands are responded to during the calibration process.

[0032] In step 4, after the cRIO device is powered on, the RT real-time controller program resets the FPGA backplane, completing the initialization work before the cRIO data acquisition system runs. The RT real-time controller program first configures the acquisition parameters according to the acquisition instructions from the host computer, and then transmits these parameters to the FPGA data acquisition program via the read / write control. The FPGA data acquisition program then completes the corresponding module configuration based on the parameters and instructions, such as the data sampling rate, loop execution rate and number of loops, running I / O mode, and FIFO parameter configuration. Simultaneously, the RT real-time controller program establishes data file records, data transmission queues, and sets FIFO parameters. After the module configuration is complete, the FPGA data acquisition program transmits an interrupt response to the RT real-time controller program via the read / write control, indicating to the RT program that the FPGA data acquisition program configuration is complete.

[0033] In step 5, the encoder is connected to the digital I / O board of the cRIO acquisition device via an SSI serial port. The encoder divides 360° into 8192 parts, represented using Gray code. The angle encoder is connected to the motor; the motor's rotation drives the angle encoder to rotate, and the encoder reads the rotation angle value. This data is transmitted to the FPGA program via the SSI serial port. The FPGA program reads the angle and determines whether it is within the set range. The encoder reading system reads the data and continuously transmits it to the parallel / serial converter. When this monostable current is activated by a clock signal, the data is stored and transmitted to the output terminal with a clock synchronization signal.

[0034] Angle encoder operating timing: The most significant bit of the stored data is transmitted on the first falling edge of the clock signal and the first rising edge of the clock signal in the conversion register. On the data signal output line, when the clock signal is at its falling edge, the controller obtains the required level value from the data signal output line. With each rising edge of the pulse, , Output one by one until the last character. After transmission is complete, the data line jumps to the least significant bit to transmit the data signal. At the end of the clock pulse, the controller obtains the level value of the least significant bit, the clock pulse stops, and the monostable circuit is no longer activated. Once the monostable time expires, the data signal jumps to a logic high level, and the monostable circuit stops working.

[0035] The angle encoder uses the SSI serial port to transmit the level value to the cRIO and outputs a TTL level signal to represent a 13-bit Gray code. The SSI controller program is designed according to the SSI protocol. After receiving the trigger falling edge, the SSI controller is started. After that, for each rising edge of the clock given to the angle encoder, the encoder memory outputs one bit of data to the SSI controller. The SSI controller reads the data output by the angle encoder on the falling edge of the clock, cycling from the high bit to the low bit 13 times to collect 13 bits of data. The last falling edge is used to determine whether the acquisition is over.

[0036] In step 7, the NI cRIO data acquisition system program consists of two parts: the FPGA data acquisition program and the RT real-time control program. The FPGA data acquisition program runs on the backplane of the NI cRIO chassis, and the RT real-time controller program runs on the embedded controller in the NI cRIO. The FPGA program is mainly responsible for completing the functions of module configuration and data acquisition, while the RT real-time controller is mainly responsible for parameter transmission, data transmission, and communication with the host computer.

[0037] FPGA data acquisition program such as Figure 3 As shown, after receiving the trigger signal, the acquisition parameters are configured, and then the acquisition state is entered. It determines whether the current angle value is the trigger angle value. When the trigger angle is detected, the encoder angle value increases by 2 steps, acquiring 5 frames of data at a 10µs interval. The average of the 5 acquired frames is used to form a single frame, which includes a frame header, frame number, and checksum. This frame is then written to a FIFO and transmitted to the RT data acquisition engine. When acquiring data from the lower limit angle value towards the increasing angle value direction, the frame count increases from 00 01 to 00 E7, totaling 231 frames. When acquiring data in the decreasing angle value direction, the frame number decreases from 00 E7 to 00 01. After acquisition is complete, the program enters the default state. In continuous acquisition mode, the single acquisition process is repeated continuously. The acquisition triggering method and upload method are the same as in single acquisition. Continuous acquisition mode keeps data acquisition running until a stop command is received.

[0038] The FPGA program reads 64 analog signals from the radiometer from the data acquisition module and the encoder angle value information from the SSI serial port according to the pre-set sampling rate. The FPGA program frames the acquired data and encoder angle values ​​and writes them into a FIFO for the RT data acquisition engine to read the data from the FIFO.

[0039] In step 8, the RT real-time controller program is further divided into the RT data acquisition engine and the RT communication engine. The RT data acquisition engine is mainly responsible for reading the data acquired by the FPGA and transmitting the read data to the RT communication engine through a queue. The RT communication engine then completes the data transmission and communication with the host computer.

[0040] The RT data acquisition engine is mainly responsible for interacting with the underlying FPGA program, passing acquisition parameters to the FPGA program, reading the data acquired by the FPGA, and transmitting the data to the RT communication engine through a queue.

[0041] The workflow of the RT data acquisition engine is as follows: Figure 4 As shown: (1) After the cRIO is connected to the host computer, it enters the default state. When it receives the acquisition command from the computer, it enters the Init state, configures and runs the FPGA, and creates an instance to read data.

[0042] (2) After the FPGA is configured, a start command is sent to the RT program. When the RT program receives the start command, it starts data acquisition. (3) Once data acquisition begins, the program polls the amount of data in each FIFO at a set frequency. When the specified amount of data in the FIFO is detected, the program reads the data once.

[0043] (4) After successfully reading the data, the data is transmitted to the RT data communication engine through the queue for subsequent processing.

[0044] (5) When a stop command is received, stop data acquisition.

[0045] (6) When the Exit command is received, close the FPGA reference and end the program execution.

[0046] In step 9, the RT communication engine is responsible for communicating with the host computer, receiving and parsing the host computer's instructions, setting the acquisition parameters, and starting acquisition. The RT communication engine polls the data in the queue sent by the RT data acquisition engine, then packages and sends it. After packaging, it sends the data to the host computer via the connection-oriented TCP protocol.

[0047] RT communication engine process as follows Figure 5 As shown: (1) When the cRIO device is powered on, the RT data communication engine enters the Listen state. When a network connection request is received from the bound port, a network connection is established. When no connection request is received from the host computer, the program repeatedly enters the Listen state to listen for network connection requests from the host computer.

[0048] (2) After establishing a network connection, the RT data communication engine enters the default state. If it receives a data acquisition instruction from the host computer, it initializes the RT communication engine according to the host computer's data acquisition instruction, such as setting the FIFO depth and creating an instance for reading data.

[0049] (3) When there is data in the DAQ Data queue transmitted by the RT data acquisition engine, it enters the data receiving state, reads the data in the queue, encapsulates the network data packet, and adds it to the network data packet set.

[0050] (4) When data is detected in the network data packet set, the system enters the data packet sending state and sends the data out via TCP. If the sending fails, the data packet is cleared and the system re-enters the Listen state to reconnect to the network.

[0051] (5) When the Stop command is received, the RT communication engine is shut down.

[0052] (6) When the Exit instruction is received, the program will exit execution.

[0053] In step 10, when the cRIO acquisition device receives a calibration command in standby mode, it outputs a high level on DIO5 and a low level on DIO6 for 3 seconds. After that, it acquires and uploads data (5 frames of data are acquired continuously at 10µs intervals, and the average of the 5 frames is used to form a calibration data frame). Then, it outputs a low level on DIO5 and a high level on DIO6 for 5 seconds, and then outputs a low level on DIO5 and a low level on DIO6 again, entering standby mode. It does not respond to other commands during the calibration process.

[0054] In step 11, the host computer determines the data type of the received data based on the different frame headers and completes image processing and grayscale display. The difference between the acquired data and calibration data in each frame of each group is calculated. Each frame of data is a linear array, and multiple frames are stitched together to form a planar array. Each data point represents the quantized voltage value output by the radiometer, and the quantized voltage value is mapped to a grayscale value for display.

[0055] To verify the system's functionality and the accuracy of the data acquired by each acquisition channel, a standard voltage source was used as the input signal to replace the voltage signal sensed by the radiometer. A single acquisition command was sent via the host computer to acquire data from 64 channels. The voltage range of the acquisition module was ±10V, where (FFFF) H = 65535, the theoretical value corresponding to the +2V voltage is (199A). H =6554.

[0056] The first two frames of the 231 frames of data collected were analyzed, as shown in Table 2. The 64 hexadecimal channels of each frame of data acquisition were converted into voltage values. The voltage values ​​of the 64 channels were compared with the standard power supply +2V. The minimum error was 0.002 / 2, the maximum error was 0.010 / 2, and the average error was 0.4%. Within the allowable error range of 1%, it was verified that the developed data acquisition system can work normally and accurately acquire sensor signals.

[0057]

[0058] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent substitutions, and improvements made to the above embodiments without departing from the scope of the present invention, based on the technical essence of the present invention and within the spirit and principles of the present invention, shall still fall within the protection scope of the present invention.

Claims

1. A design method for a passive millimeter-wave imaging information acquisition system based on the cRIO platform, characterized in that, The specific steps include: Step 1: Design the data acquisition system architecture, using 64 channels to simultaneously acquire data from a linear array passive millimeter-wave sensor, and then stitching the data into a planar array millimeter-wave image after multiple acquisitions at equal intervals through scanning. Step 2: Design the data acquisition system software; Step 3: Design a multi-channel millimeter-wave sensor calibration method to solve the imbalance problem between the sensors.

2. The design method for a passive millimeter-wave imaging information acquisition system based on the cRIO platform according to claim 1, characterized in that, Step 1 specifically includes: Step 101: Analyze the requirements of the passive millimeter-wave imaging information acquisition system, and design the data acquisition system implementation scheme and performance indicators; Step 102: Select a hardware platform and development software for synchronous acquisition of 64-channel passive millimeter-wave sensors; Step 103: Complete the overall architecture design of the data acquisition system. Use FPGA as the data acquisition processor, and implement instruction control, information processing and network uploading on the embedded real-time controller. Use FIFO temporary memory as the data transmission channel between the embedded real-time controller and FPGA.

3. The design method for a passive millimeter-wave imaging information acquisition system based on the cRIO platform according to claim 2, characterized in that, In step 101, based on the requirements of the passive millimeter-wave imaging information acquisition system, a method is proposed to use a linear array passive millimeter-wave sensor to present a planar array imaging effect through scanning. Based on this, a data acquisition system is designed to acquire equally spaced linear array information triggered by an angle encoder. After being uploaded via the network, the linear array information is stitched together into planar array information on a host computer to obtain the millimeter-wave imaging image. Multiple data acquisitions are performed each time the reflector rotation angle output by the angle encoder reaches the trigger angle, and the average value is taken as the result of one linear array acquisition, reducing interference during the acquisition process.

4. The design method for a passive millimeter-wave imaging information acquisition system based on the cRIO platform according to claim 2, characterized in that, In step 102, NI cRIO-9039 is selected as the embedded real-time controller, four NI cRIO-9220 acquisition cards are selected as the acquisition module, NI cRIO-9401 is selected as the digital I / O control interface, and LabVIEW is selected as the development software.

5. The design method for a passive millimeter-wave imaging information acquisition system based on the cRIO platform according to claim 1, characterized in that, Step 2 involves designing the data acquisition system software, including: Step 201: Design system functions; Step 202: Design the FPGA-side data acquisition program, including the design of the scanning angle acquisition program, the angle control acquisition program, and the multi-channel data acquisition program. Step 203: Design the embedded real-time controller program, including the data acquisition engine and the communication engine.

6. The design method for a passive millimeter-wave imaging information acquisition system based on the cRIO platform according to claim 1, characterized in that, Step 3, the procedure verification of the data acquisition system, includes: Step 301: Design and implementation of a multi-channel passive millimeter-wave sensor calibration method; Step 302: Data collection and verification.

Images