CN112698294A - Millimeter wave-based device and method for positioning personnel and detecting vital signs in fire scene - Google Patents

Millimeter wave-based device and method for positioning personnel and detecting vital signs in fire scene Download PDF

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CN112698294A
CN112698294A CN202011635182.1A CN202011635182A CN112698294A CN 112698294 A CN112698294 A CN 112698294A CN 202011635182 A CN202011635182 A CN 202011635182A CN 112698294 A CN112698294 A CN 112698294A
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target
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韩炜杰
岳克强
李文钧
孙洁
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Hangzhou Dianzi University
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/41—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00 using analysis of echo signal for target characterisation; Target signature; Target cross-section
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
    • G01S13/06—Systems determining position data of a target
    • G01S13/08—Systems for measuring distance only
    • G01S13/32—Systems for measuring distance only using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
    • G01S13/50—Systems of measurement based on relative movement of target
    • G01S13/58—Velocity or trajectory determination systems; Sense-of-movement determination systems
    • G01S13/583—Velocity or trajectory determination systems; Sense-of-movement determination systems using transmission of continuous unmodulated waves, amplitude-, frequency-, or phase-modulated waves and based upon the Doppler effect resulting from movement of targets
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
    • G01S13/50—Systems of measurement based on relative movement of target
    • G01S13/58—Velocity or trajectory determination systems; Sense-of-movement determination systems
    • G01S13/62—Sense-of-movement determination
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/41—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00 using analysis of echo signal for target characterisation; Target signature; Target cross-section
    • G01S7/411—Identification of targets based on measurements of radar reflectivity
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
    • G01V8/00—Prospecting or detecting by optical means
    • G01V8/005—Prospecting or detecting by optical means operating with millimetre waves, e.g. measuring the black losey radiation
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
    • G01V8/00—Prospecting or detecting by optical means
    • G01V8/10—Detecting, e.g. by using light barriers

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  • Engineering & Computer Science (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geophysics (AREA)
  • Radar Systems Or Details Thereof (AREA)

Abstract

The invention discloses a millimeter wave-based device and a millimeter wave-based method for locating personnel and detecting vital signs in a fire scene, wherein the device comprises a central control and processing module, and a DAC (digital-to-analog converter), an ADC (analog-to-digital converter), an optional data storage module, a millimeter wave radar module, a camera module, a WIFI module and an intermediate frequency signal processing module which are connected with the central control and processing module; according to the method, the DAC, the ADC and the central processing and controller module are used for processing and identifying the positions of personnel in the fire and vital sign key data, FMCW millimeter wave data collection is achieved, the MCU processes and analyzes the data, the SD card caches the data, the positions and vital sign states of the personnel in the fire are given, the SCCB communication protocol is used for controlling the camera to give specific position information, and the data are transmitted to the local terminal device in cooperation with the WIFI module based on the SPI.

Description

Millimeter wave-based device and method for positioning personnel and detecting vital signs in fire scene
Technical Field
The invention relates to the technical field of target positioning and vital signs detection, in particular to a millimeter wave-based device and method for positioning personnel and detecting vital signs in a fire scene.
Background
With the development of society and economy, new processes of using electricity and fire and new materials are increasing, people have frequent activities, and fire safety accidents are rapidly increased in recent years. In fire rescue, the search method for rescued people still depends on the mode that information is provided by the masses or firefighters search manually, so omission is easily caused and the firefighters are probably injured. The fire scene personnel location of current adoption is mostly by the scheme of unmanned aerial vehicle carry on the camera, and unmanned aerial vehicle can't get into the fire scene, and is limited to personnel's detectability. Millimeter wave radar equipment has good detectability in the complex environment of scene of a fire, receives environmental impact little, and can avoid causing the condition that personnel were omitted because of equipment can't get into the scene of a fire.
Disclosure of Invention
In order to solve the defects of the prior art and realize the purposes of positioning personnel in a fire scene, detecting vital signs and observing in different places, the invention adopts the following technical scheme:
a millimeter wave-based method for locating personnel and detecting vital signs in a fire scene comprises the following steps:
s1, the central control and processing module sends out a waveform generation instruction to control the DAC module to send out continuous frequency modulation waves;
s2, the millimeter wave module obtains an analog signal from the DAC module, transmits continuous frequency modulation waves, receives an echo signal, performs frequency mixing filtering processing on the echo signal and the transmitted signal, and outputs an amplified beat signal, namely an intermediate frequency signal; the millimeter wave module emits linear frequency modulation continuous waves, namely TX signals, the frequency modulation pulse bandwidth is B, and the period of a single linear modulation pulse signal is TC，
Figure BDA0002876088540000011
Receiving a reflected wave, namely an RX signal, and outputting an intermediate frequency signal by a mixer;
s4, the central control and processing module processes the data through the intermediate frequency signal processing module to obtain personnel positioning and vital sign information; the method comprises the following steps:
s41, detecting the object distance, wherein the RX signal is used as the signal after the TX signal is time-shifted, SτThe difference between the frequencies of TX-chirp and RX-chirp, BW is bandwidth, tau is the round trip time of radar to a target, S is the slope of phase difference of chirp, and the following formula is adopted for ranging:
Figure BDA0002876088540000012
Figure BDA0002876088540000013
wherein d is a distance between the detection object and the wave source, and considering that there are interference factors in the detection environment, the RX antenna may receive echoes of a plurality of targets, which cannot be accurately identified in the time domain spectrum, and needs to perform FFT on the reflected wave, examine the phase in the frequency domain spectrum, and further analyze the target detection object, and it needs to satisfy the following relations:
Figure BDA0002876088540000021
Figure BDA0002876088540000022
forming intermediate frequency signals of multi-signal superposition for reflected waves at different distances in a frequency domain spectrum, and generating a plurality of peak values;
the omega corresponding to the peak value is in direct proportion to the distance from the wave source, and an appropriate range of omega is selected according to the detection distance, and the corresponding relation of the omega and the tau is as follows:
ω＝Sτ
then by
Figure BDA0002876088540000023
The distance between the target and the wave source can be estimated to obtain the aim of people in the fire sceneA target unit;
s42, target acceleration is detected, the target acceleration detection is solved by using the frequency domain spectrum of the intermediate frequency signal, the change of the target micro-motion caused in the time domain is extremely small, but the change of the target micro-motion caused in the frequency domain is obvious, and the displacement, the speed and other data of a single target can be solved by using two adjacent TCIs determined at TCThe moving distance of the target in the system is calculated as follows:
Figure BDA0002876088540000024
Δ Φ being two adjacent TCPhase difference between fCAt millimeter wave frequency, Δ τ is twice TCRelative time difference of intermediate and intermediate frequency signals, lambda is millimeter wave wavelength, and delta d is TCThe distance the inner target moves;
the initial phase is ω corresponding to the peak in the frequency domain spectrum, so the velocity of the detection target can be estimated:
Figure BDA0002876088540000025
the fire scene environment is complicated, must receive the echo of a plurality of targets, and fire scene environment is complicated and this system work in multi-target detection, and the RX antenna must receive the echo of a plurality of targets, can't separate out the initial phase of different detection target intermediate frequency signals in the frequency domain spectrum, so need carry out 2D-FFT to intermediate frequency signal, two-dimensional Fourier transform promptly:
defining n periods TCFor one frame, namely:
Tf＝nTC
taking each period T in the frameCAnd performing doppler-FFT, i.e. doppler-fast fourier transform, on ω corresponding to the peak in the frequency domain spectrum to obtain:
Figure BDA0002876088540000026
the acceleration is found from the speed/time difference between adjacent frames:
Figure BDA0002876088540000027
the subscript n represents the corresponding data for the different objects; a represents acceleration;
Figure BDA0002876088540000028
is the speed difference; omega represents the phase corresponding to the peak value after doppler-FFT transformation;
s43, detecting the arrival angle of the target, wherein the small change of the object distance can cause the phase change omega of the range-FFT peak value, at least 2 RX antennas are needed to estimate the angle, that is, a one-transmission and multi-reception working mode is needed, the distance between the target and each antenna causes the phase change of the 2D-FFT peak value, the arrival angle is estimated by using the peak value, and the arrival angle is calculated:
Figure BDA0002876088540000031
d is the distance between 2 RX antennas, d sin (θ) is the path difference of the reflected waves received by the 2 RX antennas, λ is the wavelength, and the following constraints are applied:
Figure BDA0002876088540000032
the fire scene environment is complex, the system works in multi-target detection, the RX antenna can receive echoes of a plurality of targets inevitably, and the initial phases of intermediate frequency signals of different detection targets cannot be separated from the frequency domain spectrum, so a similar algorithm to the acceleration detection algorithm is adopted, N RX antennas are added, a phase sequence formed by N phases is obtained, 2D-FFT is carried out on the phase sequence, the phase sequence is called angle-FFT, namely angle-Fourier transform, so far, N peak values appear in the frequency domain spectrum, N is an integer larger than 0 and respectively corresponds to omeganThe method comprises the following steps:
Figure BDA0002876088540000033
because the device is suitable for positioning personnel in a fire scene, the precision required on the angle is higher;
the larger the RX antenna spacing, the more the number of RX antennas, the greater the angular resolution, which is known from the above equation:
Figure BDA0002876088540000034
to improve the instantaneity of the product, let
Figure BDA0002876088540000035
When theta is 0, the following components are available:
Figure BDA0002876088540000036
wherein, theta res is the biggest angular resolution, for the resolving power that improves range-FFT, makes the phase difference that different objects correspond more obvious, and when using, the 1 st RX antenna should be as far as possible with the detection target on unified straight line, the same angular difference, when one is for directly penetrating, when theta equals 0 promptly, the phase spectrum looks difference is the biggest, promptly:
θ＝0＝>cos(θ)max
from the maximum angular resolution formula, Δ ω is maximum at this time;
s44, the vital sign detects, this device working scene is the scene of a fire, can't carry out effectual detection to temperature etc., so detect vital sign mainly breathing, rhythm of the heart detect, human normal heart and lung activity can make the thorax rise and fall (breathe, rhythm of the heart, internal organs peristalsis etc.) according to a plurality of frequency stack ground, the echo after the millimeter wave radar produced the modulation after arriving the thorax, obtain the intermediate frequency signal relevant with target breathing and heartbeat after the mixing is enlargied, model the signal, the analysis intermediate frequency signal, extract the vital signal from the intermediate frequency signal, the thorax displacement expression of adoption is as follows:
R(t)＝αsin(2πfrt)+βsin(2πfht)
wherein, alpha and beta represent the maximum relative displacement caused by human respiration and heartbeat respectively, and fr、ftRespiratory and heartbeat frequencies;
and S5, after the information is detected, transmitting the field data back to the local terminal.
Through knowing the specific state of personnel in the fire scene locally to the remote inspection of personnel location and vital sign in the fire scene is realized to lower cost, is favorable to solving the inaccurate, big drawback of implementation risk of traditional artifical location mode location.
Further, in step S44, a time domain graph of vital signals and a respiratory rate f, which are obtained by simulating noise in MATLAB, are addedrSet to 0.6Hz, heartbeat frequency fhSet to 2.2Hz, the radar waveform adopts sawtooth wave, TcFor signal period, BW for bandwidth modulation, set TLFor a sawtooth wave repetition period, i.e. a frame period, the signal during one period can be represented in an exponential form:
Figure BDA0002876088540000041
wherein f isiIs the signal center frequency, s is the sawtooth slope,
Figure BDA0002876088540000042
for the initial phase of the transmit signal, the echo signal may be represented as the signal after the time shift of the transmit signal:
Figure BDA0002876088540000043
wherein, C represents the speed of light, and sigma is the attenuation degree of the echo signal and is inversely proportional to the reflection sectional area and the distance between the target and the radar.
Figure BDA0002876088540000044
Is an echo delay, wherein:
RP(τ)＝R(τ)+do
d0the distance from the radar antenna to the fluctuation center of the thoracic cavity of the detected target is calculated; the radar intermediate frequency signals are as follows:
SIF(t)＝STX(t)SRX*(t)
simplifying to obtain:
Figure BDA0002876088540000045
wherein the content of the first and second substances,
Figure BDA0002876088540000046
is the intermediate frequency signal phase; the time interval of the radar between two adjacent waves is extremely small, and the distance delta d between the radar antenna and the chest cavity of the target can be considered to be unchanged, so that the radar can be obtained by a formula of maximum angular resolution and a formula of the distance for moving the target:
Δφ∝y(t)
wherein, delta phi is a phase difference signal, y (t) is the displacement change of two adjacent sawtooth wave thoracic cavities, and the respiratory and heartbeat frequency of the detected target can be obtained through the phase difference signal delta phi.
Further, in step S44, the breathing frequency is between 0.4Hz and 0.7Hz, the heartbeat frequency is between 1.5Hz and 2.6Hz, and the breathing and heartbeat generally fluctuate within a range of 0.2 Hz to 2Hz, so that the vital signal belongs to a low-frequency signal, the frequency of the vital signal can be increased due to factors such as lack of oxygen and high temperature in a fire scene, the breathing frequency generally fluctuates between 0.4Hz and 0.7Hz, the heart rate generally fluctuates between 1.5Hz and 2.6Hz, and detection is emphasized for the signal of the frequency.
The device for the millimeter wave-based method for locating personnel and detecting vital signs in a fire scene comprises the following steps: the device comprises a central control and processing module, and a DAC module, a radar module, an ADC module, a data storage module, a camera module and a data transmission module which are connected with the central control and processing module, wherein the central control and processing module is internally provided with an intermediate frequency signal processing module, the intermediate frequency signal processing module comprises a target distance detection unit, an acceleration detection unit, an arrival angle detection unit and a vital sign detection unit, the radar module is a millimeter wave radar module, and the device is connected with a local terminal through the data transmission module;
the DAC module is used for receiving the digital signal of the central control and processing module and driving the millimeter wave module to generate frequency modulation continuous waves;
the millimeter wave module outputs the intermediate frequency output signal to the ADC module;
the ADC module is used for transmitting data to the central control and processing module after analog-to-digital conversion;
the data storage module is used for temporarily storing data;
the camera module is used for transmitting the image data back to the central control and processing module;
and the intermediate frequency signal processing module is used for locally resolving millimeter wave radar return data, acquiring personnel position and vital sign data, opening the camera by the central control and processing module under the condition that personnel are detected to be trapped, and transmitting the image to the local terminal through the data transmitting module.
Through DAC, ADC and central processing and controller module handle and discernment personnel's in the fire scene position and vital sign key data, realize handling FMCW millimeter wave data acquisition, MCU is to data processing analysis, the SD card caches data, give out personnel's in the fire scene position and vital sign state, give concrete positional information through SCCB communication protocol control camera, cooperate the data transmission local terminal equipment with data transmission based on SPI interface's data transmission module, know personnel's specific state in the fire scene through the local, realize personnel's location and vital sign's remote detection in the fire scene with lower cost, be favorable to solving traditional manual positioning mode and fix a position inaccurate, implement the drawback that the risk is big.
Furthermore, the DAC module adopts a low-power-consumption programmable waveform generator AD7403-EP chip, can generate sine wave, triangular wave and square wave outputs, can be used for programming and modifying the frequency and the phase, can realize the resolution of 0.02-0.06 Hz under the condition that the clock frequency is 5-16 MHz, and is used for generating frequency modulation continuous wave signals by communicating the AD7403-EP chip with the central control and processing module through a three-wire SPI protocol, namely three wires of MOSI, SCLK and CS.
Furthermore, the millimeter wave radar module adopts an IMD2411 chip, namely a 24GHz millimeter wave front end sensor, an integrated analog circuit part comprises a transmitter, a receiver, an intermediate frequency amplifier and no auxiliary circuit, adopts an FMCW working mode, namely frequency modulated continuous wave, has the stability of a continuous wave radar and the ranging capability of an ultra wide band radar, has multi-target detection capability and stronger anti-interference capability, is suitable for complex environments of fire fields, has small influence of environmental factors such as climate and the like on the 24GHz millimeter wave, is more suitable for complex environments of the fire fields compared with laser and ultrasonic waves, has the radiation range of a receiving and transmitting antenna in the horizontal and vertical directions of 60 degrees, has the highest distance resolution ratio of 2cm in specific scenes, and a V _ TUNE pin is responsible for receiving linear frequency modulated pulses, is connected with a pin of a DAC module, sends out the linear frequency modulated pulses by a transmitter, and receives echoes reflected by an object by the receiver, the echo signals and the sent signals are subjected to mixing filtering processing to be converted into beat signals, namely intermediate frequency signals, and the signals are amplified and then output to an ADC module through an IFQ _ AMP pin.
Furthermore, the ADC module adopts an ADS7038-Q1 chip, the working voltage range of the ADC module is 1.65V-3.6V, the analog-to-digital conversion type of the device is a single-channel successive approximation register type and belongs to a high-speed low-power consumption analog-to-digital converter series with compatible pin-to-pin, a VINP pin of the ADS7038-Q1 chip is connected with a pin of an IFQ _ AMP of the millimeter wave module and is responsible for collecting forward analog signals, namely intermediate frequency signals, and the converted digital signals are sent to the central control and processing module through a three-wire SPI communication protocol, namely MISO, SCLK and CS three wires.
Furthermore, the camera module is an OV5640 module of an ATK-OV5640 chip, and is an 1/4-inch CMOS VGA (2592 × 1944) image sensor, the sensor has small volume and low working voltage, and provides all functions of a single-chip VGA camera and an image processor, the VGA image output of the module can reach 60 frames/second at most, the ATK-OV5640 chip is communicated with a central control and processing module through a Serial Camera Control Bus (SCCB) protocol, the SCCB protocol consists of a clock line SIO _ C and a signal line SIO _ D, single data is 9 bits [8 bits of effective data +1 bits of NA (read) or unnecessary care bits (write) ], in order to reduce power consumption, the camera module is kept in a dormant state before people are detected, and is opened when people targets are detected, so as to provide image information for assisting the determination of the positions of the people, and improve rescue efficiency.
Furthermore, the data sending module is a WIFI module, an ESP-07S chip is adopted to communicate with a local terminal, high-speed transmission can be achieved, the module is a high-speed transmission WIFI module, the power supply voltage is 3.3v, the effective transmission distance is 100m, SMD-16 packaging is adopted, the effective transmission speed exceeds megabytes per second, video data collected by the camera can be well transmitted, the operation is stable and reliable, MCU resources are few, and an MCU integrated operating system or a protocol stack is not needed.
Furthermore, the data storage module is an SD card, and since the ADC chip has a high sampling frequency, in the signal processing process, the calculation amount is large, the data amount is huge, a part of data to be processed needs to be output and buffered in the SD card, and when the fire signal is unstable, the data sending module buffers the video or picture data in the SD card first during the data transmission process, and continues to transmit the data after the signal is recovered.
The invention has the advantages and beneficial effects that:
according to the invention, the specific state of the personnel in the fire scene is locally known, so that the positioning of the personnel in the fire scene and the remote detection of the vital signs are realized at lower cost, and the defects of inaccurate positioning and high implementation risk in the traditional manual positioning mode are favorably overcome.
Drawings
Fig. 1 is a schematic structural diagram of the device module of the present invention.
Fig. 2 is a diagram of a continuous chirp waveform in the present invention.
Fig. 3 is a schematic diagram of a target angle-of-arrival detection algorithm in the present invention.
Fig. 4 is a time domain diagram of a vital signal in the present invention.
Fig. 5 is a frequency domain diagram of a vital signal in the present invention.
Detailed Description
The following detailed description of embodiments of the invention refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.
As shown in figure 1, personnel location and vital sign detection device in the scene of a fire based on millimeter wave includes MCU, SD card, DAC chip, camera, millimeter wave module, ADC chip, WIFI module, intermediate frequency signal processing module, and intermediate frequency signal processing module is connected with MCU, and detection device is connected with local terminal equipment.
The DAC receives the digital signal of the MCU through the SPI interface and drives the millimeter wave module to generate frequency modulation continuous waves;
the intermediate frequency output signal output pin of the millimeter wave module is connected with the ADC, and the ADC performs analog-to-digital conversion and then transmits data to the MCU by using the SPI bus;
the SD card is connected with the MCU for temporarily storing data;
the camera transmits image data back to the MCU through the SCCB bus and transmits the image data to the local terminal through the WIFI;
the MCU is internally provided with target distance detection, acceleration detection, arrival angle detection and vital sign detection algorithms and is used for locally resolving millimeter wave radar return data, acquiring personnel position and vital sign data, opening the camera and transmitting an image to a local terminal under the condition that personnel are detected to be trapped.
Through DAC, ADC and central processing and controller module handle and discernment personnel's in the fire scene position and vital sign key data, realize handling FMCW millimeter wave data acquisition, MCU is to data processing analysis, the SD card caches data, give out personnel's in the fire scene position and vital sign state, give concrete positional information through SCCB communication protocol control camera, the WIFI module based on SPI interface in coordination with data transmission local terminal equipment, know personnel's specific state in the fire scene through the local, realize personnel's location and vital sign's remote detection in the fire scene with lower cost, be favorable to solving traditional manual positioning mode and fix a position inaccurately, implement the drawback that the risk is big.
1. The DAC chip adopts a low-power-consumption programmable waveform generator AD7403-EP module, can generate sine wave, triangular wave and square wave outputs, can be used for programming and modifying frequency and phase, can realize the resolution of 0.02-0.06 Hz under the condition that the clock frequency is 5-16 MHz, and is used for generating frequency modulation continuous wave signals by communicating the AD7403-EP with a central control and processing module MCU through three-wire SPI protocols (MOSI, SCLK and CS), and the DAC waveform generating method comprises the following steps:
1) the central control and processing module sends out a waveform generation instruction;
2) configuring a system clock required by triggering a DAC;
3) initializing a DAC working mode and an output channel;
4) configuring an AD7403-EP control register, and writing continuous frequency modulation wave waveform data;
5) an OPBITEN bit and a MODE bit of an AD7403-EP control register are configured.
2. The millimeter wave radar module adopts an IMD2411 module (24GHz millimeter wave front end sensor), and the module integrates an analog circuit part, including a transmitter, a receiver, an intermediate frequency amplifier and the like, without an auxiliary circuit.
The working mode of adoption is FMCW (frequency modulated continuous wave), has the stability of continuous wave radar and the range finding ability of ultra wide band radar concurrently, has multi-target detectability and stronger interference killing feature, is applicable to the complex environment of scene of a fire. The 24GHz millimeter wave is slightly influenced by environmental factors such as weather and the like, and is more suitable for complex environments of fire fields compared with laser and ultrasonic waves. The module integrates all analog circuit parts such as a transmitter, a receiver, an intermediate frequency amplifier and the like, the radiation ranges of the transceiving antennas of the IMD2411A series 24GHz millimeter wave radar modules in the horizontal direction and the vertical direction are both 60 degrees, and the distance resolution can reach 2cm at most in a specific scene. The V _ TUNE pin of the module is responsible for receiving chirps, which are connected to the VOUT pin of the AD7403-EP and are sent by the transmitter. The receiver receives the echo reflected by the object, the echo signal and the sent signal are subjected to mixing filtering processing to be converted into a beat signal, namely an intermediate frequency signal, and the signal is amplified and then output by an IFQ _ AMP pin of the module.
3. The ADC chip adopts an ADS7038-Q1 chip, the working voltage range of the ADC chip is 1.65V-3.6V, the analog-to-digital conversion type of the ADC chip is a single-channel successive approximation register type, and the ADC chip belongs to a high-speed low-power-consumption analog-to-digital converter series with compatible pins. The pin of the IFQ _ AMP of the IMD2411A mm-wave module is connected to the VINP pin of the chip, and is responsible for collecting forward analog signals, i.e., intermediate frequency signals in the system. And transmitting the converted digital signal to the MCU through a three-wire SPI communication protocol (MISO, SCLK and CS), wherein the DC acquisition method comprises the following steps:
1) the central control and processing module sends out an acquisition command;
2) configuring a system clock required for triggering the ADC;
3) configuring the ADS7038-Q1 chip to be in an ACQ mode;
4) the frame signal is converted and data is transmitted when CS is pulled down;
5) the SDO pin outputs ADC acquisition data, which is transmitted by SPI 2.
4. The waveform data storage module 8GB capacity SD card, because ADC chip sampling frequency is high, so in the signal processing process calculated amount is big, the data bulk is huge, need to wait to process a part of output and buffer in SD card, the waveform storage method includes the following steps:
1) the central control and processing module acquires waveform data through an SPI2 bus;
2) configuring and acquiring a SD card communication environment;
3) the waveform data is written after the card is confirmed to be usable.
5. The intermediate frequency signal processing module comprises a target distance detection unit, an acceleration detection unit, an arrival angle detection unit and a vital sign detection unit, wherein a millimeter wave module transmits a linear frequency modulation continuous wave (TX signal), the bandwidth of a frequency modulation pulse is B, and the period of a single linear modulation pulse signal is TC，
Figure BDA0002876088540000081
The reflected wave (RX signal) is received, and the intermediate frequency signal IF output by the mixer is used by the central control to acquire signal data through the ADS7038-Q1 through the SPI. The specific implementation comprises the following steps:
1) a target distance detection unit:
as shown in fig. 2, the RX signal may be considered to be the signal after the TX signal is time shifted. sτIs the difference between the frequencies of TX-chirp and RX-chirp, BW is the bandwidth of the tone. Since the TX transmission is linear frequency modulationPulse of so sτIs a straight line. Where τ is the round trip time of the radar to the target and S is the slope of chirp phase difference. The following formula is adopted for ranging:
Figure BDA0002876088540000091
Figure BDA0002876088540000092
wherein d is the distance of the detection object from the wave source. The RX antenna may receive echoes from multiple targets, taking into account interference factors in the detection environment. It can not be accurately identified in the time domain spectrum, and needs to perform FFT (range-FFT) on the time domain spectrum, examine the phase in the frequency domain spectrum, and further analyze the target detection object, and need to satisfy the following relations:
Figure BDA0002876088540000093
Figure BDA0002876088540000094
the intermediate frequency signal of the multi-signal superposition formed for the reflected waves at different distances in the frequency domain spectrum generates a plurality of peaks.
The omega corresponding to the peak value is in direct proportion to the distance from the wave source, and an appropriate range of omega is selected according to the detection distance, and the corresponding relation of the omega and the tau is as follows:
ω＝Sτ
then by
Figure BDA0002876088540000095
The distance of the target from the source of the waves can be estimated to yield a unit of target that is likely to be a person in the fire.
2) Target acceleration detection means:
and the target acceleration detection is solved by using the frequency domain spectrum of the intermediate frequency signal. Micro movement of targetThe change caused in the time domain is extremely tiny, while the change caused in the frequency domain is more remarkable, and the displacement, speed and other data of a single target can be solved accordingly. Using two adjacent TCIs determined at TCThe moving distance of the target in the system is calculated as follows:
Figure BDA0002876088540000096
Δ Φ being two adjacent TCPhase difference between fCAt millimeter wave frequency, Δ τ is twice TCRelative time difference of intermediate and intermediate frequency signals, lambda is millimeter wave wavelength, and delta d is TCThe distance the inner target moves.
The initial phase is ω corresponding to the peak in the frequency domain spectrum, so the velocity of the detection target can be estimated:
Figure BDA0002876088540000097
the fire scene environment is complex, the echoes of a plurality of targets can be received inevitably, the fire scene environment is complex, the system works in multi-target detection, the echoes of a plurality of targets can be received inevitably by the RX antenna, the initial phases of intermediate frequency signals of different detection targets can not be separated from frequency domain spectrums, and therefore 2D-FFT (two-dimensional Fourier transform) needs to be carried out on the intermediate frequency signals:
defining n periods (T)C) For one frame, namely:
Tf＝nTC
taking each period (T) in the frameC) And performing doppler-FFT (doppler-fast fourier transform) on ω corresponding to the peak in the frequency domain spectrum to obtain:
Figure BDA0002876088540000101
the acceleration is found from the speed/time difference between adjacent frames:
Figure BDA0002876088540000102
the subscript n represents the corresponding data for the different objects; a represents acceleration;
Figure BDA0002876088540000103
is the speed difference; and omega represents the phase corresponding to the peak after doppler-FFT transformation.
3) Target arrival angle detection unit:
as shown in fig. 3, a small change in the object distance may cause a phase change (ω) of a range-FFT peak, and at least 2 RX antennas are required to estimate the angle, i.e. a one-transmit-multiple-receive operation mode is required. The target-to-each-antenna distance results in a phase change of the 2D-FFT peak, which is used to estimate the angle of arrival. And (3) calculating an arrival angle:
Figure BDA0002876088540000104
d is the distance between 2 RX antennas, d sin (θ) is the path difference of the reflected waves received by the 2 RX antennas, and λ is the wavelength. There are the following constraints:
Figure BDA0002876088540000105
the fire scene environment is complicated and the system works in multi-target detection, the RX antenna can receive the echo of a plurality of targets inevitably, and the initial phase of intermediate frequency signals of different detection targets can not be separated from the frequency domain spectrum. Therefore, an algorithm similar to that in the acceleration detection algorithm is adopted, the number of RX antennas is increased to N, a phase sequence formed by N phases is obtained, and 2D-FFT (angle-Fourier transform) is carried out on the phase sequence, wherein the FFT is called angle-FFT. So far, n peaks (n is an integer greater than 0) appear in the frequency domain spectrum, and correspond to ω respectivelynThe method comprises the following steps:
Figure BDA0002876088540000106
because this device is applicable to the scene of a fire personnel location, requires the precision higher to the angle.
The larger the RX antenna spacing, the more the number of RX antennas, the greater the angular resolution, which is known from the above equation:
Figure BDA0002876088540000107
to improve the instantaneity of the product, let
Figure BDA0002876088540000108
When theta is 0, the following components are available:
Figure BDA0002876088540000109
where θ res is the maximum angular resolution. In order to improve the range-FFT resolution capability and make the phase difference corresponding to different objects more obvious, the 1 st RX antenna should be as uniform as possible with the detection target in a straight line when in use. The same angular difference, when one is direct (i.e. θ is 0), the phase spectrum is the largest difference, i.e.:
θ＝0＝＞cos(θ)max
from the maximum angular resolution formula, Δ ω is maximum.
4) Vital sign detection algorithm
The device working scene is a fire scene, and the temperature and the like can not be effectively detected, so that vital sign detection is mainly carried out on respiration and heart rate detection. The normal cardiopulmonary activity of the human body causes the thorax to rise and fall (respiration, heart rate, organ peristalsis, etc.) with a plurality of frequencies superposed. The radar generates modulated echo after reaching the thoracic cavity, and intermediate frequency signals related to target respiration and heartbeat are obtained after mixing and amplification. Modeling is carried out on the signals, the intermediate frequency signals are analyzed, a proper algorithm is selected, and the vital signals are extracted from the intermediate frequency signals.
Respiration and heartbeat generally fluctuate within the range of 0.2 to 2Hz, so vital signals belong to low-frequency signals, the frequency of the vital signals can be improved due to factors such as lack of oxygen, high temperature and the like in a fire scene, the respiration frequency generally fluctuates between 0.4Hz and 0.7Hz, the heart rate generally fluctuates between 1.5Hz and 2.6Hz, and the signals with the frequency need to be emphatically detected. The thoracic displacement expression is as follows:
R(t)＝αsin(2πfrt)+βsin(2πfht)
wherein, alpha and beta represent the maximum relative displacement caused by human respiration and heartbeat respectively, and fr、ftThe displacement of the thoracic cavity caused by respiratory motion is generally far larger than that caused by heartbeat, the displacement of the thoracic cavity caused by respiration ranges from 3 mm to 10mm, and the displacement of the thoracic cavity caused by heartbeat ranges from 0.1 mm to 2 mm.
As shown in fig. 4 and 5, the time domain diagrams of the vital signals obtained by simulation in MATLAB by adding noise in the above-mentioned vital signal modeling manner. Respiratory frequency frSet to 0.6Hz, heartbeat frequency fhSet to 2.2 Hz.
Similarly, the respiration and heart rate detection is still solved by adopting the distance detection algorithm, the acceleration detection algorithm and the arrival angle detection algorithm.
From FIG. 4, the radar waveform is a sawtooth wave, TcFor signal period, BW for bandwidth modulation, set TLFor a sawtooth wave repetition period (frame period), the signal can be represented in exponential form during one period:
Figure BDA0002876088540000111
wherein f isiIs the signal center frequency, s is the sawtooth slope,
Figure BDA0002876088540000112
for the initial phase of the transmit signal, the echo signal may be represented as the signal after the time shift of the transmit signal:
Figure BDA0002876088540000113
where C represents the speed of light and σ is the echoThe attenuation degree of the signal is inversely proportional to the reflection sectional area and the distance between the target and the radar.
Figure BDA0002876088540000114
Is an echo delay, wherein:
RP(τ)＝R(τ)+d0
d0the distance from the radar antenna to the fluctuation center of the chest of the detected target.
The radar intermediate frequency signals are as follows:
SIF(t)＝STX(t)SRX*(t)
simplifying to obtain:
Figure BDA0002876088540000121
wherein the content of the first and second substances,
Figure BDA0002876088540000122
is the intermediate frequency signal phase.
The time interval of the radar between two adjacent waves is extremely small, and the distance delta d between the radar antenna and the chest cavity of the target can be considered to be unchanged, so that the radar can be obtained by a formula of maximum angular resolution and a formula of the distance for moving the target:
Figure BDA0002876088540000123
wherein, delta phi is a phase difference signal, and y (t) is the displacement change of two adjacent sawtooth wave thorax. The respiration and heartbeat frequency of the detected object can be obtained through the phase difference signal delta phi.
6. The camera module is an ATK-OV5640 module. OV5640 is an 1/4 inch CMOS VGA (2592 x 1944) image sensor from OmniVision corporation. The sensor has small volume and low working voltage, and provides all functions of a single-chip VGA camera and an image processor. The VGA image output of the module can reach 60 frames/second at most, the module is communicated with an MCU (microprogrammed control Unit) through a Serial Camera Control Bus (SCCB) protocol, the SCCB protocol consists of a clock line SIO _ C and a signal line SIO _ D, and single data is 9 bits [8 bits of effective data +1 bit of NA bit (read) or unnecessary care bit (write) ]. In order to reduce power consumption, the camera is kept in a dormant state before people are detected, and is opened when a person target is preliminarily detected, so that the position of the people is assisted by image information, and the rescue efficiency is improved. The image acquisition method comprises the following steps:
1) the central control and processing module sends an acquisition instruction;
2) the image acquisition module configures and starts an SCCB bus;
3) outputting image data through VGA time sequence by utilizing an SCCB bus initialization module;
4) the single frame image is transmitted through the FIFO.
7. And the data sending module (WIFI module) adopts an ai-thinker ESP-07S module to communicate with the local terminal and the detection system. The high-speed transmission can be realized, the module is a high-speed transmission WIFI module, the power supply voltage is 3.3v, the effective transmission distance is 100m, SMD-16 packaging is adopted, the effective transmission speed exceeds megabytes per second, the video data collected by the camera can be well transmitted, the running is stable and reliable, the occupied MCU resources are few, and an MCU integrated operating system or a protocol stack is not needed. When the fire scene signal is unstable, the video or picture data can be firstly cached in the SD card in the transmission process, and the signal is recovered and then continuously transmitted. The image acquisition method comprises the following steps:
1) the central control and processing module sends an instruction;
2) initializing an ESP-07S module;
3) and subpackaging and sending the read image data to the local terminal.
A millimeter wave-based method for locating personnel and detecting vital signs in a fire scene comprises the following steps:
1) the central control and processing module sends out a waveform generation instruction and controls the DAC module to send out continuous frequency modulation waves through the SPI;
2) the millimeter wave module obtains an analog signal from the DAC, transmits continuous frequency modulation waves, receives an echo signal, performs frequency mixing filtering processing on the echo signal and the transmission signal, and outputs an amplified beat signal (intermediate frequency signal);
3) the ADC module collects the intermediate frequency signal output of the millimeter wave module, converts the intermediate frequency signal into a digital signal, inputs the digital signal into the MCU through the SPI bus, and waits for processing;
4) processing the data in the MCU, caching the data in the SD card when the data is more, and obtaining effective information such as the position, vital signs and the like of the person to be tested after processing;
5) after the person is detected, the camera module and the WiFi are started to transmit the field data back to the local terminal.
The specific state of the personnel in the fire scene is known locally, so that the personnel positioning and the remote detection of vital signs in the fire scene are realized at low cost, and the defects of inaccurate positioning and high implementation risk in the traditional manual positioning mode are overcome.
The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims (10)

1. A millimeter wave-based method for locating personnel and detecting vital signs in a fire scene is characterized by comprising the following steps:
s1, the central control and processing module sends out a waveform generation instruction to control the DAC module to send out continuous frequency modulation waves;
s2, the millimeter wave module obtains an analog signal from the DAC module, transmits continuous frequency modulation waves, receives an echo signal, performs frequency mixing filtering processing on the echo signal and the transmitted signal, and outputs an amplified beat signal, namely an intermediate frequency signal; the millimeter wave module emits linear frequency modulation continuous waves, namely TX signals, the frequency modulation pulse bandwidth is B, and the period of a single linear modulation pulse signal is TC，
Figure FDA0002876088530000011
Receiving a reflected wave, namely an RX signal, and outputting an intermediate frequency signal by a mixer;
s4, the central control and processing module processes the data through the intermediate frequency signal processing module to obtain personnel positioning and vital sign information; the method comprises the following steps:
s41, detecting the object distance, wherein the RX signal is used as the signal after the TX signal is time-shifted, SτThe difference between the frequencies of TX-chirp and RX-chirp, BW is bandwidth, tau is the round trip time of radar to a target, S is the slope of phase difference of chirp, and the following formula is adopted for ranging:
Figure FDA0002876088530000012
Figure FDA0002876088530000013
wherein d is the distance between the detection object and the wave source, FFT is carried out on the reflected wave, the phase of the reflected wave is considered in the frequency domain spectrum, and then the target detection object is analyzed, and the following relation is required to be satisfied:
Figure FDA0002876088530000014
Figure FDA0002876088530000015
forming intermediate frequency signals of multi-signal superposition for reflected waves at different distances in a frequency domain spectrum, and generating a plurality of peak values;
the omega corresponding to the peak value is in direct proportion to the distance from the wave source, and an appropriate range of omega is selected according to the detection distance, and the corresponding relation of the omega and the tau is as follows:
ω＝Sτ
then by
Figure FDA0002876088530000016
The distance of the target from the wave source can be estimated to obtain a target unit which is probably a person in the fire；
S42, detecting the target acceleration, wherein the target acceleration detection is solved by using the frequency domain spectrum of the intermediate frequency signal and two adjacent TCIs determined at TCThe moving distance of the target in the system is calculated as follows:
Figure FDA0002876088530000017
Δ Φ being two adjacent TCPhase difference between fCAt millimeter wave frequency, Δ τ is twice TCRelative time difference of intermediate and intermediate frequency signals, lambda is millimeter wave wavelength, and delta d is TCThe distance the inner target moves;
the initial phase is ω corresponding to the peak in the frequency domain spectrum, so the velocity of the detection target can be estimated:
Figure FDA0002876088530000021
2D-FFT, two-dimensional Fourier transform, is carried out on the intermediate frequency signal:
defining n periods TCFor one frame, namely:
Tf＝nTC
taking each period T in the frameCAnd performing doppler-FFT, i.e. doppler-fast fourier transform, on ω corresponding to the peak in the frequency domain spectrum to obtain:
Figure FDA0002876088530000022
the acceleration is found from the speed/time difference between adjacent frames:
Figure FDA0002876088530000023
the subscript n represents the corresponding data for the different objects; a represents acceleration;
Figure FDA0002876088530000024
is the speed difference; omega represents the phase corresponding to the peak value after doppler-FFT transformation;
s43, detecting the target arrival angle, adopting a one-shot multiple-shot working mode, leading the distance between the target and each antenna to cause the phase change of the 2D-FFT peak value, estimating the arrival angle by using the peak value, and calculating the arrival angle:
Figure FDA0002876088530000025
d is the distance between 2 RX antennas, d sin (θ) is the path difference of the reflected waves received by the 2 RX antennas, λ is the wavelength, and the following constraints are applied:
Figure FDA0002876088530000026
adopting an algorithm similar to that in the acceleration detection algorithm, adding N RX antennas to obtain a phase sequence consisting of N phases, and performing 2D-FFT (angle-FFT), namely angle-Fourier transform, on the phase sequence, so that N peak values appear in a frequency domain spectrum, wherein N is an integer greater than 0 and respectively corresponds to omeganThe method comprises the following steps:
Figure FDA0002876088530000027
the larger the RX antenna spacing, the more the number of RX antennas, the greater the angular resolution, which is known from the above equation:
Figure FDA0002876088530000028
order to
Figure FDA0002876088530000029
When theta is 0, the following components are available:
Figure FDA00028760885300000210
when the antenna is used, the 1 st RX antenna and a detection target are on a unified straight line, the same angle difference is obtained, and when one of the RX antennas is direct light, namely, when θ is 0, the phase spectrum phase difference is the largest, namely:
θ＝0＝＞cos(θ)max
from the maximum angular resolution formula, Δ ω is maximum at this time;
s44, detecting vital signs, generating modulated echo after the millimeter wave radar reaches the thoracic cavity, obtaining intermediate frequency signals related to target respiration and heartbeat after frequency mixing and amplification, modeling the signals, analyzing the intermediate frequency signals, extracting the vital signals from the intermediate frequency signals, and adopting a thoracic displacement expression as follows:
R(t)＝αsin(2πfrt)+βsin(2πfht)
wherein, alpha and beta represent the maximum relative displacement caused by human respiration and heartbeat respectively, and fr、ftRespiratory and heartbeat frequencies;
and S5, after the information is detected, transmitting the field data back to the local terminal.
2. The millimeter wave based method for locating personnel and detecting vital signs in a fire scene as claimed in claim 1, wherein in step S44, a time domain diagram of vital signals simulated in MATLAB by noise is added, and the respiratory rate frSet to 0.6Hz, heartbeat frequency fhSet to 2.2Hz, the radar waveform adopts sawtooth wave, TcFor signal period, BW for bandwidth modulation, set TLFor a sawtooth wave repetition period, i.e. a frame period, the signal during one period can be represented in an exponential form:
Figure FDA0002876088530000031
wherein f isiIs the signal center frequency, s is the sawtooth slope,
Figure FDA0002876088530000032
for the initial phase of the transmit signal, the echo signal may be represented as the signal after the time shift of the transmit signal:
Figure FDA0002876088530000033
wherein C represents the speed of light, and sigma is the attenuation degree of the echo signal and is inversely proportional to the reflection sectional area and the distance between the target and the radar;
Figure FDA0002876088530000034
is an echo delay, wherein:
RP(τ)＝R(τ)+d0
d0the distance from the radar antenna to the fluctuation center of the thoracic cavity of the detected target is calculated; the radar intermediate frequency signals are as follows:
SIF(t)＝STX(t)SRX *(t)
simplifying to obtain:
Figure FDA0002876088530000035
wherein the content of the first and second substances,
Figure FDA0002876088530000036
is the intermediate frequency signal phase; the time interval of the radar between two adjacent waves is extremely small, and the distance delta d between the radar antenna and the chest cavity of the target can be considered to be unchanged, so that the radar can be obtained by a formula of maximum angular resolution and a formula of the distance for moving the target:
Δφ∝y(t)
wherein, delta phi is a phase difference signal, y (t) is the displacement change of two adjacent sawtooth wave thoracic cavities, and the respiratory and heartbeat frequency of the detected target can be obtained through the phase difference signal delta phi.
3. The millimeter wave based method for locating persons and detecting vital signs in fire, according to claim 1, wherein in the step S44, the breathing frequency is between 0.4Hz and 0.7Hz, the heartbeat frequency is between 1.5Hz and 2.6Hz, and the signal for the frequency emphasizes the detection.
4. The apparatus for millimeter wave based in-fire personnel localization and vital sign detection method as claimed in one of claims 1-3, comprising: the device comprises a central control and processing module, a DAC module, a radar module, an ADC module, a data storage module, a camera module and a data transmission module, wherein the DAC module, the radar module, the ADC module, the data storage module, the camera module and the data transmission module are connected with the central control and processing module;
the DAC module is used for receiving the digital signal of the central control and processing module and driving the millimeter wave module to generate frequency modulation continuous waves;
the millimeter wave module outputs the intermediate frequency output signal to the ADC module;
the ADC module is used for transmitting data to the central control and processing module after analog-to-digital conversion;
the data storage module is used for temporarily storing data;
the camera module is used for transmitting the image data back to the central control and processing module;
and the intermediate frequency signal processing module is used for locally resolving millimeter wave radar return data, acquiring personnel position and vital sign data, opening the camera by the central control and processing module under the condition that personnel are detected to be trapped, and transmitting the image to the local terminal through the data transmitting module.
5. The apparatus of claim 4, wherein the DAC module employs an AD7403-EP chip, and the AD7403-EP chip communicates with the central control and processing module via three-wire SPI protocol, i.e. MOSI, SCLK and CS, for generating the frequency modulated continuous wave signal.
6. The apparatus according to claim 4, wherein the millimeter wave radar module employs an IMD2411 chip, i.e. a 24GHz millimeter wave front end sensor, the integrated analog circuit part comprises a transmitter, a receiver and an intermediate frequency amplifier, and the integrated analog circuit part adopts an FMCW (frequency modulated continuous wave) working mode, the V _ TUNE pin is responsible for receiving a linear tunable pulse, the V _ TUNE pin is connected with the VOUT pin of the DAC module, the transmitter sends out a linear tunable pulse, the receiver receives an echo reflected by an object, the echo signal and the sent signal are subjected to frequency mixing filtering processing to be converted into a beat signal, i.e. an intermediate frequency signal, and the beat signal is amplified and then output to the ADC module through the IFQ _ AMP pin.
7. The device of claim 4, wherein the ADC module employs an ADS7038-Q1 chip, a VINP pin of the ADS7038-Q1 chip is connected to a pin of an IFQ _ AMP of the millimeter wave module, and is responsible for collecting a forward analog signal, i.e., an intermediate frequency signal, and transmitting the converted digital signal to the central control and processing module through a three-wire SPI communication protocol, i.e., MISO, SCLK, and CS.
8. The apparatus of claim 4 wherein said camera module is an OV5640 module of an ATK-OV5640 chip, said ATK-OV5640 chip being in communication with the central control and processing module, the camera module remaining dormant until a human target is detected and being turned on upon initial detection of a human target.
9. The apparatus of claim 4, wherein the data transmission module is a WIFI module, and the ESP-07S chip is used to communicate with the local terminal.
10. The apparatus according to claim 4, wherein the data storage module is an SD card, the data to be processed is output and buffered in the SD card during the signal processing, and the data transmission module buffers the data in the SD card during the data transmission, and continues the transmission after the signal is restored.
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TWI825488B (en) * 2021-10-01 2023-12-11 緯創資通股份有限公司 Doppler radar apparatus and power saving method thereof
CN113729677A (en) * 2021-10-12 2021-12-03 九州云合(山东)智能科技有限公司 Intelligent vital sign monitoring method
CN117676758A (en) * 2024-02-02 2024-03-08 厦门拾聚科技有限公司 Communication security and protection integrated routing system, method, equipment and storage medium
CN117676758B (en) * 2024-02-02 2024-05-07 厦门拾聚科技有限公司 Communication security and protection integrated routing system, method, equipment and storage medium
CN117872322A (en) * 2024-03-12 2024-04-12 北醒（北京）光子科技有限公司 Frequency modulation continuous wave laser radar and radar navigation system

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