Non-contact newborn vital sign monitoring device and method

Abstract

The invention belongs to the technical field of vital sign monitoring, and particularly relates to a non-contact newborn vital sign monitoring device and method. Comprising a box body, a control system, a first ultrasonic transmitting / receiving plate, an infrared camera, a second ultrasonic transmitting / receiving plate and a third ultrasonic transmitting / receiving plate, the first ultrasonic transmitting / receiving plate is installed on the top of the inner wall face of the box body 1, and the second ultrasonic transmitting / receiving plate and the third ultrasonic transmitting / receiving plate are installed on the side wall face in the box body; an infrared camera is installed in the upper space of the box body, and the first ultrasonic transmitting / receiving plate, the infrared camera, the second ultrasonic transmitting / receiving plate and the third ultrasonic transmitting / receiving plate are all connected with a control system. The device has the advantages that non-contact monitoring and sound-light alarm of important vital signs such as breathing and heart rate of the newborn in the infant incubator are realized based on ultrasonic and infrared thermal imaging technologies, and the monitoring process has the advantages of no limb contact, no privacy exposure and the like.

Description

Technical Field

[0001] This invention belongs to the field of vital sign monitoring technology, specifically relating to a non-contact neonatal vital sign monitoring device and method. Background Technology

[0002] Respiration and heartbeat are the most vital physiological functions for an organism to maintain life. For premature or critically ill newborns, whose respiratory and cardiac systems are not yet fully developed or are dysfunctional, their vital signs, such as respiration and heartbeat, are very unstable and prone to sudden abnormalities. If these abnormalities are not addressed promptly, they can lead to serious consequences. For example, if a newborn experiences apnea (cessation of breathing for more than 20 seconds), it can be life-threatening or cause long-term neurological sequelae. Therefore, real-time monitoring of respiration, heart rate, and body temperature is crucial for critically ill newborns, especially premature infants. Continuous respiratory and heart rate monitoring of newborns is an important means of preventing brain damage and even death due to hypoxia.

[0003] Newborns primarily breathe abdominally, which causes vertical displacement of the abdomen. The chest also undergoes complex, superimposed displacements due to abdominal movement and heartbeat, accompanying the respiratory rhythm and heart rate. Therefore, monitoring these abdominal and chest displacements could potentially enable non-contact monitoring of respiration and heartbeat. Furthermore, the alternating inflow and outflow of air during respiration causes periodic temperature changes in the nasal region, providing another modality of respiratory monitoring information that can be acquired non-contactly using infrared thermal imaging.

[0004] Newborns have tiny bodies and delicate skin, making conventional contact-based respiratory monitoring devices unsuitable for long-term monitoring due to the need for prolonged skin contact. Existing non-contact respiratory monitoring methods are also unsuitable for independent application in newborn respiratory and heart rate monitoring due to the following shortcomings. For example, radio frequency radar methods (CN102046076A, WO2023173386A1) suffer from electromagnetic radiation, insufficient targeting, and poor stability; video or depth camera methods (CN108604376A) have drawbacks such as privacy exposure, the need for markers, and susceptibility to lighting conditions; laser Doppler methods suffer from light radiation that can easily damage the eyes. Sound waves are of particular interest! Sound waves (including ultrasound with frequencies below 500kHz; higher frequencies are excluded from this invention due to severe attenuation in air) can propagate through the air and be reflected by the human body. Utilizing sound waves promises to non-contactly monitor respiratory and heart rate displacement in the chest and abdomen, achieving respiratory and heart rate monitoring. One patent (US 11395642 B2) proposes a method for monitoring respiration by sending / receiving 40kHz ultrasound, highlighting the system architecture, orthogonal signal processing, and fast Fourier transform (FFT) methods for calculating respiratory rate. However, the orthogonal signal processing and FFT methods mentioned in this patent involve significant computational loads, making real-time monitoring of respiration and heartbeat difficult. Furthermore, in its application scenario, clothing obstructs the view of the person, resulting in low reliability of respiratory measurement results and limited practical value.

[0005] Existing non-contact respiratory monitoring technologies include (1) radio frequency radar Doppler technology, which has disadvantages such as electromagnetic radiation, insufficient targeting, and poor stability; (2) video camera / depth camera micro-motion monitoring technology, which has disadvantages such as privacy exposure, need for markers, and susceptibility to lighting effects; (3) laser reflection displacement measurement and laser Doppler technology, which has the hazard of laser radiation; and (4) infrared thermal imaging measurement of nostril temperature difference technology used alone, which has the disadvantages of body position sensitivity and unstable measurement.

[0006] In summary, there are currently no safe and highly reliable monitoring methods and devices for non-contact respiratory and heart rate monitoring of newborns or premature infants. Summary of the Invention

[0007] The purpose of this invention is to provide a non-contact neonatal vital signs monitoring device and method, which can reliably monitor and warn of the breathing and heartbeat of newborns in an incubator. Based on ultrasound and infrared thermal imaging technology, it realizes non-contact monitoring of the breathing and heart rate of newborns in an incubator and provides audible and visual alarms. The monitoring process has the advantages of no physical contact, no privacy exposure, no electromagnetic radiation, no lighting effect, no need for markers, adaptive multi-position detection, and high robustness.

[0008] The technical solution of the present invention is as follows: a non-contact neonatal vital signs monitoring device, comprising a housing, a control system, and a first ultrasonic transmitter / receiver plate, wherein the first ultrasonic transmitter / receiver plate is installed on the top of the inner wall of the housing, and the first ultrasonic transmitter / receiver plate is connected to the control system.

[0009] It also includes an infrared camera, a second ultrasonic transmitter / receiver board and a third ultrasonic transmitter / receiver board. The second ultrasonic transmitter / receiver board and the third ultrasonic transmitter / receiver board are respectively installed on the inner side wall of the housing. An infrared camera is installed on the upper part of the housing. The infrared camera, the second ultrasonic transmitter / receiver board and the third ultrasonic transmitter / receiver board are all connected to the control system.

[0010] The first, second, and third ultrasonic transmitter / receiver boards each contain at least one transmitting ultrasonic probe and one receiving ultrasonic probe, or at least one transceiver-integrated ultrasonic probe. The transmitting and receiving ultrasonic probes are arranged alternately, and the ultrasonic frequency is 20kHz to 500kHz.

[0011] The chamber, a standard infant incubator (with the basic conditions for clinical neonatal monitoring and treatment), is a semi-enclosed chamber made of acrylic material, with constant temperature and humidity and an appropriate concentration of oxygen supply inside.

[0012] The control system is used to generate ultrasound waves and receive ultrasound echoes for respiratory and heart rate monitoring. It can also collect infrared thermal images for body position determination and nasal breathing determination.

[0013] The control system includes a microprocessor system. Infrared images acquired by the infrared camera are transmitted to the microprocessor system via the camera interface. The microprocessor system includes a microprocessor and / or a central processing unit (CPU) and / or a programmable gate array (FPGA) and / or a digital signal processor (DSP). The microprocessor system also includes a human-machine interaction unit, a transmission control unit, an infrared camera module, an image enhancement unit, a body position recognition unit, a nostril temperature monitoring unit, and a respiratory rhythm calculation unit. The image enhancement unit, body position recognition unit, nostril temperature monitoring unit, and respiratory rhythm calculation unit obtain respiratory rhythm data, providing a basis for whether to generate an audible and visual alarm.

[0014] A non-contact method for monitoring neonatal vital signs includes the following: Infrared thermal images acquired from infrared cameras undergo image enhancement processing, using median or Gaussian filters to remove image noise, and histogram equalization to improve the contrast of the thermal images. Entering the body position recognition / nostril localization unit, the Canny edge detection algorithm is used to detect the precise edges of head and facial features. Morphological operations are used to optimize the contour of the segmented head region, removing small irrelevant areas or disconnected edges to extract the head and body contours. The Haar cascade classifier, deep learning object detection model, and background subtraction / threshold segmentation algorithm are used to detect body position and head position. The nostril position is determined. Next, the respiratory rhythm determination unit is entered. First, Kalman filtering and optical flow are used to track the position of the ROI in the nostril area. The average temperature value of the pixels in the ROI in the nostril area is calculated in real time to obtain the temperature time series signal. The temperature signal is converted to the frequency domain, the frequency components are analyzed, and the respiratory rate or rhythm is calculated. The obtained respiratory data is compared with the threshold to determine whether to generate an alarm signal. Based on the body position judgment and mode setting parameters, an ultrasonic excitation pulse is generated, and the pulse is reflected by the chest and abdomen to obtain an ultrasonic echo signal. Next, the unit for displacement identification and curve generation is entered to calculate the distance and displacement; Next, the respiratory and heart rate calculations are performed. The data is smoothed by low-pass filtering to remove high-frequency noise. The respiratory cycle is identified by detecting the peak and trough values ​​of the displacement waveform. The obtained respiratory data is compared with a threshold to determine whether to generate an alarm signal.

[0015] The beneficial effects of this invention are as follows: The ultrasonic frequency f used in this invention can be between 20kHz and 500kHz, ensuring that newborns cannot hear the ultrasound waves, and it has good transmission directivity without excessive attenuation during propagation. Its wavelength is between 8.5mm and 0.68mm (wavelength equals wave velocity 340m / s divided by frequency). Although the wavelength is larger than the chest and abdominal displacement caused by respiration and much larger than the chest displacement caused by heartbeat, the displacement change can still be accurately measured by comparing the phase difference between adjacent waveforms. The monitoring accuracy of the phase difference is related to the signal sampling rate. If the echo signal sampling rate is set to 1MPS, the displacement resolution can reach 0.34mm (resolution equals beam divided by sampling rate). If the sampling rate is increased to 5MPS, the displacement resolution can reach 0.068mm, providing a theoretical basis for monitoring displacement induced by respiration and heartbeat. Attached Figure Description

[0016] Figure 1 A schematic diagram of a non-contact neonatal vital signs monitoring device provided by the present invention; Figure 2 Schematic diagram of the array probe layout of the ultrasonic transmitter / receiver board. Figure 3 This is a block diagram of the control system. Figure 4The flowchart of a non-contact neonatal vital signs monitoring method provided by the present invention; Figure 5 Example diagrams of ultrasound echo waveforms corresponding to different respiratory chest and abdominal displacements; Figure 6 Example thermal imaging of temperature differences in an infant's nostrils during breathing.

[0017] In the diagram: 1. Box, 2. Control system, 3. Second ultrasonic transmitter / receiver board, 4. Infrared camera, 5. First ultrasonic transmitter / receiver board, 6. Third ultrasonic transmitter / receiver board, A. Transmitting ultrasonic probe, B. Receiving ultrasonic probe. Detailed Implementation

[0018] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0019] Ultrasound waves are mechanical waves that can propagate through the air and be reflected by objects to produce echoes. By determining the precise time or phase difference of the echo return, the position and minute displacement of the measured object can be accurately monitored. Ultrasound has many advantages, such as no electromagnetic radiation, easy multi-beam control in small spaces, no risk of privacy exposure, unaffected by lighting and electromagnetic waves, and no need for additional markers for reflection. This invention uses a multi-directional ultrasonic transducer array to achieve continuous and accurate monitoring of the chest and abdominal displacement of newborns in different positions within an incubator, ultimately achieving non-contact monitoring of newborn respiration and heart rate. Furthermore, by combining infrared thermal imaging to determine the newborn's position, appropriate measurement angles are guided for ultrasonic displacement measurement, providing conditions for tracking and locating the nostril area. Finally, by monitoring the dynamic changes in temperature difference in the nostril area, another mode of respiratory information can be obtained, ensuring that this device is suitable for medical monitoring fields with high reliability requirements.

[0020] like Figure 1 As shown, a non-contact neonatal vital signs monitoring device includes a housing 1, a control system 2, a first ultrasonic transmitter / receiver plate 5, an infrared camera 4, a second ultrasonic transmitter / receiver plate 3, and a third ultrasonic transmitter / receiver plate 6. The first ultrasonic transmitter / receiver plate 5 is installed on the top of the inner wall of the housing 1, and the second and third ultrasonic transmitter / receiver plates 3 and 6 are respectively installed on the inner side walls of the housing 1. The infrared camera 4 is installed in the upper space of the housing 1. The first ultrasonic transmitter / receiver plate 5, the infrared camera 4, the second ultrasonic transmitter / receiver plate 5, and the third ultrasonic transmitter / receiver plate 6 are all connected to the control system 2. The housing 1 serves as a conventional infant incubator, a semi-enclosed box made of acrylic material, with constant temperature and humidity and an appropriate concentration of oxygen inside. Critically ill newborns or premature infants recover and grow in the incubator. For convenient diagnosis and care, newborns typically wear only diapers, with their upper bodies exposed, providing the necessary conditions for accurate ultrasound monitoring of minute displacements in the chest and abdomen.

[0021] The first ultrasonic transmitter / receiver board 5, the second ultrasonic transmitter / receiver board 3, and the third ultrasonic transmitter / receiver board 6 each contain at least one transmitting ultrasonic probe and one receiving ultrasonic probe, or at least one transceiver integrated ultrasonic probe. The transmitting ultrasonic probe A and the receiving ultrasonic probe are arranged alternately, and the ultrasonic frequency can be 20kHz to 500kHz. Figure 2 As shown, a more complete configuration consists of an array of multiple transmitting ultrasound probes A and multiple receiving ultrasound probes B arranged in specific geometric positions and spacings. This allows for flexible control of the synthesis of the transmitted and received ultrasound beams, achieving multi-target monitoring. The layout of the three ultrasound plates—the first ultrasound transmitting / receiving plate 5, the second ultrasound transmitting / receiving plate 3, and the third ultrasound transmitting / receiving plate 6—enables accurate and reliable detection of the newborn's breathing and heartbeat in different positions. The infrared camera 4, sensitive to body temperature, serves as an optional second modal monitoring method, used to monitor the state and rhythm of the newborn's nasal breathing, increasing the robustness of respiratory monitoring. Furthermore, infrared thermal imaging can also monitor the newborn's position, providing information for the operating mode of the aforementioned ultrasound plates. Notably, infrared thermal imaging is temperature-sensitive and can monitor the newborn's outline, but it cannot clearly present facial features and other details, thus effectively protecting privacy. The control system 2 generates ultrasound waves and receives ultrasound echoes for respiratory and heartbeat monitoring, while also acquiring infrared thermal images for position determination and nasal breathing assessment.

[0022] like Figure 3As shown, the control system 2 includes a microprocessor system. The dashed boxes on the right represent an infrared camera and an ultrasonic transmitter / receiver board, respectively. Infrared images acquired by the infrared camera are transmitted to the microprocessor system via a camera interface (such as a USB interface, RJ45 LAN interface, or WIFI interface). The microprocessor system includes a microprocessor and / or a central processing unit (CPU) and / or a programmable gate array (FPGA) and / or a digital signal processor (DSP). The microprocessor system also includes a human-machine interface unit, a transmission control unit, an infrared camera module, an image enhancement unit, a body position recognition unit, a nasal temperature monitoring unit, and a respiratory rhythm calculation unit. The image enhancement unit, body position recognition unit, nasal temperature monitoring unit, and respiratory rhythm calculation unit obtain respiratory rhythm data, providing a basis for whether to generate an audible and visual alarm. The body position recognition information generated by the infrared camera module, after judgment, is used to generate ultrasonic beams in different directions, thereby ensuring that ultrasound can accurately measure the displacement of the newborn's chest and abdomen. Specifically, the control system drives the transmission control unit to generate an ultrasound trigger signal based on the patient's position information (if available) or a sequential traversal mode (if no position information is available). This trigger signal then controls the ultrasound pulse generation unit to generate a high-voltage pulse. The high-voltage pulse excites the ultrasound transmitting probe in the ultrasound transmitting / receiving board, generating an ultrasound beam that irradiates the newborn's chest and abdomen. The ultrasound echoes reflected from the chest and abdomen are amplified, filtered, sampled, and quantized by the ultrasound echo conditioning and A / D unit, ultimately becoming digitized ultrasound echo signals. These signals then pass through the echo enhancement unit, displacement recognition unit, respiratory / heartbeat curve generation unit, and respiratory / heartbeat physiological characteristic recognition unit to become useful respiratory rate and heart rate parameters. These parameters are stored for analysis by medical personnel and, in conjunction with the respiratory rhythm generated by infrared thermal imaging, compared with a set alarm threshold to ultimately determine whether to generate an audible and visual alarm.

[0023] The human-machine interface unit consists of a keyboard, touch screen, or communication interface and a display screen, used to input control commands and system parameters, and also to display key data.

[0024] like Figure 4 As shown, a non-contact method for monitoring neonatal vital signs includes the following: After the device is powered on, the system will periodically check whether thermal imaging is activated and periodically generate ultrasound pulses based on body position information and preset beam direction. The key processes and optional core algorithms for infrared thermal imaging and ultrasound respiratory and heart rate monitoring are described below.

[0025] Infrared thermal images acquired from infrared cameras undergo image enhancement processing: for example, using median filters or Gaussian filters to remove image noise and improve image quality; or using histogram equalization to improve the contrast of thermal images and make different temperature regions easier to distinguish.

[0026] Next, the body position recognition / nostril localization unit is used: for example, the Canny edge detection algorithm is used to detect the precise edges of head and facial features, morphological operations are used to optimize the contour of the segmented head region, and small irrelevant areas or disconnected edges are removed to extract the head and body contours; the Haar cascade classifier, deep learning object detection model, and background subtraction / thresholding segmentation algorithm are used to detect body position and head position; a temperature feature-based method is used, that is, the temperature distribution feature that the tip of the nose is usually colder than the surrounding area (cold spot), while the inner corner of the eye is hotter (hot spot), to determine the position of the nostrils; predefined nose or nostril templates can also be used to perform matching search in the detected facial region to accurately locate the nostril position; the anatomical features of the face (such as the relative position and size of the eyes, nose, and mouth) can also be combined to assist in nostril localization; deep learning methods can also be applied to use specially trained CNN models to directly locate the nostrils or nasal cavity region.

[0027] Next, the respiratory rhythm determination unit begins. First, Kalman filtering and optical flow are used to track the location of the ROI (Region of Interest) in the nostrils, and the average temperature value of the pixels within the ROI is calculated in real time to obtain a temperature time series signal. This signal can be low-pass filtered to remove high-frequency noise and smooth the data; the respiratory cycle is identified by detecting the peak and trough values ​​of the temperature waveform. Alternatively, Fourier transform / wavelet transform can be used to convert the temperature signal to the frequency domain, analyze the main frequency components, and thus calculate the respiratory rate or rhythm; the periodicity of the signal can also be analyzed through autocorrelation to determine the respiratory rate. The obtained respiratory data can be saved, and a threshold judgment is made to determine whether to generate an alarm signal.

[0028] On the right side of the flowchart, the system generates an ultrasonic excitation pulse based on the body position judgment and mode setting parameters. After the pulse is reflected by the chest and abdomen, an ultrasonic echo signal is obtained. The signal is then processed by the acquisition and enhancement unit: for example, by bandpass filtering to remove noise and interference signals outside the operating frequency range of the ultrasonic transducer, thereby improving the signal-to-noise ratio; and by techniques such as median filtering, Gaussian filtering, adaptive filtering, Wiener filtering, wavelet decomposition, and spectral subtraction to remove random noise and enhance the signal waveform.

[0029] Next, the system enters the displacement recognition and curve generation unit. It can estimate distance and displacement by measuring minute changes in the signal's round-trip time based on a time delay estimation algorithm, used for monitoring large movements or the actions of medical personnel in diagnosis and care. It can also perform phase estimation through cross-correlation algorithms and subsample / subpixel interpolation to obtain fine-grained displacement change information. For lightweight real-time monitoring needs, methods such as short-time energy, short-time average amplitude, short-time zero-crossing rate, and short-time autocorrelation can be used for displacement monitoring. In particular, the short-time average amplitude difference method can replace the computationally intensive autocorrelation calculation, improving the system's real-time response capability.

[0030] Next, the respiratory and heart rate rhythms are calculated. The signal can be low-pass filtered to remove high-frequency noise and smooth the data. The respiratory cycle is identified by detecting the peaks and troughs of the displacement waveform. Alternatively, Fourier transform / wavelet transform can be used to convert the displacement signal to the frequency domain, analyze the main frequency components, and thus calculate the respiratory rate or rhythm. The periodicity of the signal can also be analyzed using autocorrelation methods or zero-crossing counting algorithms to determine the respiratory rate. The obtained respiratory data can be saved and, after being compared with a threshold, determines whether to generate an alarm signal.

[0031] Figure 5 Examples of ultrasound echo waveforms corresponding to different respiratory chest and abdominal displacements are shown. These examples demonstrate that echoes from different displacements may have different waveform profiles, phases, and amplitudes. By determining the periodic differences in these parameters, the time series of displacement changes can be identified, thereby obtaining the rhythm of breathing and heartbeat.

[0032] Figure 6 This example demonstrates a thermal imaging technique used to illustrate the temperature differences in an infant's nostrils during respiration. The example shows that the image quality of infrared thermal imaging can indeed be used to determine body position and locate the nasal region; it also demonstrates that the significant periodic changes in nostril temperature can be used to monitor respiratory rhythm.

Claims

1. A non-contact neonatal vital signs monitoring device, characterized in that: It includes a housing, a control system, and a first ultrasonic transmitter / receiver board. The first ultrasonic transmitter / receiver board is installed on the top of the inner wall of the housing and is connected to the control system.

2. The non-contact neonatal vital signs monitoring device as described in claim 1, characterized in that: It also includes an infrared camera, a second ultrasonic transmitter / receiver board and a third ultrasonic transmitter / receiver board. The second ultrasonic transmitter / receiver board and the third ultrasonic transmitter / receiver board are respectively installed on the inner side wall of the housing. An infrared camera is installed on the upper part of the housing. The infrared camera, the second ultrasonic transmitter / receiver board and the third ultrasonic transmitter / receiver board are all connected to the control system.

3. The non-contact neonatal vital signs monitoring device as described in claim 1, characterized in that: The first, second, and third ultrasonic transmitter / receiver boards each contain at least one transmitting ultrasonic probe and one receiving ultrasonic probe, or at least one transceiver-integrated ultrasonic probe. The transmitting and receiving ultrasonic probes are arranged alternately, and the ultrasonic frequency can be 20kHz to 500kHz.

4. The non-contact neonatal vital signs monitoring device as described in claim 1, characterized in that: The box, as a conventional infant incubator, is a semi-enclosed box made of acrylic material, with constant temperature and humidity and an appropriate concentration of oxygen supply inside.

5. A non-contact neonatal vital signs monitoring device as described in claim 1, characterized in that: The control system is used to generate ultrasound waves and receive ultrasound echoes for respiratory and / or heart rate monitoring and / or medical behavior assessment. It can also collect infrared thermal images for body position assessment and / or nasal breathing assessment and / or body temperature assessment and / or medical behavior assessment.

6. The non-contact neonatal vital signs monitoring device as described in claim 5, characterized in that: The control system includes a microprocessor system. Infrared images acquired by the infrared camera are transmitted to the microprocessor system via the camera interface. The microprocessor system includes a microprocessor and / or a central processing unit (CPU) and / or a programmable gate array (FPGA) and / or a digital signal processor (DSP). The microprocessor system also includes a human-machine interaction unit, a transmission control unit, an infrared camera module, an image enhancement unit, a body position recognition unit, a nostril temperature monitoring unit, and a respiratory rhythm calculation unit. The image enhancement unit, body position recognition unit, nostril temperature monitoring unit, and respiratory rhythm calculation unit obtain respiratory rhythm data, providing a basis for whether to generate an audible and visual alarm.

7. A non-contact method for monitoring neonatal vital signs, characterized in that, Including the following: Infrared thermal images obtained from infrared cameras are enhanced by image enhancement processing. Median or Gaussian filters can be used to remove image noise, and histogram equalization can be used to improve the contrast of thermal images. Upon entering the body position recognition / nostril localization unit, the Canny edge detection algorithm can be used to detect the precise edges of head and facial features. Morphological operations can be used to optimize the contour of the segmented head region, removing small irrelevant areas or disconnected edges to extract the head and body contours. The Haar cascade classifier, deep learning object detection model, and background subtraction / threshold segmentation algorithm can be used to detect body position and head position, and determine the position of the nostrils. Next, the respiratory rhythm judgment unit is entered. First, Kalman filtering and optical flow method can be used to track the position of the ROI in the nostril area, calculate the average temperature value of the pixels in the ROI in real time, obtain the temperature time series signal, convert the temperature signal to the frequency domain, analyze the frequency components, and calculate the respiratory rate or rhythm. The obtained respiratory data is judged against the threshold to determine whether to generate an alarm signal. Based on the body position judgment and mode setting parameters, an ultrasonic excitation pulse is generated, and the pulse is reflected by the chest and abdomen to obtain an ultrasonic echo signal. Next, the unit for displacement identification and curve generation is entered to calculate the distance and displacement; Next, the respiratory and heart rate calculations are performed. The data is smoothed by removing high-frequency noise through low-pass filtering. The respiratory cycle is identified by detecting the peak and trough values ​​of the displacement waveform. The obtained respiratory data is compared with a threshold to determine whether to generate an alarm signal.

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