WO2017219604A1 - 一种呼吸检测方法 - Google Patents

一种呼吸检测方法 Download PDF

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WO2017219604A1
WO2017219604A1 PCT/CN2016/107858 CN2016107858W WO2017219604A1 WO 2017219604 A1 WO2017219604 A1 WO 2017219604A1 CN 2016107858 W CN2016107858 W CN 2016107858W WO 2017219604 A1 WO2017219604 A1 WO 2017219604A1
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fresnel zone
boundary
respiratory
layer
fresnel
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张大庆
王皓
吴丹
王亚沙
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Peking University
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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/08—Measuring devices for evaluating the respiratory organs
    • A61B5/0816—Measuring devices for examining respiratory frequency
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/05—Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/08—Measuring devices for evaluating the respiratory organs
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/72—Signal processing specially adapted for physiological signals or for diagnostic purposes
    • A61B5/7235—Details of waveform analysis
    • A61B5/725—Details of waveform analysis using specific filters therefor, e.g. Kalman or adaptive filters

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  • the invention relates to a breathing detection method, in particular to a method for detecting human breathing by using a radio frequency signal.
  • Breathing is an important vital sign of the human body and directly reflects the state of human health. Respiratory testing is critical for the early diagnosis and treatment of many diseases. Respiratory testing methods fall into two broad categories: contact and non-contact. The most traditional method is contact type, such as medical thoracic impedance scanners, etc., but it is expensive, intrusive, and must be carried at any time, and is difficult to use for long-term respiratory testing; currently non-contact based on RF signals Breathing detection has attracted people's attention. Compared with contact detection, it does not need to be carried or attached to any device, and RF signals (such as WiFi) have been widely used. It has the advantages of non-intrusive, convenient and low cost, especially suitable. Long-term respiratory testing.
  • the literature [1]-[4] records the feasibility study of detecting respiratory based on WiFi radio frequency signals, and designs the detection method and implements the corresponding detection system.
  • the common problem of the existing respiratory detection methods based on the WiFi radio frequency signal is that only the breathing of the human body at certain specific positions can be detected; that is, the human body breathing at different positions is detected, and some can be detected. Yes, some can't detect it.
  • the existing detection methods also fail to identify the detection blind zone, and cannot solve the problem of how to achieve optimal respiratory detection for different positions of the human body.
  • Wi-Sleep Contactless sleep monitoring via WiFi signals.
  • RTSS Real-Time Systems Symposium
  • the present invention provides a method for detecting a breath by using a radio frequency signal (RF) to detect human breathing, calibrating a position at which a human breath can be detected, and identifying a blind spot according to the position of the RF transceiver device.
  • RF radio frequency signal
  • RF means a radio frequency signal
  • Document 5 Hristo D Hristov. 2000. Fresnal Zones in Wireless Links, Zone Plate Lenses and Antennas. Artech House, Inc. describes a spatial Fresnel zone in which the RF signal distribution space is an elliptical hierarchical shape; In the present invention, the position of the RF transceiver device is an elliptical focus.
  • a spatial Fresnel zone of an elliptical hierarchical shape is constructed, which is a multi-layer space. When breathing in the middle of the Fresnel zone in each layer of space, it will cause a significant influence on the waveform of the received signal, which is conducive to the detection of respiratory frequency.
  • the waveform of the received signal When breathing in the boundary region of the Fresnel zone in each layer, the waveform of the received signal The effect is the weakest and is not conducive to respiratory frequency detection. Therefore, the vicinity of the middle region of each layer of the Fresnel zone is a position at which the human respiratory frequency can be detected; the vicinity of the boundary of each layer of the Fresnel zone is a position where the human body breathing is difficult to be detected (detection blind zone).
  • the elliptical focus of the Fresnel zone can be moved to make the human body position exactly in the vicinity of the middle region of the Fresnel zone of a certain layer of space, thereby realizing any given position.
  • the human body is tested for breathing.
  • the RF signal uses multi-carrier technology with different frequencies (for example, WiFi adopts orthogonal frequency division multiplexing OFDM technology)
  • the construction of the Fresnel zone spatial layout, the detectable range and the detection blind zone identification should be separately
  • the subcarriers of the frequencies are respectively determined and respectively applied to the above methods.
  • a method of respiratory detection includes the following steps:
  • the transceiver antenna used therein is a vertically polarized omnidirectional antenna
  • determining the RF transceiver device P1, P2 is an elliptical focus, determining an n-layer Fresnel zone;
  • the boundary of the determined n-layer Fresnel zone is a cluster of concentric ellipse with P1 and P2 as the focus;
  • the innermost ellipse is the boundary of the first Fresnel zone, and so on, the sub-inner ellipse is the boundary of the second Fresnel zone; determining the ellipse enclosed by the first and second Fresnel zone boundaries
  • the ring is the second Fresnel zone, and the elliptical ring formed by the boundary of the i-1th and i-th Fresnel zone is also determined by the analogy as the i-th Fresnel zone;
  • Scene 1 is the position of any given human body, adjust the position of the RF transceiver device to realize the breath detection;
  • scene 2 is the position of any given RF transceiver device, and calibrate the position where the human body breath can be detected; for different scenarios:
  • the optimal detection position can be obtained by further adjusting the positions of P1 and P2; specifically: further adjusting the positions of P1 and P2, so that: P1 and P2 are focused and passed through the human body position.
  • the inner normal direction of the ellipse at the position of the human body substantially coincides with the orientation of the human body, and the adjusted positions of P1 and P2 are the optimal detection conditions;
  • the original amplitude signal is preprocessed by using the Hamer filter and the moving average method, and then the peak frequency trough is calculated using the Fake Peak Removal method to obtain the respiratory frequency. statistics.
  • the RF signal uses multi-carrier technology with different frequencies (such as WiFi adopts orthogonal frequency division multiplexing OFDM technology)
  • the above method is used to construct the Fresnel zone spatial layout for each frequency subcarrier, and the human body breathing can be recognized. Detection range and undetectable blind spots, and then complete human respiratory testing.
  • the invention provides a method for detecting a breath, using a radio frequency signal to detect human breathing, according to a radio frequency signal (RF)
  • RF radio frequency signal
  • the position of the transceiver device calibrates the position at which the human breath can be detected, identifies the detection dead zone, and can detect the human body breathing for any given position by adjusting the position of the RF transceiver device.
  • the technical solution provided by the present invention can be applied to two typical scenarios: one is the position of any given human body, the position of the RF transceiver device is adjusted to realize the respiratory detection; the second is the position of any given RF transceiver device, and the calibration of the human body can be detected. s position. Therefore, the technical solution provided by the present invention can solve the problem of how to achieve optimal respiratory detection when the human body is in different positions.
  • the present invention does not require any human body to carry or abut against any device, and a radio frequency signal (such as WiFi) has been widely existed, the technical solution provided by the present invention has the advantages of non-intrusiveness, convenience, and low cost, and the detection result is determined to be reliable, in breathing.
  • the detection technology field has outstanding effects, especially suitable for long-term respiratory testing.
  • FIG. 1 is a flow chart of a method for breathing a human body according to an embodiment of the present invention.
  • the invention provides a method for detecting a breath, which uses a radio frequency signal to detect a human body breath, and calibrates a position at which a human body breath can be detected according to a position of a radio frequency signal (RF) transceiver device, and can adjust the position of the RF transceiver device to achieve any The position of the human body is tested for breathing.
  • RF radio frequency signal
  • the transmitting and receiving antenna used therein is a vertically polarized omnidirectional antenna
  • the transmitting and receiving antennas are placed vertically on the ground.
  • the transmitting and receiving antennas are placed parallel to the ground.
  • the determined RF transceiver devices P1 and P2 are elliptical focal points, and the n-layer Fresnel zone is determined by B1 to B3, from the inner layer to the outer layer respectively being the first Fresnel zone to the nth Fresnel zone; Need n can take any natural number, depending on the range of interest, the larger n, the farther the Fresnel zone is from the transceiver;
  • the boundary of the determined n-layer Fresnel zone is a cluster of concentric ellipse with P1 and P2 as the focus;
  • the RF signal distribution space is an elliptical hierarchical space Fresnel zone
  • Equation 1 shows The trajectory Qi of the i-th layer concentric ellipse of the spatial Fresnel zone.
  • the innermost ellipse (the trajectory of the first layer of concentric ellipse) is the boundary of the first Fresnel zone (the innermost ellipse is the trajectory determined by Q1 according to the B2 formula; the elliptical boundary formed by the innermost ellipse surrounds The area is the 1st Fresnel zone), and so on, the sub-inner ellipse (the second layer of concentric ellipse) is the boundary of the 2nd Fresnel zone; the boundary between the 1st and 2nd Fresnel zone is set The elliptical ring is the second Fresnel zone, and so on, the elliptical ring surrounded by the i-1th and i-th Fresnel zone boundaries is the i-th Fresnel zone; C. Scene one is arbitrary Position the human body, adjust the position of the RF transceiver device to achieve respiratory detection; scenario 2 is the position of any given
  • the positions of P1 and P2 are further adjusted such that: P1 and P2 are the focal points and the ellipse of the human body position, and the inner normal direction of the ellipse at the human body position is The human body faces roughly coincident, which is the best detection condition.
  • the following embodiment uses a WiFi signal with a center frequency of 5.24 GHz as the RF signal, and since WiFi uses OFDM technology, there are 56 subcarriers of different frequencies.
  • the method mentioned in the present invention is applied separately for each subcarrier. Taking the central subcarrier signal of 5.24 GHz as an example, the wavelength ⁇ of the subcarrier signal is 5.725 cm.
  • the TP-Link WDR5300 equipped with a WiFi omnidirectional antenna is used.
  • the router acts as an RF transmitting device.
  • n is set to 50 for a room space of 4 mx 3 m, and each set of fixed bits for the RF transceiver device
  • the position of the first Fresnel zone to the 50th Fresnel zone and the boundary of the 1st Fresnel zone to the 50th Fresnel zone at this position can be obtained; the human body is located in the 1st Fresnel zone ⁇ Within the 50th Fresnel zone, the human respiratory rate can be detected.
  • the spatial Fresnel zone of the RF signal is set to 50 Fresnel zone in this embodiment:
  • the boundary of the determined n-layer Fresnel zone is a cluster of concentric ellipse with P1 and P2 as the focus;
  • n is set to 50, Obtaining a boundary from the first Fresnel zone to the 50th Fresnel zone and the boundary of the first Fresnel zone to the 50th Fresnel zone;
  • Scene 1 is the position of any given human body, adjusting the position of the RF transceiver device to achieve respiratory detection;
  • scene 2 is the position of any given RF transceiver device, calibrating the position where human breathing can be detected; performing C1 for different scenarios or C2:
  • the vertical line of the RF transceiver device As an example:
  • the vicinity of the middle region of each Fresnel zone is calibrated, that is, the region where the breath can be detected; in this embodiment,
  • the inner layer is the outer layer, taking the mid-perpendicular line of the transceiver device as an example.
  • the best detection area is located at 14.5cm, 19cm (the first Fresnel zone and the second The middle area of the Fresnel zone); the vicinity of the boundary of each Fresnel zone is calibrated, that is, the area where the breathing is difficult to detect, also from the inner layer to the outer layer, the vertical line of the transceiver line is For example, the undetectable area is located at 12 cm, 17 cm, and the like.
  • the positions of P1 and P2 are further adjusted such that: P1 and P2 are the focal points and the ellipse of the human body position, and the inner normal direction of the ellipse at the human body position is The human body orientation is approximately coincident within 10 degrees, which is the best detection condition.
  • the method described in [1] can be used to first preprocess the original amplitude signal by using a Hample filter with a window size of 5 seconds and a moving average method with a window size of 20 seconds, and then use Fake Peak.
  • the removal method counts the number of peaks and troughs, and the respiratory frequency can be statistically obtained.

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Abstract

一种呼吸检测的方法，可标定人体呼吸可被检测的位置，可通过调整RF收发设备的位置，利用RF检测任意位置的人体呼吸。包括：放置无线射频信号收发设备、获得收发设备所确定的菲涅耳区的空间布局、使人体处于菲涅耳区空间布局中某个菲涅耳区的中间区域、根据接收端接收到无线射频信号计算得到呼吸频率。该方法能够解决当人体处于不同位置时如何实现最佳的呼吸检测的问题。此外，无需人体携带或贴靠任何设备，具有非侵扰性、方便、低成本的优点，检测结果确定可靠，在呼吸检测技术领域具有突出效果，尤其适合长期的呼吸检测。

Description

一种呼吸检测方法 技术领域
本发明涉及呼吸检测方法，尤其涉及一种利用射频信号检测人体呼吸的方法。
背景技术
呼吸是人体重要生命体征，直接反应人体健康状态。呼吸检测对于许多疾病的早期诊断、治疗非常关键。呼吸检测方法大致分为两类：接触式和非接触式。最传统的方法是接触式，例如医用的胸阻抗扫描器等穿戴设备，但是面临价格高昂、有侵扰性、且必须随时贴身携带等困难，难以用于长期呼吸检测；目前基于射频信号的非接触式呼吸检测受到人们的关注，相比于接触式检测，它无需人体携带或贴靠任何设备，且射频信号(如WiFi)已经广泛存在，具有非侵扰性、方便、低成本的优点，尤其适合长期的呼吸检测。
在非接触式呼吸检测技术方面，文献[1]-[4]记载了基于WiFi射频信号检测呼吸的可行性研究，并设计检测方法和实现了相应的检测系统。但是，现有这些基于WiFi射频信号的呼吸检测方法存在的共性问题是：只能检测到人体处于某些特定位置时的呼吸；也就是，对处于不同位置的人体呼吸进行检测，有的能够检测到，有的却检测不到。现有检测方法也无法识别出检测盲区，无法解决针对人体处于不同位置情况下如何实现最佳的呼吸检测的问题。
引用文献：
[1]Jian Liu,Yan Wang,Yingying Chen,Jie Yang,Xu Chen,and Jerry Cheng.2015.Tracking Vital Signs During Sleep Leveraging Off-the-shelf WiFi.In Proceedings of the 16th ACM International Symposium on Mobile Ad Hoc Networking and Computing.ACM,267–276.
[2]Xuefeng Liu,Jiannong Cao,Shaojie Tang,and Jiaqi Wen.2014.Wi-Sleep:Contactless sleep monitoring via WiFi signals.In Real-Time Systems Symposium(RTSS),2014IEEE.IEEE,346–355.
[3]Xuefeng Liu,Jiannong Cao,Shaojie Tang,Jiaqi Wen,and Peng Guo.2016.Contactless Respiration Monitoring via WiFi Signals.Mobile Computing,IEEE Transactions on(2016).
[4]Chenshu Wu,Zheng Yang,Zimu Zhou,Xuefeng Liu,Yunhao Liu,and Jiannong Cao.2015.Non-Invasive Detection of Moving and Stationary Human With WiFi.Selected Areas in Communications,IEEE Journal on 33,11(2015),2329–2342.
发明内容
为了克服上述现有技术的不足，本发明提供一种呼吸检测的方法，利用无线射频信号(RF)检测人体呼吸，根据RF收发设备的位置标定人体呼吸可被检测的位置和识别出检测盲区，可通过调整RF收发设备的位置，实现针对任意给定位置的人体呼吸进行检测。
为了便于说明，本文约定：“RF”表示无线射频信号。
本发明的原理是：文献5(Hristo D Hristov.2000.Fresnal Zones in Wireless Links,Zone Plate Lenses and Antennas.Artech House,Inc.)记载了RF信号分布空间为椭圆层次形状的空间菲涅耳区；本发明以RF收发设备的位置为椭圆焦点，依据上述文献5记载，构建椭圆层次形状的空间菲涅耳区，是一个多层空间。在每一层空间菲涅尔区中间区域呼吸时，会对接收信号波形引起显著的影响模式，利于呼吸频率检测；而在每一层空间菲涅尔区边界区域呼吸时，对接收信号的波形的影响是最微弱的，不利于呼吸频率检测。因此每一层空间菲涅耳区的中间区域附近为人体呼吸频率可被检测的位置；每一层空间菲涅耳区的边界附近为人体呼吸难以被检测的位置(检测盲区)。可通过调整RF收发设备的位置，达到调整椭圆焦点继而调整空间菲尼尔区布局的目的。为了在给定人体位置下检测人体呼吸频率，可通过移动空间菲涅耳区的椭圆焦点使得人体所处位置正好落在某一层空间菲涅耳区中间区域附近，从而实现针对任意给定位置的人体呼吸进行检测。若RF信号采用不同频率的多载波技术(如WiFi采用正交频分多路复用OFDM技术)，则上述菲涅尔区空间布局的构建、可检测范围与检测盲区的识别，要分别针对每个频率的子载波分别确定并分别适用上述方法。最后具体可根据文献[1]-[4]的记载的任一检测方法，针对接收信号，对波形进行预处理后，计算得到波峰波谷的数量，即为人体呼吸次数。
本发明提供的技术方案如下：
一种呼吸检测的方法，包括如下步骤：
A.确定获得装有至少一根发射天线和至少一根天线的RF收发设备P1,P2，以及该RF的波长λ；
A1.其中使用的收发天线是垂直极化的全向天线；
A2.若人体胸脯垂直于地面，则收发天线垂直地面摆放；
A3.若人体胸脯平行于地面，则收发天线平行地面摆放；
B.以确定的RF收发设备P1,P2为椭圆焦点，确定n层菲涅耳区；
B1.确定的n层菲涅耳区的边界是以P1,P2为焦点的一簇同心椭圆；
B2.令Qi是第i层同心椭圆的轨迹，则Qi的轨迹满足：
|P1Qi|+|QiP2|-|P1P2|＝nλ/2       (式1)
其中，|P1Qi|是Qi到发射设备P1的距离；|QiP2|是Qi到接收设备P2的距离；|P1P2|为收发设备的距离；λ为RF收发设备的波长；n为菲涅尔区的最大层数，可根据实际情况设置取值；
B3.确定最内层椭圆是第1菲涅耳区的边界，以此类推，次内层椭圆是第2菲涅耳区的边界；确定第1和第2菲涅耳区边界围成的椭圆环是第2菲涅耳区，同样以此类推确定第i-1和第i菲涅耳区边界围成的椭圆环是第i菲涅耳区；
C.场景一是任意给定人体的位置，调整RF收发设备的位置实现呼吸检测；场景二是任意给定RF收发设备的位置，标定人体呼吸可被检测的位置；针对不同场景：
C1.针对场景一，调整P1,P2位置从而调整菲涅耳区的空间布局，使得新的空间布局下，人体位置刚好处于某个菲涅耳区的中间区域附近；
C2.针对场景二，根据P1和P2位置所确定的菲涅耳区的空间布局，标定每一层菲涅耳区的中间区域附近，即为呼吸可被检测的区域；标定每一层菲涅耳区的边界附近，即为呼吸难以被检测的区域；
D.针对C1所述场景一条件满足的情况下，可通过进一步调整P1和P2位置获得最佳检测位置；具体是：进一步调整P1和P2位置，使得：以P1和P2为焦点并过人体位置的椭圆在人体位置处的内侧法线方向与人体朝向大致重合，调整得到的P1和P2位置即为最佳检测条件；
E.呼吸频率计算；
以文献[1]记载的方法为例，首先利用Hample滤波器和滑动平均方法对原始振幅信号进行预处理，然后使用伪波峰/波谷去除(Fake Peak Removal)方法统计波峰波谷即可获得呼吸频次的统计。
当RF信号采用不同频率的多载波技术(如WiFi采用正交频分多路复用OFDM技术)时，分别针对每个频率的子载波采用上述方法构建菲涅尔区空间布局，识别人体呼吸可检测范围和不可检测的盲区，再完成人体呼吸检测。
与现有技术相比，本发明的有益效果是：
本发明提供一种呼吸检测的方法，利用射频信号检测人体呼吸，根据无线射频信号(RF) 收发设备的位置标定人体呼吸可被检测的位置，识别出检测盲区，并可通过调整RF收发设备的位置，实现针对任意给定位置的人体呼吸进行检测。
本发明提供的技术方案可应用在两种典型场景：一是任意给定人体的位置，调整RF收发设备的位置实现呼吸检测；二是任意给定RF收发设备的位置，标定人体呼吸可被检测的位置。因此，本发明提供的技术方案能够解决当人体处于不同位置时如何实现最佳的呼吸检测的问题。此外，由于本发明无需人体携带或贴靠任何设备，且射频信号(如WiFi)已经广泛存在，本发明提供的技术方案具有非侵扰性、方便、低成本的优点，检测结果确定可靠，在呼吸检测技术领域具有突出效果，尤其适合长期的呼吸检测。
附图说明
图1本发明实施例提供的人体呼吸方法的流程框图。
具体实施方式
下面结合附图，通过实施例进一步描述本发明，但不以任何方式限制本发明的范围。
本发明提供一种呼吸检测的方法，利用射频信号检测人体呼吸，根据无线射频信号(RF)收发设备的位置标定人体呼吸可被检测的位置，可通过调整RF收发设备的位置，实现针对任意给定位置的人体呼吸进行检测。本发明的具体实施方式如下：
A.放置射频信号收发设备，确定获得装有至少一根发射天线和至少一根接收天线的RF收发设备P1和P2，该RF收发设备的波长为λ；RF收发设备可以是笔记本电脑、MiniPC以及任何支持RF信号收发的设备；
A1.其中使用的收发天线是垂直极化的全向天线
A2.若人体胸脯垂直于地面，则收发天线垂直地面摆放
A3.若人体胸脯平行于地面，则收发天线平行地面摆放
B.以确定的RF收发设备P1和P2为椭圆焦点，通过B1～B3确定n层菲涅耳区，由内层到外层分别为第1菲涅耳区到第n菲涅耳区；根据需要n可取任意自然数，取决于关注的范围，n越大，该层菲涅尔区距离收发设备越远；
B1.确定的n层菲涅耳区的边界是以P1和P2为焦点的一簇同心椭圆；
B2.令Qi是第i层同心椭圆的轨迹，则Qi的轨迹满足式1：
|P1Qi|+|QiP2|-|P1P2|＝nλ/2     (式1)
其中，|P1Qi|是Qi到发射设备P1的距离；|QiP2|是Qi到接收设备P2的距离；|P1P2|为收发设备的距离；λ为RF收发设备的波长；n为菲涅尔区的最大层数，可根据实际情况设置取值。
根据文献5(Hristo D Hristov.2000.Fresnal Zones in Wireless Links,Zone Plate Lenses and Antennas.Artech House,Inc.)中记载的RF信号分布空间为椭圆层次形状的空间菲涅耳区，式1表示了空间菲涅耳区第i层同心椭圆的轨迹Qi。
B3.设定最内层椭圆(第1层同心椭圆的轨迹)是第1菲涅耳区的边界(最内层椭圆是由Q1根据B2式确定的轨迹；最内层椭圆形成的椭圆边界围绕的区域是第1菲涅耳区)，以此类推，次内层椭圆(第2层同心椭圆)是第2菲涅耳区的边界；设定第1和第2菲涅耳区边界围成的椭圆环是第2菲涅耳区，同样以此类推，设定第i-1和第i菲涅耳区边界围成的椭圆环是第i菲涅耳区；C.场景一是任意给定人体的位置，调整RF收发设备的位置实现呼吸检测；场景二是任意给定RF收发设备的位置，标定人体呼吸可被检测的位置；针对不同场景：
C1.针对场景一，调整P1和P2位置从而调整菲涅耳区的空间布局，使得新的空间布局下，人体刚好处于某个菲涅耳区的中间区域附近；
C2.针对场景二，根据P1,P2位置所确定的菲涅耳区的空间布局，标定每一层菲涅耳区的中间区域附近，即为呼吸可被检测的区域；标定每一层菲涅耳区的边界附近，即为呼吸难以被检测的区域。
D.针对C1所述场景(1)条件满足的情况下，进一步调整P1,P2位置，使得：以P1,P2为焦点并过人体位置的椭圆，该椭圆在人体位置处的内侧法线方向与人体朝向大致重合，即为最佳检测条件。
E.呼吸频率计算，利用文献[1]记载的呼吸频率计算方法，对接收端接收到信号的波形进行预处理后，计算波峰波谷的数量，即对应呼吸次数。
以下实施例使用中心频率为5.24GHz的WiFi信号作为RF信号，由于WiFi采用OFDM技术，对应有56个不同频率的子载波。在本实施例中，每一个子载波单独适用本发明专利提及的方法。以5.24GHz的中心子载波信号为例，该子载波信号的波长λ为5.725cm；使用搭载WiFi全向天线、WiFiIntel 5300网卡的MiniPC作为RF接收设备，使用搭载WiFi全向天线的TP-Link WDR5300路由器作为RF发射设备。
本实施例中，针对4mx3m的房间空间设定n等于50，针对RF收发设备的每一组固定位 置，均可得到该位置下的第1菲涅耳区～第50菲涅耳区和第1菲涅耳区的边界～第50菲涅耳区的边界；人体位于第1菲涅耳区～第50菲涅耳区范围内，即可检测获得人体呼吸频率。
以4mx3m的房间为例，根据本发明提供的呼吸检测方法，执行如下步骤：
A.将RF接收设备(MiniPC)上的接收天线垂直地面放置，该设备的位置标记为P1；将RF发射设备的路由器(TP-Link WDR5300路由器)上的发射天线垂直地面放置，该设备的位置标记为P2；设定P1与P2的间距为1m，人体胸脯垂直于地面(人体坐着或站立)；
B.以P1和P2为椭圆焦点，在4m×3m的房间，本实施例设定RF信号的空间菲涅耳区为50层菲涅耳区：
B1.确定的n层菲涅耳区的边界是以P1和P2为焦点的一簇同心椭圆；
B2.令Qi是第i层同心椭圆的轨迹，则Qi的轨迹满足式1；
B3.确定最内层椭圆是第1菲涅耳区的边界，以此类推，次内层椭圆是第2菲涅耳区的边界；确定第1和第2菲涅耳区边界围成的椭圆环是第2菲涅耳区，同样以此类推确定第i-1和第i菲涅耳区边界围成的椭圆环是第i菲涅耳区；本实施例中设定n等于50，可得到第1菲涅耳区～第50菲涅耳区和第1菲涅耳区的边界～第50菲涅耳区的边界；
C.场景一是任意给定人体的位置，调整RF收发设备的位置实现呼吸检测；场景二是任意给定RF收发设备的位置，标定人体呼吸可被检测的位置；针对不同场景分别执行C1或C2：
C1.针对场景一，调整P1和P2位置，从而调整菲涅耳区的空间布局，使得新的空间布局下，人体刚好处于某个菲涅耳区的中间区域；
具体地，从内层向外层，以RF收发设备连线的中垂线为例：
(a)假设人此时位于RF收发设备连线的中垂线的第14.9cm处，即处于第2菲涅耳区的中间区域，则可直接测量呼吸；
(b)假设人此时位于RF收发设备连线的中垂线的第12cm处，即处于第1菲涅耳区的边界附近，则调整P1和P2的位置，使得在新的菲涅耳区布局中，人体刚好处于某个菲涅耳区的中间区域附近即可。
C2.针对场景二，根据P1和P2位置所确定的菲涅耳区的空间布局，标定每一层菲涅耳区的中间区域附近，即为呼吸可被检测的区域；本实施例中，从内层向外层，以收发设备连线的中垂线为例，最佳检测区域依次位于14.5cm、19cm(第1菲涅耳区和第2 菲涅耳区的中间区域)等处；标定每一层菲涅耳区的边界附近，即为呼吸难以被检测的区域，同样从内层向外层，以收发设备连线的中垂线为例，无法检测区域依次位于12cm、17cm等处。
D.针对C1所述场景(1)条件满足的情况下，进一步调整P1,P2位置，使得：以P1,P2为焦点并过人体位置的椭圆，该椭圆在人体位置处的内侧法线方向与人体朝向大致重合在10度以内，即为最佳检测条件。
E.呼吸频率计算，可采用文献[1]记载的方法，首先依次利用窗口大小为5秒的Hamplel滤波器和窗口大小为20秒的滑动平均方法对原始振幅信号进行预处理，然后使用Fake Peak Removal方法统计波峰波谷数量，即可统计获得呼吸频次。
需要注意的是，公布实施例的目的在于帮助进一步理解本发明，但是本领域的技术人员可以理解：在不脱离本发明及所附权利要求的精神和范围内，各种替换和修改都是可能的。因此，本发明不应局限于实施例所公开的内容，本发明要求保护的范围以权利要求书界定的范围为准。

Claims (10)

  1. 一种呼吸检测的方法，包括如下步骤：
    A)放置无线射频信号收发设备，包括发射设备P1和接收设备P2，所述发射设备P1装有至少一根发射天线；所述接收设备P2装有至少一根接收天线；所述无线射频信号的波长设为λ；所述发射天线和接收天线是垂直极化的全向天线；
    B)以所述收发设备P1和P2为椭圆焦点，以P1和P2为焦点的一簇同心椭圆构成多层菲涅耳区的边界，每两层相邻的菲涅耳区的边界所围成的椭圆环为一层菲涅耳区，由此得到所述收发设备P1和P2所确定的菲涅耳区的空间布局；所述菲涅耳区的空间布局包括多层菲涅耳区；
    C)根据P1和P2位置所确定的菲涅耳区的空间布局，标定每一层菲涅耳区的中间区域附近为呼吸可被检测的区域；标定每一层菲涅耳区的边界附近为呼吸难以被检测的区域；
    D)当人体处于所述难以被检测的区域时，调整P1和P2的位置从而调整菲涅耳区的空间布局，使得人体位置处于新的菲涅耳区空间布局中某个菲涅耳区的中间区域；
    E)接收端接收到无线射频信号，根据所述无线射频信号的波形，计算得到呼吸频率，完成呼吸检测。
  2. 如权利要求1所述呼吸检测的方法，其特征是，在B)所述以P1和P2为焦点的一簇同心椭圆中，设定所述菲涅耳区的空间布局包括n层菲涅耳区，设定n层菲涅耳区的第i层同心椭圆的轨迹为Qi，所述Qi通过式1得到：
    |P1Qi|+|QiP2|-|P1P2|＝nλ/2            (式1)
    式1中，|P1Qi|是Qi到发射设备P1的距离；|QiP2|是Qi到接收设备P2的距离；|P1P2|为收发设备的距离；λ为RF收发设备的波长；n为菲涅尔区的最大层数。
  3. 如权利要求2所述呼吸检测的方法，其特征是，在B)中，设定第1层同心椭圆的轨迹是第1菲涅耳区的边界，由第1菲涅耳区的边界形成的椭圆边界围绕的区域是第1菲涅耳区；以此类推，第2层同心椭圆是第2菲涅耳区的边界；设定第1菲涅耳区边界和第2菲涅耳区边界围成的椭圆环是第2菲涅耳区；同样以此类推，设定第i层同心椭圆是第i菲涅耳区的边界；设定第i-1菲涅耳区边界和第i菲涅耳区边界围成的椭圆环为第i菲涅耳区；由此得到所述收发设备P1和P2所确定的菲涅耳区的空间布局。
  4. 如权利要求1所述呼吸检测的方法，其特征是，在D)中，当人体胸脯垂直于地面时， P1和P2的天线垂直地面摆放；当人体胸脯平行于地面时，P1和P2的天线平行地面摆放。
  5. 如权利要求1所述呼吸检测的方法，其特征是，在D)中，优选地，通过进一步调整P1和P2位置获得最佳检测条件；具体是：进一步调整P1和P2位置，使得：以P1和P2为焦点并过人体位置的椭圆在人体位置处的内侧法线方向与人体朝向大致重合，调整得到的P1和P2位置即为最佳检测条件。
  6. 如权利要求1所述呼吸检测的方法，其特征是，在E)中所述计算呼吸频率采用文献[1](Jian Liu,Yan Wang,Yingying Chen,Jie Yang,Xu Chen,and Jerry Cheng.2015.Tracking Vital Signs During Sleep Leveraging Off-the-shelf WiFi.In Proceedings of the 16th ACM International Symposium on Mobile Ad Hoc Networking and Computing.ACM,267–276.)记载的呼吸频率计算方法，计算得到呼吸频率。
  7. 如权利要求6所述呼吸检测的方法，其特征是，所述计算得到呼吸频率，首先利用Hamplel滤波器和滑动平均方法对无线射频信号进行预处理，然后利用Fake Peak Removal方法统计波峰波谷数目，由此获得呼吸频率。
  8. 如权利要求1所述呼吸检测的方法，其特征是，使用搭载WiFi全向天线、WiFiIntel 5300网卡的MiniPC作为无线射频信号接收设备。
  9. 如权利要求1所述呼吸检测的方法，其特征是，使用搭载WiFi全向天线的TP-Link WDR5300路由器作为无线射频信号发射设备。
  10. 如权利要求1所述呼吸检测的方法，其特征是，当无线射频信号采用不同频率的多载波技术时，分别针对每个频率的子载波构建子载波的菲涅尔区空间布局，根据子载波的菲涅尔区空间布局识别人体呼吸可检测范围和不可检测的盲区；由此完成人体呼吸检测。
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