CN103315741B - Respiration monitoring method based on wireless link information - Google Patents

Abstract

The invention provides a respiration monitoring method based on wireless link information, belongs to the fields of health monitoring, patient and the old caring, wireless communication and wireless networks and relates to non-contact respiration monitoring method based on the wireless link information. The respiration monitoring method comprises the steps of utilizing multiple wireless links formed by multiple wireless scanning nodes and distributed on the periphery of a bed, monitoring periodic influence of human body respiration to the signal strength of the multiple wireless links to estimate a change cycle of the signal strength of the wireless links and then estimating respiratory rate of a human body. A system adopted by the respiration monitoring method consists of N wireless scanning nodes, wireless convergence nodes, a universal personal computer (PC), a respiratory rate monitoring method and the bed for bearing a human body. The respiration monitoring method adopts non-contact monitoring, does not need any facility installed on a monitored human body, enables the monitoring system to be humanized and is suitable for monitoring of infants and postoperative patients, and a non-contact monitoring technology has wide application prospect.

Description

Monitoring of respiration method based on wireless link information

Technical field

The invention belongs to health monitoring, patient and old man's monitoring, radio communication and field of wireless, relate to a kind of contactless monitoring of respiration method based on wireless link information.

Background technology

Respiratory frequency monitoring has very important using value in people's daily life.Marked feature when numerous patients with severe symptoms are critically ill is respiratory frequency generation larger fluctuation, and therefore, hospital need to carry out monitoring of respiration to critically ill patient, thereby effectively monitors the generation of accident.Obstructive sleep apnea syndrome is the common chronic disease that a kind of sickness rate is higher, harm is larger, utilizes custodial care facility to monitor reliably patient's respiratory frequency, and this sick clinical prevention is had very important significance.Because standing up, to cause dyspnea be a key factor that causes baby's life danger to baby, and therefore, family is necessary baby's breathing to monitor, thereby understands better baby's sleep state.Monitoring of respiration is with a wide range of applications in medical treatment and health monitoring field.

Current existing monitoring of respiration technology is all based on carbon dioxide monitoring technology, and this scheme is installed suction pipe to children under guardianship's nostril, and while utilizing human body respiration, the variation of carbon dioxide carrys out the respiratory frequency of monitoring human.Related work, as, P.Sebel, M.Stoddart, waits people's " Respiration:The Breath of Life ", Torstar Books, 1985; Ou Qiong etc. " the application comparisons of portable sleep monitoring and two kinds of methods of sleep analysis monitor ", foreign medical science, respiratory system fascicle, 2005, the 25 volumes, P562-P565 page.Such technical monitoring result is more accurate, still, breathing catheter need to be installed to people's nose, inconvenience is installed, and baby is difficult to use.

In recent years, along with the development of wireless technology, radio node has obtained applying more and more widely cheaply.Due to the inherent character of electric wave, meeting crested when electric wave passes human body, thus received signal strength is changed.When the volume of human body changes, the wireless link of crested can change, thereby causes link signal intensity to change.People's breathing causes the cyclically-varying of body size, and then causes the cyclically-varying through the wireless link signals intensity of human body; Therefore, can utilize the cycle variation characteristic of wireless link signals intensity to estimate the periodic law of link change, realize the estimation of respiratory frequency.

Summary of the invention

The object of the invention is to overcome the defect of prior art, invent a kind of contactless breathing state monitoring method based on wireless link information, utilize wireless measurement signal between each radio node as input message, by estimating that wireless link signals intensity cyclically-varying rule realizes the technology that people's respiratory frequency is estimated.For utilizing the respiratory frequency information through the multi wireless links signal sensing human body of human body, realize the contactless monitoring to patient and sleeping condition of baby.

Technical scheme of the present invention is a kind of monitoring of respiration method based on wireless link information, it is characterized in that, this monitoring method is utilized N multi wireless links that is arranged in the wireless scan node formation of a surrounding, by monitoring human breathing, the periodicity of multi wireless links signal intensity is affected, estimate the period of change of wireless link signals intensity, and then estimate the respiratory frequency of human body; The concrete steps of monitoring of respiration method are:

1) N wireless scan node J1-JN is arranged in to the surrounding of bed, placing height is higher than bed, so that wireless signal passes from human body; A plurality of wireless scan nodes be responsible for taking turns each radio node of scan flow to and each wireless link signals strength information measuring is sent to wireless aggregation node 1; The radio communication operating frequency of wireless scan node, power can regulate, battery and external power power supply, and wideband omnidirectional antenna, apart from ground, regulating is highly 0.3m to 1.5m;

2) wireless aggregation node 1 is collected all wireless link metrical informations, and is sent to general purpose PC 2; On general purpose PC 2, the respiratory frequency algorithm for estimating of operation, judges respiratory frequency based on link metrical information; The radio communication operating frequency of wireless aggregation node 1 can regulate, battery and external power power supply, and wideband omnidirectional antenna, has USB interface or the USB (universal serial bus) of carrying out transfer of data with universal PC, apart from ground, regulates height 0.3m to 1.5m;

3) utilize the cycle variation characteristic of wireless link signals intensity to estimate the periodic law of link change, realize the estimation of respiratory frequency; Respiratory frequency algorithm for estimating: algorithm is usingd wireless link received signal strength information as input message, estimates the change in signal strength cycle, the respiratory frequency of output estimation; Suppose that each wireless scan node of current time forms L wireless links altogether, the change in signal strength of each link is every link has gathered N signal strength data altogether, and the human body respiration frequency F of current time can adopt following formula to estimate:

$\text{F=arg}{\max }_F\underset{l=1}{\overset{L}{\mathrm{\Σ}}}\left|\underset{n=i-N+1}{\overset{i}{\mathrm{\Σ}}}{R}_l^n{e}^{-j2\mathrm{\πFTn}}\right|$

Wherein, F _max> F > F _min, F _maxfor maximum breathing frequency, be generally 50, F _minfor minimum respiratory frequency, be generally 8; Respiratory frequency algorithm for estimating, by multi wireless links signal strength information is done to Fourier transformation, is analyzed its frequency domain spectral characteristic, finds out the frequency numerical value that power spectrum peak is corresponding, thereby finds out the respiratory frequency of human body;

4) the respiratory frequency algorithm for estimating moving on universal PC is usingd wireless link received signal strength information as input message, by analyzing the frequency domain spectral characteristic of multi wireless links signal strength information, estimate the change in signal strength cycle, the respiratory frequency of output estimation is found out the frequency numerical value that power spectrum peak is corresponding; More than adopting the dominant frequency 1GHz of general purpose PC, more than internal memory 256M, there is USB interface or the USB (universal serial bus) of carrying out transfer of data with wireless aggregation node;

5) workflow: general purpose PC send start monitoring order to wireless aggregation node 1, wireless aggregation node 1 each wireless scan node of order is started working, each wireless scan node starts to carry out without line sweep afterwards, and the signal strength information of each wireless links is sent to wireless aggregation node; Wireless aggregation node is sent to general purpose PC by the signal strength information of each wireless links, and the signal strength information of the respiratory frequency Estimation Software of moving on general purpose PC based on wireless link, estimates human body respiration frequency, realizes the estimation to human body respiration frequency.

The described monitoring of respiration method based on wireless link information, it is characterized in that: the system that monitoring method adopts is by N wireless scan node J1 ... JN, wireless aggregation node 1, general purpose PC 2, respiratory frequency algorithm for estimating and form for carrying the bed 3 of human body, respiratory frequency algorithm for estimating is arranged on general purpose PC (2).

Beneficial effect of the present invention is: 1) can utilize wireless measurement signal to realize the estimation to human body respiration frequency; 2) can realize contactless respiratory frequency measures; 3) monitoring system is convenient to Fast Installation layout, convenient disassembly; 4) equipment is comprised of a plurality of cheap radio nodes, and cost is low.

Accompanying drawing explanation

Fig. 1 is system architecture diagram of the present invention, in figure: J1-the 1st wireless scan node, J2-the 2nd wireless scan node, J3-the 3rd wireless scan node, J4-the 4th wireless scan node, J5-the 5th wireless scan node, J6-the 6th wireless scan node, J7-the 7th wireless scan node, J8-the 8th wireless scan node, J9-the 9th wireless scan node, J10-the 10th wireless scan node, 1-is wireless aggregation node, 2-general purpose PC, 3-bed

Fig. 2 is respiratory frequency algorithm for estimating flow chart.

The specific embodiment

Below in conjunction with technical scheme and accompanying drawing, specifically elaborate enforcement of the present invention, but the present invention is not limited to specific embodiment.A kind of method of utilizing wireless signal monitoring human breathing frequency of the present invention, utilizes the signal strength information of multi wireless links, by analyzing the cyclically-varying rule of wireless link signals strength information, estimates the respiratory frequency of human body.

Embodiment: accompanying drawing 1 is system architecture diagram of the present invention, system has 10 wireless scan node J1, J10, wireless scan node and wireless aggregation node 1 be the CC2520 chip design based on Texas Instruments all, meet Zigbee industrial standard, be operated in 2.45GHz frequency range, adopt battery powered, spider supports, height 0.3m to 1.5m scalable.10 wireless scan nodes are placed on for carrying four limits of the bed 3 of human body, spacing 0.6m, placing height is a little more than bed 13cm, to guarantee that wireless signal is as much as possible through human body.Wireless aggregation node 1 and general purpose PC 2 are placed on distance bed 3m place, and wireless aggregation node 1 is collected all wireless link metrical informations, and is sent to general purpose PC 2; On general purpose PC 2, the respiratory frequency algorithm for estimating of operation, judges respiratory frequency based on link metrical information.The radio communication operating frequency scalable of wireless aggregation node 1, by battery and external power power supply wideband omnidirectional antenna, has USB interface or the USB (universal serial bus) of carrying out transfer of data with universal PC, apart from ground, regulates height 0.3m to 1.5m.Each is wireless scan node J1 ... J10 forms queue, broadcast transmission wireless signal successively, and other is the wireless scan node J1 of transmitted signal not ... J10 receives the wireless signal that sending node current time sends, and measures received signal strength information.The received signal strength information of other wireless scan node that the information of each is wireless scan node J1....J10 broadcast receives while being last round of scanning separately, namely go up the signal strength information of each wireless link of the moment.

Accompanying drawing 2 is respiratory frequency algorithm for estimating flow charts, when general purpose PC 2 send start monitoring order to wireless aggregation node 1, each wireless scan node of wireless aggregation node order is started working, each wireless scan node starts to carry out without line sweep afterwards, and the signal strength information of each wireless links is sent to wireless aggregation node; Wireless aggregation node is sent to general purpose PC by the signal strength information of each wireless links, the signal strength information of the respiratory frequency Estimation Software of moving on general purpose PC based on wireless link done Fourier transformation to wireless link information, hunt out the most significant cycle variation characteristic, and then estimate human body respiration frequency, realize the estimation to human body respiration frequency.

Wireless aggregation node 1 is intercepted the wireless signal information of each wireless link, and the received signal strength information of each wireless link is delivered to general purpose PC 2.On general purpose PC 2, the respiratory frequency algorithm for estimating of operation is usingd wireless link metrical information as input, signal is carried out to spectrum transformation analysis, estimate the power spectrum of wireless link measuring-signal, find out the frequency that power spectrum peak is corresponding, this frequency is human body respiration frequency.Respiratory frequency algorithm for estimating exports the human body respiration frequency information of calculating to general purpose PC 2 screens.

According to respiratory frequency algorithm for estimating, algorithm is usingd wireless link received signal strength information as input message, estimates the change in signal strength cycle, the respiratory frequency of output estimation; Suppose that each wireless scan node of current time forms L wireless links altogether, the change in signal strength of each link is every link has gathered N signal strength data altogether, and the human body respiration frequency F of current time can adopt following formula to estimate:

$\text{F=arg}{\max }_F\underset{l=1}{\overset{L}{\mathrm{\Σ}}}\left|\underset{n=i-N+1}{\overset{i}{\mathrm{\Σ}}}{R}_l^n{e}^{-j2\mathrm{\πFTn}}\right|$

Wherein, F _max> F > F _min, F _maxfor maximum breathing frequency, be generally 50, F _minfor minimum respiratory frequency, be generally 8; Respiratory frequency algorithm for estimating, by multi wireless links signal strength information is done to Fourier transformation, is analyzed its frequency domain spectral characteristic, finds out the frequency numerical value that power spectrum peak is corresponding, thereby finds out the respiratory frequency of human body.Test shows, arrange that 10 nodes can realize the efficient monitoring to human body respiration frequency, adult and child are tested respectively, true respiratory frequency is that adult's monitoring result of 14 beats/min is 13.8 beats/min, and true respiratory frequency is that baby's monitoring result of 37 beats/min is 37.3 beats/min.

The present invention utilizes the frequency domain characteristic of wireless link signals Strength Changes to realize the estimation to human body respiration frequency.People's respiratory variations can cause the cyclically-varying of body size, and then causes the variation through the wireless link signals intensity of human body, therefore, can utilize the variation characteristic of wireless link signals intensity to realize respiratory frequency estimation.Breathing state monitoring technology based on wireless link information belongs to contactless monitoring, and without any facility being installed to children under guardianship's body, this makes monitoring system more humane, is particularly useful for monitoring baby, postoperative patient.These features have determined that the contactless monitoring technology of the breathing state based on wireless link information has application prospect more widely.

Claims (2)

1. the monitoring of respiration method based on wireless link information, it is characterized in that, the multi wireless links that this monitoring method utilizes a plurality of wireless scan nodes that are arranged in a surrounding to form, by monitoring human breathing, the periodicity of multi wireless links signal intensity is affected, estimate the period of change of wireless link signals intensity, and then estimate the respiratory frequency of human body; The concrete steps of monitoring of respiration method are:

1) by N wireless scan node (J1 ... JN) be arranged in the surrounding of bed (3), placing height is higher than bed, so that wireless signal passes from human body; N wireless scan node be responsible for taking turns each radio node of scan flow to and each wireless link signals strength information measuring is sent to wireless aggregation node (1); The radio communication operating frequency of wireless scan node, power can regulate, battery and external power power supply, and wideband omnidirectional antenna, apart from ground, regulating is highly 0.3m to 1.5m;

2) wireless aggregation node (1) is collected all wireless link metrical informations, and is sent to general purpose PC (2); The respiratory frequency algorithm for estimating of the upper operation of general purpose PC (2), judges respiratory frequency based on link metrical information; The radio communication operating frequency of wireless aggregation node (1) can regulate, battery and external power power supply, wideband omnidirectional antenna, has USB interface or the USB (universal serial bus) of carrying out transfer of data with general purpose PC (2), apart from ground, regulates height 0.3m to 1.5m;

3) general purpose PC (2) send start monitoring order to wireless aggregation node (1), each wireless scan node of wireless aggregation node order is started working, each wireless scan node starts to carry out without line sweep afterwards, and the signal strength information of each wireless links is sent to wireless aggregation node; Wireless aggregation node is sent to general purpose PC (2) by the signal strength information of each wireless links, the signal strength information of the respiratory frequency Estimation Software of the upper operation of general purpose PC (2) based on wireless link, estimate human body respiration frequency, realize the estimation to human body respiration frequency;

Above-mentioned three steps have been described the workflow of system; The respiratory frequency algorithm for estimating of the upper operation of general purpose PC (2) is usingd wireless link received signal strength information as input message, by analyzing the frequency domain spectral characteristic of multi wireless links signal strength information, estimate the change in signal strength cycle, the respiratory frequency of output estimation, finds out the frequency numerical value that power spectrum peak is corresponding; Suppose that each wireless scan node of current time forms L wireless links altogether, the change in signal strength of each link is every link has gathered N signal strength data altogether, and the human body respiration frequency F of current time can adopt following formula to estimate:

$F={\arg \max }_F\underset{l=1}{\overset{L}{\mathrm{\Σ}}}\left|\underset{n=i-N+1}{\overset{i}{\mathrm{\Σ}}}{R}_l^n{e}^{-j2\mathrm{\πFTn}}\right|$

Wherein, F _max> F > F _min, F _maxfor maximum breathing frequency is 50, F _minfor minimum respiratory frequency is 8; Respiratory frequency algorithm for estimating, by multi wireless links signal strength information is done to Fourier transformation, is analyzed its frequency domain spectral characteristic, finds out the frequency numerical value that power spectrum peak is corresponding, thereby finds out the respiratory frequency of human body; The dominant frequency of the general purpose PC (2) adopting is more than 1GHz, more than inside saving as 256M, has USB interface or the USB (universal serial bus) of carrying out transfer of data with wireless aggregation node.

2. the monitoring of respiration method based on wireless link information according to claim 1, it is characterized in that: the system that monitoring method adopts is by N wireless scan node (J1 ... JN), wireless aggregation node (1), general purpose PC (2), respiratory frequency algorithm for estimating and form for carrying the bed (3) of human body, respiratory frequency algorithm for estimating is arranged on general purpose PC (2).