WO2021180049A1

WO2021180049A1 - Method for determining that person has fainted and room therefor

Info

Publication number: WO2021180049A1
Application number: PCT/CN2021/079633
Authority: WO
Inventors: Ming Chuen CHUNG; Wai Woon Aman CHU; Wing Hon Tsang
Original assignee: United Wheels Technology Limited
Priority date: 2020-03-10
Filing date: 2021-03-09
Publication date: 2021-09-16

Abstract

A non-imaging method suitable for use in monitoring physiological data of an occupant in a toilet. If the occupant is deemed to have fainted, an alarm may be raised. Fainting is distinguished from sleeping by the method to prevent false alarm.

Description

[Title established by the ISA under Rule 37.2] METHOD FOR DETERMINING THAT PERSON HAS FAINTED AND ROOM THEREFOR

Field of Invention

This invention relates to safety detection devices. In particular, this invention relates to detection of people passing out in solitary circumstances such as in a toilet.

Background of Invention

Urban lifestyle has evolved such that ability of individuals to travel independently and to far distances has greatly improved. Disabled or elderly people who used to need constant nursing supervision are now capable of leaving their homes all by themselves to wander in social places such as shopping centres. Contributing factors include electric wheelchairs which provide mobility, and also include smart mobile phones, the GPS system and closed circuit televisions which make it possible to monitor these people remotely, thereby reducing the need of a companion in person. Together, these technologies restore a sense of independence and dignity to many such people.

However, even in densely populated urban areas, there are places in which everyone is solitary and without companionship, such as in the public toilets, also known as the lavatories, and especially in the toilets for the handicap. The handicap toilet is usually not a dedicated cubicle among a row of several cubicles. Instead, most handicap toilets tend to be isolated, spacious single rooms with toilet facilities for the use of a lone occupant. The handicap toilet also tends to be constructed of solid walls that have somewhat sound-proofing effects.

In such isolation, there is often serious danger if the occupant suffers an episode of unconsciousness from stroke or heart attack. If the occupant collapses, it is unlikely that anyone outside is able to hear any sound of him falling onto the floor. By the time janitors become suspicious of an overly long occupancy of a handicap toilet, the best time for providing effective medical first aid to the collapsed occupant might have passed.

It is quite possible for the elderly and infirmed to suffer from fainting spells when they are alone in a handicap toilet, as many are often plagued with blood pressure problems. It is known that even relief of constipation may cause a tendency of fainting. In fact, this problem that is more common than meets the eye. See https: //www. ctvnews. ca/health/fainting-on-the-toilet-is-a-real-medical-problem-but- doctors-say-it-can-be-avoided-1.3895702.

According to existing technology, to observe an occupant in a toilet would require a video camera. However, it is illegal and offensive to install any sort of camera or even any sound detection device in a place as private as a toilet. Hence, handicap toilets have always remain unmonitored.

Therefore, it is desirable to provide methods or devices which could possibly be used for alerting building management of a possible episode of fainting in a private, isolated space, but which does not compromise the basic need of privacy.

Summary of the Invention

In the first aspect, the invention proposes a method for determining that a person has fainted, comprising the steps of: detecting a simultaneous reduction of heart rate with reduction of body movements of the person; and determining that the person has fainted if onset of the reduction of heart rate precedes onset of the reduction of body movements.

An advantage of the method is that it provides the possibility of distinguishing a sleeping person from a person who has fainted (syncope) . If a tired elderly or handicap person has fallen asleep in the toilet, the property management is now empowered to make a decision to let him rest undisturbed rather than to raise an embarrassing alarm.

Preferably, the method further comprises the steps of detecting a simultaneous increase in expiration magnitude with reduction of body movements of the person; and that the increased expiration magnitude of the person precedes the reduction of heart rate and the reduction of body movements of the person; such that the fainting is determined as related to breathing difficulty.

This feature provides further insight as to whether the occupant was suffering from breathing difficulties before he fainted. It is possible that breathing difficulties could come from an asthmatic attack. Also, it is possible that the person might have fainted due to pneumonia-like illness, such as an infection by a deadly virus like the corona- virus or SARS. In this case, the building security could be warned to take special precautions before accessing the occupant.

Preferably, the reduction of heart rate and/or the reduction of body movements and/or the increased expiration magnitude (and/or determining that increased inhalation periods) is detected by radar.

Examples of other private spaces which the invention may be used include bank vaults or dressing rooms where an occupant is likely to be alone, and imaging technology is often inappropriate for observing the occupant.

By monitoring heart rate without using a camera to observe a person, the method may be used in a private space such as a toilet without transgressing any law of privacy. Life-saving first aid may be dispensed quickly to a person who has collapsed in a toilet. The reputation of a property may be maintained by preventing an occasion of death in the toilet.

However, in spaces where imaging of the person is permissible, such as monitoring of a baby in the cot, and privacy is not a concern, other detection technologies may be used, which can detect the pulse, breathing and body movements besides radar, such as optical imaging techniques using infrared light.

Preferably, the method further comprises obtaining the temperature of the person. Typically, the temperature of the person is obtained remotely. For example, the temperature of the person is obtained by an infrared monitor. Nevertheless, other methods of obtaining the temperature are possible such as by a contact thermometer on the toilet seat.

In a second aspect, the invention discloses a room, comprising: a radar device; the radar device being configured to obtain data on the heart rate of an occupant in the room; wherein the data is suitable for monitoring whether there is a drop in heart rate.

Preferably, the room is capable of issuing an alarm if the heart rate has fallen below a predetermined threshold. Typically, the predetermined threshold is determined according to the threshold as shown in Figure 8.

Preferably, the radar device is suitable for monitoring occupant movements and occupant heart rate; and the data obtained by the radar device being suitable for determining whether movement stillness of the occupant precedes a drop in heart rate.

Optionally, the radar device is suitable for monitoring occupant breathing; and the data obtained by the radar device being suitable for determining whether change in the breathing of the occupant precedes the drop in heart rate.

Preferably, the room further comprises an infrared monitor for monitoring temperature of the occupant.

In some examples, the room is a toilet. In other examples, the room is a private bank vault or room. In yet other examples, the room is a dressing room.

Unlike the afore-mentioned method that may be used in any location to distinguish if a person has fallen asleep or has fainted, a smart-toilet is already a confined space. In this case, a straightforward monitoring of the heart rate is sufficient to determine if an alarm needs to be raised.

In a further aspect, the invention proposes a use of radar to detect that the heart rate of a person has fallen below a predetermined threshold to determine that the person has fainted. Typically, the predetermined threshold is determined according to the threshold as shown in Figure 8.

In a further aspect, the invention proposes a use of radar to detect that onset of the reduction of heart rate precedes onset of the reduction of body movements of a person, to determine that the person has fainted. Preferably, the use of radar further detects that onset of a change in the breathing of the person precedes the onset of a reduction of heart rate and the onset of a reduction of body movements, to determine that the person has breathing difficulties when he faints.

Brief Description of the Drawings

It will be convenient to further describe the present invention with respect to the accompanying drawings that illustrate possible arrangements of the invention, in which like integers refer to like parts. Other arrangements of the invention are possible, and consequently the particularity of the accompanying drawings is not to be understood as superseding the generality of the preceding description of the invention.

Figure 1 is the plan view of a Hong Kong public toilet for a handicap user, in which an embodiment of the invention may be used;

Figure 2 illustrates a situation in which the embodiment used in Figure 1 may be applied;

Figure 3 is a schematic diagram of a radar device used in an embodiment of the invention;

Figure 4 illustrates a Doppler Radar System that may be as the radar device of Figure 3;

Figure 5 illustrates the front end of the Doppler Radar System of Figure 4;

Figure 6 illustrates how the radar device of Figure 3 works;

Figure 7 is a drawing that further explains Figure 6;

Figure 8 illustrates a method which the radar device of Figure 3 uses for raising an alarm;

Figure 8a is a flowchart corresponding to the method illustrated in Figure 8;

Figure 9 illustrates a further method which the radar device of Figure 3 uses for raising an alarm;

Figure 9a is a flowchart corresponding to the method illustrated in Figure 9;

Figure 10 illustrates the converse of the method of Figure 9;

Figure 11 illustrates another possible method which the radar device of Figure 3 uses for raising an alarm;

Figure 11a is a flowchart corresponding the method illustrated in Figure 11; and

Figure 12 illustrates an electrocardiogram of a pulse that the radar device of Figure 3 may monitor.

Description of Embodiments

Figure 1 is the plan view of a typical Hong Kong public handicap toilet 101. The drawing was published in a research report on "Universal Accessibility: Best Practices and Guidelines” by the Hong Kong Architectural Services Department, 2004, and may be downloaded from https: //www. archsd. gov. hk/archsd/html/ua/06b- chapter6. pdf.

The items visible in the plan are typical toilet installations such as a sink, a water closet, a mirror and handles for the occupant to hold onto. There is no cubicle partitioning in the handicap toilet 101 for accommodating more than one occupant. The space in the handicap toilet 101 is dedicated to the use of a single occupant, and is spacious enough to contain any wheelchair that may be carrying the occupant. The handicap toilet 101 isolates the occupant from the outside with solid walls.

Figure 2 illustrates schematically a cubical room representing the handicap toilet 101. An occupant 200 is shown fainted and lying on the floor. A radar device 201 is attached to the ceiling of the room, so that the occupant 200 is within the detection range of the radar device 201 regardless of the occupant 200’s position in the handicap toilet 101. The radar device 201 is capable of detecting movements of the occupant 200, including that of the occupant 200’s body and limbs, respiratory heavings of the occupant 200’s rib cage and beatings of the occupant 200’s heart, and comprises processing capabilities for analysing these movements to determine whether the occupant 200 has fainted.

By comparing data on heart rate with data on body movements, it is possible to determine if the occupant 200 has merely fallen asleep (a loss of consciousness in a safe way) or has an episode of syncope. Syncope is another word for ‘fainting’ , and it means a brief loss of consciousness due to decreased blood flow to the brain.

Many different conditions can cause fainting and it may happen to anyone; fainting does not happen only to sickly or elderly people. For example, vasovagal attack or neurally-mediated fainting occurs most commonly in children and young adults, and is caused by blood pressure drop. If a fainting episode is left unattended for too long, it can trigger a seizure. Hence, if anyone has fainted inside the handicap toilet 101, help ought to be despatched immediately.

The radar device 201 is in communication with a remote building management server 203 by a network connection 205 that may be wired or wireless. On detection of the occupant 200 fainting in the handicap toilet 101, the radar device 201 is capable of raising an alarm to the building management server 203, in order to alert building management personnel that someone in the handicap toilet 101 needs medical attention.

It is possible that a handicap, elderly or infirmed person falls asleep in the handicap toilet 101 because he is easily tired and cannot help himself from falling asleep.

While this may be a concern if there is a queue of people waiting to use the occupied handicap toilet 101, there is no urgent medical cause for alarm. People waiting to use the handicap toilet 101 may simply knock the door to hurry the occupant 200, and the occupant 200 is free to respond in any way he may wish. Accordingly, fainting must be differentiated from sleeping so that an unnecessary alarm would not be raised. This also goes some way in preserving the dignity of the occupant 200, preventing embarrassment, and avoiding unnecessarily reminding the public that the handicap toilet 101 monitors occupants 200 for fainting.

Advantageously, a radar device 201 does not reconstruct any image of the occupant 200. Hence, there is no concern of invasion of privacy. The radar device 201 may be deployed even in any other space which is as private as a handicap toilet 101, such as an isolated bank vault.

Radar technology is well-known. Hence, only a short description here need be given for the purpose of completeness. Figure 3 illustrates a simple radar device 201 schematically. The radar device 201 comprises a transmitter 301 and a receiver 303. The transmitter 301 and the receiver 303 are antennae respectively tuned to transmit an electromagnetic radar signal of a predetermined frequency and tuned to receive radar signals of a range of pre-determined frequencies. Possibly, both transmitter 301 and receiver 303 functions are provided by the same physical antenna. As the skilled man would understand, the radar device 201 contains all necessary processors and memory 305 for the collection, recordation and processing of received radar signals.

Locations of target objects 307 can be determined from the transition time or time of flight of radar signal. The time for an electromagnetic wave to travel forth to hit a target object 307 and back to the receiver 303 is the time required to travel two times the distance between the target object 307 and the radar device 201, marked x as shown in Figure 3, in the speed of light. A transmitted radar signal aimed at a further target object 307 will take a longer time to be reflected and received than a nearer target object 307. If the target object 307 moves, the radar device 201 is capable of tracking movements of the target object 307 by monitoring changes in the position of the target object 307.

The radar signal emitted by the transmitter 301 may be pulsed or continuous. However, a pulse signal is discrete and not suitable for following the continuous movements of the target object 307. A preferred method to monitor the changing position of a continuously moving target object 307, among other possible methods, is to monitor the Doppler Effect in reflected radar signals.

The Doppler Effect refers to frequency shift caused by motion of a surface. If a surface is moving away from a radar device 201, the wavelength of the transmitted radar signal, on being reflected by the moving surface, gradually increases. Alternatively, if a surface is moving towards a radar device 201, the wavelength of the transmitted radar signal, on being reflected by the moving surface, is gradually compressed and decreases. The extent of wavelength change can be used to plot the movements of the surface, relatively to the fixed position of the radar device 201. In this case, as time of flight is not used to determine distance, the radar signal need not be a discrete signal but may be a signal that is continuously transmitted by the radar device 201.

As the skilled man knows, wavelength is inversely proportional to frequency of the radar signal: radar signals with higher frequencies have shorter wavelengths, and lower frequencies have longer wavelengths.

The Doppler frequency shift is expressed as follows,

where

F _D is Doppler frequency,

F _T is transmit frequency,

V _R is the object’s radial velocity relative to the radar detector

C is the speed of light

Accordingly, the Doppler Effect can be used to detect movements of the occupant 200, including monitoring the occupant 200’s body movements, respiratory chest movements, as well as heart movements. Body movements herein refer to movements of the limbs, trunk and head of the occupant 200. The radar signal must have a wavelength that is in the order of the movement magnitude of the target object 307 so that the target object 307 may be observed unambiguously. The pumping movement of the heart is the smallest among these movements. Thus, the wavelength of the radar signal must be at least in the order of the change magnitude of the heart, i.e. variations in the size of the heart, or displacements of heart muscles, as the heart pumps.

Typically, the transmitter 301 of the radar device 201 transmits a radar signal in the microwave frequency range so as to be able to detect heart movements. The preferred frequency is 24GHz, although other frequencies may be used. This frequency has a wavelength that is in the order of millimetres, such that changes in the size of heart muscles are well within detection resolution.

Figure 4 is a schematic diagram of a Doppler Radar System that may be used as the radar device 201. The Doppler Radar System comprises a radar front-end 401, a baseband module 403, a digital signal processing (DSP) module 405, and an analyser 407 for determining the state of the occupant 200 based on processed signals that are output by the DSP module 405. Figure 4 shows how a transmitted radar signal is reflected from a heaving chest of the occupant 200. Figure 5 shows the front-end 401 of the Doppler Radar System of Figure 4 in greater detail. An oscillator 501 generates the radar signal of the pre-determined frequency, and an amplifier 503 amplifies the magnitude of the radar signal before the transmitter 301 broadcast the radar signal into the handicap toilet 101. The receiver 303 is able to detect the reflected radar signals.

Any reflected radar signals detected by the receiver 303 is down-converted with the transmitted radar signal through a mixer 505. The output is the in-phase signal, I, and the quadrature signal, Q. As the skilled man knows, phase difference between the two signals, I and Q, may then be easily observed in order to determine the phase position of the target object 307. By measuring the frequency of the reflected signal and comparing that with the frequency of the transmitted radar signal, the extent of change in frequency due to change in position of the target object 307 can be easily measured. Continual detection of the target object 307 in this way allows real-time monitoring of the movements of the target object 307. In this way, the frequency change detected by the radar device 201 is indicative of the phase position of the heart muscles of the occupant 200, and continuous observation of the occupant 200’s heart muscles may then be reconstructed to reproduce movement signals representing heart beats.

The skilled reader should note that there are two types of “signals” in this description and they ought not to be confused with one another. In particular, the waveforms shown in Figure 6 are not reflected radar signals. Instead, the waveforms in Figure 6 represent movements of the occupant 200, reconstructed by interpreting radar signals that are reflected by the moving surfaces of various parts of the occupant 200’s body, based on the Doppler Effects. Hence, ‘radar signal’ is used herein to identify electromagnetic signals used by the radar device 201, and ‘movement signal’ is used herein to identify waveforms that represent movements of the occupant 200’s body, respiration and heart beats.

The DSP module 405 in the radar device 201 receives the output from the baseband module 403, and applies techniques such as frequency filtration to eliminate noise or unwanted signals of unwanted frequency ranges, as well to extract required information from reflected radar signals. Subsequently, the output of the DSP modules 405 is provided as data to the analyser 407 to determine characteristics of the target object 307, which is the occupant 200.

Figure 6 illustrates how different parts of the body may reflect radar signals differently. When electromagnetic waves of a frequency suitable for use as a radar signal travelling through one material (medium) meets another material having a different dielectric constant, the electromagnetic waves will reflect off the boundary or intersection between the two materials. In this way, all the different layers of material making up the human body reflect a certain amount of a radar signal. Therefore, a radar signal can penetrate into the body of the occupant 200, passing from air into the layers of skin, muscles, blood, bones and so on, and the intersection between every two of these layers reflects a portion of the radar signal. As the human body moves, the change of positions of these layers can be monitored by observing the Doppler Effects in the reflected radar signals.

There are three main types of movements that are significant to the present embodiments. Movements of the body, respiratory movements of the chest 605 and movements of the heart 603 all cause observable Doppler Effects. It is possible to distinguish movements of these different body parts by monitoring the periodicity or randomness, and magnitude of the movements. The relative magnitude of these types of movement signals are schematically illustrated in Figure 6. In particular, movements of the body itself, i.e. the trunk, head and limbs, provide the largest movement signals. These body movement signals 601 are, random, usually irregular and unpredictable, and may move over a relatively huge distance as compared to the movements of the heart 603 and respiratory movements of the chest 605. Accordingly, body movement signals 601 maybe identified by their randomness and often large movement magnitudes.

Respiratory movements of the chest 605, i.e. expansion movements of the lungs and rib cage, produce the next largest movement signals of possible significance to this embodiment, which are easily dwarfed by the afore-mentioned larger body movements 601. Respiratory movements within a narrow time frame may be characterised as almost periodic. The respiration rate when a person is in a rest position is between 0.1 Hz to 0.3Hz. Respiratory movements also have a typical extent of chest displacement despite the many sizes of different people, and these falls between 4 millimetres to 12 millimetres. These characteristics allow respiratory movement signals to be identified and distinguished from other movement signals observed from the occupant 200.

The heart produces the smallest movement signals 603 that are of significance to this embodiment. In any narrow time frame, heart beats may also be considered almost periodic and are identifiable by a certain range of movement frequencies. Generally, heart rate variation as the heart pumps ranges between 0.2 millimetres to 0.5 millimetres, with a pulse of between 1 Hz to 3Hz typically. Hence, movement signals 603 showing movement frequencies around this range and magnitude may be identified as movement signals caused by the heart.

As the movement signals of the heart and the chest are characteristically different, suitable frequency filters or other DSP techniques may be used to distinguish heart beats from respiration.

Radar signals is also reflected by all the surfaces inside the room, which becomes signal noise and clutter that may obscure the reflected radar signals representing the occupant 200’s movements. Hence, to allow the heart rate, the respiratory rate and body movements to be distinguished, noise signals caused by radar signals reflected from the surroundings must be identified and removed. That is, the radar signals detected must be treated to eliminate signal noise in order to extract the wanted information.

Figure 7 illustrates a black box 701 representing all manner of DSP techniques including bandwidth selection, phase selection, and so on for identifying body movement signals 601, heartbeat movements signals 603 and respiratory chest movements signals 605 from all the radar signals 703 detected by the receiver 303. A black box representation is sufficient here because there are many well-known DSP techniques useable for processing of movement signals, such as filter design. For example, Figure 12 shows an example of a typical heartbeat 1201 observable by electrocardiogram. It is possible with a high frequency electromagnetic radar signal to reconstruct the whole of a single heartbeat, with all the peaks and troughs PQRST. The broken lines in Figure 12 represent sampling points provided by the signal frequency. In such a case, a template of a reference heart beat signal can be used to identify heart beats from the body movements by deconvolution or correlation techniques, so that the heart rate may be accurately obtained.

Table 1 shown below shows how observations of the occupant 200’s movements using the radar device 201 may determine if the occupant 200 has fainted. Each row of Table 1 shows different observations required for determining a particular state of the occupant 200.

Table 1: order of occurrence of radar observable movements of handicap toilet 101 occupant 200

The second column from the left of Table 1 shows the different states of the occupant 200 as may be determined. The third column from the left of Table 1 specifically shows whether an observation of reduction in heart rate is required for each state. The fourth column of Table 1 shows whether observation of body movements is required for each state. The right most column of Table 1 shows whether observation of respiratory movements is required for each state.

Not all the different states of the occupant 200 require observation of respiratory movements. Therefore, respiratory movement observation is indicated as optional for determining some states.

Row 1 of Table 1 explains a Method 1. Method 1 is for deeming that the occupant 200 in the handicap toilet 101 is in a state of having fainted, based on detecting a sufficiently drastic change the occupant 200’s heart rate. This is the simplest of the methods shown in Table 1. Body movements of the occupant 200 are not monitored. Furthermore, respiration of the occupant 200 is also not monitored.

Method 1 is based on an assumption that anyone who has a sudden and significant decrease in his heart rate must have fainted. Of course, it is possible in rare cases that the occupant 200 may well be awake and still capable of moving despite an abnormal drop in heart rate. The assumption that the occupant 200 having fainted is simply made for the purpose of erring on the safe side.

Figure 8 is a graph 801 that plots the threshold levels of relative change in heart rate that should give cause for alarm. The horizontal axis shows the heart rates of ordinary people under normal circumstances. The vertical axis shows the thresholds corresponding to different initial heart rates. The graph 801 shows that if the occupant 200’s heart rate is 100 beats per minute when he enters the handicap toilet 101, detection of a drop in his heart rate to 60 beats per minute or below is taken to mean that the occupant 200 must have fainted. Accordingly, the radar device 201 issues an alarm to the building management server 203 that someone has fainted in the handicap toilet 101. Furthermore, if the occupant 200’s heart rate is 60 beats per minute when he enters the handicap toilet 101, detection of a drop in his heart rate to 40 beats per minute or below is required before the alarm may be raised. The relationship between the threshold and the original heart rate is almost linear, and the gradient is preferably about (100-60) / (60-40) .

Method 1 is also illustrated in the flowchart of Figure 8a. As shown, the radar device 201 detects and monitors the occupant 200’s heart rate as soon as the occupant 200 enters the handicap toilet 101, at step 1301. The radar device 201 then checks if the occupant 200 is still in the handicap toilet 101, at step 1303. If the occupant 200 is detected to be no longer in the handicap toilet 101, the method is deemed completed and ends. If the occupant 200 is still in the handicap toilet 101, however, the method proceeds to observe the occupant 200’s heart rate, at step 1305. If the occupant 200’s heart rate drops below a pre-determined threshold level that is considered significant relative to the heart rate as initially detected, at step 1307, the radar device 201 issues an alarm of fainting, at step 1309, to the building management server 203, so that the building management may check on the occupant 200. On the other hand, if the heart rate does not drop to the threshold level, the method repeats the steps starting from checking if the occupant 200 is still in the handicap toilet 101, at step 1303.

It is easy to determine that, when the occupant 200 has a very low heart rate such as 40 beats per minute or a very high heart rate such as 180 beats per minute, medical attention is required. In contrast, whether a heart rate that remains within the typical range of normal heart rate, despite having slowed down drastically, requires medical attention is less straightforward. This is because people’s heart rate changes all the time, and any such change should be referenced against with the original heart rate measured when the occupant 200 has just entered the handicap toilet 101. If the change is sudden enough and significant enough, the alarm is raised.

In a Method 2, heart rate and body movements are both monitored to determine whether the occupant 200 has fainted or has merely fallen asleep inside the handicap toilet 101. Not everyone’s heart rate drops drastically when he faints, and merely monitoring the heart rate might be inadequate to identify some occasions of fainting. Method 2, expressed in Row 2 of Table 1, requires observing whether the heart rate has decreased first, before body movements have decreased drastically or ceased. If heart rate has decreased before body movements have decreased, then the occupant 200 may be deemed to have fainted. It is unnecessary, or optional, to observe the occupant 200’s respiration in Method 2.

Method 2 is also illustrated in Figure 9, which shows two

graphs

901, 903 that are not drawn to scale. The vertical axis of top graph 901 represents the magnitude of heart rate while the horizontal axis represents time. The top graph 901 shows the heart rate reducing significantly after the point of time α. The vertical axis of the lower graph 903 represents the magnitude of body movements while the horizontal axis shows the same horizontal axis timeline as the top graph 901. The lower graph 903 shows that the body movements of the occupant 200 decreasing significantly or ceasing after the point of time β.

As α is earlier β, it means that while the occupant 200 shows reduced heart rate simultaneously with decreased body movements, the heart rate of the occupant 200 has begun to decrease first before the occupant 200 slowly stops moving. This suggests that the decrease in heart rate causes the occupant 200 to become motionless, and it is therefore likely that the occupant 200 has fainted. Fainting will be assumed even if the slower heart rate is within normal range for heart rate. Consequently, the radar device 201 issues an alarm to the building management server 203, so that the building management may check on the occupant 200.

Method 2 is also illustrated in the flowchart of Figure 9a. As shown, the radar device 201 detects and monitors the occupant 200’s heart rate as soon as the occupant 200 enters the handicap toilet 101, at step 1301. The radar device 201 then checks if the occupant 200 is still in the handicap toilet 101, at step 1303. If the occupant 200 is detected to be no longer in the handicap toilet 101, the method is deemed completed and ends. If the occupant 200 is still in the handicap toilet 101, the method proceeds to observe the occupant 200’s heart rate, at step 1305, as well as to observe body movements of the occupant 200, at step 1401. If the radar device 201 determines that the occupant 200’s heart rate has reduced first, ahead of any significant cessation of body movements, at step 1403, the radar device 201 issues an alarm of fainting, at step 1309, to the building management server 203, so that the building management may check on the occupant 200. On the other hand, if the heart rate is not observed to have reduced ahead of any significant reduction of body movements, the method repeats the steps starting from checking if the occupant 200 is still in the handicap toilet 101, at step 1303. It is not necessary to observe the occupant 200’s respiratory movements in Method 2.

Conversely, if body movements has ceased or reduced drastically before the heart rate begins to decrease, then the occupant 200 may be deemed to have fallen asleep, at step 1403, and no alarm is raised. Figure 10 illustrates the converse of Figure 9, and corresponds to Row 3 in Table 1. Figure 10 shows similar graphs as those in Figure 9, except that the point in time α in the top graph 1001 comes after the point in time β in the bottom graph 1003. This means the heart rate of the occupant 200 has started to decrease only after the occupant 200 has become motionless. This is a normal sequence of events: people fall asleep by remaining still first, before their pulse slows down. Provided that the heart rate has not dropped to a very low heart rate that would require medical attention, no alarm needs to be raised.

In a Method 3, heart rate and body movements are both monitored along with the respiratory movements. If breathing difficulty is observed first, followed by a decrease in heart rate, and which is further followed by a cessation or significant reduction of body movements, then the occupant 200 may be deemed to have fainted from an asthmatic attack.

Method 3 corresponds to Figure 11, which is a variation of the embodiment of Figure 9, except that the occupant 200’s respiration is also monitored, and also corresponds to Row 4 in Table 1. The vertical axis of top graph 1101 in Figure 11 represents the magnitude of heart rate while the horizontal axis represents time. The top graph 1101 shows the heart rate reducing significantly after the point of time α. The vertical axis of the lower graph 1105 represents the magnitude of body movements while the horizontal axis represents time. The lower graph 1105 shows that the body movements of the occupant 200 decreasing significantly or ceasing after the point of time β. The vertical axis of the middle graph 1103 represents the magnitude of chest or respiratory movements of the occupant 200, while the horizontal axis represents time.

The middle graph 1103 shows the breathing of the occupant 200 becoming more laboured, that is, the rib cage expanding more as time passes. This laboured breathing is represented by an increasing movement magnitude, owing to narrowed airway. This is because exhaling 1107 is laboured and prolonged, as shown by slower collapse of the rib cage represented by the gentler downward slope. Inhaling 1109 becomes gasping, and is more desperate and faster as shown by the quicker raising of the rib cage represented by the sharper upward slope. This suggests that the occupant 200 is breathing with a resistance to exhalation as commonly seen in asthmatic breathing.

Figure 11 shows that the occupant 200 experiences breathing difficulty from the point of time γ, followed by a decrease in heart rate at the point of time α which is then followed by a cessation of body movements at the point of time β. This suggests that the occupant 200 has difficulty breathing, and then his heart rate drops followed by unconsciousness setting in. This information is useful to alert the building management to despatch first aid with equipment for dealing with an asthmatic attack, or a pneumonia related condition.

Method 3 is also illustrated in the flowchart of Figure 11a. As shown, the radar device 201 detects and monitors the occupant 200’s heart rate as soon as the occupant 200 enters the handicap toilet 101, at step 1301. The radar device 201 then checks if the occupant 200 is still in the handicap toilet 101, at step 1303. If the occupant 200 is detected to be no longer in the handicap toilet 101, the method is deemed completed and ends. If the occupant 200 is still in the handicap toilet 101, the method proceeds to observe the occupant 200’s heart rate, at step 1305, as well as observe body movements of the occupant 200, at step 1401, and also observe the respiratory movements of the occupant 200, at step 1501. If the embodiment detects that the occupant 200 has laboured breathing, as well as observes that the occupant 200’s heart rate has reduced before significant cessation of body movements, at step 1503, the radar device 201 issues an alarm of someone having fainted with breathing difficulty, at step 1505, to the building management server 203. Preferably, regardless of any breathing difficulty that may be present, if the heart rate is not observed to have reduced before significant reduction of body movements, the radar device 201 does not deem the occupant 200 as having fainted, and the method repeats the steps starting from checking if the occupant 200 is still in the handicap toilet 101, at step 1303.

Optionally, the radar device 201 may be accompanied by a non-imaging infrared temperature monitor (not illustrated) . If the occupant 200 is detected to suffer breathing difficulty followed by a drop in heart rate and loss of consciousness, as illustrated in Figure 11, and also has a high fever as detected by the infrared temperature monitor, it could mean an attack of pneumonia or coronavirus causing occupant 200 collapse. The building management may then despatch first aid with suitable protective clothing to prevent infection of first aid personnel.

In order not to create an alarm if the occupant 200 is merely performing breathing exercise in the handicap toilet 101, comparison of heart rate and body movements is made for the embodiment of Figure 11, in a similar way as that explained for the method of Figure 9. That is, if there is no reduction in heart rate or body movements accompanying the greater breathing effort, no alarm is raised by the radar device 201.

Optionally, when the radar device 201 raises an alarm, an audio announcement is played in the handicap toilet 101, announcing that the radar device 201 has sensed irregularity in the heart rate of the occupant 200, and help is on the way. Such an announcement could provide some mental comfort for the occupant 200 who is on the verge of fainting or, if there is nothing wrong with the occupant 200, could allow the occupant 200 to get himself ready to greet the arriving unwanted help.

Row 5 in Table 1 shows how to determine that the occupant 200 has merely stayed still: there is no observable change in his heart rate or his respiration. Only body movements are observed to have stopped. In this case, there is no need for any alarm to be raised.

Although radar technology has been described for detecting heart rate and body movements, other methods of detections are within the contemplation of the embodiments. For example, it is possible to use optical technologies to monitor the pulse of a person, as well as movements of his limbs and chest. The same comparison of the movements of a person’s pulse rate and body movements, as well as breathing may be made as described. There might be a problem with using optical imagery in some situations such as a toilet, but this is a matter of practical use and privacy matters, which depends on the location of deployment of the embodiments. Accordingly, the described embodiments include a method for determining that a person has fainted, comprising the steps of: detecting a simultaneous reduction of heart rate with reduction of body movements of the person; and determining that the person 200 has fainted if onset of the reduction of heart rate precedes onset of the reduction of body movements.

The described embodiments also include a toilet, comprising: a radar 200 suitable for monitoring occupant 200 heart rate; the radar 200 being configured to obtain data on the occupant 200 heart rate; wherein the data is suitable for monitoring whether there is a drop in heart rate.

While there has been described in the foregoing description preferred embodiments of the present invention, it will be understood by those skilled in the technology concerned that many variations or modifications in details of design, construction or operation may be made without departing from the scope of the present invention as claimed.

For example, although detailed description is not given, the skilled reader would understand that the embodiments may also be applied to detect epileptic seizures of the occupant 200. Furthermore, cardiac arrests and ventricular tachycardia leading to unconsciousness may be identified by radar signals indicating a rapid heart rate before collapse of the occupant 200.

Also, other systems similar to radar make use of other parts of the electromagnetic spectrum. One example is LIDAR, which uses predominantly infrared light from lasers rather than radio waves.

In some situations, two or more radar devices 201 are used in the handicap toilet 101 to monitor the occupant 200, as this could provide better body movement detection and cancellation.

Furthermore, it is possible to for the radar device 201 to be trained by artificial intelligence (A.I. ) to be able to recognise the different states requiring medical attention.

Although a toilet has been described as a single-occupant solid wall room, the skilled reader understands that variations of the embodiments are possible, in which the toilet is a cubicle in a multi-user toilet hall, or a private bank vault as mentioned, or a dressing room in a clothing retail outlet, also called fitting rooms.

Furthermore, it is possible that variations of the embodiments include using one radar device to monitor two or more people in a single room, or use of multiple radar devices having different operational frequency ranges for monitoring two or more people. Hence, where a “radar” is mentioned here, the skilled reader would understand that the “radar” may be composed of two or more radar devices each providing a partial function of the whole embodiment.

Claims

A method for determining that a person has fainted, comprising the steps of:

detecting a simultaneous reduction of heart rate with reduction of body movements of the person; and

determining that the person has fainted if onset of the reduction of heart rate precedes onset of the reduction of body movements.
A method for determining that a person has fainted as claimed in claim 1, further comprising the steps of

detecting a simultaneous increase in expiration magnitude with reduction of body movements of the person; and

that the increased expiration magnitude of the person precedes the reduction of heart rate and the reduction of body movements of the person;

such that

the fainting is determined as related to breathing difficulty.
A method for determining that a person has fainted as claimed in claim 1 or claim 2, wherein the reduction of heart rate and/or the reduction of body movements and/or the increased expiration magnitude is detected by radar.
A method for determining that a person has fainted as claimed in claim 1, claim 2 or claim 3, further comprising obtaining the temperature of the person.
A method for determining that a person has fainted as claimed in claim 4, wherein the temperature of the person is obtained remotely.
A method for determining that a person has fainted as claimed in claim 5, wherein the temperature of the person is obtained by an infrared monitor.
A method for determining that a person has fainted as claimed in any of the preceding claims, wherein the method is executed in a room intended for the person to occupy as a single occupant.
A method for determining that a person has fainted as claimed in claim 7, wherein the steps in anyone of the preceding claims are executed in a toilet.
A method for determining that a person has fainted as claimed in claim 7, wherein the steps in anyone of the preceding claims are executed in private room in a bank.
A method for determining that a person has fainted as claimed in claim 7, wherein the steps in anyone of the preceding claims are executed in a dressing room.
A room, comprising:

a radar device;

the radar device being configured to obtain data on the heart rate of an occupant in the room; wherein

the data is suitable for monitoring whether there is a drop in heart rate.
A room as claimed in claim 11, wherein:

the room is capable of issuing an alarm if the heart rate has fallen below a predetermined threshold.
A room as claimed in claim 12, wherein:

the predetermined threshold is determined according to the threshold as shown in Figure 8.
A room as claimed in claim 11, wherein:

the radar device is suitable for monitoring occupant movements and occupant heart rate; and

the data obtained by the radar device being suitable for determining whether movement stillness of the occupant precedes a drop in heart rate.
A room as claimed in claim 11, wherein

the radar device is suitable for monitoring occupant breathing; and

the data obtained by the radar device being suitable for determining whether change in the breathing of the occupant precedes the drop in heart rate.
A room as claimed in any of claim 11 to claim 15, further comprising

an infrared monitor for monitoring temperature of the occupant.
A room as claimed in claim 11 to 16 wherein the room is a toilet.
A room as claimed in claim 11 to 16 wherein the room is a private bank vault or room.
A room as claimed in claim 11 to 16 wherein the room is a dressing room.
Use of radar to detect that the heart rate of a person has fallen below a predetermined threshold to determine that the person has fainted.
Use of radar as claimed in claim 18 wherein the predetermined threshold is determined according to the threshold as shown in Figure 8.
Use of radar to detect that onset of the reduction of heart rate precedes onset of the reduction of body movements of a person, to determine that the person has fainted.
Use of radar as claimed in claim 22 to further detect that onset of a change in the breathing of the person precedes the onset of a reduction of heart rate and the onset of a reduction of body movements, to determine that the person has breathing difficulties when he faints.
A method for determining that a person has fainted substantially as described in the description or illustrated in the drawings.
A room substantially as described in the description or illustrated in the drawings.