JP2018015209A - On-bed state monitoring system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an on-bed state monitoring system capable of performing sleeping posture determination highly reliably even when a body axis direction of a subject changes on a bed.SOLUTION: An on-bed state monitoring system monitoring an on-bed state of a subject on a bed includes: a plurality of load detectors arranged in a bed or under a leg of a bed and detecting a load by a subject; a load separation section separating a load component of vibrating corresponding to a heart beat of a subject from a load by the subject; a gravity center calculation section acquiring the position of the gravity center of heart beat of a subject based on the load component of vibrating corresponding to the heart beat of the subject; and a sleeping posture determination section determining whether the sleeping posture of a subject is a supine posture or face-down posture based on a vibration direction of the gravity center of heart beat.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an in-situ state monitoring system that monitors the in-situ state of a subject on a bed using a load detector.

  A system for managing a patient on a bed and a cared person from a remote location is used in hospitals and nursing care facilities. For example, if a system for detecting the presence / absence of a patient in a hospital is used, the nurse at the nurse station can check whether the patient is on the bed of the patient room without visiting the patient room. In addition, if it is detected whether the patient or caregiver is lying in the supine position, the lying position (side position), or the prone position, prevention of bedsores and improvement of sleep state (for example, treatment of sleep apnea syndrome) ) Can be useful.

  Patent Document 1 discloses that the subject's sleeping posture is supine, prone, left-sided, based on changes in the X-axis component, Y-axis component, and Z-axis component of the subject's load according to the subject's breathing. A sleeping posture determination device for determining whether the position is the right position or the right-side position is disclosed.

JP 2014-97193 A

  In the sleeping posture determination apparatus of Patent Document 1 that determines the sleeping posture of the subject based on the variation of the subject's load in the X-axis component, the Y-axis component, and the Z-axis component according to the subject's breathing, the body of the subject If the direction of the axis (spine) is inclined with respect to the Y-axis direction (longitudinal direction of the bed), the reliability of determination may be reduced.

  An object of the present invention is to provide a bed-holding state monitoring system capable of performing a reliable sleeping posture determination even when the direction of the body axis of a subject changes on the bed.

According to the first aspect of the present invention,
An in-bed monitoring system for monitoring the in-bed state of a subject on a bed,
A plurality of load detectors provided under the bed or under the legs of the bed and for detecting a load by the subject;
A load separation unit that separates a load component that vibrates according to the heartbeat of the subject from the load by the subject;
A center-of-gravity position calculation unit for determining the position of the subject's heart rate center of gravity based on a load component that vibrates according to the heart rate of the subject;
There is provided a bed-holding state monitoring system including a sleeping posture determination unit that determines whether the sleeping posture of the subject is in the supine position or the prone position based on the vibration direction of the heartbeat center of gravity.

  In the occupancy state monitoring system according to the first aspect, the load separation unit may separate a load component that vibrates according to the breathing of the subject from the load by the subject, and the center-of-gravity position calculation unit The position of the subject's breathing center of gravity may be obtained based on a load component that vibrates in response to breathing, and the sleeping posture determination unit is configured to determine whether the subject sleeps based on the vibration direction of the heartbeat center of gravity relative to the vibration direction of the breathing center of gravity. You may determine whether the figure is a supine position or a prone position.

  In the occupancy state monitoring system according to the first aspect, the center-of-gravity position calculation unit may determine the position of the center of gravity of the subject based on the load by the subject, and the sleeping posture determination unit is configured to respire the subject at the center of gravity. It may be determined whether the subject's sleeping position is in the supine position or the prone position based on the vibration direction of the heart rate center of gravity relative to the direction of vibration according to.

  The bed-holding state monitoring system of the present invention can perform a reliable sleeping posture determination regardless of the direction of the subject's body axis on the bed.

FIG. 1 is a block diagram illustrating a configuration of a occupancy state monitoring system according to an embodiment of the present invention. FIG. 2 is an explanatory diagram showing the arrangement of the load detector with respect to the bed. FIG. 3 is a flowchart showing a sleeping posture determination method according to the embodiment of the present invention. FIG. 4 is an explanatory diagram showing the relationship between the direction of the body axis of the subject and the direction of the respiratory axis. FIG. 4A shows a state of viewing the subject from the front, and FIG. 4B shows a state of viewing the subject from the side. FIG. 5 is an explanatory diagram showing the relationship between the direction of the body axis of the subject and the direction of the heartbeat axis. Fig.5 (a) shows a mode that the test subject was seen from the front, and FIG.5 (b) shows a mode that the test subject was seen from the side. FIG. 6 is an explanatory diagram showing the positional relationship between the projected respiratory axis and the projected heartbeat axis of the subject. 6A shows the positional relationship between the projected respiratory axis and the projected heartbeat axis when the subject is in the supine position, and FIG. 6B shows the projected respiratory axis and the projected heartbeat axis when the subject is in the lying position. FIG. 6C shows the positional relationship between the projected respiratory axis and the projected heartbeat axis when the subject is in the prone position. FIG. 7 is an explanatory diagram for explaining a method of obtaining directions of the projected respiratory axis and the projected heartbeat axis of the subject. FIG. 8 is an explanatory diagram for explaining another method for obtaining the directions of the projected respiratory axis and the projected heartbeat axis of the subject. FIG. 9 is a block diagram illustrating an overall configuration of a bed system according to a modification.

<Embodiment>
An embodiment of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, the occupancy state monitoring system 100 of this embodiment mainly includes a load detection unit 1, a control unit 3, a storage unit 4, and a display unit 5. The load detection unit 1 and the control unit 3 are connected via an A / D conversion unit 2. Further, a notification unit 6 and an input unit 7 are connected to the control unit 3.

  The load detection unit 1 includes four load detectors 11, 12, 13, and 14. Each of the load detectors 11, 12, 13, and 14 is a load detector that detects a load using, for example, a beam-type load cell. Such a load detector is described in, for example, Japanese Patent No. 4829020 and Japanese Patent No. 4002905. Each of the load detectors 11, 12, 13, and 14 is connected to the A / D converter 2 by wiring.

The four load detectors 11, 12, 13, and 14 of the load detection unit 1 are arranged under the legs of the bed used by the subject. Specifically, as shown in FIG. 2, the load detectors 11, 12, 13, and 14 are below casters C ₁ , C ₂ , C ₃ , and C ₄ attached to the lower ends of the legs at the four corners of the bed BD. Each is arranged.

  The A / D converter 2 includes an A / D converter that converts an analog signal from the load detector 1 into a digital signal, and is connected to the load detector 1 and the controller 3 by wiring.

  The control unit 3 is a dedicated or general-purpose computer, in which a signal separation unit (load separation unit) 31, a gravity center position calculation unit 32, and a sleeping posture determination unit 33 are constructed.

  The memory | storage part 4 is a memory | storage device which memorize | stores the data used in the occupancy state monitoring system 100, for example, can use a hard disk (magnetic disk). The display unit 5 is a monitor such as a liquid crystal monitor that displays information output from the control unit 3 to a user of the in-bed state monitoring system 100.

  The notification unit 6 includes a device that aurally performs predetermined notification based on information from the control unit 3, for example, a speaker. The input unit 7 is an interface for performing a predetermined input to the control unit 3 and can be a keyboard and a mouse.

  As shown in FIG. 3, the monitoring of the sleeping posture of the subject using the in-bed monitoring system 100 includes a load detection step S1 for detecting the subject's load, a load component that varies the detected load according to the subject's breathing, and the subject. Signal separation step S2 that separates into a load component that fluctuates according to the heartbeat of the subject, and a gravity center position calculation step S3 that obtains a respiratory center of gravity locus (details will be described later) and a heartbeat center of gravity locus (details will be described later) using the separated load components. And a sleeping step determination step S4 for determining the sleeping posture of the subject based on the obtained respiratory center of gravity locus and heart rate center of gravity locus, and a display step S5 for displaying the determined sleeping posture of the subject on the display unit.

[Load detection process]
In the load detection step S1, the load of the subject S on the bed BD is detected using the load detectors 11, 12, 13, and 14. Since the load detectors 11, 12, 13, and 14 are respectively disposed below the casters C ₁ , C ₂ , C ₃ , and C ₄ as described above, loads applied to the upper surface of the bed BD are four loads. The detectors 11, 12, 13, and 14 are dispersed and detected.

Each of the load detectors 11, 12, 13, and 14 detects a load (load change) and outputs it as an analog signal to the A / D conversion unit 2. The A / D conversion unit 2 converts the analog signal into a digital signal with a sampling period of 5 milliseconds, for example, and outputs the digital signal to the control unit 3. Hereinafter, the load signals output from the load detectors 11, 12, 13, and 14 and digitally converted by the A / D converter 2 are referred to as load signals s ₁ , s ₂ , s ₃ , and s ₄ , respectively.

[Signal separation process]
In the signal separation step S2, the signal separation unit 31 performs a load component (hereinafter referred to as “breathing component”) s ₁₁ that varies depending on the breathing of the subject S from the load signals s ₁ , s ₂ , s ₃ , s _4. , S ₂₁ , s ₃₁ , s ₄₁ and load components (hereinafter referred to as “heart rate components”) s ₁₂ , s ₂₂ , s ₃₂ , s ₄₂ that vary according to the heart rate of the subject are separated.

First, the signal separation unit 31 performs Fourier analysis on at least one of the load signals s _{1 to} s ₄ to obtain a frequency spectrum in a frequency band corresponding to the breathing and heartbeat of the subject S. Since the frequency of human breathing is about 12-20 times per minute, the frequency of breathing is about 0.2-0.33 Hz. Further, since the number of human heartbeats, that is, the heart rate is about 30 to 200 times per minute, the heartbeat frequency is about 0.5 to 3.3 Hz. Therefore, for example, in a frequency spectrum in a frequency band of 0.1 Hz to 3.5 Hz, frequency peaks appear at positions corresponding to the breathing frequency of the subject S and the heartbeat frequency of the subject S, respectively. From the position of this frequency peak, the respiration frequency ν ₁ and the heartbeat frequency ν ₂ of the subject S can be specified.

Next, the signal separation unit 31 varies from the load signals s ₁ , s ₂ , s ₃ , and s ₄ at the specified respiratory frequency ν ₁ (that is, the respiratory components s ₁₁ , s ₂₁ , s ₃₁ , and s _41). ) And components that fluctuate at the specified heartbeat frequency ν ₂ (that is, heartbeat components s ₁₂ , s ₂₂ , s ₃₂ , s ₄₂ ) are separated and extracted. These respiratory components and heart rate components are extracted by performing a band pass filter process on each of the load signals s _{1 to} s ₄ , for example. Thereafter, the signal separation unit 31 outputs the extracted respiratory components s ₁₁ , s ₂₁ , s ₃₁ , s ₄₁ and the heart rate components s ₁₂ , s ₂₂ , s ₃₂ , s ₄₂ to the barycentric position calculation unit 32.

[Center of gravity position calculation process]
In the center of gravity position calculating step S3, the center of gravity position calculating unit 32, the position of the respiratory center of gravity G ₁ of the subject S, the position of the heart center of gravity G _2, and respiration centroid trajectory GT 1 is a locus of these _mobile, heart centroid trajectory GT ₂ Is calculated.

Respiratory center of gravity _{G 1} is the position of the center of gravity of the subject S which is calculated using the respiratory component _s 11 _{~s 41} of the load signal _s 1 ~s _4, heart centroid _{G 2} is a load signal _s 1 ~s ₄ is the position of the center of gravity of the subject S calculated using the heartbeat components s _{12 to} s ₄₂ of ₄ . Position of the respiratory center of gravity G _1, and calculates the position of the heart center of gravity G ₂ is carried out by the following calculation.

On the bed BD, XY coordinates are set as shown in FIG. 2, and the coordinates of the load detectors 11, 12, 13, 14 are set to (X ₁₁ , Y ₁₁ ), (X ₁₂ , Y ₁₂ ), (X _{13, respectively} ). , Y ₁₃ ), (X ₁₄ , Y ₁₄ ), and the load detection values of the load detectors ₁₁ , ₁₂ , ₁₃ , and ₁₄ are W ₁₁ , W ₁₂ , W ₁₃ , and W ₁₄ , respectively, are added to the bed BD. The center-of-gravity position G (X, Y) of the loaded load is calculated by the following equation.

Here, as the detected values W ₁₁ , W ₁₂ , W ₁₃ , and W ₁₄ of the loads of the load detectors ₁₁ , ₁₂ , ₁₃ , and ₁₄ , the respiratory components s ₁₁ of the load signals s ₁ , s ₂ , s ₃ , and s ₄ , by using the output value of each sampling time _{s 21, s 31, s 41} , the position of the respiratory center of gravity _{G 1} for each sampling time is calculated, respiratory centroid track GT ₁ from the time variation of the respiratory center of gravity _{G 1} Is calculated. Similarly, by using the output values at each sampling time of the heart rate components s ₁₂ , s ₂₂ , s ₃₂ , and s ₄₂ as the detection values W ₁₁ , W ₁₂ , W ₁₃ , and W ₁₄ , the heart rate centroid at each sampling time is used. The position of G ₂ is calculated, and the respiratory centroid locus GT ₂ is calculated from the temporal variation of the heart centroid G ₂ . The determined positions of the respiratory centroid G ₁ and the heart centroid G ₂ , the respiratory centroid locus GT ₁ , and the heart centroid locus GT ₂ are stored in the storage unit 4.

[Sleeping determination process]
In Nesugata decision step S4, Nesugata determination unit 33, based on at least one of the respiratory center of gravity trajectory GT ₁ and heart centroid trajectory GT _2, determines Nesugata the subject S. In the present specification and the present invention, the determination of the sleeping posture means determining whether the subject is in the supine position, the lying position or the prone position.

  The determination of sleeping posture in the sleeping posture determination unit 33 is performed based on the following principle.

Human breathing is performed by moving the thorax and diaphragm to expand and contract the lungs. Here, when inhaling, that is, when the lungs expand, the diaphragm descends downward, and the internal organs also move downward. On the other hand, when exhaling, that is, when the lungs contract, the diaphragm rises upward and the internal organs also move upward. The inventor of the present invention has found through research that the respiratory center of gravity G1 slightly vibrates in _one axial direction as the internal organs move. Hereinafter, this vibration is referred to as “breathing vibration”, and an axis extending in the vibration direction of the breathing vibration is defined as “breathing axis”. The vibration direction of the respiratory vibration is also referred to as “respiratory axis direction”.

As shown in FIGS. 4A and 4B, the inventor of the present invention has the direction of the respiratory axis A1 substantially along the extending direction of the spine (the direction of the body axis A0) in the front view. cage (FIG. 4 (a)), in side view, is inclined by a significant angle theta ₁ with respect to the direction of the body axis A0 (FIG. 4 (b)) have found that. In FIG. 4 (b), (in the figure, clockwise direction) behind the subject S head side of the breathing axis A1 is to the body axis A0 is shown a state in which inclined by an angle theta ₁ to, some subjects, sometimes head side of the breathing axis A1 is (in the figure, a counterclockwise direction) forward with respect to the body axis A0 is the angle theta ₁ inclined to. Further, the magnitude of the angle θ ₁ varies depending on the subject.

On the other hand, beating of the heart and heart rate, that is, means an expansion and contraction of the heart, the inventors of the present invention, research, the heart center of gravity G ₂ is slightly in a uniaxial direction with the expansion and contraction of the heart I found that it vibrates. Hereinafter, this vibration is referred to as “heartbeat vibration”, and an axis extending in the vibration direction of the heartbeat vibration is defined as “heartbeat axis”. The vibration direction of the heartbeat vibration is also referred to as “the direction of the heartbeat axis”.

As shown in FIGS. 5A and 5B, the inventor of the present invention rotates the direction of the heartbeat axis A2 counterclockwise by an angle θ _{2 in} the front view. It was the direction (azimuth) (FIG. 5 (a)), and in a side view, it was found to be substantially parallel to the direction of the body axis A0 (FIG. 5 (b)). In addition, the magnitude | size of angle (theta) ₂ changes with test subjects.

  From the above knowledge, when the sleeping posture of the subject S is each of the supine position, the recumbent position, and the prone position, the axis (hereinafter referred to as “projected respiratory axis”) that projects the respiratory axis A1 on the upper surface (bed surface BDS) of the bed BD. (Referred to as “PA1”) and the axis obtained by projecting the heartbeat axis A2 onto the bed surface BDS (hereinafter referred to as “projected heartbeat axis PA2”).

When the sleeping posture of the subject S is in the supine position, as shown in FIG. 6 (a), the projected respiratory axis PA1 is parallel to the body axis A0, and the projected cardiac axis PA2 rotates the projected respiratory axis PA1 counterclockwise. and it extends in an angle theta ₂ is rotated direction.

If Nesugata the subject S is lying down, as shown in FIG. 6 (b), the projection cardiac axis PA2 is parallel to the body axis A0, projection breathing axis PA1 is a projection cardiac axis PA2 angle theta ₁ It extends in the direction of rotation. Incidentally, in FIG. 6 (b), although the projection breathing axis PA1 indicates a state extending in a direction rotated by an angle theta ₁ projection heartbeat axis PA2 counterclockwise, depending subject projection breathing axis PA1 is extending projection heartbeat axis PA2 is rotated clockwise by the angle theta ₁ direction.

When the sleeping posture of the subject S is in the prone position, as shown in FIG. 6C, the projected respiratory axis PA1 is parallel to the body axis A0, and the projected cardiac axis PA2 is angled clockwise with respect to the projected respiratory axis PA1. It extends in a direction rotated by theta _2.

Nesugata judging unit 33, from the respiratory center of gravity trajectory GT ₁ and heart centroid trajectory GT _2, determine the direction of the projection respiratory axes PA1 and projection cardiac axis PA2, the direction of projection breathing axis PA1, the direction of projection heartbeat axis PA2, projection breathing The sleeping posture of the subject S is determined based on the positional relationship between the axis PA1 and the projected heartbeat axis PA2. Specifically, the determination of the sleeping figure is executed by the following procedure.

Nesugata determination unit 33 first extracts the respiratory center of gravity trajectory GT ₁ subject S from the storage unit 4, from the trajectory of the vibration corresponding to the breathing vibration included in the respiratory center of gravity trajectory GT _1, 1 one extreme point (one-way And the other extreme point that appears immediately before or after the extreme point (the point where the amplitude is maximized in the reverse direction). Then, the direction of the axis connecting the extreme points is determined as the direction of the respiratory vibration projected on the bed surface BDS, that is, the direction of the projected respiratory axis PA1. The direction of the projected heartbeat axis PA2 is similarly determined.

  Next, the sleeping posture determination unit 33 determines the sleeping posture of the subject S based on at least one of the direction of the projected respiratory axis PA1 and the direction of the projected heartbeat axis PA2. As a specific example, a method for determining whether the subject S is in the lying position or the supine position or the prone position will be described.

  After the sleeping posture of the subject S is once known, the sleeping posture determination unit 33 can track the change in the sleeping posture of the subject S based only on the direction of the projected respiratory axis PA1 or the direction of the projected heartbeat axis PA2. it can.

For example, when the subject S is moved to the recumbent position from supine or prone position, the projection breathing axis PA1 rotates instantaneously by an angle theta ₁ in the clockwise direction or counterclockwise direction. At this time, if it is known that the sleeping posture of the subject S is the supine position or the prone position, the sleeping posture determination unit 33 determines that the subject S is based on the rotation of the angle θ _{1 on} the projected respiratory axis PA1. It can be determined that the recumbent position has been reached.

Similarly, when the subject S is moved to the recumbent position from supine or prone position, the projection cardiac axis PA2 rotates instantaneously by an angle theta ₂ in the clockwise direction or counterclockwise direction. At this time, if it is known that the sleeping posture of the subject is in the supine position or the prone position, the sleeping posture determination unit 33 determines that the subject S is lying on the basis of the rotation of the angle θ _{2 on} the projected heartbeat axis PA2. It can be determined that the position has been moved.

Even when the subject S is known that in a lying position, Nesugata judging unit 33, the projection breathing axis PA1 is rotated by an angle theta _1, or that the projected heartbeat axis PA2 is rotated by an angle theta ₂ Based on this, it can be determined that the subject S has reached the supine position or the prone position.

  In this way, the sleeping posture determination unit 33 grasps the occurrence of rotation in the projected respiratory axis PA1 or the projected heartbeat axis PA2, so that the subject S is in the lying position, the supine position, or the prone position. You can track if there is.

When the sleeping posture of the subject S is unknown, the sleeping posture determination unit 33 determines whether the subject S is in the supine position or the supine position based on both the direction of the projected respiratory axis PA1 and the direction of the projected heartbeat axis PA2. Determine whether one of them is prone. Further, by performing the determination based on both the direction of the direction of the projection heartbeat axis PA2 projection breathing axis PA1 Thus, projection breathing shaft which may occur when the subject S rotates the body axis AO angle theta ₁ The rotation of the angle θ ₁ of the PA _{1 or} the rotation of the angle θ ₂ of the projected respiratory axis PA ₂ that may occur when the subject S rotates the body axis AO by the angle θ _2, And the rotation of the projected respiratory axis PA1 and the projected heartbeat axis PA2 that occur when the position changes between the prone position and the prone position.

As shown in FIGS. 6A and 6C, when the subject S is in the supine position or the prone position, the projected heartbeat axis PA2 is inclined by the angle θ _{2 with} respect to the projected respiratory axis PA1. Meanwhile, as shown in FIG. 6 (b), when the subject S is lying down, the projection cardiac axis PA2 is inclined by an angle theta ₁ with respect to the projection respiratory axis PA1. The angle between the thus Nesugata judging unit 33, the subject S as long as the angle is a theta ₁ between the projection breathing axis PA1 and projection heartbeat axis PA2 is lying down, a projection respiratory axis PA1 and projection heartbeat axis PA2 If is θ ₂ , the subject S is determined to be in either the supine position or the prone position.

  As another specific example of the method in which the sleeping posture determination unit 33 determines the sleeping posture of the subject S, a method of determining whether the subject S is in the supine position or the prone position will be described.

  Once it is known that the sleeping posture of the subject S is the supine position or the prone position, the sleeping posture determination unit 33 determines that the sleeping posture of the subject S is the supine position based only on the direction of the projected heartbeat axis PA2. It can be determined whether the position is prone or prone.

For example, when the subject S has moved to the prone position from supine projection cardiac axis PA2 rotates instantaneously by an angle 2 [Theta] ₂ in the clockwise direction. At this time, if known to be subject Nesugata is supine, Nesugata judging unit 33, the subject S based on the rotation angle 2 [Theta] ₂ in the clockwise direction to the projection heartbeat axis PA2 has occurred It can be determined that the prone position has been reached.

Similarly, when the subject S has moved in a supine position from the prone position, the projection cardiac axis PA2 is rotated by momentarily angle 2 [Theta] ₂ in the counterclockwise direction. At this time, if known to be subject Nesugata is prone position, Nesugata determination unit 33 subjects S based on the rotation angle 2 [Theta] ₂ in the counterclockwise direction to the projection heartbeat axis PA2 has occurred It can be determined that the supine position has been reached.

When the sleeping posture of the subject S is unknown, the sleeping posture determination unit 33 is in the supine position or the prone position based on both the direction of the projected respiratory axis PA1 and the direction of the projected heartbeat axis PA2. Determine whether. In addition, by performing determination based on both the direction of the projected respiratory axis PA1 and the direction of the projected heartbeat axis PA2 in this way, a projected heartbeat axis that can occur when the subject S rotates the body axis AO by an angle 2θ _2. PA2 rotation angle 2 [Theta] ₂ of the can Nesugata subject S is distinguished from the rotation of the projection heartbeat axis PA2 caused when the change between the supine and prone position.

As shown in FIG. 6 (a), when the subject S is supine, the direction of the projection heartbeat axis PA2 is the direction of rotating the direction of the projection breathing axis PA1 counterclockwise by an angle theta _2. Meanwhile, as shown in FIG. 6 (c), if the subject S is prone position, the direction of the projection heartbeat axis PA2 is a direction in which the direction of the projection breathing axis PA1 is rotated clockwise by an angle theta ₂ . Therefore Nesugata determination unit 33 determines that the subject S as long extends in a direction projecting heartbeat axis PA2 is rotated by an angle theta ₂ of the projection breathing axis PA1 counterclockwise it is in a supine position, the projection heartbeat axis PA2 there is determined that the subject S as long extends in the direction of rotating the projected breathing axis PA1 clockwise angle theta ₂ is in the prone position.

  The sleeping posture determination unit 33 may further determine the direction of the body axis A0 of the subject S after determining the sleeping posture of the subject S based on the direction of the projected respiratory axis PA1 and the direction of the projected heartbeat axis PA2. For example, after determining that the subject S is in the supine position or the prone position, the sleeping posture determination unit 33 is such that the direction of the projected respiratory axis PA1 when the determination is performed is the direction in which the body axis A0 of the subject S extends. It can be determined that there is. Similarly, after determining that the subject S is in the recumbent position, the sleeping posture determination unit 33 determines that the direction of the projected heartbeat axis PA2 when the determination is made is the direction in which the body axis A0 of the subject S extends. Can be determined.

[Display process]
In the display step S5, the control unit 3 displays the sleeping posture of the subject S determined by the sleeping posture determination unit 33 on the display unit 5. The display is performed, for example, by displaying character information or a symbol mark. In addition, when the sleeping posture of the subject S satisfies a predetermined condition (for example, when the prone position is continued for a certain period of time), the notification unit 6 may be used to perform voice notification.

  The effects of the occupancy state monitoring system 100 of this embodiment are summarized below.

  The bed-holding state monitoring system 100 according to the present embodiment is based on at least one of the direction of the respiratory axis A1 of the subject S (the direction of the projected respiratory axis PA1) and the direction of the heartbeat axis A2 (the direction of the projected respiratory axis PA2). Therefore, the sleeping posture of the subject S can be determined with high reliability regardless of the direction of the body axis A0 of the subject on the bed. Further, by performing determination using both the direction of the respiratory axis PA1 and the direction of the heartbeat axis A2 (the direction of the projected respiratory axis PA1 and the direction of the heartbeat respiratory axis PA2), the reliability of the determination can be further increased.

The bed-holding state monitoring system 100 according to the present embodiment calculates the respiratory centroid G ₁ and the heart centroid G ₂ based only on the respiratory component of the subject S, the respiratory component that is a load component that vibrates at the heartbeat frequency, and the heartbeat component. The center-of-gravity locus GT1 and the heart rate center-of-gravity locus GT2 are obtained, and the projected respiratory axis PA1 and the projected heartbeat axis PA2 are obtained. The respiratory center of gravity G ₁ and the heart rate center of gravity G ₂ have respiratory frequencies and heart rate frequencies different from those of the subject S. The same applies to the projected respiratory axis PA1 and the projected cardiac axis PA2 without being affected by the load of three persons (visitors or the like) or the load of inanimate objects (such as bags) that do not breathe or beat. Therefore, the occupancy state monitoring system of the present embodiment can more accurately determine the sleeping posture of the subject S while suppressing errors due to external factors.

  In the above embodiment, the following modification can be used.

In the bed state monitoring system 100 of the above embodiment, the center-of-gravity position calculating unit 32 calculates the breathing center of gravity G ₁ and respiratory center of gravity trajectory GT ₁ subject S, Nesugata determination unit 33, based on the respiratory center of gravity trajectory GT ₁ The subject S is determined using the direction of the projected respiratory axis PA1 obtained in the above. However, the center-of-gravity position calculation unit 32 calculates the position of the center of gravity of the subject S (hereinafter referred to as “simple center-of-gravity position G ₀ ”) using the load signals s _{1 to} s ₄ as they are, and moves the simple center-of-gravity position G ₀ . may be calculated simply centroid trajectory GT ₀ is the locus, Nesugata determination unit 33 may determine the direction of the projection breathing axis PA1 based on a simple centroid trajectory GT _0. Since the load applied on the bed BD is substantially coincident with simple centroid trajectory GT ₀ if only the load due to the subject S and respiratory center of gravity trajectory GT _1, a vibration corresponding to the respiration of a simple centroid trajectory GT ₀ The direction of the projected respiratory axis PA1 can be obtained from the vibration direction.

  It is also possible to determine the sleeping postures of a plurality of subjects on the bed BD by the in-bed state monitoring system 100 of the above embodiment.

Since there are individual differences in the cycle of breathing and heartbeat, for example, when the signal separation step S2 of the above embodiment is performed in a state where two subjects S1 and S2 are present on the bed BD, the frequency of 0.1 Hz to 3.5 Hz In the frequency spectrum of the frequency band, frequency peaks appear at positions corresponding to the breathing frequency of the subject S1, the breathing frequency of the subject S2, the heartbeat frequency of the subject S1, and the heartbeat frequency of the subject S2. From the position of this frequency peak, the respiration frequency ν ₁₁ and heart rate frequency ν ₂₁ of the subject S1 can be specified, and the respiration frequency ν ₁₂ and heart rate frequency ν ₂₂ of the subject S2 can be specified.

  The subsequent steps are the same as in the above embodiment. Specifically, the signal separation unit 31 obtains a respiratory component and a heart rate component for each of the subjects S1 and S2, and the center-of-gravity position calculation unit 32 uses the respiratory component and the heart rate component of each of the subjects S1 and S2. The respiratory centroid, respiratory centroid locus, heartbeat centroid, and heartbeat centroid locus of each of S1 and S2 are calculated. Thereafter, the sleeping figure determination unit 33 obtains the direction of the projected respiratory axis and the direction of the projected heartbeat axis of each of the subjects S1 and S2 from the respiratory center of gravity locus and heartbeat center of gravity locus of each of the subjects S1 and S2, and based on these, the subject Each sleeping figure of S1 and S2 is determined.

In the bed state monitoring system 100 of the above embodiments, Nesugata judging unit 33, a projection by identifying two extreme points consecutive in the trajectory of the vibration corresponding to the breathing vibration included in the respiratory center of gravity trajectory GT ₁ seeking direction of the breathing axis PA1, had sought direction of the projection heartbeat axis PA2 by identifying two extreme points consecutive in the trajectory of the vibration corresponding to the heartbeat vibration included in the heartbeat centroid trajectory GT _2, which It is not limited to. The sleeping posture determination unit 33 can also determine the directions of the projected respiratory axis A1 and the projected heartbeat axis A2 by the following method, for example.

により求め、平均重心Ｇ０（Ｘ０、Ｙ０）を通り、Ｘ軸に対して角度ａを有して延びる線分が投影呼吸軸ＰＡ１の位置を示すとみなす方法によっても求め得る。このようにして求められた投影呼吸軸ＰＡ１を図７に示す。投影心拍軸ＰＡ２の方向も同様にして求めることができる。 As an example, the direction of the projected respiratory axis PA1 is obtained by calculating an average centroid G0 from an average value of n respiratory centroid positions G1 to Gn (FIG. 7) included in a certain sampling period, and calculating the average centroid G0 (X0, Y0) and n , Gk1 (Xk1, Yk1),... Gk2 (Xk2, Yk2),... Gn (Xn, Yn) The average inclination angle a of the angle between the X axis,

It can also be obtained by a method in which a line segment passing through the average gravity center G0 (X0, Y0) and extending at an angle a with respect to the X axis indicates the position of the projected respiratory axis PA1. The projected respiratory axis PA1 thus obtained is shown in FIG. The direction of the projected heartbeat axis PA2 can be obtained in the same manner.

  As another example, linear distances dh1,... Dhk1,..., Gn passing through the average centroid G0 and with the centroids G1, ..., Gk1, ..., Gk2, ..., Gk3, ... Gn. A method may be used in which it is assumed that the line Ha that minimizes the standard deviation of dhk2, ..., dhk3, ..., dhn indicates the position of the projected respiratory axis PA1. An example of the line Ha is shown in FIG. The direction of the projected heartbeat axis PA2 can be obtained in the same manner.

  In the above embodiment, the load detectors 11, 12, 13, and 14 are not limited to load sensors using a beam-type load cell, and for example, force sensors may be used.

  In the above embodiment, the number of load detectors is not limited to four. Five or more load detectors may be used with additional legs on the bed BD. Or you may arrange | position a load detector only to three of the legs of bed BD. Even when there are three load detectors, if they are not arranged in a straight line, the position of the center of gravity of the subject S on the bed BD surface can be detected.

In the above embodiment, the load detector 11, 12, 13 and 14 are arranged under the bed casters _C 1 attached to the lower end of the leg of the _{BD, C 2, C 3,} C 4 However, it is not limited to this. Each of the load detectors 11, 12, 13, and 14 may be provided between the four legs of the bed BD and the floor plate of the bed BD, or the four legs of the bed BD can be divided vertically. For example, it may be provided between the upper leg and the lower leg. Further, the load detectors 11, 12, 13, and 14 may be integrated with the bed BD, and a bed system BDS including the bed BD and the occupancy information monitoring system 100 of the present embodiment may be configured (FIG. 9). In the present specification, “the load detector provided on the bed” means a load detector provided between the four legs of the bed BD and the floor plate of the bed BD as described above, an upper leg, It means a load detector provided between the lower leg.

  In the above embodiment, a signal amplification unit that amplifies the load signal from the load detection unit 1 and a filtering unit that removes noise from the load signal are provided between the load detection unit 1 and the A / D conversion unit 2. May be.

  Note that in the bed-floor monitoring system 100 of the above embodiment, the display unit 5 is not limited to displaying information on a monitor so that the user can visually recognize it. For example, the display unit 5 may be a printer that prints and outputs the sleeping posture of the subject S, or turns on the blue lamp when the subject S is supine, turns on the yellow lamp when lying down, and turns on the red lamp when lying down. You may display using simple visual expressions, such as lighting. Alternatively, the display unit 5 may convey the presence state by voice. Furthermore, the presence-in-room monitoring system 100 does not have to include the display unit 5 and may include only an output terminal that outputs information. A monitor (display device) or the like for performing display is connected to the occupancy state monitoring system 100 via the output terminal.

  In addition, although the alerting | reporting part 6 of the said embodiment performed alerting | reporting auditorily, the alerting | reporting part 6 may be the structure which alert | reports visually by blinking of light etc., and is the structure which alert | reports by vibration. There may be. Moreover, the in-bed state monitoring system 100 of the said embodiment does not need to have the alerting | reporting part 6. FIG.

  As long as the characteristics of the present invention are maintained, the present invention is not limited to the above embodiments, and other forms conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention. .

  The bed-holding state monitoring system according to the present invention can accurately determine the sleeping posture of a subject. Therefore, if this is used in a hospital or a care facility, the patient or the care recipient is prevented from slipping and the sleep state is improved. be able to.

DESCRIPTION OF SYMBOLS 1 Load detection part 11, 12, 13, 14 Load detector 2 A / D conversion part 3 Control part 31 Signal separation part 32 Center of gravity position calculation part 33 Sleeping form determination part 4 Storage part 5 Display part 6 Notification part 7 Input part 100 Attic monitoring system A1 Respiratory axis A2 Heart rate axis BD Bed BDS Bed system GT ₁ Respiration center of gravity locus GT ₂ Heart rate center of gravity locus S Subject

Claims (3)

An in-bed monitoring system for monitoring the in-bed state of a subject on a bed,
A plurality of load detectors provided under the bed or under the legs of the bed and for detecting a load by the subject;
A load separation unit that separates a load component that vibrates according to the heartbeat of the subject from the load by the subject;
A center-of-gravity position calculation unit for determining the position of the subject's heart rate center of gravity based on a load component that vibrates according to the heart rate of the subject;
A bed-holding state monitoring system comprising: a sleeping posture determination unit that determines whether the sleeping posture of the subject is in the supine position or the prone position based on the vibration direction of the heart rate center of gravity. The load separation unit separates a load component that vibrates according to the breathing of the subject from the load by the subject,
The center-of-gravity position calculation unit obtains the position of the subject's breathing center of gravity based on a load component that vibrates according to the subject's breathing,
The presence / absence determination unit according to claim 1, wherein the sleeping posture determination unit determines whether the sleeping posture of the subject is in a supine position or a prone position based on a vibration direction of the heart rate center of gravity relative to a vibration direction of the respiratory center of gravity. Floor condition monitoring system. The center-of-gravity position calculation unit obtains the position of the center of gravity of the subject based on the load by the subject,
The sleeping posture determination unit determines whether the sleeping posture of the subject is in a supine position or a prone position based on the vibration direction of the heart rate center of gravity relative to the vibration direction of the center of gravity according to the breathing of the subject. The in-situ state monitoring system according to claim 1.

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