JP5111889B2 - Bed equipment - Google Patents

Description

  The present invention is provided with a bed leaving prediction / detection system that realizes bed leaving prediction based on the movement of a user on the bed and the discrimination of bed leaving / bed presence for elderly people with dementia and patients just after surgery. The present invention relates to a bed apparatus.

  Recently, a dementia elderly person's heel and fall / fall accidents around the bed have become social problems, and countermeasures are required. In addition, by monitoring the movement of a user who has been in the bed for a long period of time, such as an elderly person or a patient who has just been postoperatively, using bed load information, it is possible to more quickly in the event of an abnormal situation. It is expected to be able to cope with it.

  The technology disclosed in Patent Document 1 uses weight information to determine whether a user is in the bed or has left the bed, and can monitor the movement of the user on the bed. Can not.

  In order to improve this problem, the techniques disclosed in Patent Documents 2 to 4 and Non-Patent Document 1 determine the position of the center of gravity from the load information of four points on the bed, and use this center of gravity position information to find the floor. It is to monitor the movement of the user at the time.

JP-A-2-280733 Japanese Patent No. 3093745 Japanese Patent No. 3322632 USP 5,276,432 J.C.Barbenel et al., Monitoring the mobility of patients in bed, Medical & Biological Engineering & Computing, pp.466-468 (Sep 1985)

  However, in the techniques of Patent Documents 2 to 4, even if it is possible to detect that there is a user at the end of the bed, for example, by monitoring based only on the position of the center of gravity of the user on the bed, Whether the user is at the end of the bed, is at the end of the bed trying to get out of bed, or places an item on the bed where the user is sleeping, or another person who is not a user leans on the bed It is impossible to distinguish whether the center of gravity changes due to sitting. In addition, when the movement of the center of gravity occurs due to an action such as removing an accessory such as a fence, there is a problem in that it cannot be distinguished from a rising motion and may be erroneously determined.

  Further, in Non-Patent Document 1, in order to monitor the movement of the patient on the bed, the load of the four bed feet is measured by a load cell, the weight of the patient on the bed is measured, and the load measurement value of each bed foot is measured. A technique for calculating the position of the center of gravity on the bed based on the difference between the two and calculating the movement distance of the position of the center of gravity and a technique for determining the state of the patient from the number of movements of the patient on the bed are disclosed.

  However, even in the technique disclosed in Non-Patent Document 1, since the movement of the user on the bed is monitored only by the movement distance of the center of gravity position on the bed, the article is placed on the bed part where the user is sleeping. There is a problem in that it may not be possible to distinguish whether it is a movement of the center of gravity due to placing or another person who is not a user leaning on the bed or sitting down, and erroneous determination may be made.

  The present invention has been made in view of such problems, and by determining information combining the weight information of the user and the gravity center position information, the movement of the user can be monitored more accurately, and erroneous detection is reduced. It is another object of the present invention to provide a bed apparatus provided with a detection system that has high detection accuracy and can monitor a user's movement with high reliability.

The bed apparatus according to the present invention comprises a load measuring means for detecting a load on the bed portion and generating a load signal, a weight calculating means for calculating the weight of a user located on the bed portion based on the load signal, Weight threshold value determining means for determining whether or not the weight is equal to or less than a predetermined weight threshold value, gravity center position calculating means for calculating the gravity center position of the user based on the load signal, and the gravity center position of the bed portion Based on the determination results of the center-of-gravity position region determination unit that determines whether or not the region is the monitoring target region, and the weight threshold value determination unit and the center-of-gravity position region determination unit, the weight is equal to or less than the predetermined weight threshold and but has a weight center-of-gravity position monitoring means for monitoring the time in the monitored area, wherein when the body weight center-of-gravity position monitoring means exceeds a predetermined time by continuous time to monitor, the user stanza position that it is in Characterized in that it detects.
Preferably, the weight threshold is set to a value of 73% to 96% of the weight of the bed user, and the predetermined time is set to a value of 1 second to 10 seconds.

Another bed apparatus according to the present invention includes a load measuring unit that detects a load on the bed and generates a load signal, and a weight calculating unit that calculates the weight of a user located on the bed based on the load signal. A weight threshold determination means for determining whether the weight is equal to or less than a first weight threshold Ws1 or a second weight threshold Ws2 (Ws1 <Ws2); and the center of gravity of the user based on the load signal The determination results of the center-of-gravity position calculating means for calculating the position, the center-of-gravity position area determining means for determining whether or not the center-of-gravity position is in the monitoring target area of the bed, A weight center-of-gravity position detecting unit that detects that the weight is equal to or less than the first weight threshold value Ws1 and the center-of-gravity position is in the monitoring target area; A weight center-of-gravity position monitoring unit that monitors a time during which the weight is equal to or less than a second weight threshold Ws2 and the center-of-gravity position is in the monitoring target area based on a fixed result, , When it is detected that the weight is equal to or less than the first weight threshold Ws1 and the gravity center position is in the monitoring target area, or the time monitored by the weight gravity center position monitoring means continuously exceeds a predetermined time. Further, it is detected that the user is in the end sitting position.
The first weight threshold is set to 80% of the bed user's weight, the second weight threshold is set to a value that is greater than 80% and less than or equal to 96% of the bed user's weight, and the predetermined time is It is preferable to set a value between 1 second and 10 seconds.

  When the user moves on the bed, the center of gravity of the user moves on the bed. When the center-of-gravity position area determination unit determines that the center-of-gravity position is in the monitoring target area (for example, the end seat position), it can be detected that the bed user is at the end seat position. However, there is a possibility that the center of gravity position is located in the monitoring target area after the bed user turns over. Therefore, in the present invention, when the weight measurement value is equal to or less than the weight threshold value, it is determined that the weight measurement value has fallen as a result of the bed user sitting at the end seat position and the foot landing on the floor, and turned over. Instead, it detects that the bed user is sitting at the end position. Therefore, it is detected that the bed user is sitting at the end seat position by determining that the position of the center of gravity is in the monitoring target region and that the weight measurement value is equal to or less than the threshold value. However, when the bed user is sitting at the end seat position, a clear change in the weight measurement value does not necessarily occur, and there is a possibility that the decrease in the weight measurement value is small and does not fall below the weight threshold value. Therefore, in order to increase the detection accuracy, the weight threshold value is set to a value close to the weight of the bed user, and when there is even a slight decrease in the weight measurement value, this is detected as being in the end seat position. You can also However, if this is done, it will be detected as an end seat position when there is a slight decrease in the body weight measurement value, so that false alarms are likely to occur. Therefore, in the present invention, the weight center-of-gravity position monitoring means monitors the time when the center-of-gravity position is in the monitoring target area and the weight measurement value is equal to or less than the weight threshold, and the monitoring time continuously exceeds a predetermined time. Sometimes it detects that the user is at the end position. Thereby, edge position detection when the user does not intend to leave can be prevented without increasing misinformation. Thereby, it can be detected with high accuracy that the bed user is in the end seat position and is about to leave the bed.

  According to the present invention, when the weight information of the user and the gravity center position information are determined in combination, and the weight is equal to or less than the weight threshold value, and the time that the gravity center position is within the monitoring target area continues for a predetermined time, Since it is detected that the bed user is going to get out of bed, it is possible to accurately detect the user's getting out of the bed, and it is possible to prevent erroneous detection and reduction in detection accuracy. This improves the reliability of the system.

  Hereinafter, a bed apparatus according to an embodiment of the present invention will be specifically described with reference to the accompanying drawings. First, a bed apparatus according to an embodiment having a bed leaving detection prediction function will be described. The bed leaving detection prediction function is a function for detecting and predicting that the patient (user) on the bed is located at the end seat position (monitoring target region) at the edge of the bed. FIG. 1 is a schematic view of a bed apparatus according to an embodiment of the present invention, FIG. 2 is a schematic view showing an example in which four load sensors 3-1 to 3-4 are arranged at four ends of the bed part 1, and FIG. A block diagram when the signal of the load sensor 3 is processed by the controller 5 and each function is operated is shown. As shown in FIG. 1, load sensors 3 (3-1, 3-2) that generate load signals by detecting loads on the bed portion 1 at four corners of a legged frame 2 that supports the bed portion 1. 3-3, 3-4) are provided one by one. The load signal generated by the load sensor 3 is output at regular intervals by a bed leaving prediction / detection system controller 5 (hereinafter referred to as controller 5) provided on one of the wall portions 4 provided on the two short sides of the bed portion 1. Is read.

The controller 5 includes a weight calculation unit, a gravity center position calculation unit, a weight threshold value determination unit, a gravity center position region determination unit, a weight gravity center position monitoring unit, a gravity center position monitoring target region setting unit, a storage unit, an alarm device, an alarm selection unit, and the like. It is provided, and detection of each part is implemented by software. The controller 5 reads the load signal generated by the load sensor 3 at regular intervals. The weight calculation unit calculates the weight of the user on the bed 1 based on the read signal. Since the bed part 1 is provided with accessories such as mattresses, comforters and fences (not shown), the weight calculation unit uses this state as a reference (= 0 kg, correction of the origin of the center of gravity), and the user There calculates the weight W _T of the user by calculating reads a load signal of the bed section 1 when lying on the bed section 1 by the controller 5, a load increase from the reference.

The center-of-gravity position calculation unit calculates the center-of-gravity position of the user on the bed 1 based on the load signal generated by the load sensor 3 that the controller 5 reads at regular intervals. As shown in FIG. 2, the side connecting the first load sensor 3-1 and the third load sensor 3-3 is the head side, the second load sensor 3-2 and the fourth load sensor 3-4 are The side that connects is the foot side. The distance between the first load sensor 3-1 and the second load sensor 3-2 with the head side left end of the bed 1 (the lower left end of the bed 1 in FIG. 2) as the origin (0, 0). Is B _X , and the distance between the first load sensor 3-1 and the third load sensor 3-3 is _BY . When the user sleeps on the bed 1, W _{1 to} W ₄ are calculated values of the load increase from the reference of the load signals generated by the first to fourth load sensors 3-1 to 3-4. Assuming that (W ₁ + W ₂ + W ₃ + W ₄ = W _T ), the gravity center position (X, Y) of the user can be expressed by the following Equation 1. According to this equation, the center-of-gravity position calculation unit calculates the center-of-gravity position of the user on the bed 1.

Weight threshold determination unit monitors the body weight W _T of the user on the bed section 1 is computed by the body weight computing unit, determines whether the body weight W _T of the user is below a predetermined weight threshold W _T1 To do. That is, when the bed user is sitting at the end position of the bed and the foot is on the floor, the weight detection value is lower than the weight of the user and becomes less than the weight threshold _WT1 . This weight threshold is, for example, 96% of the weight of the bed user. Further, the center of gravity location area determining unit monitors the center-of-gravity position of the user (X _{1, Y 1),} the center of gravity position of the user (X _{1, Y 1)} is in the center-of-gravity position monitored area of the bed section 1 It is determined whether or not. The center-of-gravity position monitoring area is the edge of the base head, a stanza position when ie lifting. Therefore, the center-of-gravity position monitoring target region may be all four edges that surround the bed, and when one side edge of the bed is in contact with a wall or the like, the wall side bed side edge does not become the end seat position.

Weight threshold setting unit sets the body weight threshold W _T1 when the user on the bed section 1 determines whether or not the position on the bed. The center-of-gravity position monitoring target area setting unit sets the monitoring target area of the center-of-gravity position. The weight threshold value _WT1 and the monitoring target area are input from a personal computer connected to the controller 5, calculated by the calculation unit of the controller 5, and stored in the storage unit.

  The alarm device generates an alarm according to the determination results of the weight threshold value determination unit and the gravity center position region determination unit, and the alarm selection unit has a function of selecting the presence and type of the alarm.

FIG. 3 shows a block diagram when the signals of the first load sensor 3-1 to the fourth load sensor 3-4 in FIG. 1 are processed by the controller 5 to operate each function. The load signals generated by the first to fourth load sensors 3-1 to 3-4 are read and calculated by the calculation unit 21 of the controller 5 at regular intervals. Calculation unit 21 body weight computing unit for computing the body weight W _T of the user on the bed section 1, the center-of-gravity position computing unit for computing a user position of the center of gravity on the bed section 1, the user weight is given weight weight threshold determination unit determines whether the following threshold _{W T1,} and monitors the position of the center of gravity of the user _(X 1, _{Y 1),} the center of gravity position of the user _(X 1, _{Y 1)} is the bed section 1 A center-of-gravity position area determination unit that determines whether the center-of-gravity position is in the monitoring target area, and a weight center of gravity that monitors the time when the weight is equal to or less than a predetermined threshold and the center-of-gravity position is in the monitoring target area based on the determination result of each determination unit It has a position monitoring unit, a weight threshold setting unit for setting a weight threshold, a center of gravity position monitoring target region setting unit for setting a center of gravity position monitoring target region, a storage unit, an alarm device, an alarm selection unit, and the like, and is used for determination The weight threshold value and the center-of-gravity position monitoring target area are stored. The storage unit 22 includes an alarm signal transmission unit 31 that generates an alarm according to the determination result of each determination unit. Further, the controller 5 further includes a setting operation unit 24 such as an operation switch and a power switch, an alarm display / stop operation unit 26 such as an alarm display unit 25 and a nurse call 29.

  Each alarm device transmits an alarm signal from the controller 5 and notifies the nurse station 30 via the nurse call 29 or, when managing a plurality of beds, a LAN (Local Area Network) access point 27 from the communication connector 12. Can be relayed to the PC 30 at a remote location.

Next, the operation of the end sitting position detection system according to the first embodiment of the present invention configured as described above will be described. Since the bed part 1 is provided with accessories such as mattresses, comforters and fences (not shown), the weight calculation unit uses this state as a reference (= 0 kg, correction of the origin of the center of gravity), and the user There calculates the weight W _T of the user by calculating reads a load signal of the bed section 1 when lying on the bed section 1 by the controller 5, a load increase from the reference. The weight of the user is stored in the storage unit 22 of the controller 5 by pressing an operation switch (not shown) of the controller 5 or operating a personal computer immediately after the user has slept on the bed 1. it can be, as a reference body weight W _S of the user the weight of the user at this time. Further, by inputting from a personal computer connected to the weight of the user obtained by the scales or the like to the controller 5, it is also possible to store the reference weight W _S of the user in the storage unit of the controller 5.

  FIG. 4 shows a flowchart of edge sitting position detection. The reference weight Wt of the user on the bed 1 is calculated in advance by the weight calculation unit of the calculation unit 21 of the controller 5, the weight threshold Ws2 is set by the weight threshold setting unit, and the weight center position monitoring target region setting unit sets the end point. A sitting position detection region Ds (monitoring target region) is set, and a monitoring time Ts for monitoring that the weight is equal to or less than a predetermined threshold and the center of gravity position is in the monitoring target region in the weight center of gravity position monitoring unit is set. Each of these values is stored in the storage unit 22 of the controller 5 (step S1). Further, in the present embodiment, when the weight Wt is greatly reduced, such as Ws1 or less (Ws1 <Ws2), the time Ts does not elapse, and the position of the center of gravity is within the monitoring region. This is determined to be in the end seat position. For this reason, such a low weight threshold value Ws1 is also set in step S1. The weight threshold Ws1 is, for example, 80% of the user's weight.

  In step S2, it is determined whether or not the weight measurement value Wt is less than or equal to the weight threshold value Ws1, and it is determined whether or not the position of the center of gravity is within the monitoring target area (D ≧ Ds). When it is satisfied, at the moment of the determination, it is detected that the bed user is at the end seat position, and an alarm is activated (step S5).

  On the other hand, in step S3, it is determined whether or not the weight measurement value Wt is equal to or less than the weight threshold value Ws2, and it is further determined whether or not the center of gravity position is in the monitoring target region (end seat position). When both conditions are satisfied, the control interval is Δt, and the monitoring time t is t + Δt. When the time t is less than the predetermined time T (step S4), the process returns to steps S2 and S3 again, and the weight threshold value and the gravity center position are determined. If it is determined in step S3 that the position of the center of gravity is within the monitoring region and the weight measurement value is equal to or less than the threshold value Ws2, the monitoring time t is further increased by Δt, and again in step S4, the time t Is determined to be equal to or longer than a predetermined monitoring time T, and when the time t is equal to or longer than T, it is detected that the bed user is in the end seat position. Then, an alarm is issued (step S5).

  In this way, in this embodiment, it is determined whether the bed user is in the end seat position on the bed in consideration of the weight, and when this state has passed for a predetermined time, the end seat position is set. Therefore, the threshold value Ws2 for determining the weight is set to a value close to the weight but less than the weight. In step S3, it is determined that the position is sensitive to the end position, and this state is determined in step S4. Since it is detected for the first time that the position is the end seat position when the time is continued for a predetermined time T, it can be performed with high accuracy and without erroneous detection whether or not the bed user is at the end seat position.

  It was 43 seconds on average when the operation time (excluding the case of standing up immediately from the end sitting position) of the 4 elderly people in hospital was measured from the end sitting position to getting out of bed. This measurement target operation number was 94 times. Thus, it can be seen that the end-sitting state is often maintained for a long time when the standing-up operation is not performed immediately after the end-sitting position. Therefore, the time T for monitoring the continuation of the end sitting state is set to at least 1 second in the sense that the standing operation is not performed immediately after the end sitting position. On the other hand, in the end-sitting position, the user lowers his / her foot on the floor, so the weight on the bed decreases. This weight loss becomes significant when the height of the bed from the floor when using the bed is low. Therefore, in a normal bed, the height is set to the lowest height, and at the height obtained by adding 330 mm, which is the thickness of the mattress, a large number of people are seated in the end sitting position, and the weight change on the bed is changed. Measured. As a result, the weight decrease rate on the bed at the end sitting position based on the subject's body weight was 26.7% on average and 7.6% with standard deviation (FIG. 5). Therefore, when 3σ is taken into consideration, it becomes 96.1%. That is, since the weight reduction rate is 26.7% of the body weight on average, when 3σ is seen in the direction where the weight reduction is small, 26.7-3 × 7.6 = 3.9%. When this is taken as a threshold value, 100-3.9 = 96.1% of the body weight.

  Therefore, the weight threshold is set to 96% or less of the bed user's weight, and the time T for monitoring the detection of the end sitting position is set to 1 second or more, so that the end sitting position detection suitable for a large number of users can be performed. Without increasing, the end sitting posture when the user does not intend to get out of bed is not erroneously detected as getting out of bed, and the getting out of bed can be detected with high accuracy.

  Further, since it is easy to detect the amount of change in the bed weight due to the end sitting posture, it is not necessary to consider up to 3σ. Therefore, the lower limit of the weight threshold is set to 73% (100−26.7 = 73.3) from the average value of the weight loss of 26.7%. Furthermore, when the weight center of gravity position monitoring unit that monitors the time when the weight is below the predetermined weight threshold and the center of gravity position is in the monitoring target area continues for 1 second to 10 seconds, Is detected when the user is in the end sitting position. It takes a certain time from the end-sitting position to the detection. For early detection, it is not preferable to set the monitoring time to a long time. For this reason, the upper limit of the monitoring time is preferably 10 seconds. On the other hand, if the monitoring time is too short, the nurse will lift the bed side fence and the bed weight will be reduced, and the center of gravity will be included in the monitored area. There is a possibility that. For this reason, it is preferable that the lower limit of the monitoring time is 1 second.

  The alarm device generates an alarm according to the detection result of the end sitting position, and the alarm selection unit has a function of selecting presence / absence and type of the alarm. While the alarm is being generated, the alarm can be reported to the nurse via the nurse call 29 or the personal computer 28 or the alarm display unit 25 of the controller 5.

  As described above, in the embodiment of the present invention, each threshold value, predetermined range, end seat position, and the like are input from a personal computer connected to the controller 5 and calculated by the calculation unit 21 of the controller 5. The operation can also be performed by a personal computer, and the calculation result can be input to the controller 5 from the personal computer.

It is the schematic of the bed apparatus which concerns on embodiment of this invention. 4 is a schematic view showing an example in which four load sensors 3-1 to 3-4 are arranged at four ends of the bed part 1. FIG. The block diagram when the signal of each load sensor 3 is information-processed by the controller 5 and each function is operated is shown. It is a figure which shows the flow of edge seat position detection of embodiment of this invention. It is a graph which shows a weight loss rate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1; Bedding part 2; Frame 3; Load sensor 3-1; 1st load sensor 3-2; 2nd load sensor 3-3; 3rd load sensor 3-4; 4th load sensor 4; Unit 5; bed leaving prediction / detection system controller 6; edge sitting position detection region 20; control unit 21; arithmetic unit 22; storage unit 23; operation display unit 24; setting operation unit 25; alarm display unit 26; LAN AP
28; PC 29; Nurse call 30; Nurse station 31; Alarm signal transmitter

Claims (4)

A load measuring means for detecting a load on the bed and generating a load signal; a weight calculating means for calculating a weight of a user located on the bed based on the load signal; and the weight is equal to or less than a predetermined weight threshold A body weight threshold value judging means for judging whether or not the person is in the center, a center-of-gravity position computing means for computing the center-of-gravity position of the user based on the load signal, and whether or not the center-of-gravity position is in the monitoring target area of the bed A time when the weight is equal to or less than the predetermined weight threshold and the position of the center of gravity is in the monitoring target region based on the determination results of the center-of-gravity position region determining unit and the weight threshold value determining unit and the center-of-gravity position region determining unit Weight weight center of gravity position monitoring means, and detecting that the user is in the end sitting position when the time monitored by the weight center of gravity position monitoring means continues for a predetermined time. Characterize Die assembly. A load measuring means for detecting a load on the bed and generating a load signal; a weight calculating means for calculating a weight of a user located on the bed based on the load signal; and the weight is a first weight threshold value A weight threshold value judging means for judging whether or not Ws1 or less or a second weight threshold value Ws2 (Ws1 <Ws2) or less, a center-of-gravity position calculating means for calculating the center-of-gravity position of the user based on the load signal, Based on the determination results of the center-of-gravity position area determination means for determining whether the center-of-gravity position is in the monitoring target area of the bed, and the weight threshold value determination means and the center-of-gravity position area determination means, the weight is the first weight. Based on the determination results of the body weight center position detecting means for detecting that the position of the center of gravity is equal to or less than the threshold value Ws1 and that the position of the center of gravity is in the monitoring target area; A weight center of gravity position monitoring unit that monitors a time during which the gravity center position is in the monitoring target area, and the weight is equal to or less than a first weight threshold value Ws1. And the user is in the end-sitting position when it is detected that the position of the center of gravity is in the monitoring target area, or when the time monitored by the weight center-of-gravity position monitoring means continues for a predetermined time. A bed apparatus characterized by detecting the above. The bed according to claim 1, wherein the weight threshold is set to a value of 73% to 96% of the weight of the bed user, and the predetermined time is set to a value of 1 second to 10 seconds. apparatus. The first weight threshold is set to 80% of the bed user's weight, the second weight threshold is set to a value that is greater than 80% and less than or equal to 96% of the bed user's weight, and the predetermined time is The bed apparatus according to claim 2, wherein the bed apparatus is set to a value of 1 second to 10 seconds.

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