JP4565234B2 - How to monitor human movement and posture - Google Patents

Description

  This invention attaches an accelerometer to a human body, and whether the person is in a static state or a dynamic state, whether it is in a dangerous state or in a stable state, The present invention relates to a method for monitoring a human motion and posture for automatically determining with higher accuracy.

  With the declining birthrate and aging population, nursing care for elderly people is becoming a social problem. Some care recipients need to be accompanied when they go out because they may go missing or suddenly fall over. In addition, there are people who do not need nursing care, but are not confident in free behavior due to body weakness, etc., and tend to stay at home. The latter, also called the care-reserve reserve army, are people who will increase the burden of care in the near future.

  It is a social responsibility to allow such people to go out alone and have the joy of living, especially to enable the latter people to contribute to society again. To this end, a system is needed that can monitor a person's operating state while protecting privacy, and can immediately start rescue if a dangerous state is predicted or becomes dangerous.

Such a system has been proposed in the past, and sensors that use an accelerometer are known as sensors that are attached to the human body and monitor the operating state of the person. A two-axis accelerometer is installed on the waist of the human body. Wear and determine whether the person is standing, sitting, jealous, walking, riding a train, car, bicycle, etc. (For example, refer nonpatent literature 1).
In addition, it is shown that a three-axis accelerometer is attached, and each state of walking, running, standing still, and falling is determined from changes in acceleration in three orthogonal axes in the vertical direction, the front-rear direction, and the horizontal direction ( For example, see Patent Document 1).
However, with the techniques of the above-mentioned known documents, it is not possible to obtain sufficient accuracy for determining whether a person is in a specific operating state, particularly a stable state or a dangerous state, and the specific contents of the dynamic state and the static state As a result, the accuracy of the determination was not sufficiently obtained, and there was a problem in reliability.
Journal of the Japan Society of Mechanical Engineers 1996 Vol. 101No. 950p14-16 Japanese Patent Laid-Open No. 10-295649

  The problem to be solved by the present invention is to wear an accelerometer on a human body and determine whether the person is in a static state or a dynamic state and whether it is a stable state or a dangerous state. In addition, in the static state, determine the postures of standing, sitting, and lying down, and in the dynamic state, also determine the dynamic states of walking, climbing stairs, and descending stairs. Thus, it is to provide a highly reliable operation and monitoring method of a person.

  In order to solve the above-mentioned problems, the present inventor has conducted many theoretical and experimental studies on a method for monitoring a person's movement and posture, and as a result, has obtained the following knowledge.

  Although it is the most desirable technique to be able to accurately discriminate all the movement states and postures of a person who changes in a complex and diverse manner, (a) a static state of standing, sitting and lying positions, (b) Most of the movement states and postures of people who change in a complex and diverse manner, even if they can be classified into normal movements such as walking, climbing stairs, descending stairs, and dangerous movements such as (c) falling, etc. Can meet the above social demands.

A triaxial accelerometer consisting of a longitudinal direction (X direction), a horizontal direction (Y direction) and a gravitational direction (Z direction) orthogonal to each other is attached to the human body, and the acceleration obtained from each axis is measured for a predetermined time. It is possible to determine whether the state is a static state or a dynamic state from the magnitude of the change amount of each acceleration.
Specifically, the predetermined time Δt0 = 0.5 seconds is set, and when all of the following three conditions are satisfied, it can be determined that the static state is satisfied and when it is not satisfied, the dynamic state is determined.
ΔX / Δt0 ≦ 0.1G (1)
ΔY / Δt0 ≦ 0.1G (2)
ΔZ / Δt0 ≦ 0.1G (3)

And when it determines with a static state, each position of a standing position, a sitting position, and a supine position can be discriminate | determined from the magnitude | size of the acceleration of the front-back direction (X direction) and a gravitational direction (Z direction).
When the dynamic state is determined, the power spectrum of each acceleration value at a predetermined time is calculated, and the operation states of walking, climbing stairs, and descending stairs are determined from the distribution of the spectrum at a specific frequency. What can be done.

In addition, it is possible to determine the transition from the static state to the dynamic state from the magnitude of the change amount of each acceleration in a predetermined time.
Specifically, when the predetermined time Δt1 = 0.5 seconds is set and all of the following three conditions are satisfied, it can be determined that the state has shifted from the static state to the dynamic state.
ΔX / Δt1 ≧ 0.1G (4)
ΔY / Δt1 ≧ 0.1G (5)
ΔZ / Δt1 ≧ 0.1G (6)

In addition, it is possible to determine a transition from a static state or a dynamic state to a dangerous operation state such as a fall from the magnitude of the change amount of each acceleration in a predetermined time.
Specifically, when the predetermined time Δt2 = 0.2 seconds is set, all of the following three conditions are satisfied, and there is no periodicity in the change of each acceleration, there is a risk of falling from a static state or a dynamic state. It is possible to determine that it has shifted to a different operating state.
ΔX / Δt2 ≧ 3.0G (7)
ΔY / Δt2 ≧ 1.5G (8)
ΔZ / Δt2 ≧ 1.0G (9)

  Based on the above findings, the present inventor has determined whether a person is in a static state or a dynamic state, whether the person is in a stable state or a dangerous state, and in the static state, We have come up with a method for automatically and accurately discriminating each dynamic state of walking, climbing stairs, and descending stairs when in a dynamic state. The gist is as follows.

(A) A human body is equipped with an accelerometer, the acceleration obtained from the accelerometer is measured, and the human motion state or posture is determined from the magnitude of the acceleration or the amount of change in acceleration over a predetermined time. In the method of monitoring human movement and posture, a triaxial accelerometer consisting of a longitudinal direction, a lateral direction and a gravitational direction orthogonal to each other is attached to the human body, the acceleration obtained from each axis is measured, and the acceleration at a predetermined time is measured. Determine whether it is a static state or a dynamic state from the magnitude of the amount of change in each acceleration, and if it is determined to be a dynamic state, calculate the power spectrum of each acceleration value at a predetermined time and specify From the distribution of the spectrum in frequency, it is possible to distinguish between the walking, climbing stairs, and descending stairs, and when it is determined to be static, standing and sitting from the magnitude of acceleration in the longitudinal and gravitational directions. , 臥Monitoring method of operation and the posture of the person and performs the determination of the orientation of.

(B) An accelerometer is attached to the human body, the acceleration obtained from the accelerometer is measured, and the human motion state or posture is determined from the magnitude of the acceleration or the amount of change in acceleration over a predetermined time. In the monitoring method of human movement and posture, a three-axis accelerometer consisting of a front-rear direction, a left-right direction, and a gravitational direction that are orthogonal to each other is attached to a human body, and the acceleration obtained from each axis is measured. Determine whether it is a static state or a dynamic state from the magnitude of the amount of change in each acceleration, and if it is determined to be a dynamic state, calculate the power spectrum of each acceleration value at a predetermined time and specify A method for monitoring a person's movement and posture, characterized in that each movement state of walking, climbing stairs, and descending stairs is discriminated from the spectrum distribution in frequency.

(C) An accelerometer is attached to the human body, the acceleration obtained from the accelerometer is measured, and the human motion state or posture is determined from the magnitude of the acceleration or the amount of change in acceleration over a predetermined time. In a method for monitoring human movement and posture, a human body is equipped with a triaxial accelerometer composed of a longitudinal direction, a lateral direction, and a gravitational direction orthogonal to each other, and the acceleration obtained from each axis is measured. While determining the transition from the static state to the dynamic state from the magnitude of the change in acceleration, for the determination of the dynamic state after the transition, calculate the power spectrum of each acceleration value in a predetermined time, A method for monitoring a person's movement and posture, wherein each of the movement states of walking, climbing stairs, and descending stairs is determined from the distribution of the spectrum at a specific frequency .

According to the present invention, it is possible to discriminate with high accuracy dangerous postures such as standing postures, sitting postures, and lying postures, walking, climbing stairs, descending stairs, and falling. As a result, the weak, such as the elderly, can move freely with peace of mind, such as going out alone.
In addition, privacy is protected, and in the event of an emergency, it is possible to carry out quick relief activities.
Therefore, the care recipient is also given the joy of living, and the care-reserving reserve army who tends to stay behind can be provided with opportunities for social contribution, and the burden on the caregiver can be significantly reduced.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to FIGS. FIG. 1 is a flowchart illustrating a determination method according to the present invention, FIG. 2 is a diagram illustrating acceleration in each operation state, FIG. 3 is a diagram illustrating a determination method for standing, sitting, and lying, and FIGS. ) Is a diagram showing a method for determining walking, climbing stairs, and descending stairs, FIG. 5 is a diagram showing an embodiment of an apparatus for carrying out the method according to the present invention, and FIG. It is a figure which shows a form.

In the present invention, a triaxial accelerometer composed of a longitudinal direction (X direction), a lateral direction (Y direction), and a gravitational direction (Z direction) orthogonal to each other is attached to a human body, and acceleration obtained from each axis is measured. Based on the value, the operation state or posture of the person wearing the accelerometer is determined. Specifically, as shown in FIG. 5 or FIG. 6, the three-axis accelerometer 2 is attached to the human body. Measure the acceleration of each axis.
In addition, although the accelerometer in a present Example uses CXL04LP3 of Crossbow in which the XYZ axis was packaged in one, the accelerometer in the present invention is not limited to this.

FIG. 2 shows the temporal change in acceleration in each operation state. FIG. 2 (a) is a standing position (still standing still), (b) is a walking state, (c) is a diagram showing a temporal change in acceleration at the time of falling, and the acceleration of each axis is It can be seen that the characteristic changes depending on the operating state.
That is, in a static state such as standing, the magnitude of the acceleration and the amount of change over time are small, large in a dynamic state such as walking, and the magnitude and amount of change of the acceleration further increase during an abnormality such as a fall.
The present invention intends to determine the movement state or posture of the person to be measured by measuring the acceleration that shows a specific change according to the movement state or posture of the person and analyzing the acceleration.

Whether it is a static state or a dynamic state is determined by setting a predetermined time Δt0 = 0.5 seconds. When all of the following three conditions are satisfied, the static state is satisfied. It is determined that Here, the left side of the equation (1) indicates the amount of change (ΔX) in the longitudinal direction (X direction) at a predetermined time Δt0.
ΔX / Δt0 ≦ 0.1G (1)
ΔY / Δt0 ≦ 0.1G (2)
ΔZ / Δt0 ≦ 0.1G (3)

And when it determines with a static state, each attitude | position of standing position, sitting position, and a supine position is determined from the magnitude | size of the acceleration of the front-back direction (X direction) and a gravitational direction (Z direction).
The postures of the standing position, the sitting position, and the supine position are determined according to which region the measured acceleration is located in the XZ coordinate plot diagram. This utilizes the fact that, as a result of numerous theoretical and experimental studies by the present inventor, plots are aggregated in a specific area according to each posture as shown in FIG.
That is, the postures of standing, sitting, and lying are determined by plotting the acceleration in the front-rear direction (X direction) and the acceleration in the gravitational direction (Z direction) obtained from the triaxial accelerometer attached to the measurement subject. If it is positioned in the standing position determination area, it is determined to be in the standing position, if it is positioned in the sitting position determination area, it is determined to be in the sitting position, and if it is positioned in the lying position determination area, it is determined to be in the lying position.

On the other hand, when the dynamic state is determined, the power spectrum of each acceleration value is calculated, and the respective motion states of walking, climbing stairs, and descending stairs are determined from the distribution of the spectrum at a specific frequency.
The determination of each motion state of walking, climbing stairs, and descending stairs is performed by calculating the power spectrum of the measured acceleration values in the horizontal direction (Y direction) and gravity direction (Z axis) by FFT (Fast Fourier Transform). , Plot each of the spectra and determine in which region it is located. This also utilizes the fact that, as a result of numerous theoretical and experimental studies conducted by the present inventor, plots are aggregated in a specific region according to each operating state, as shown in FIGS. 4 (a) and 4 (b). It is a thing.
That is, the determination of each motion state of walking, climbing stairs, and descending stairs is based on the acceleration in the horizontal direction (Y direction) and the acceleration in the gravitational direction (Z direction) obtained from a triaxial accelerometer attached to the subject. The power spectrum is calculated and plotted, and if it is located in the stairs climb judgment area, it is judged that the stairs are rising, and if it is located in the stairs climb judgment area, it is judged that the stairs are descending. If it is located, it will determine with it being a walking state.
Thereby, it is possible to detect in advance the ascending / descending of the person to be measured, and in the event of an emergency, it is also possible to perform a quick rescue operation.

By the above method, the standing, sitting, and standing postures of the subject wearing the accelerometer, and the walking, climbing stairs and descending stairs can be determined with high accuracy. Transition from a static state or a dynamic state to a dangerous operation state such as a fall can also be determined from the magnitude of the change amount of each acceleration in a predetermined time.
Specifically, when the predetermined time Δt2 = 0.2 seconds is set, all of the following three conditions are satisfied, and there is no periodicity in the change of each acceleration, there is a risk of falling from a static state or a dynamic state. It can be determined that the operation state has been changed.
ΔX / Δt2 ≧ 3.0G (7)
ΔY / Δt2 ≧ 1.5G (8)
ΔZ / Δt2 ≧ 1.0G (9)
As a result, it is possible to detect a dangerous state such as a fall of the person being measured, and in the event of an emergency, it is also possible to perform a quick rescue operation.

Further, the transition from the static state to the dynamic state can be determined from the magnitude of the change amount of each acceleration during the predetermined time.
Specifically, when the predetermined time Δt1 = 0.5 seconds is set and all of the following three conditions are satisfied, it can be determined that the state has shifted from the static state to the dynamic state.
ΔX / Δt1 ≧ 0.1G (4)
ΔY / Δt1 ≧ 0.1G (5)
ΔZ / Δt1 ≧ 0.1G (6)

  In the present invention, the position of the accelerometer worn on the human body is preferably the waist in normal walking and running conditions, but depending on the individual circumstances, characteristics, behavioral characteristics, etc., it is worn on the toes, legs, knees, arms, heads, etc. Sometimes it is good to do. According to each, it is good to wear on the part which can be determined with the highest accuracy.

  In addition, as shown in FIG. 5, the apparatus which implements the method based on this invention is the terminal 1 with which a human body is mounted | worn, the monitoring machine 5 installed in the monitoring center, and the terminal 1 to the monitoring machine 5 The terminal 1 includes an accelerometer 2 that outputs acceleration data and a transmitter 4 that transmits the data, and the monitoring device 5 includes a receiver 6 that receives data from the terminal 1 and the data. A host computer 7 for processing.

As described above, the host computer 7 is a mechanism for determining whether the state is a static state or a dynamic state based on the magnitude of the amount of change in acceleration during a predetermined time. A mechanism that determines each posture of standing, sitting, and supine from the magnitude of acceleration in the gravity direction, a mechanism that calculates the power spectrum of the acceleration value at a predetermined time, and a specific It has a mechanism for judging each operation state of walking, climbing stairs, and descending stairs from the spectrum distribution in frequency.
In addition, the host computer 7 has a mechanism for determining the transition from the static state to the dynamic state based on the magnitude of the change in acceleration during a predetermined time, and a dangerous operating state such as a fall from the static state or the operating state. It has a mechanism for judging that it has shifted to.
In FIG. 5, an input unit 8 inputs an appropriate value according to the characteristics of each individual for a predetermined time required for determination, a magnitude of a reference acceleration change amount, and the like.

As shown in FIG. 6, the apparatus for carrying out the method according to the present invention is such that the terminal 1 has a portable terminal 3, and the above-described determination mechanisms can be shared between the portable terminal 3 and the host computer 7. All the determinations can be made by the portable terminal 3, and the host computer 7 can only input an appropriate value, display the result, and issue an alarm.
Further, when the rescue operation 11 is determined to be in a dangerous state, the location of the target person heading for the rescue can be detected using position information by PHS or GPS.

It is a flowchart which shows the determination method which concerns on this invention. It is a figure which shows the acceleration in each operation state. It is a figure which shows the determination method of a standing position, a sitting position, and a supine position. It is a figure which shows the determination method of a walk, stairs climb, and stairs descend It is a figure which shows one form of the apparatus which implements the method concerning this invention. It is a figure which shows the other form of the apparatus which implements the method concerning this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Terminal device 2 3-axis accelerometer 3 Portable terminal 4 Transmitter 5 Monitoring device 6 Receiver 7 Host computer 8 Input device 9 Display device 10 Alarm device 11 Relief activity

Claims (3)

A person's movement that wears an accelerometer on a human body, measures the acceleration obtained from the accelerometer, and determines the person's movement state or posture from the magnitude of the acceleration or the amount of change in acceleration at a predetermined time And posture monitoring method,
A triaxial accelerometer consisting of a longitudinal direction, a lateral direction, and a gravitational direction that are orthogonal to each other is attached to a human body, the acceleration obtained from each axis is measured, and the amount of change in each acceleration over a predetermined time is measured statically. To determine whether the state is dynamic or dynamic,
When it is determined as a dynamic state, the power spectrum of each acceleration value at a predetermined time is calculated, and each operating state of walking, climbing stairs, and descending stairs is determined from the distribution of the spectrum at a specific frequency,
A method for monitoring a person's movement and posture, characterized in that when it is determined as a static state, the postures of standing, sitting and lying are determined from the magnitudes of acceleration in the front-rear direction and the gravitational direction. A person's movement that wears an accelerometer on a human body, measures the acceleration obtained from the accelerometer, and determines the person's movement state or posture from the magnitude of the acceleration or the amount of change in acceleration at a predetermined time And posture monitoring method,
A triaxial accelerometer consisting of a longitudinal direction, a lateral direction, and a gravitational direction that are orthogonal to each other is attached to a human body, the acceleration obtained from each axis is measured, and the amount of change in each acceleration over a predetermined time is measured statically. To determine whether the state is dynamic or dynamic,
When the dynamic state is determined, the power spectrum of each acceleration value at a predetermined time is calculated, and the operating states of walking, climbing stairs, and descending stairs are determined from the distribution of the spectrum at a specific frequency. A method for monitoring a person's movement and posture. A person's movement that wears an accelerometer on a human body, measures the acceleration obtained from the accelerometer, and determines the person's movement state or posture from the magnitude of the acceleration or the amount of change in acceleration at a predetermined time And posture monitoring method,
A triaxial accelerometer consisting of a longitudinal direction, a lateral direction, and a gravitational direction that are orthogonal to each other is attached to a human body, the acceleration obtained from each axis is measured, and the amount of change in each acceleration over a predetermined time is measured statically. The transition from the dynamic state to the dynamic state ,
Regarding the determination of the dynamic state after the transition, the power spectrum of each acceleration value at a predetermined time is calculated, and the respective operating states of walking, climbing stairs, and descending stairs are determined from the distribution of the spectrum at a specific frequency. A method for monitoring the movement and posture of a person.

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