Method for monitoring vital signs according to posture change

Abstract

A physical activity sign monitoring method disclosed herein includes: defining an absolute coordinate system for a subject when standing normally; determining a first posture of the subject using measured acceleration values obtained in each of an X-axis direction, a Y-axis direction, and a Z-axis direction using an acceleration sensor; and determining a second posture different from the first posture from a transition posture after sensing a posture change from the first posture to the transition posture when the vector direction of the measured acceleration (aZ) for each of the Z-axis directions is converted from a positive value to a negative value. Subsequently, physical activity signs of the subject are measured in the transition posture and the second posture. Accordingly, the physical activity signs of the subject can be easily measured when the subject changes posture.

Description

A method for monitoring vital signs according to postural changes

[0001] Embodiments of the present invention relate to a method for monitoring vital signs according to changes in posture. More specifically, embodiments of the present invention relate to a method for monitoring vital signs by generating data related to changing vital signs accompanying sudden changes in posture.

[0002] There are three methods used to measure electrocardiograms (ECGs), depending on the subject's level of activity. These include the resting ECG measurement method, the exercise stress test method, and the holder monitoring method.

[0003] The above-mentioned resting electrocardiogram (ECG) measurement method, the most common, involves attaching electrodes to specific areas such as the chest, arms, and legs to measure the electrical activity of the heart while the patient is at rest. This method is used to diagnose various heart conditions, including arrhythmias, heart attacks, and abnormal heart rhythms.

[0004] Meanwhile, the exercise stress test (treadmill test) monitors cardiac activity using an ECG measurement method while a patient exercises on a treadmill or stationary bicycle. The treadmill test is used to assess how the heart performs under stress and to detect abnormal electrical activity in the heart that does not appear under resting conditions. This method is used to assess coronary artery disease, assess exercise capacity, and identify irregular heart rhythms caused by physical activity.

[0005] Next, in the Holter monitoring method, the patient wears a portable device called a Holter monitor to measure the ECG. This monitor continuously records the heart's electrical activity for 24 to 48 hours or longer. It includes a switch that can mark the data when the patient feels discomfort in the heartbeat. Holter monitoring is a method for diagnosing irregular heart rhythms that may occur intermittently and assessing cardiac health by providing comprehensive information on cardiac activity over a long period of time.

[0006] However, because resting-state (resting) ECG measurements are taken while the patient is still, they cannot detect cardiac problems or abnormalities that occur during activity. Furthermore, paroxysmal cardiac abnormalities that occur temporarily may not be apparent during rest, making them difficult to detect with a resting-state ECG.

[0007] Additionally, in the case of exercise stress testing (treadmill testing), it is difficult for patients with severe heart disease to run on a treadmill, and since the ECG is measured under stress due to physical activity, it may cause side effects or heart function problems in some patients.

[0008] Furthermore, Holter monitoring requires the subject to wear the device for a period ranging from 24 hours to two weeks, which can interfere with daily activities. While transient cardiac abnormalities may occur, patients may not experience any abnormalities during the test, potentially undetected on the electrocardiogram.

[0009] In addition, orthostatic dizziness and orthostatic hypotension, which are common in tall people who have a long distance from the lower body to the heart and brain, people who lack the muscles in the lower body that compress the veins and pump blood up to the heart, and the elderly who have lost muscle mass due to aging, occur when blood collected in the lower body cannot return to the heart or brain in a timely manner when standing up suddenly or standing for a long time. Symptoms of blurred vision may also occur due to a decrease in blood volume in the occipital region where the optic nerve is located. Although these symptoms are closely related to vital indicators such as blood pressure and electrocardiogram, it is difficult to apply the three electrocardiogram measurement methods mentioned above.

[0010] This is because the resting state ECG measurement method measures in a state where there is no change in posture, the exercise stress test (treadmill test) aims for gradual maximization of stress rather than changes in stress in the human body, and the Holter monitoring method has the problem of having no information about posture at all.

[0011] Furthermore, there is a growing need for important cardiac function assessment methods that are difficult to assess using existing cardiac function assessment methods alone. For example, recent studies have shown that the rate of heart rate recovery (HRR) after exercise is a significant predictor of cardiovascular disease and mortality risk. Regulating parasympathetic nerve reactivation is particularly crucial for heart rate recovery within the first 30 seconds and 2 minutes after exercise.

[0012] At this time, decreased parasympathetic nerve reactivation or increased sympathetic nerve activation is also associated with increased incidence and mortality of cardiovascular disease. Recent studies have also shown that parasympathetic nerves function to regulate inflammatory signals.

[0013] Meanwhile, when a change in body position occurs, the sympathetic and parasympathetic nervous systems play an important role in regulating cardiovascular and humoral responses.

[0014] When the sympathetic and parasympathetic nervous systems respond to changes in body position, vital signs undergo rapid physiological responses to maintain homeostasis. Examples of these physiological responses include maintaining skeletal muscle balance and reflexes that regulate arterial and cardiopulmonary blood pressure.

[0015] For example, in the supine position, the average position of the veins and arteries is at the same height. However, in the standing position, approximately 500 / 700 mL (10 mL / kg) of the central blood flow is diverted to the periphery, and the return blood volume to the veins is reduced.

[0016] Figure 1 is a graph showing changes in heart rate and blood pressure after the human body stands up.

[0017] Referring to Figure 1, when a human body suddenly stands up, the heart rate increases rapidly within a few seconds after standing up to offset the drop in blood pressure caused by gravity.

[0018] A temporary maximum heart rate is reached approximately 10 seconds after standing. This is due to a rapid suppression of parasympathetic activity and a temporary stimulation of the sympathetic system.

[0019] Afterwards, the heart rate, which had reached its maximum instantaneous heart rate, rapidly decreases due to the rebound of arterial pressure. That is, the heart rate decreases rapidly between 10 and 20 seconds after standing.

[0020] The antagonistic effects of heart rate and blood pressure described above vary depending on age and heart health, and are also used to predict long-term mortality. For example, in 2016, a research team led by Professor Rose Anne Kenny of Trinity College, Ireland, announced the results of a study showing that the orthostatic heart rate recovery (HRR) speed can be a predictor of aging and death after middle age. The research team selected approximately 4,500 people aged 50 and older who participated in the Irish Longitudinal Study of Aging and followed them for an average of 4.2 years to investigate the correlation between HRR and mortality risk. After standing up from a supine position, blood pressure and HRR speed were measured for 110 seconds. The heart rate recovery speed began to accelerate a few seconds after standing, peaked at 10 seconds, and then slowed most rapidly between 10 and 20 seconds. After that, the recovery speed gradually slowed.

[0021] The study found that the rate of heart rate recovery within 20 seconds of standing, particularly between 10 and 20 seconds, was most strongly correlated with mortality. When participants were divided into four groups based on recovery rate, the slowest group had a sevenfold higher risk of death 4.2 years later than the fastest group. The adjusted rate, which took into account other factors that could affect health and mortality, such as age, diabetes, lung disease, socioeconomic status, smoking, and weight, was 2.3 times higher on average. A clear positive correlation was found between slower heart rate recovery and a higher risk of death. Specifically, for every 1 beat per minute (bpm) slower heart rate recovery rate between 10 and 20 seconds after standing, the risk of death increased by 6%.

[0022] There is a need for a method that can measure rapid postural changes in daily life and, when such situations occur, effectively derive information on physical activity signs such as electrocardiogram and blood pressure to monitor cardiovascular health.

[0023] Embodiments of the present invention provide a method for monitoring physical activity signs that can easily measure physical activity signs that occur when a posture changes from a first posture to a second posture.

[0024] According to embodiments of the present invention for solving the above technical problem, in a method for monitoring physical activity signs according to a change in posture using a mobile device including an acceleration sensor having a local coordinate system and which can be fixed to a chest area of ​​a subject in a normal standing state, an absolute coordinate system is defined, in which a direction extending from the right shoulder to the left shoulder when the subject is in a normal standing state is an X-axis direction, a direction having the smallest angle with the opposite direction of gravity among tangents to the skin surface of the area where the mobile device is mounted is a Y-axis direction, and an axis generated by a vector multiplication between the X-axis direction and the Y-axis direction is a Z-axis direction, and an acceleration value (a) for each of the X-axis direction, the Y-axis direction, and the Z-axis direction according to the absolute coordinate system is defined using the acceleration sensor. X , a Y & a Z ) is secured. Using the above measured acceleration value, the first posture of the subject is determined, and the measured acceleration (a) for each of the Z-axis directions is Z ) is converted from a positive to a negative value, detecting a change in posture from the first posture to a transition posture, and then determining a second posture different from the first posture from the transition posture. Subsequently, physical activity signs of the subject are measured in the transition posture and the second posture.

[0025] In one embodiment of the present invention, the step of determining the first or second posture comprises: determining, on the absolute coordinate system, the coordinates of the acceleration values ​​and the reference acceleration values ​​(a) for each posture stored in the data storage unit according to the absolute coordinate system X0 , a Y0 & a Z0) are calculated for each distance between the coordinates, and the posture corresponding to the minimum value among the distances is determined as the judgment posture.

[0026] Here, the standard acceleration values ​​for each posture may correspond to Table 1 below. In addition, the transition posture may correspond to the slump.

[0027] In one embodiment of the present invention, the acceleration in the x-axis direction according to the local coordinate system of the sensor itself is α x , the acceleration in the y-axis direction is α y , the acceleration in the z-axis direction is α z , is defined as the acceleration (α) in the x-axis direction, y-axis direction and z-axis direction, respectively. x, α y and α z ) satisfies the mathematical expressions 1 and 2 below,

[0028] Acceleration value (α) according to the above absolute coordinate system X , α Y & α Z ), the acceleration (α) in the x-axis direction according to the local coordinate system x ) and the acceleration in the y direction (α y ) can be performed through mathematical expressions 3 and 4 below.

[0029] Mathematical formula 1

[0030]

[0031] Mathematical formula 2

[0032]

[0033] Mathematical formula 3

[0034]

[0035] Here, the above X is a unit vector in the X direction of the absolute coordinate system, and the above x is a unit vector in the x direction of the local coordinate system.

[0036] Mathematical formula 4

[0037]

[0038] In one embodiment of the present invention, it may be additionally performed to determine whether the second posture corresponds to a qualified posture.

[0039] According to the embodiments of the present invention described above, it is possible to easily measure physical activity signs that occur when a posture changes from a first posture to a second posture via a transition posture by using an acceleration sensor included in a mobile device fixed to a subject.

[0040] Figure 1 is a graph showing changes in heart rate and blood pressure after the human body stands up.

[0041] Figure 2 is a perspective view defining the x-axis direction, y-axis direction, and z-axis direction according to the local coordinate system of the sensor itself included in the mobile device.

[0042] Figure 3 is a conceptual diagram illustrating a state in which a mobile device is fixed to the chest area of ​​a subject.

[0043] FIG. 4 is a flowchart illustrating a method for monitoring vital signs according to posture changes according to one embodiment of the present invention.

[0044] Fig. 5 is a graph showing the reference acceleration value and measured acceleration value for each posture in the absolute coordinate system using the method for determining the posture of the subject of Fig. 3.

[0045] Figure 6 is a graph showing the acceleration values ​​of the absolute coordinate system changing over time when changing posture between sitting and standing.

[0046] Figure 7 is a graph showing the acceleration values ​​of the absolute coordinate system changing over time during posture changes between exercise, standing, and sitting.

[0047] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings. The present invention can be modified in various ways and can take various forms, and thus specific embodiments are illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to a specific disclosed form, but it should be understood that all modifications, equivalents, and substitutes included in the spirit and technical scope of the present invention are included. In describing each drawing, similar reference numerals are used to indicate similar components. In the attached drawings, the dimensions of structures are shown larger than actual size to ensure clarity of the present invention.

[0048] While terms like "first" and "second" may be used to describe various components, these components should not be limited by these terms. These terms are used solely to distinguish one component from another. For example, without departing from the scope of the present invention, a first component could be referred to as a "second component," and similarly, a second component could also be referred to as a "first component."

[0049] The terminology used in this application is only used to describe specific embodiments and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this application, it should be understood that the terms "comprise" or "have" indicate the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, but do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0050] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and will not be interpreted in an idealized or overly formal sense unless explicitly defined herein.

[0051] Fig. 2 is a perspective view defining the x-axis, y-axis, and z-axis directions according to the local coordinate system of the sensor included in the mobile device. Fig. 3 is a conceptual diagram illustrating a state in which the mobile device is fixed to the chest area of ​​the subject. Fig. 4 is a flowchart illustrating a method for monitoring vital signs according to changes in posture according to one embodiment of the present invention.

[0052] First, referring to Figure 2, both the Android OS and the iOS system that runs the iPhone use the same coordinate system. That is, when the phone is placed on a flat surface with the screen facing up, the direction of the display from the floor is the z-axis, and the counterclockwise rotation around the z-axis is the roll momentum. In addition, when the bottom of the phone is stood upright, the direction from left to right is the x-axis, and the counterclockwise rotation around the x-axis is called the yaw moment. At this time, the direction from bottom to top of the phone when stood upright is the y-axis, and the counterclockwise rotation around the y-axis is defined as the pitch. The direction in which the rotational momentum increases for each axis is the direction that the remaining four fingers point when the positive direction of the axis is aligned with the thumb and held.

[0053] Accordingly, all acceleration sensors installed inside mobile phones use the same axis definition. In the following specification, the x-axis direction, y-axis direction, and z-axis direction of [Fig. 2] are each defined as the local coordinate system of the sensor.

[0054] Furthermore, when there is no external force acting on the phone, the sum of the three-axis acceleration vectors in the x, y, and z directions displayed by the phone's accelerometer is always equal to the acceleration due to gravity. This can be used to measure how much the phone is tilted with respect to the ground plane perpendicular to the direction of gravity. The azimuth value, which indicates how much the phone is rotated in the plane perpendicular to gravity, cannot be determined with the accelerometer alone, and can be obtained by using a Kalman filter, a geomagnetic sensor that provides a reference for absolute coordinates, or GPS in combination.

[0055] Referring to FIGS. 3 and 4, an absolute coordinate system is defined, including the direction extending from the right shoulder to the left shoulder when the subject is standing normally as the X-axis direction, the direction having the smallest angle with the direction opposite to gravity among the tangents to the skin surface of the chest area where the mobile device is mounted as the Y-axis direction, and the axis generated by the vector multiplication between the X-axis direction and the Y-axis as the Z-axis direction.

[0056] The mounting surface where the mobile device is mounted on the chest is parallel to the tangent plane of the mounting surface, so the x-axis, y-axis, X-axis, and Y-axis are all on the same plane or are contained within two mutually parallel planes that are a few mm apart from the mounting surface to the part where the acceleration sensor is embedded. Therefore, z, defined as the vector product x × y, and Z, defined as the vector product X × Y, correspond to mutually identical vectors.

[0057] In order to determine the posture of the subject, a sensor attached inside a pentagonal cuboid space, which is the chest area of ​​the subject, is used. Here, the pentagonal cuboid space is defined as the inside of a pentagon connecting the tips of the pectoralis major muscles on both sides of the patient, the tips of the deltoid muscles on both shoulders, and the chin.

[0058] First, a coordinate system is defined in which the direction extending from the right shoulder to the left shoulder when the subject is standing normally is converted to the X-axis direction, one of the y-axis and the z-axis having a smaller value among the angles between the y-axis and the z-axis according to the local coordinate system of the geomagnetic sensor and the direction opposite to gravity is converted to the Y-axis direction, and an axis generated by the vector multiplication between the X-axis direction and the Y-axis is converted to the Z-axis direction (S110).

[0059] Next, using the acceleration sensor, acceleration values ​​(a) for each of the X-axis direction, Y-axis direction, and Z-axis direction according to the absolute coordinate system X , a Y & a Z ) is secured (S120).

[0060] Here, the acceleration in the x-axis direction according to the local coordinate system of the acceleration sensor itself is α x , the acceleration in the z-direction according to the local coordinate system is α z is defined as . At this time, the acceleration α in the y-axis direction y satisfies mathematical expressions 1 and 2 below.

[0061]

[0062]

[0063] That is, the acceleration sensor is subjected to a gravitational acceleration of 9.8 m / s^2 toward the center of the Earth, i.e., in the direction of gravity. This is because, when the mobile device is fixed near the chest of a standing subject and the subject is standing, an acceleration of 9.8 m / s^2 is applied in the negative direction of the Z-axis, which is opposite to the direction of gravity.

[0064] Therefore, when using an acceleration sensor, the vector sum of the gravitational acceleration values ​​of the sensor in a standing state without any shaking of the subject is always a vector with a magnitude of 1G (9.8 m / sec2) and a direction of -Z. That is, α of a stationary accelerometer x, α y, αz The magnitude of the vector sum (the square root of the sum of the squares of the three values) always converges to the value 9.8.

[0065] At this time, using the acceleration sensor, the acceleration in the x-axis direction according to the local coordinate system is α x , the acceleration in the z-direction according to the local coordinate system is α z Measure (S121)

[0066] The acceleration in the x-direction according to the above local coordinate system is α x , acceleration α in the y-axis direction y And the acceleration in the z-direction according to the local coordinate system is α z Acceleration value (a) according to the absolute coordinate system including the X-axis direction, Y-axis direction and Z-axis direction X , a Y & a Z ) is converted into (S122). For this purpose, mathematical expressions 3 and 4 below can be used.

[0067]

[0068] Here, the above X is a unit vector in the X direction of the absolute coordinate system, and the above x is a unit vector in the x direction of the sensor coordinate system.

[0069]

[0070] That is, when mounting a mobile device on the chest, it is recommended that the x-axis direction of the acceleration sensor itself be fixed parallel to the x-axis according to the absolute coordinate system. However, the x-axis, y-axis, and z-axis directions may slightly change each time the mobile device is mounted on the chest.

[0071] When the angle between the x-axis of the sensor itself and the X-axis according to the absolute coordinate system is defined as θ when mounted, since the Z-axis and the z-axis are identical, even if the mounting angle changes, the measurement coordinates (x, y, z) that change each time they are mounted are converted into absolute coordinates (X, Y, Z) according to the standard coordinate system through a rotation on the plane formed by the X, Y axes centered on the 3D Z-axis or a 2D rotation formed by the X, Y axes centered on the origin of the z-axis.

[0072] That is, the angle θ between the x-axis and the X-axis is calculated as the vector inner product X·X' = |X||X'|COS(θ), θ = ARCCOS[(X·X') / (|X||X'|)],

[0073] The magnitude of the unit vector (1,0,0) in the x-axis direction is 1, and the x-axis vector measured at any posture is defined as the unit vector in the x-axis direction.

[0074] Thus, the acceleration in the x-axis direction according to the local coordinate system is α x , acceleration α in the y-axis direction y And the acceleration in the z-direction according to the local coordinate system is α z Acceleration value (a) according to the absolute coordinate system including the X-axis direction, Y-axis direction and Z-axis direction X , a Y & a Z ) can be converted to .

[0075] In this case, the first posture of the subject is determined using the above acceleration value (S130).

[0076] For this purpose, on the absolute coordinate system, the acceleration values ​​and the reference acceleration values ​​for each posture stored in the data storage unit according to the absolute coordinate system (a X0 , a Y0 & a Z0 ) are calculated for each distance between them (S131). The standard acceleration values ​​for each posture (a X0 , a Y0 & a Z0 ) corresponds to Table 1 below.

[0077] Posture X-axis acceleration (a X0, g) Y-axis acceleration (a) Y0, g)Z-axis acceleration (a) Z0, g) Right angle standing 00.93 0.21 Right angle left half-0.94 0.15 0.36 Right angle right half-0.91-0.10 60 Sitting 00.85 0.52 Fowler's position 00.75 0.66 Semi-Fowler's position 00.40 91 Supine 0-0.34 0.97 Trendelberg 0-0.5 0.88 Slump position 00.95-0.33 Prone 00.2-0.98

[0078] That is, on the absolute coordinate system, the measured acceleration values ​​and the reference acceleration values ​​for each posture stored in the data storage unit according to the absolute coordinate system (a X0 , a Y0 & a Z0 ) calculate the respective distances between them.

[0079] At this time, in the step of determining the first posture, the measured acceleration values ​​in the absolute coordinate system and the posture-specific reference acceleration values ​​(a) stored in the data storage unit according to the absolute coordinate system X0 , a Y0 & a Z0 ) can measure the respective distances between them.

[0080] At this time, on the absolute coordinate system, the reference acceleration values ​​for each posture (a X0 , a Y0 & a Z0 ) is shown in Fig. 5.

[0081] Fig. 5 is a graph showing the reference acceleration value and measured acceleration value for each posture in the absolute coordinate system using the method for determining the posture of the subject included in Fig. 4.

[0082] Referring to Figure 5, the standard acceleration values ​​for each posture (a X0 , a Y0 & a Z0 ) has already been entered into the data storage.

[0083] Meanwhile, in the first, second and third cases, the measured acceleration values ​​(aX, aY & aZ) are expressed as coordinates of (0.14, 0.37, 0.9), (0.15, -0.13,0.97) and (0.14, 0.59,0.78) on the absolute coordinate system and the corresponding posture-specific reference acceleration values ​​(a X0 , a Y0 & a Z0 ) The distance between coordinates is calculated in Table 2 below.

[0084] Distance from (0.14, 0.37, 0.9) to each posture coordinate (case 1) Distance from (0.15, -0.13, 0.97) to each posture coordinate (case 2) Distance from (0.14, 0.59, 0.78) to each posture coordinate (case 3) Right angle Standing 0.57091.42590.2757 Right angle Left half 2.24651.71472.2561 Right angle Right hemisphere 1.68652.23471.6961 Left hemisphere 0.399451.177850.16025 Fowler's hemisphere 0.1220.79020.0136 Anti-Fowler's hemisphere 0.00170.30650.0669 Supine 0.21840.06420.5028 Trendelberg 0.59450.13070.9961 Slump sphere 1.71532.73291.2421 Abdominal sphere 3.00053.87472.5101

[0085] Afterwards, the posture corresponding to the minimum value among the above distances is determined as the judgment posture.

[0086] That is, referring to Table 2, in the first case, the position corresponding to the minimum value (0.0017) can be determined as the semi-Fowler position, in the second case, the position corresponding to the minimum value (0.0642) can be determined as the supine position, and in the third case, the position corresponding to the minimum value (0.0136) can be determined as the Fowler position.

[0087]

[0088] Afterwards, the acceleration (a) for each of the Z-axis directions Z ) is converted from a positive to a negative value, a posture change from the first posture to the transition posture is detected (S140).

[0089] The above transition posture corresponds to the posture a person assumes before changing from the first posture to the second posture. That is, the human body generally assumes the transition posture while changing from the first posture to the second posture.

[0090] For example, when a person transitions from a first posture in which he or she is statically supported by an external force to a second posture in which he or she is standing, where the soles of the feet and the center of gravity of the body must be aligned with the line of gravity, he or she assumes a transition posture by bending the upper body forward in the opposite direction from the position in which he or she was in the supporting posture, with respect to the center of gravity of the body. This can minimize the energy consumed in transitioning to the second posture, the standing posture. The transition posture may correspond to a slump.

[0091] Slump is a posture in which the upper body is bent forward by 10-30 degrees from a standing position, and it is a result of the psychological state of being depressed or anxious being reflected in the musculoskeletal system.

[0092] In particular, referring to Table 1 described above, the slump position has a negative vector direction value, unlike other positions except for the recovery position.

[0093] That is, the acceleration (a) along the Z-axis direction Z ) can determine the posture change to the above transition posture when the value changes from a positive value to a negative value.

[0094] Next, a second posture different from the first posture is determined from the above transition posture (S150).

[0095] The above second posture can be determined in the same manner as the step of determining the first posture.

[0096] Thereafter, the physical activity signs of the subject are measured in the above transition posture and the second posture (S160).

[0097] In a method for acquiring data on the physical activity signs of a subject, the physical activity signs are unique bioactivity signs that only the human body has, and include, for example, body temperature, respiration, pulse, blood oxygen saturation, and electrocardiogram.

[0098] Meanwhile, after measuring the physical activity signs of the patient, data regarding the physical activity signs are transmitted externally.

[0099] In one embodiment of the present invention, an additional step may be performed to determine whether the second posture corresponds to a qualified posture. That is, a specific second posture may be required to measure a specific bioactivity sign.

[0100] If the above second posture corresponds to a specific posture, data regarding a specific bioactivity sign can be effectively determined.

[0101] Meanwhile, by applying mathematical expressions 1 to 4, the acceleration value (a) along the x-axis direction of the sensor mounted on the chest is calculated so that the x-axis is tilted 6 to 13 degrees from the horizontal line with the ground. x ) value is converted to the acceleration value (a) along the X-axis direction close to 0. X ) Examples showing the values ​​are randomly extracted by time measured in 0.05 second units and are described in Table 3 below.

[0102] Time (seconds)a x a y a za X a Y a ZCoordinate systemLocal coordinatesLocal coordinatesLocal coordinatesAbsolute coordinatesAbsolute coordinatesAbsolute coordinates0.05-0.230.820.52-0.03520.85090.520.1-0.250.820.52-0.03710.85650.520.15-0.240.820.50-0.03620.85360.501.35-0.250.820.51-0.03710.85650 .511.4-0.240.820.51-0.03620.85360.512.7-0.230.820.50-0.03520.85090.504.15-0.240.820.51-0.03620.85360.514.2-0.230.820.51-0.03520.85090.519.05-0.230.820.51-0.0352 0.85090.5113.25-0.060.97-0.11-0.00170.9719-0.1113.3-0.070.99-0.16-0.00050.9925-0 .1613.4-0.051.00-0.246E-051.0012-0.2420.5-0.210.890.37-0.01840.91430.3735.15-0.0 81.020.100.00191.02310.1054.2-0.230.820.50-0.03520.85090.5056.85-0.090.930.24-0. 00590.93430.2464.25-0.200.900.37-0.0160.92180.37800.010.949-0.3283E-070.949-0.33

[0103]

[0104] Figure 6 is a graph showing the acceleration values ​​of the absolute coordinate system changing over time when changing posture between sitting and standing.

[0105] Referring to Figure 6, when tracking the acceleration value of the absolute coordinate system that changes over time when changing posture between sitting and standing, the acceleration (a) along the Z-axis direction in the first posture Z ) It can be confirmed that the value changes to the second position through the transition position (slump) where it changes from a positive value to a negative value.

[0106] Figure 7 is a graph showing the acceleration values ​​of the absolute coordinate system changing over time during posture changes between exercise, standing, and sitting.

[0107] Acceleration (a) along the Z-axis direction during the cycle of the subject's movement and rest through sitting Z ) It can be confirmed that the value changes to the second position through the transition position (slump) where it changes from a positive value to a negative value.

[0108] In particular, when converting from the local coordinate system to the absolute coordinate system, the aY value in the Y-axis direction becomes relatively larger than the ay value in the Y-axis direction, thereby improving the ease and accuracy of posture judgment based on the difference between the aZ value and the aY value.

[0109] Furthermore, the noise of the acceleration value (aX) along the X direction of the absolute coordinate system is greatly reduced compared to the acceleration value (ax) along the X direction of the local coordinate system, which has the advantage of increasing the accuracy of reading the acceleration value.

[0110] A device according to embodiments of the present invention may include a processor, a memory for storing and executing program data, permanent storage such as a disk drive, a communication port for communicating with an external device, a user interface device such as a touch panel, a key, a button, etc. Methods implemented as software modules or algorithms may be stored on a computer-readable recording medium as computer-readable codes or program instructions executable on the processor. Here, the computer-readable recording medium includes a magnetic storage medium (e.g., read-only memory (ROM), random-access memory (RAM), floppy disk, hard disk, etc.) and an optical reading medium (e.g., CD-ROM, DVD: Digital Versatile Disc)). The computer-readable recording medium may be distributed to computer systems connected through a network, so that the computer-readable code may be stored and executed in a distributed manner. The medium may be readable by a computer, stored in a memory, and executed by a processor.

[0111] Embodiments of the present invention may be represented by functional block configurations and various processing steps. These functional blocks may be implemented by various hardware and / or software components that perform specific functions. For example, embodiments may employ integrated circuit components, such as memory, processing, logic, and look-up tables, that may perform various functions under the control of one or more microprocessors or other control devices. Similarly, embodiments may be implemented in a programming or scripting language, such as C, C++, Java, or an assembler, including various algorithms implemented as a combination of data structures, processes, routines, or other programming components. Functional aspects may be implemented as algorithms that execute on one or more processors. Furthermore, embodiments may employ conventional techniques for electronic configuration, signal processing, and / or data processing. Terms such as "mechanism," "element," "means," and "composition" can be used broadly and are not limited to mechanical or physical structures. These terms can also encompass a series of software routines, such as those associated with a processor.

[0112] The specific implementations described in the embodiments are merely exemplary and do not limit the scope of the embodiments in any way. For the sake of brevity of the specification, descriptions of conventional electronic components, control systems, software, and other functional aspects of the systems may be omitted. In addition, the lines connecting or connecting members between components illustrated in the drawings are merely exemplary functional connections and / or physical or circuit connections, and may be replaced or represented as various additional functional connections, physical connections, or circuit connections in an actual device. In addition, unless specifically mentioned as "essential," "important," etc., a component may not be absolutely necessary for the application of the present invention.

Claims

1. A method for monitoring physical activity signs according to changes in posture using a mobile device that can be fixed to the chest area of ​​a subject in a normal standing state and includes an acceleration sensor having a local coordinate system, A step for defining an absolute coordinate system in which the direction extending from the right shoulder to the left shoulder when the subject is standing normally is defined as the X-axis direction, the direction having the smallest angle with the direction opposite to gravity among the tangents to the skin surface of the area where the mobile device is mounted is defined as the Y-axis direction, and the axis generated by the vector multiplication between the X-axis direction and the Y-axis direction is defined as the Z-axis direction; Using the above acceleration sensor, the measured acceleration values ​​(a) for each of the X-axis direction, Y-axis direction, and Z-axis direction according to the above absolute coordinate system X , a Y & a Z ) to secure; A step of determining the first posture of the subject using the above measured acceleration value; Measurement acceleration (a) for each of the above Z-axis directions Z ) is converted from a positive to a negative value, thereby detecting a posture change from the first posture to a transition posture; A step of determining a second posture different from the first posture from the above transition posture; and A step of measuring physical activity signs of the subject in the above transition posture and the second posture; A method for monitoring physical activity signs according to changes in posture, including:

2. In the first paragraph, the step of determining the first posture or the second posture is, On the above absolute coordinate system, the coordinates of the measured acceleration values ​​and the reference acceleration values ​​(a) for each posture stored in the data storage unit according to the above absolute coordinate system X0 , a Y0 & a Z0 ) a step of calculating the respective distances between each coordinate; and A step of determining a posture corresponding to the minimum value among the above distances as the judgment posture; A method for monitoring physical activity signs according to changes in posture, characterized by including:

3. A method for monitoring physical activity signs according to changes in posture, characterized in that in the second paragraph, the standard acceleration values ​​for each posture correspond to the contents described in Table 4 below. Acceleration of the X-axis (a) X0, g) Y-axis acceleration (a Y0 g)Z-axis acceleration (a Z0, g) Right angle standing 00. 930.21 Right angle left half-side -0.94-0.150.36 Right angle right half-side 0.91-0.10.6 Left half-side 00. 850.52 Fowler CW 00.750.66 Anti-Fowler CW 00.40.91 Angwa-wi 0-0.340.97 Trendelberg 0-0.50.88 Slump-wi 00.95-0.33 Recovery 00.2-0.98 4. A method for monitoring physical activity signs according to a change in posture, characterized in that in the third paragraph, the transition posture corresponds to the slump.

5. In the first paragraph, the acceleration in the x-axis direction according to the local coordinate system of the sensor itself is α x , the acceleration in the y-axis direction is α y , acceleration in the z-axis direction is α z , is defined as, Acceleration (α) in the x-axis, y-axis, and z-axis directions, respectively x, α y and α z ) satisfies the mathematical expressions 1 and 2 below, Acceleration value (α) according to the above absolute coordinate system X , α Y & α Z ) is the step of producing Acceleration (α) in the x-direction according to the local coordinate system above x ) and the acceleration in the y direction (α) y ) is characterized by performing a method for monitoring physical activity signs according to a change in posture using the following mathematical expressions 3 and 4. Mathematical Formula 1 Mathematical Formula 2 Mathematical Formula 3 Here, X is a unit vector in the X direction of the absolute coordinate system, and x is a unit vector in the x direction of the local coordinate system. Mathematical Formula 4 6. A method for monitoring physical activity signs according to a change in posture, characterized in that the method further comprises a step of determining whether the second posture corresponds to an eligible posture in the first paragraph.

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