Method for measuring body rotation amount according to posture determination

Abstract

In a method for measuring a body rotation amount according to a posture determination, a first reference coordinate system is defined, and a measured acceleration value based on a local coordinate system (X axial direction, Y axial direction, and Z axial direction) is converted into a converted acceleration value (AX, AY & AZ) based on the first reference coordinate system. Thereafter, the posture of a subject is determined using a converted acceleration value (aXg, aYg & aZg). Meanwhile, when the converted acceleration value maintains a value within a reference range, a second reference coordinate system (Xm, axial direction, Ym axial direction, and Zm axial direction ) of an earth magnetic field sensor is defined, and a measured magnetic field value based on the local coordinate system is converted into a converted magnetic field value (BX, BY & BZ) on the basis of the second reference coordinate system. Thereafter, the amount of rotation for the posture of the subject is calculated by using the converted magnetic field value (BX, BY & BZ).

Description

Method for measuring body rotation according to posture judgment

[0001] Embodiments of the present invention relate to a method for measuring body rotation amount based on posture determination. More specifically, embodiments of the present invention relate to a method for measuring body rotation amount using magnetic field values ​​measured from a geomagnetic sensor, based on the posture of the subject determined using acceleration values ​​measured from an acceleration sensor by attaching a mobile device including a sensor to the body of the subject.

[0002] Modern wearable devices include a 9-axis inertial measurement unit (IMU), such as a 3-axis accelerometer sensor, a 3-axis gyroscope, and a 3-axis magnetometer sensor.

[0003] The accelerometer sensor detects the user's movements and shaking. The three-axis gyroscope measures rotation and rotation speed.

[0004] Meanwhile, posture measurement technology using IMUs is primarily implemented by utilizing various sensors to detect and analyze the user's movements. This allows for the assessment and monitoring of the user's posture. Furthermore, apps are being used to distinguish between activities such as walking, running, and cycling, or to detect static posture and recommend exercise.

[0005] The posture measurement capabilities of existing wearable devices can be improved by accumulating user data and leveraging machine learning and artificial intelligence algorithms. This can help provide users with more accurate and useful posture-related feedback.

[0006] These posture measurement technologies help monitor users' health and movements, and are being used to improve exercise effectiveness, posture, rehabilitation, and athletic performance.

[0007] However, when measuring the user's posture using the above inertial measurement device, there are cases where the information generated from the IMU's accelerometer sensor, gyroscope, and magnetometer sensor ignores the correlation with the posture.

[0008] For example, in the case of an accelerometer sensor used for posture determination, due to the mismatch between the posture and measurement vectors, it is only used to distinguish whether the subject is in a stable or moving state based on the amplitude and vibration of the acceleration value.

[0009] Meanwhile, gyroscope sensors used to monitor the body's rotational state provide angular velocity information. Therefore, to detect changes from a specific posture to another, the integral of the angular change per unit time must be calculated. Recently, the burden of data usage has been reduced by applying techniques such as the Kalman filter, which evaluates numerical changes using only the average of previous data.

[0010] However, when measuring posture using a gyroscope sensor, it's impossible to know the starting point of a specific angle. The next posture must be determined based on the angular information at the start of the measurement. However, if the starting point information isn't provided externally, the posture cannot be determined based solely on angular velocity information.

[0011] Additionally, geomagnetic sensors detect the Earth's magnetic field and measure changes in its magnitude. Therefore, geomagnetic sensors can be used to track or measure the angle of the human body. However, there are several major issues when using geomagnetic sensors. Because not only the Earth but also all surrounding ferromagnetic materials are magnetic, geomagnetic sensors can have difficulties with accurate measurements when there are steel structures or electronic devices present. Furthermore, geomagnetic sensors often require calibration. For example, sensor accuracy can vary depending on the initial position or sensor placement.

[0012] In other words, the Earth's magnetic field, the basis of measurement for geomagnetic sensors, can vary depending on geographic location, time, and natural factors. These changes can adversely affect the sensor's measurement results. The declination and field strength, which vary depending on geographic conditions, must be compensated for by reading regional statistics.

[0013] Furthermore, the measured values ​​of a geomagnetic sensor are closely related to the magnetization rate of the sensor components. When power is applied to a geomagnetic sensor, the coil or dipole of the magnetic material used for measurement is generated, saturating, and the measurement signal takes time to stabilize. In other words, the typical time required for a geomagnetic sensor to stabilize after power is applied has been measured to be approximately 50 seconds. In an unstable sensor signal, attitude measurement using a geomagnetic sensor is difficult.

[0014] Therefore, measuring a user's posture using only a geomagnetic sensor is extremely difficult. Furthermore, because accelerometers reflect the human body's angle relative to gravity in a stable state, they cannot detect rotation perpendicular to gravity. Therefore, assessing human posture using accelerometers alone poses a challenge.

[0015] Meanwhile, when a gyro sensor measures the rotation of the human body by continuous angular velocity integration, the sensor must measure the angular velocity at every moment and the CPU must continuously perform integration calculations, which consumes a lot of power and has the disadvantage of being unsuitable for long-term measurement with the small battery of a wearable device.

[0016] Figure 1 is a drawing defining the coronal, sagittal, and transverse planes based on the human body.

[0017] Referring to Figure 1, the coronal plane (or frontal plane - a cross-section plane that divides the front and back of the body, also known as the frontal plane), the saggital plane (a cross-section plane that divides the body symmetrically into the right and left sides), and the transverse plane (a cross-section plane that divides the body into the top and bottom) are defined based on the human body.

[0018] Embodiments of the present invention provide a method for measuring body rotation amount based on posture determination capable of determining a posture of a subject and then calculating a rotation amount in the specified posture.

[0019] In accordance with embodiments of the present invention for solving the above technical problem, a method for measuring body rotation amount according to posture determination using a mobile device including an acceleration sensor and a geomagnetic sensor that can be fixed to the chest area of ​​a subject and have the same local coordinate system, wherein when the subject stands normally, the direction extending from the right shoulder to the left shoulder is X g In the axial 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 is Y g In the axial direction, the above X g Axial and Y g The axis direction generated by the vector multiplication between the axes is Z g Define a first reference coordinate system defined in the axial direction, and measure acceleration values ​​according to the local coordinate system (x-axis direction, y-axis direction and z-axis direction) and transform acceleration values ​​(A) according to the first reference coordinate system X , A Y & A Z ) is converted into. Afterwards, the above conversion acceleration value (A X , A Y & A Z) is used to determine the posture of the subject on the sagittal plane. Meanwhile, if the converted acceleration value maintains a value within the reference range, the second reference coordinate system (X) of the geomagnetic sensor m, Axial direction, Y m Axial and Z m axial direction) and the measured magnetic field value according to the local coordinate system is converted to the magnetic field value (B) based on the second reference coordinate system. X , B Y & B Z ) is converted into. Afterwards, the converted magnetic field value (B X , B Y & B Z ) is used to calculate the amount of rotation in the cross-sectional or coronal plane for the subject's posture.

[0020] In one embodiment of the present invention, the conversion acceleration value (A X , A Y & A Z ) is to rotate the x-axis direction according to the local coordinate system to the X g Using the rotation angle (θ) to match the axial direction, the measured acceleration value (a x , a y & a z ) is the transformation acceleration value (A) according to the first reference coordinate system. X , A Y & A Z ) can be converted to .

[0021] In one embodiment of the present invention, the step of determining the posture of the subject is, on the first reference coordinate system, the transformed acceleration value (A X , A Y & A Z ) and the standard acceleration values ​​for each posture stored in the coordinate and data storage unit (A X0 , A Y0 & A Z0 ) can be calculated to calculate the distances between the coordinates, and the posture corresponding to the minimum value among the distances can be determined as a specific posture.

[0022] In one embodiment of the present invention, it can be determined that the conversion acceleration value maintains a value within a reference range by maintaining the judgment posture for a certain period of time.

[0023] In one embodiment of the present invention, the step of defining the second reference coordinate system of the geomagnetic sensor is to rotate the Y in the opposite direction of gravity in a clockwise direction. g A rotation angle (δ) can be used to align with the axial direction.

[0024] In one embodiment of the present invention, the measured magnetic field value is converted to a magnetic field value (B) based on the second reference coordinate system. X , B Y & B Z ) is to rotate the Y in the opposite direction of gravity clockwise. g A rotation angle (δ) can be used to align with the axial direction.

[0025] In one embodiment of the present invention, the converted magnetic field value (B X , B Y & B Z ) is used to calculate the rotation amount for the subject's posture, the conversion magnetic field value (B X , B Y & B Z ) is the XY plane (X) of the second reference coordinate system m, Axial and Y m axial plane) and the XZ plane (X) of the second reference coordinate system m, Axial and Z m The first angle (β) and the second angle (γ) formed by the axial direction can be used, respectively.

[0026] Here, each of the first angle (β) and the second angle (γ) may be proportional to the amount of rotation of the subject in the coronal plane and the transverse plane.

[0027] According to the embodiments of the present invention described above, after specifying the posture of the subject, the amount of body rotation can be measured based on posture determination that can calculate the amount of rotation in the specified posture.

[0028] Figure 1 is a drawing defining the coronal, sagittal, and transverse planes based on the human body.

[0029] Figure 2 is a photograph defining the x-axis direction, y-axis direction, and z-axis direction according to the local coordinate system of the sensor included in the mobile device.

[0030] Figure 3 shows the X while the mobile device is fixed to the subject's chest area. g Axial direction, Y g Axial and Z g This is a drawing for explaining the first reference coordinate system including the axial direction.

[0031] FIG. 4 is a flowchart for explaining a method for measuring body rotation amount according to posture determination according to one embodiment of the present invention.

[0032] Figure 5 shows the x-axis direction and y-axis direction of the local coordinate system and the X-axis direction of the first reference coordinate system when the mobile device is arbitrarily mounted on the chest area. g Axial direction and Y g This is a drawing to explain the relationship between the axial directions.

[0033] Figure 6 shows the z-axis direction of the local coordinate system and the Z-axis direction of the first reference coordinate system when the mobile device is arbitrarily mounted on the chest area. g This is a drawing to explain the relationship between the axial directions.

[0034] Figure 7 is a graph showing the reference acceleration value and measured acceleration value for each posture in a transformed coordinate system using a method for determining the posture of the subject.

[0035] Figure 8 shows X in a specific posture of the subject. m Axial direction, Y m Axial and Z m This is a drawing for explaining a second reference coordinate system including the axial direction.

[0036] Figure 9 shows the transformed magnetic field values ​​(B) within the second reference coordinate system. X , B Y & B Z ) is a drawing for explaining a step of calculating the amount of rotation for the subject's posture.

[0037] 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.

[0038] 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."

[0039] 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.

[0040] 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.

[0041] Figure 2 is a photograph defining the x-axis direction, y-axis direction, and z-axis direction according to the local coordinate system of the sensor included in the mobile device. Figure 3 is an X-axis direction while the mobile device is fixed to the chest area of ​​the subject. g Axial direction, Y g Axial and Z g This is a drawing for explaining a first reference coordinate system including an axial direction. FIG. 4 is a flowchart for explaining a method for measuring body rotation amount according to posture determination according to one embodiment of the present invention.

[0042] Referring to FIGS. 2 to 4, the method for determining the body position of a subject according to embodiments of the present invention uses a mobile device that is fixed to the chest area of ​​the subject and includes a sensor.

[0043] 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 yaw momentum. In addition, when the phone is held upright, the direction from left to right is the y-axis, and the counterclockwise rotation around the y-axis is called roll. In this case, the direction from bottom to top of the phone when held upright is the z-axis, and the amount of rotation around the z-axis is defined as pitch. The direction in which the rotational momentum increases for each axis is the direction pointed by the remaining four fingers when the positive direction of the axis is aligned with the thumb and grasped.

[0044] Therefore, the accelerometer / gyro / magnetic sensor installed inside the mobile phone all 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.

[0045] Referring to Figures 2 to 4, the direction extending from the right shoulder to the left shoulder when the subject is standing normally is X. g In the axial 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 is Y g In the axial direction, the above X g Axial and Y g The axis direction generated by the vector multiplication between the axes is Z g Define a first reference coordinate system defined in the axial direction (S110).

[0046] The opposite direction of gravity is a line close to a vertical line using the mastoid process of the temporal bone, the center of the acromion, the back of the second sacral vertebra, the front of the knee joint, and the front of the ankle joint as reference points in the sagittal plane.

[0047] Next, the measured acceleration value (a) according to the local coordinate system (x-axis direction, y-axis direction and z-axis direction) X , a Y & a Z ), the first reference coordinate system (X g , Y g , Z g Transformation acceleration value (A) according to the axial direction X , A Y & A Z ) when converted to (S120).

[0048] Here, the measured acceleration in the x-direction in the local coordinate system is a x , the measured acceleration in the z-axis direction is α z is defined as . At this time, the measured acceleration α in the y-axis direction y satisfies mathematical expressions 1 and 2 below.

[0049]

[0050]

[0051] That is, the 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 the mobile device is fixed near the chest of a standing subject, and if the subject is standing, an acceleration of 9.8 m / s^2 is applied in the direction opposite to the direction of gravity.

[0052] 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 , α z 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.

[0053] Figure 5 shows the x-axis direction and y-axis direction of the local coordinate system and the X-axis direction of the first reference coordinate system when the mobile device is arbitrarily mounted on the chest area.g Axial direction and Y g This is a drawing to explain the relationship between the axial directions. Figure 6 shows the z-axis direction of the local coordinate system and the Z-axis direction of the first reference coordinate system when the mobile device is arbitrarily mounted on the chest area. g This is a drawing to explain the relationship between the axial directions.

[0054] Referring to Figure 5, when the mobile device is worn around the chest, the x-axis direction of the accelerometer chip is X g It is recommended to be fixed parallel to the axis, but in reality, when a mobile device is mounted on a person's hand on the chest to measure posture, the x, y, and z-axis directions of the accelerometer chip in the measuring device are always included in the first reference coordinate system. g , Y g , Z g It is mounted in a different direction.

[0055] Therefore, the measured acceleration value (a) according to the local coordinate system as defined above X , a Y & a Z ) is the acceleration value (A) converted according to the first reference coordinate system. X , A Y & A Z ) is corrected (S120).

[0056] Measurement acceleration value (a) X , a Y & a Z ) value converted to acceleration value (A X , A Y & A Z ) When the IMU is mounted on the chest at an arbitrary angle to compensate for the angle between the x-axis and the Xg-axis, the angle is defined as θ. At this time, the inner product between the unit vectors x■Xg= |x||Xg|COS(θ) and satisfies θ = COS-1(x■Xg) = COS-1(y■Yg).

[0057] Referring to Figure 6, the angle δ is in the opposite direction of gravity and Y immediately after mounting the IMU in a standing or sitting position or in a Fowler position. gDefined as the angle between the axes.

[0058] The above angle δ has a value of 8 to 15° when standing normally, 20° when sitting, and approximately 30° in the Fowler position. When rotating δ clockwise from the direction opposite to gravity and reaching the Yg-axis, δ has a positive value, and when rotating δ counterclockwise from the direction opposite to gravity and reaching the Y-axis, δ has a negative value.

[0059] Afterwards, the above conversion acceleration value (A X , A Y & A Z ) determines the posture of the subject (S130).

[0060] To this end, on the first reference coordinate system, the transformed acceleration values ​​and the reference acceleration values ​​for each posture stored in the data storage unit according to the first reference coordinate system (A X0 , A Y0 & A Z0 ) calculates the respective distances between the above posture-specific reference acceleration values ​​(A X0 , A Y0 & A Z0 ) corresponds to Table 1 below.

[0061] Posture Acceleration (g) based on X-axis Acceleration (g) based on Y-axis Acceleration (g) Right angle standing 00.93 0.21 Right angle left half-0.94 0.15 0.36 Right angle right half-0.91-0.10.6 Sitting 00.85 0.52 Fowler's position 00.75 0.66 Semi-Fowler's position 00.4 0.91 Supine 0-0.34 0.97 Trendelberg 0-0.5 0.88 Prone 00.2-0.98

[0062] That is, on the first reference coordinate system, the reference acceleration values ​​(A) for each posture stored in the data storage unit according to the first reference coordinate system X0 , A Y0 & A Z0 ) are calculated for each distance between them. For example, in the first case, the second case, and the third case, the transformation acceleration value (A X , A Y& A Z ) can be represented by the coordinates (0.14, 0.37, 0.9), (0.15, -0.13,0.97), and (0.14,0.59,0.78).

[0063] On the other hand, in embodiments of the present invention, the transformed acceleration values ​​in the first reference coordinate system and the posture-specific reference acceleration values ​​(a) stored in the data storage unit according to the transformed coordinate system X0 , a Y0 & a Z0 ) can measure the respective distances between them.

[0064] At this time, on the above transformation coordinate system, the standard acceleration values ​​for each posture (a X0 , a Y0 & a Z0 ) is shown in Fig. 7.

[0065] Fig. 7 is a graph showing the reference acceleration value and measured acceleration value for each posture in the first reference coordinate system using the method for determining the posture of the subject of Fig. 4.

[0066] Referring to Figure 7, the standard acceleration values ​​for each posture (a X0 , a Y0 & a Z0 ) has already been entered into the data storage.

[0067] 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 transformed 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.

[0068] 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

[0069] Afterwards, the posture corresponding to the minimum value among the above distances is determined as the judgment posture.

[0070] 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.

[0071] Referring to FIG. 4 and FIG. 8, when the above-mentioned conversion acceleration value maintains a value within the reference range, the second reference coordinate system (X) of the geomagnetic sensor m Axial direction, Y m Axial and Z m Defines the axial direction (S140).

[0072] That is, if the conversion acceleration value maintains a value within the reference range, it is determined that the subject maintains the same posture for a reference time, for example, 1 second or more. In this case, a geomagnetic sensor needs to calculate the magnetic field value to calculate the rotation amount. To calculate the magnetic field value, a second reference coordinate system is defined.

[0073] For this purpose, an angle (δ) can be used. In this case, the angle (δ) is defined as the angle between the direction opposite to gravity and the Yg axis immediately after mounting the IMU in a standing, sitting, or Fowler position.

[0074]

[0075] Here, vector (x m , y m , z m ) is a unit vector along the x-axis, y-axis, and z-axis directions according to the local coordinate system, and vector (X m , Y m , Z m ) is a vector that penetrates the human body measured by the IMU regardless of the angle the human body forms with respect to gravity, and serves as a reference vector within the second reference coordinate system for evaluating the rotation of the human body in the coronal and transverse planes.

[0076] Next, the measured magnetic field value (b) according to the local coordinate system x , b y , b z ), the transformed magnetic field value (B) based on the second reference coordinate system X , B Y & B Z ) is converted into (S150).

[0077] For example, if the posture of the same subject in the sagittal plane is specified, the angle in the sagittal plane is fixed. At this time, if a change in posture in the transverse or coronal plane occurs, the geomagnetic sensor measures the measured magnetic field value (b) according to the local coordinate system. x , b y , b z ) has.

[0078] Afterwards, the measured magnetic field value (b) is measured according to the local coordinate system. x , b y , b z ) is converted to the magnetic field value (B) based on the second reference coordinate system. X , B Y & B Z) Converted to . At this time, the following mathematical formula 4 is used.

[0079]

[0080] At this time, the transformed magnetic field value vector shares the by-axis with the center line penetrating the human body.

[0081] Referring to Figures 4 and 9, the transformed magnetic field value (B) based on the second reference coordinate system X , B Y & B Z) The amount of rotation of the human body is calculated using (S160).

[0082] For this purpose (B x , 0, B z ) vector and (b x , 0, b z ) vectors, the angle (γ) between them can be calculated to measure the amount of rotation of the waist in the cross-section of the human body. Meanwhile, the amount of rotation (β) of the waist in the coronal plane can be measured by calculating the angle between the vectors (Bx, By, 0) and (bx, by, 0).

[0083]

[0084] 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.

[0085] 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.

[0086] 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.

[0087] A method of measuring body rotation amount by using a magnetic field value measured from a geomagnetic sensor for a subject's posture determined using an acceleration value measured from an acceleration sensor by attaching a mobile device including a sensor to the subject's body can be applied to medical and sports fields as well as industrial devices.

Claims

1. A method for measuring body rotation amount based on posture determination using a mobile device that can be fixed to the chest area of a subject and includes an acceleration sensor and a geomagnetic sensor having the same local coordinate system, When the subject is standing normally, the direction extending from the right shoulder to the left shoulder is X g In the axial 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 is Y g In the axial direction, the above X g Axial and Y g The axis direction generated by the vector multiplication between the axes is Z g A step of defining a first reference coordinate system defined in the axial direction; The measured acceleration value according to the local coordinate system (x-axis direction, y-axis direction and z-axis direction) is converted to the transformed acceleration value (A) according to the first reference coordinate system. X , A Y & A Z ) to convert it into; The above conversion acceleration value (A X , A Y & A Z ) to determine the posture of the subject in the sagittal plane; If the above conversion acceleration value maintains a value within the reference range, the second reference coordinate system (X) of the geomagnetic sensor m, Axial direction, Y m Axial and Z m Step of defining the axial direction; The measured magnetic field value according to the above local coordinate system is converted to a magnetic field value (B) based on the second reference coordinate system. X , B Y & B Z ) to convert it into; and The above conversion magnetic field value (B X , B Y & B Z ) to calculate the amount of rotation in the cross-section or coronal plane with respect to the subject's posture; A method for measuring body rotation amount according to posture judgment including .

2. In the first paragraph, the conversion acceleration value (A X , A Y & A Z ) to convert it into, Rotate the x-axis direction according to the above local coordinate system to the above X g Using the rotation angle (θ) to match the axial direction, the measured acceleration value (a x , a y & a z ) is the transformation acceleration value (A) according to the first reference coordinate system. X , A Y & A Z ) to convert to; A method for measuring body rotation amount according to posture judgment including .

3. In the first paragraph, the step of determining the posture of the subject is: On the first reference coordinate system, the transformation acceleration value (A X , A Y & A Z ) and the standard acceleration values for each posture stored in the coordinate and data storage unit (A X0 , A Y0 & A Z0 ) a step of calculating distances between coordinates; and A step of determining a posture corresponding to the minimum value among the above distances as a specific posture; A method for measuring body rotation amount according to posture judgment, characterized in that it includes.

4. A method for measuring body rotation amount, characterized in that in the third paragraph, the standard acceleration values for each posture correspond to Table 3 below. Acceleration based on X-axis (g)Acceleration based on Y-axis (g)Acceleration based on Z-axis (g)Right angle standing 00. 930.21 Right angle left half-0.940.150.36 Right angle right half0.91-0.10.6 Left half00. 850.52 Fowler's 00.75 0.66 Anti-Fowler's 00.4 0.91 Supine 0-0.3 40.97 Trendelberg 0-0.5 0.88 Resting 00.2-0.98 5. A method for measuring body rotation amount according to posture judgment, characterized in that in the first paragraph, the conversion acceleration value is determined to maintain a value within a reference range by maintaining the judgment posture for a certain period of time.

6. In the first paragraph, the step of defining the second reference coordinate system of the geomagnetic sensor is: Rotate the Y clockwise in the opposite direction of gravity g A method for measuring body rotation amount according to posture judgment, characterized by using a rotation angle (δ) to match the axial direction.

7. In the first paragraph, the measured magnetic field value is converted to a magnetic field value (B) based on the second reference coordinate system. X , B Y & B Z ) is to rotate the Y in the opposite direction of gravity clockwise. g A method for measuring body rotation amount according to posture judgment, characterized by using a rotation angle (δ) to match the axial direction.

8. In the first paragraph, the conversion magnetic field value (B X , B Y & B Z ) is used to calculate the rotation amount for the subject's posture. The above conversion magnetic field value (B X , B Y & B Z ) is the XY plane (X) of the second reference coordinate system m, Axial and Y m axial plane) and the XZ plane (X) of the second reference coordinate system m, Axial and Z m A method for measuring body rotation amount according to posture judgment, characterized by using a first angle (β) and a second angle (γ) formed by a plane formed by an axial direction, respectively.

9. A method for measuring body rotation amount according to posture judgment, characterized in that in paragraph 8, each of the first angle (β) and the second angle (γ) is proportional to the amount of rotation of the subject in the coronal plane and the transverse plane.

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