Method and apparatus for evaluating balance of body

Abstract

The present invention comprises: a data acquisition step of acquiring a received signal strength indicator (RSSI) value between a first smart device and a second smart device and inertial measurement unit (IMU) data of each of the first smart device and the second smart device; a body axis detection step of detecting an axis position of the body by determining whether the first smart device and the second smart device are in the same direction or different directions by using at least one of the RSSI value and the IMU data; a static balance evaluation step of evaluating a static balance with the degree of axis deflection of the body calculated through a change in the RSSI value; and a dynamic balance evaluation step of evaluating a dynamic balance by using at least one of a change period of the RSSI value and a period of the IMU data.

Description

Method and device for evaluating body balance

[0001] This patent application claims priority to Korean Patent Application No. 10-2024-0160527 filed with the Korean Intellectual Property Office on November 12, 2024, and the disclosures of said patent application are incorporated herein by reference.

[0002] The present invention was carried out under the support of the Pan-Governmental Full-Cycle Medical Device Research and Development Corporation, under project unique number 2710002317 and project number RS-2023-00248118, wherein the project management agency for the above project is the Pan-Governmental Full-Cycle Medical Device Research and Development Corporation, the research project name is "Leading the 4th Industrial Revolution and Future Medical Environment," the research project name is "Advanced Smart Board Medical Device for Improving and Evaluating Upper Extremity Function in Patients with Brain Diseases and Development of Non-Face-to-Face Rehabilitation Treatment Technology Using Artificial Intelligence," the project performing agency is Neofect Co., Ltd., and the research period is April 1, 2023 – December 31, 2025.

[0003] In addition, the present invention was carried out under the support of the Ministry of Health and Welfare under project unique number 2460000440 and project number 00266207, wherein the project management agency for the said project is the Korea Health Industry Development Institute, the research project name is "Demonstration and Introduction Support for Digital Healthcare Based on Medical Institutions," the research project name is "Advanced and Demonstration Research on Home-based Non-face-to-face Rehabilitation Medical Services for Improving Upper Extremity Function in Patients with Brain Diseases," the project performing agency is Neofect Co., Ltd., and the research period is July 1, 2023 – December 31, 2025.

[0004] The present invention relates to a method and apparatus for evaluating body balance, and more particularly to a method and apparatus for evaluating body balance using devices such as smartphones and smartwatches to evaluate body axial symmetry, static balance, and dynamic balance.

[0005] Physical symmetry and balance are key factors in functional activities and motor performance in daily life. Particularly with the increase in the elderly population, the importance of assessing balance ability in fall risk assessment and prevention, as well as in the rehabilitation process, is growing.

[0006] Conventional methods for evaluating body balance can be broadly classified into clinical and mechanical evaluation methods. Clinical evaluation methods include the Berg Balance Scale (BBS), the Timed Up and Go Test (TUG), and the Single Leg Stance Test (SLS); however, these methods have limitations in that they rely on the subjective judgment of experts, are difficult to measure quantitatively, and make continuous monitoring impossible.

[0007] Mechanical evaluation methods that have been used include force platforms, 3D motion analyzers, and Inertial Measurement Units (IMUs). Force platforms can evaluate static balance by measuring the movement path of the Center of Pressure (COP), but they are expensive equipment with limitations that restrict measurements to the installed location. 3D motion analyzers provide accurate data for gait analysis and dynamic balance evaluation, but they require a specialized laboratory environment and make continuous monitoring in daily life impossible.

[0008] Recently, balance evaluation methods utilizing IMU sensors embedded in wearable devices and smartphones have been proposed. These methods have the advantages of being portable, cost-effective, and capable of continuous monitoring during daily life. However, existing IMU-based evaluation methods have limitations, such as failing to capture the body's overall movement patterns by using only a single IMU sensor, making accurate dynamic balance evaluation difficult due to the lack of consideration for the temporal nonlinearity of sensor data, causing user inconvenience due to the fixed attachment position of the sensor, and providing limited real-time feedback.

[0009] In addition, a distance measurement technique utilizing RSSI (Received Signal Strength Indicator) values ​​between smartphones and wearable devices has recently been proposed, but this was limited to measuring the distance between devices and was used only restrictively for evaluating body balance.

[0010] Therefore, there is a need for a method and device for evaluating body balance that can be conveniently used in daily life while enabling accurate assessment.

[0011] [Prior Art Literature]

[0012] [Patent Literature]

[0013] Korean Registered Patent No. 10-2625749

[0014] The present invention aims to provide a method and device for evaluating body balance that can comprehensively evaluate static and dynamic balance and provide real-time feedback by utilizing everyday devices such as smartphones and smartwatches.

[0015] To achieve the above objective, the present invention is characterized by comprising: a data acquisition step of acquiring an RSSI (Received Signal Strength Indicator) value between a first smart device and a second smart device and IMU (Inertial Measurement Unit) data of each of the first smart device and the second smart device; a body axis detection step of detecting the body axis position by determining whether the first smart device and the second smart device are in the same direction or different directions using at least one of the RSSI value and the IMU data; a static balance evaluation step of evaluating static balance by the degree of body axis deviation calculated through the change in the RSSI value; and a dynamic balance evaluation step of evaluating dynamic balance using at least one of the change period of the RSSI value and the period of the IMU data.

[0016] Preferably, the data acquisition step can acquire acceleration, angular velocity, and geomagnetic vector values ​​using the IMU data.

[0017] Preferably, the body axis detection step measures the absolute distance between the first smart device and the second smart device using the RSSI value, detects that the first smart device and the second smart device are in the same direction if the absolute distance is less than or equal to a preset value, and detects that the first smart device and the second smart device are in different directions if the absolute distance exceeds a preset value.

[0018] Preferably, the body axis detection step may determine that the first smart device is located in the back pocket of the lower garment or the upper pocket of the upper garment if the geomagnetic vector value among the IMU data is included in a preset vertical area, and determine that the first smart device is located in the side pocket of the lower garment if the geomagnetic vector value among the IMU data is included in a preset horizontal area.

[0019] Preferably, the static balance evaluation step can evaluate the degree of body axis position deviation by accumulating the change in RSSI values ​​over time through the following mathematical formula 1.

[0020] [Mathematical Formula 1]

[0021]

[0022] (here, x phone is the RSSI value of the first smart device, x watch is the RSSI value of the second smart device, represents the accumulated change in RSSI values ​​over time.

[0023] Preferably, the static balance evaluation step can determine whether the user is in a static state by using acceleration and angular velocity among the IMU data, and correct the degree of axial position deviation of the body by the difference in gravitational acceleration angle between the first smart device and the second smart device using the following Equation 2.

[0024] [Mathematical Formula 2]

[0025]

[0026] (here, a y is the y-axis component of acceleration, a z represents the z-axis component of acceleration)

[0027] Preferably, the dynamic balance evaluation step can convert the acceleration and angular velocity among the RSSI value and IMU data into phase through a Hilbert transform and calculate the phase difference between the first smart device and the second smart device.

[0028] Preferably, the dynamic balance evaluation step can evaluate the dynamic balance through the regularity of the phase difference.

[0029] Preferably, the dynamic balance evaluation step can evaluate the dynamic balance by finding the optimal matching of time series data (RSSI, acceleration, or angular velocity) of the first smart device and the second smart device through dynamic time warping and by the time taken to match.

[0030] In addition, the present invention is further characterized by comprising: a data acquisition unit that acquires an RSSI (Received Signal Strength Indicator) value between a first smart device and a second smart device and IMU (Inertial Measurement Unit) data of each of the first smart device and the second smart device; a body axis detection unit that detects the body axis position by determining whether the first smart device and the second smart device are in the same direction or different directions using at least one of the RSSI value and the IMU data; a static balance evaluation unit that evaluates static balance by calculating the degree of body axis position deviation through a change in the RSSI value; and a dynamic balance evaluation unit that evaluates dynamic balance using at least one of the change period of the RSSI value and the period of the IMU data.

[0031] The present invention has the advantage of being able to accurately determine the relative positions of a smartphone and a smartwatch by combining RSSI-based distance measurement technology with DTW and Hilbert transforms of IMU data, and to improve accuracy by utilizing a correction index for the smartphone's position through directional assistance analysis using a geomagnetic sensor, and to provide immediate feedback to the user by evaluating the static and dynamic balance of the body in real time during walking and quantitatively analyzing asymmetry.

[0032] In addition, the present invention has the advantage of monitoring changes in a user's balance and gait patterns through long-term data collection and analysis, effectively utilizing this for personalized health management and rehabilitation treatment, and managing the quality of user experience and health management in the fields of digital healthcare, sports training, and rehabilitation treatment through this technology.

[0033] Figure 1 shows a flowchart of a method for evaluating body balance according to an embodiment of the present invention.

[0034] FIG. 2 is a diagram illustrating the body axis detection step, where FIG. 2 (a) shows a method for detecting the body axis position through RSSI values ​​and FIG. 2 (b) shows a method for detecting the body axis position through geomagnetic vector values.

[0035] Figure 3 is a diagram illustrating the dynamic balance evaluation step, where Figure 3 (a) shows the Hilbert transform method and Figure 3 (b) shows the dynamic time warping method.

[0036] Figure 4 shows a configuration diagram of a device for evaluating body balance according to an embodiment of the present invention.

[0037] The present invention is characterized in that it comprises: a data acquisition step of acquiring an RSSI (Received Signal Strength Indicator) value between a first smart device and a second smart device and IMU (Inertial Measurement Unit) data of each of the first smart device and the second smart device; a body axis detection step of detecting the body axis position by determining whether the first smart device and the second smart device are in the same direction or different directions using at least one of the RSSI value and the IMU data; a static balance evaluation step of evaluating static balance by the degree of body axis deviation calculated through the change in the RSSI value; and a dynamic balance evaluation step of evaluating dynamic balance using at least one of the change period of the RSSI value and the period of the IMU data.

[0038] The present invention will be described in detail below with reference to the contents described in the attached drawings. However, the present invention is not limited or restricted by exemplary embodiments. Identical reference numerals in each drawing indicate components that perform substantially the same function.

[0039] The purpose and effects of the present invention may be naturally understood or become clearer through the following description, and the purpose and effects of the present invention are not limited solely to the description below. Furthermore, in describing the present invention, if it is determined that a detailed description of known technology related to the present invention may unnecessarily obscure the essence of the present invention, such detailed description will be omitted.

[0040] The terms used in this invention are used merely to describe specific embodiments and are not intended to limit the invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this application, terms such as "comprising" or "having" are intended to specify the presence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the description of the invention, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0041] Terms such as "first," "second," etc., may be used to describe various components, but said components should not be limited by said terms. These terms are used solely for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be named the second component, and similarly, the second component may be named the first component.

[0042] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which this invention pertains. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an ideal or overly formal sense unless explicitly defined in this invention.

[0043] In interpreting the components, they are interpreted to include a margin of error even without a separate explicit indication. In the case of descriptions regarding temporal relationships, for example, where the temporal sequence is described using 'after,' 'following,' 'next,' 'before,' etc., cases that are not continuous are included unless 'immediately' or 'directly' is used.

[0044] Hereinafter, the technical configuration of the present invention will be described in detail with reference to the attached drawings.

[0045] FIG. 1 shows a flowchart of a method for evaluating body balance according to an embodiment of the present invention. Referring to FIG. 1, the method for evaluating body balance may include a data acquisition step (S110), a body axis detection step (S130), a static balance evaluation step (S150), and a dynamic balance evaluation step (S170).

[0046] Methods for evaluating body balance can be utilized in the field of digital healthcare to assess static and dynamic balance. These methods can evaluate a user's static and dynamic balance and provide real-time feedback on proper posture and gait based on their balance status. Furthermore, since these methods can be used to monitor health conditions by collecting long-term data to analyze user movement patterns and tracking changes in balance and gait, they can be effectively applied in various fields such as personalized health management, rehabilitation therapy, and sports training.

[0047] A method for evaluating body balance combines RSSI-based distance measurement with Dynamic Time Warping (DTW) and Hilbert transformation of IMU data to correct temporal distortion and precisely analyze body asymmetry. Through this, the method for evaluating body balance can more accurately detect the relative positions of smartphones and smartwatches and improve static and dynamic balance evaluation, thereby enabling real-time feedback and long-term health monitoring.

[0048] Static balance refers to the body's ability to maintain its posture when in a fixed or stationary position. For example, a method to assess body balance can evaluate it by detecting subtle swaying or axis twisting while the positions of smartphones and smartwatches remain largely unchanged.

[0049] Dynamic balance refers to the ability to maintain stability while the body is in motion. For example, dynamic balance can refer to the ability to maintain physical stability in situations involving movement, such as walking, changing direction, or climbing stairs. Dynamic balance can be assessed by analyzing wrist swing motions and pelvic movement patterns during walking to evaluate left-right symmetry and regularity of movement.

[0050] As mentioned earlier, static and dynamic balance are important functions for both daily living and exercise performance, and are both key factors that must be considered in rehabilitation therapy and fall risk assessment.

[0051] The data acquisition step (S110) can acquire the RSSI (Received Signal Strength Indicator) value between the first smart device and the second smart device and the IMU (Inertial Measurement Unit) data of each of the first smart device and the second smart device.

[0052] Here, the first smart device may be a portable terminal such as a smartphone, tablet PC, or PDA (Personal Digital Assistant), and the second smart device may be a wearable device worn on the hand, wrist, or arm such as a smartwatch, smart band, fitness tracker, or smart ring. However, the first smart device and the second smart device in the present invention are not limited to the examples described above and may be implemented as a combination of various types of smart devices equipped with a communication function capable of measuring RSSI values ​​and an IMU sensor.

[0053] RSSI (Received Signal Strength Indicator) is an indicator representing the strength of a received wireless signal, and in the present invention, it refers to the signal strength measured in Bluetooth communication between a first smart device and a second smart device. The RSSI value is generally displayed in dBm units and has the characteristic that the RSSI value decreases as the distance between the two devices increases, causing the signal strength to weaken.

[0054] In the present invention, changes in the relative distance between a first smart device and a second smart device can be measured through changes in these RSSI values. That is, the present invention utilizes the antennas of a smartphone and a smartwatch to detect Bluetooth communication strength, thereby measuring the absolute or relative distance between the wrist and the mobile phone. For example, by analyzing the pattern of RSSI value changes between the smartphone and the smartwatch during walking, swing motions of the wrist and movements of the body's center of gravity can be detected.

[0055] However, since RSSI values ​​may fluctuate depending on the surrounding environment (e.g., obstacles, electromagnetic interference, etc.), relative change patterns over time, rather than the absolute numerical value of the RSSI, can be utilized in the analysis when evaluating balance in this invention. Additionally, RSSI can be implemented to enable more accurate motion analysis through fusion with IMU sensor data.

[0056] IMU (Inertial Measurement Unit) data is data collected from an IMU sensor, and in the present invention, it may refer to data measured through a 3-axis accelerometer, a 3-axis gyroscope, and a 3-axis magnetometer. In particular, the data acquisition step (S110) can acquire acceleration, angular velocity, and magnetometer vector values ​​using IMU data. The accuracy of the measurement can be improved through fusion with RSSI data and periodic correction of the IMU data.

[0057] The first smart device and the second smart device can have an IMU sensor embedded.

[0058] An accelerometer is a sensor that measures linear acceleration and can provide acceleration values ​​for the three axes x, y, and z. The unit of the measurement is m / s² or g (gravitational acceleration), and in a static state, only the effect of gravitational acceleration is measured, while in a dynamic state, acceleration due to movement can be additionally measured. In the present invention, the tilt of the device and the intensity of movement can be detected through accelerometer data.

[0059] A gyroscope is a sensor that measures angular velocity and can provide rotational speed around three axes: x, y, and z. The unit of the measurement is rad / s (radians / second) or deg / s (degrees / second) and can be used to detect rotational motion of a device. In the present invention, changes in direction and rotational movement of a device can be detected through gyroscope data (angular velocity).

[0060] A geomagnetic sensor is a sensor that measures direction based on the Earth's magnetic field and can provide magnetic field strength along the three axes of x, y, and z. The unit of the measurement is μT (microtesla) or gauss, and it can be used to detect the absolute orientation of a device. In the present invention, geomagnetic sensor data can be used to correct the orientation of the device and as an auxiliary indicator to estimate the location of a smartphone (e.g., side pocket, back pocket).

[0061] FIG. 2 is a diagram illustrating the body axis detection step, where FIG. 2 (a) shows a method for detecting the body axis position through RSSI values ​​and FIG. 2 (b) shows a method for detecting the body axis position through geomagnetic vector values.

[0062] Referring to FIG. 2(a), the body axis detection step (S130) can detect the body axis position by determining whether the first smart device and the second smart device are in the same direction or different directions using at least one of the RSSI value and IMU data.

[0063] The body axis detection step (S130) may receive input from the user regarding the wearing position of the second smart device. For example, when the user sets the left / right wearing position after wearing the smartwatch, the body axis detection step (S130) can detect the body center axis by acquiring RSSI between the smartwatch and the smartphone and IMU data of each device from the smartphone, confirming whether the current state is in place or walking (moving), and simultaneously determining whether the smartphone and the smartwatch are located on the same side (Ipsilateral) or opposite side (Contralateral).

[0064] In one embodiment, the body axis detection step (S130) can detect that the body axis is on the right side of each device when it is determined that the user is wearing the smartwatch on the left side and the smartphone and the smartwatch are in the same position. The body axis detection step (S130) can detect that the body axis is on the left side of each device when it is determined that the user is wearing the smartwatch on the right side and the smartphone and the smartwatch are in the same position.

[0065] In one embodiment, the body axis detection step (S130) can detect that the body axis is between each device when it is determined that the user is wearing the smartwatch on the left or right side and the smartphone and the smartwatch are in different positions (directions).

[0066] Referring to FIG. 2(b), the body axis detection step (S130) measures the absolute distance between the first smart device and the second smart device using an RSSI value, and if the absolute distance is less than or equal to a preset value, it is determined that the first smart device and the second smart device are in the same direction, and if the absolute distance exceeds a preset value, it is determined that the first smart device and the second smart device are in different directions.

[0067] The body axis detection step (S130) is a formula The distance between the first smart device and the second smart device can be measured using . Here, d is the distance between the first smart device and the second smart device, P t is the transmission power, x RSSI represents the received signal strength, and n represents the path loss index.

[0068] The body axis detection step (S130) can determine that the first smart device is located in the back pocket of the lower garment or the upper pocket of the upper garment if the geomagnetic vector value among the IMU data is included in a preset vertical area, and determine that the first smart device is located in the side pocket of the lower garment if the geomagnetic vector value among the IMU data is included in a preset horizontal area. Here, the geomagnetic vector value may represent the angle formed by the first smart device and the second smart device.

[0069] The preset vertical area may refer to an area close to the vertical set by the user, and the preset horizontal area may refer to an area close to the horizontal set by the user. Additionally, a blank area may exist between the preset vertical area and the preset horizontal area, and the body axis detection step (S130) may suspend judgment if the geomagnetic field vector value exists in the blank area, and may re-collect data and make a judgment again.

[0070] The body axis detection step (S130) is a formula Using this, the geomagnetic vector value can be calculated. Here, Mphone represents the geomagnetic vector value of the smartphone, Mwatch represents the geomagnetic vector value of the smartwatch, and θ represents the angle between the geomagnetic vectors of the smartphone and the smartwatch.

[0071] The static balance evaluation step (S150) can evaluate static balance based on the degree of body axis deviation calculated through changes in RSSI values.

[0072] The static balance evaluation step (S150) can evaluate the degree of body axis position deviation by accumulating the change in RSSI values ​​over time through the following mathematical formula 1.

[0073] [Mathematical Formula 1]

[0074]

[0075] (here, x phone is the RSSI value of the first smart device, x watch is the RSSI value of the second smart device, represents the accumulated change in RSSI values ​​over time.

[0076] The static balance evaluation step (S150) can evaluate static balance through the degree of body axis deviation (twisting) and duration by accumulating changes in RSSI values ​​over time. Specifically, the static balance evaluation step (S150) can evaluate that the body is biased toward the side wearing the smartwatch if the center of the body is set to 1 and decimal values ​​accumulate. The static balance evaluation step (S150) can evaluate that the body is biased toward the side not wearing the smartwatch (opposite side) if the center of the body is set to 1 and values ​​greater than 1 accumulate.

[0077] The static balance evaluation step (S150) determines whether the user is in a static state by using acceleration and angular velocity among the IMU data, and can correct the degree of axial position deviation of the body by the difference in gravitational acceleration angle between the first smart device and the second smart device using the following mathematical formula 2.

[0078] [Mathematical Formula 2]

[0079]

[0080] (here, a y is the y-axis component of acceleration, a z represents the z-axis component of acceleration)

[0081] The static balance evaluation step (S150) determines the left and right sides (watch side, opposite side) through the RSSI value and can correct the bias through the gravity value accumulated from each device.

[0082] The static balance evaluation step (S150) can determine a static state when the acceleration and angular velocity are very small values. Specifically, the static balance evaluation step (S150) may have preset acceleration and angular velocity reference values ​​for determining a static state.

[0083] The dynamic balance evaluation step (S170) can evaluate dynamic balance using at least one of the change period of the RSSI value and the period of the IMU data.

[0084] Specifically, the dynamic balance evaluation step (S170) can detect directionality and periodicity by utilizing the Hilbert Transform and Dynamic Time Warping (DTW) methods based on data (RSSI, acceleration, angular velocity) acquired from the first smart device and the second smart device. The dynamic balance evaluation step (S170) can analyze dynamic balance in real time through periodicity and directionality analysis via the movement of the wrist and pocket (hip or chest) during walking.

[0085] Figure 3 is a diagram illustrating the dynamic balance evaluation step, where Figure 3 (a) shows the Hilbert transform method and Figure 3 (b) shows the dynamic time warping method.

[0086] Referring to FIG. 3(a), the dynamic balance evaluation step (S170) can convert the RSSI value, acceleration and angular velocity among the IMU data into phase through Hilbert transformation, and calculate the phase difference between the first smart device and the second smart device.

[0087] The Hilbert transform is a mathematical tool used to analyze the instantaneous phase and amplitude of a time series signal. The dynamic balance evaluation step (S170) can convert the RSSI value, acceleration, and angular velocity into phase using the following mathematical formula 3.

[0088] [Mathematical Formula 3]

[0089]

[0090] (Here, represents RSSI, acceleration, or acceleration over time, t represents the current time, t1 represents the start time, and t2 represents the end time)

[0091] In one embodiment, the dynamic balance evaluation step (S170) can analyze the periodicity (wrist swing or gait period) of the smartphone and smartwatch movements by converting the RSSI, acceleration, and acceleration into phase space.

[0092] The dynamic balance evaluation step (S170) can evaluate dynamic balance through the regularity of the phase difference. The dynamic balance evaluation step (S170) can calculate the phase difference between the first smart device and the second smart device using the following mathematical formula 4.

[0093] [Mathematical Formula 4]

[0094]

[0095] (Here, represents the status of the first smart device, and signifies the status of a second smart device, and represents the phase difference between the first smart device and the second smart device.

[0096] The dynamic balance evaluation step (S170) can evaluate normal gait if the wrist swing and hip (or chest) movement show a periodic phase difference. The dynamic balance evaluation step (S170) can evaluate abnormal gait if the phase difference shows irregular or abnormal values. For example, a regular phase difference, such as the left leg moving forward when the right arm is swung forward, can be evaluated as normal gait, while a desynchronized movement of the arms and legs or an irregular phase difference can be evaluated as abnormal (asymmetric) gait.

[0097] Referring to FIG. 3(b), the dynamic balance evaluation step (S170) can evaluate dynamic balance by comparing the RSSI, acceleration, and angular velocity measured at the first smart device and the second smart device through dynamic time warping, finding the optimal matching of the two time series data through the difference in the movement patterns of the two devices over time, and the time taken to match. Dynamic time warping can be implemented through the following Equation 5.

[0098] [Mathematical Formula 5]

[0099]

[0100] (Here, x1 represents the acceleration or angular velocity of the first smart device, x2 represents the acceleration or angular velocity of the first smart device, and t represents time)

[0101] In another embodiment, the dynamic balance evaluation step (S170) can correct the time distortion phenomenon by non-linearly adjusting the time axis for acceleration and angular velocity measured by the first smart device and the second smart device through dynamic time warping. Even in normal walking, the speed or timing of movement on the left and right sides may differ slightly, which is referred to as the time distortion phenomenon. For example, the right step may be slightly faster or slower than the left.

[0102] Dynamic time warping refers to a method of analyzing similarity by considering the non-linear temporal changes between two time series signals.

[0103] FIG. 4 shows a configuration diagram of a device (10) for evaluating body balance according to an embodiment of the present invention. Referring to FIG. 4, the device (10) for evaluating body balance may include a data acquisition unit (110), a body axis detection unit (130), a static balance evaluation unit (150), and a dynamic balance evaluation unit (170).

[0104] The data acquisition unit (110) can acquire the RSSI (Received Signal Strength Indicator) value between the first smart device and the second smart device and the IMU (Inertial Measurement Unit) data of each of the first smart device and the second smart device. The data acquisition unit (110) can perform the aforementioned data acquisition step (S110).

[0105] The body axis detection unit (130) can detect the body axis position by determining whether the first smart device and the second smart device are in the same direction or different directions using at least one of the RSSI value and IMU data. The body axis detection unit (130) can perform the body axis detection step (S130) described above.

[0106] The static balance evaluation unit (150) can evaluate static balance by calculating the degree of axial positional deviation of the body through changes in RSSI values. The static balance evaluation unit (150) can perform the aforementioned static balance evaluation step (S150).

[0107] The dynamic balance evaluation unit (170) can evaluate dynamic balance using at least one of the change period of the RSSI value and the period of the IMU data. The dynamic balance evaluation unit (170) can perform the aforementioned dynamic balance evaluation step (S170).

[0108] Although the present invention has been described in detail above through representative embodiments, those skilled in the art will understand that various modifications can be made to the above-described embodiments within the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined by the claims set forth below as well as all modifications or variations derived from the claims and equivalent concepts.

[0109] The present invention has the advantage of being able to accurately determine the relative positions of a smartphone and a smartwatch by combining RSSI-based distance measurement technology with DTW and Hilbert transforms of IMU data, and to improve accuracy by utilizing a correction index for the smartphone's position through directional assistance analysis using a geomagnetic sensor, and to provide immediate feedback to the user by evaluating the static and dynamic balance of the body in real time during walking and quantitatively analyzing asymmetry.

[0110] In addition, the present invention has the advantage of monitoring changes in a user's balance and gait patterns through long-term data collection and analysis, effectively utilizing this for personalized health management and rehabilitation treatment, and managing the quality of user experience and health management in the fields of digital healthcare, sports training, and rehabilitation treatment through this technology.

Claims

1. A data acquisition step for acquiring RSSI (Received Signal Strength Indicator) values ​​between the first smart device and the second smart device and IMU (Inertial Measurement Unit) data of each of the first smart device and the second smart device; A body axis detection step for detecting the body axis position by determining whether the first smart device and the second smart device are in the same direction or different directions using at least one of the above RSSI value and IMU data; A static balance evaluation step that evaluates static balance by calculating the degree of body axis position deviation through the change in the above RSSI value; and A dynamic balance evaluation step that evaluates dynamic balance using at least one of the change period of the RSSI value and the period of the IMU data; A method for evaluating body symmetry and balance, including 2. In Paragraph 1, The above data acquisition step is, A method for evaluating body symmetry and balance, wherein acceleration, angular velocity, and geomagnetic vector values ​​are obtained using the above IMU data.

3. In Paragraph 1, The above body axis detection step is, A method for evaluating symmetry and balance of a body, wherein the absolute distance between a first smart device and a second smart device is measured using the above RSSI value, and if the absolute distance is less than or equal to a preset value, the first smart device and the second smart device are determined to be in the same direction, and if the absolute distance exceeds a preset value, the first smart device and the second smart device are determined to be in different directions.

4. In Paragraph 1, The above body axis detection step is, A method for evaluating the symmetry and balance of a body, wherein if the geomagnetic vector value among the above IMU data is included in a preset vertical area, it is determined that the first smart device is located in the back pocket of the lower garment or the upper pocket of the upper garment, and if the geomagnetic vector value among the above IMU data is included in a preset horizontal area, it is determined that the first smart device is located in the side pocket of the lower garment.

5. In Paragraph 1, The above static balance evaluation step is, A method for evaluating the symmetry and balance of the body, which evaluates the degree of axial positional deviation of the body by accumulating the change in RSSI values ​​over time using the following mathematical formula 1. [Mathematical Formula 1] (here, x phone is the RSSI value of the first smart device, x watch is the RSSI value of the second smart device, represents the accumulated change in RSSI values ​​over time.

6. In Paragraph 1, The above static balance evaluation step is, Using acceleration and angular velocity from the above IMU data, determine whether the user is in a static state, and A method for evaluating the symmetry and balance of a body, wherein the degree of axial position deviation of the body is corrected by the difference in gravitational acceleration angle between the first smart device and the second smart device using the following mathematical formula 2. [Mathematical Formula 2] (here, a y is the y-axis component of acceleration, a z represents the z-axis component of acceleration) 7. In Paragraph 1, The above dynamic balance evaluation step is, A method for evaluating the symmetry and balance of a body, wherein the acceleration and angular velocity among the RSSI values ​​and IMU data are converted into phases through a Hilbert transformation, and the phase difference between a first smart device and a second smart device is calculated.

8. In Paragraph 7, The above dynamic balance evaluation step is, A method for evaluating the symmetry and balance of the body, which evaluates dynamic balance through the regularity of the above-mentioned phase difference.

9. In Paragraph 7, The above dynamic balance evaluation step is, A method for evaluating body symmetry and balance, which evaluates dynamic balance by finding the optimal match of time-series data (RSSI, acceleration, or angular velocity) between a first smart device and a second smart device through dynamic time warping and assessing the time taken to match.

10. A data acquisition unit that acquires the RSSI (Received Signal Strength Indicator) value between the first smart device and the second smart device and the IMU (Inertial Measurement Unit) data of each of the first smart device and the second smart device; A body axis detection unit that detects whether a first smart device and a second smart device are in the same direction or different directions with respect to the body axis using at least one of the above RSSI value and IMU data; A static balance evaluation unit that evaluates static balance by calculating the degree of axial position deviation of the body through the change in the above RSSI value; and A dynamic balance evaluation unit that evaluates dynamic balance using at least one of the change period of the RSSI value and the period of the IMU data; A method for evaluating body symmetry and balance, including

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