A multi-modal coronal centroid monitoring method and device based on wearable technology

Abstract

This invention discloses a multimodal coronal centroid monitoring device based on wearable technology, characterized by: an inertial sensing unit fixed to the sacrum to collect motion data of the sacrum during gait, enabling posture calculation and obtaining the centroid acceleration of the human body's coronal plane in a global coordinate system; a flexible strain sensing unit disposed on the skin of both hip joints to collect motion signals of the hip joint's coronal plane, thereby obtaining the zero-velocity moment of the centroid during forward movement and correcting the drift error of the inertial sensing unit; and a main control board that samples the inertial sensing unit and the flexible strain sensing unit at a specified frequency to obtain sensor data, processes and locally stores the sensor data, and calculates the changes in the wearer's coronal centroid motion state. This invention achieves real-time monitoring of the human body's coronal centroid motion state without range limitations in a low-cost and portable manner.

Description

Technical Field

[0001] This invention relates to the field of gait detection technology, specifically to a method and device for monitoring the centroid of the coronal plane based on wearable technology. Background Technology

[0002] The center of mass refers to the overall center of gravity of the human body during movement, usually considered to be located at 55% of body height (directly in front of the second sacral vertebra). Center of mass monitoring refers to the measurement and recording of changes in the position of the human center of mass during movement. The significance of center of mass monitoring lies in its ability to help us understand the movement patterns of the human center of mass, thus providing strong objective data support for sports training, rehabilitation, postural correction, and clinical diagnosis. In particular, changes in the center of mass movement in the coronal plane are an important indicator of gait stability, and can provide early warning of balance decline caused by neuromuscular-skeletal degeneration in the elderly, reducing the probability of falls.

[0003] Existing technologies for center of mass monitoring can be broadly categorized into laboratory research and wearable device (inertial sensor) monitoring. Laboratory-based center of mass monitoring primarily involves segmental analysis, using multiple infrared cameras to capture changes in the position of reflection points attached to various segments of the body. By analyzing the acceleration changes and mass distribution of each segment, the overall center of mass change during gait can be analyzed. Another laboratory method uses a six-dimensional force plate to acquire changes in ground reaction forces during gait, using inverse kinematics (Newton's second law of motion) to analyze the relative motion changes of the center of mass. Laboratory-based center of mass monitoring is unsuitable for everyday life due to environmental limitations (fixed test site location, limited number of steps measured), high cost, and complex operation. Wearable devices for center of mass monitoring primarily replace the segmental analysis approach used in the laboratory environment by attaching inertial sensing units to various segments of the body to monitor activity. However, this still requires synchronous analysis between multiple inertial measurement units (IMUs), which is costly and cannot overcome the inevitable drift errors of IMUs under long-term use.

[0004] In summary, existing technologies typically require expensive equipment and complex computational processes, and are significantly affected by environmental interference. They cannot achieve monitoring of the coronal plane's center of mass motion in the wearer's daily life. Summary of the Invention

[0005] This invention was made to solve the above-mentioned problems, and its purpose is to provide a method and device for multimodal coronal centroid monitoring based on wearable technology.

[0006] This invention provides a multimodal coronal centroid monitoring device based on wearable technology, characterized by: an inertial sensing unit fixed to the sacrum to collect motion data of the sacrum during gait, enabling attitude calculation and obtaining the centroid acceleration of the human body on the coronal plane in a global coordinate system; a flexible strain sensing unit disposed on the skin of both hip joints to collect motion signals of the coronal plane of the hip joint to obtain the zero-velocity moment of the centroid during forward movement and correct the drift error of the inertial sensing unit; and a main control board that samples the inertial sensing unit and the flexible strain sensing unit at a specified frequency to obtain sensor data, processes and stores the sensor data locally, and calculates the changes in the coronal centroid motion state of the wearer.

[0007] The multimodal coronal centroid monitoring device based on wearable technology provided by the present invention may also have the following features: the inertial sensing unit is a single nine-axis motion sensor or a six-axis motion sensor, which is attached to the sacrum by strapping; the flexible strain sensing unit includes two flexible strain sensors, which are respectively fixed to the two hip joints by straps.

[0008] The multimodal coronal centroid monitoring device based on wearable technology provided by this invention may also have the following feature: wherein the motion data are triaxial acceleration, angular velocity and magnetic field strength in a local coordinate system.

[0009] The multimodal coronal centroid monitoring device based on wearable technology provided by this invention may also have the following feature: the main control board performs real-time or post-analysis of data in an online or offline manner.

[0010] This invention provides a multimodal coronal centroid monitoring method based on wearable technology, characterized by the following steps: Step 1, an inertial sensing unit collects motion data of the sacrum during gait, fuses the motion data using an extended Kalman digital filter algorithm, calculates the sacrum's posture relative to the global coordinate system, obtains a rotation matrix, and projects the acceleration data measured in the inertial sensor's local coordinate system onto the global coordinate system through the rotation matrix to obtain the sacral coronal plane acceleration during human movement; Step 2, a flexible strain sensing unit collects hip joint coronal... The motion signal of the coronal plane is analyzed using a peak finding algorithm to identify the first peak value of the change in capacitance of the flexible strain sensor in each gait cycle, which is the maximum value of the coronal plane displacement of the centroid during the support phase, i.e., the moment when the motion velocity is zero. Step 3: The main control board directly performs a numerical trapezoidal integration on the acceleration of the sacral coronal plane to obtain the centroid motion velocity. Combining the moment when the motion velocity is zero, the linear drift caused by the direct integration of the motion velocity is corrected to obtain the corrected velocity result. Step 4: Based on the corrected velocity result, the main control board performs another trapezoidal numerical integration to obtain the motion displacement change of the coronal plane centroid.

[0011] The multimodal coronal centroid monitoring method based on wearable technology provided by this invention may also have the following features: before the measurement begins, all sensors are synchronized and the synchronization process is repeated every certain period of time. By repeating steps 1 to 4, the change in the coronal centroid motion state at each step during the human body's forward movement is calculated, thereby obtaining the variability of the corresponding indicators before and after, and realizing the quantitative assessment of the wearer's gait stability and the corresponding early warning of falls or gait abnormalities.

[0012] The multimodal coronal centroid monitoring method based on wearable technology provided by this invention may also have the following features: In step 3, the main control board uses a zero-velocity correction algorithm to suppress the drift error caused by the inertial sensing unit integrating the attitude calculation results in each gait cycle, based on the prior knowledge of the zero-velocity moment of the captured centroid motion.

[0013] The multimodal coronal centroid monitoring method based on wearable technology provided by this invention may also have the following feature: in step 4, the main control board stores the original data and the corrected velocity results locally or uploads them to the computer wirelessly.

[0014] The role and effect of invention

[0015] The multimodal coronal centroid monitoring device based on wearable technology according to the present invention includes: an inertial sensing unit fixed to the sacrum for collecting motion data of the sacrum during gait, realizing attitude calculation, and obtaining the centroid acceleration of the human body on the coronal plane in the global coordinate system; a flexible strain sensing unit disposed on the skin on both sides of the hip joint for collecting motion signals of the coronal plane of the hip joint to obtain the zero velocity moment during the centroid's forward movement, and correcting the drift error of the inertial sensing unit; and a main control board for sampling the inertial sensing unit and the flexible strain sensing unit at a specified frequency to obtain sensor data, processing and storing the sensor data locally, and calculating the changes in the wearer's coronal centroid motion state.

[0016] Therefore, this embodiment uses only a single inertial measurement unit (IMU) and a flexible strain sensor to measure the position and motion of the human body's center of mass. The flexible strain sensor captures the zero-velocity moment of the coronal plane center of mass motion and corrects the drift error caused by the IMU integral calculation of velocity displacement during each gait cycle. This achieves real-time monitoring of the human body's coronal plane center of mass motion state without range limitations in a low-cost and portable manner.

[0017] Finally, the multimodal coronal centroid monitoring method based on wearable technology described in this embodiment can achieve real-time monitoring of the motion state of the human coronal centroid with lower cost, simpler calculation process and stronger anti-interference ability. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a multimodal coronal centroid monitoring device based on wearable technology in an embodiment of the present invention;

[0019] Figure 2 This is a schematic diagram of a nine-axis motion sensor in an embodiment of the present invention;

[0020] Figure 3 This is a schematic diagram of a flexible strain sensor in an embodiment of the present invention;

[0021] Figure 4 This is a schematic diagram of the main control board in an embodiment of the present invention;

[0022] Figure 5 This is a graph showing the correspondence between the peak time of the hip joint flexible strain sensing signal and the time of the maximum displacement of the coronal centroid in an embodiment of the present invention.

[0023] Figure 6 This is a flowchart of a multimodal coronal centroid monitoring method based on wearable technology, as described in an embodiment of the present invention.

[0024] Figure 7 This is a diagram showing the estimated coronal centroid shift during gait. Detailed Implementation

[0025] To make the technical means, creative features, objectives and effects of the present invention easy to understand, the following embodiments, in conjunction with the accompanying drawings, specifically illustrate the multimodal coronal centroid monitoring method and device based on wearable technology of the present invention.

[0026] This embodiment provides a multimodal coronal centroid monitoring device 100 based on wearable technology. This centroid monitoring device can accurately monitor centroid motion in real time and has advantages such as low cost and portability. By continuously monitoring the wearer's gait stability, it can provide timely warnings when gait instability occurs, reducing the probability of falls and injuries for patients with gait disorders / balance dysfunction.

[0027] Figure 1 This is a schematic diagram of a multimodal coronal centroid monitoring device based on wearable technology in an embodiment of the present invention.

[0028] like Figure 1 As shown, the multimodal coronal centroid monitoring device 100 based on wearable technology in this embodiment includes an inertial sensing unit 10, a flexible strain sensing unit 20, and a main control board 30.

[0029] The inertial sensing unit 10 is a single nine-axis motion sensor 11, which is attached to the sacrum to collect the three-axis acceleration, angular velocity and magnetic field strength of the sacrum during gait. This is mainly because the sacrum is usually considered to have a strong correlation with the motion of the center of mass. Therefore, using only a single nine-axis inertial sensing unit can approximately obtain the motion state of the center of mass and realize attitude calculation to obtain the acceleration of the center of mass of the human body on the coronal plane in the global coordinate system.

[0030] Figure 2 This is a schematic diagram of a nine-axis motion sensor in an embodiment of the present invention.

[0031] The flexible strain sensing unit 20 includes two flexible strain sensors 21, which are respectively bound and fixed to the hip joints on both sides by straps 22. Specifically, one flexible strain sensor 21 is fixed to each hip joint. The upper and lower ends of the flexible strain sensor 21 are connected to the straps 22. The upper strap 22 is wrapped around the hip joint at the waist and the lower strap 22 is wrapped around the thigh, thereby fixing the flexible strain sensor 21 to the hip joint.

[0032] The flexible strain sensor 21 can capture subtle changes in the coronal plane motion of the hip joint. By utilizing the correlation between the hip joint's adduction and abduction movements and the center of mass's motion, it obtains the moment of zero velocity of the center of mass during walking and corrects for drift errors in the inertial sensing unit. The working principle is that hip joint movement causes a change in strain in the flexible strain sensor 21, which in turn changes its capacitance. Therefore, the change in sensor capacitance can approximate the motion state of the hip joint during walking.

[0033] Figure 3 This is a schematic diagram of a flexible strain sensor in an embodiment of the present invention.

[0034] The main control board 30 samples the inertial sensing unit 10 and the flexible strain sensing unit 20 at a specified frequency according to different needs to obtain sensor data. It then processes and stores the sensor data locally, and fuses the two types of sensor data. At the zero-velocity moment of the center of mass motion, it suppresses the drift error caused by the direct acceleration integration of the nine-axis inertial sensing unit. Finally, it calculates the changes in the coronal plane center of mass motion state of the wearer, providing objective data support for clinical diagnosis and life monitoring and early warning.

[0035] Figure 4 This is a schematic diagram of the main control board in an embodiment of the present invention.

[0036] Accurate capture of the moment when the center of mass reaches zero velocity is crucial for achieving accurate real-time estimation of the coronal plane center of mass motion state, as it suppresses drift errors of the nine-axis inertial motion sensor 11 through data processing. The horizontal projection of the human body's coronal plane center of mass motion oscillates back and forth between the feet. The maximum shift typically occurs when body weight shifts towards one lower limb (mid-stance phase of gait), which can be reflected by changes in the adduction angle of the hip joint's coronal plane. The moment of maximum shift in the coronal plane of the center of mass is the moment when the center of mass velocity reaches zero. Therefore, the principle of this monitoring device is to indirectly obtain the moment of maximum shift (zero velocity) in the coronal plane of the center of mass by monitoring the hip joint's motion changes during gait using bilateral hip joint flexible strain sensors 21, thus suppressing the velocity drift error caused by the nine-axis inertial sensor 11, installed at the sacrum, directly integrating acceleration.

[0037] Figure 5 This is a graph showing the correspondence between the peak time of the hip joint flexible strain sensing signal and the time of maximum displacement of the coronal centroid in an embodiment of the present invention.

[0038] The aforementioned human coronal plane centroid monitoring device includes calculations of centroid velocity, displacement, and peak-to-valley values ​​during a single gait cycle, as well as analysis of the variability of corresponding indicators during continuous multi-gait cycles.

[0039] This embodiment also provides a multimodal coronal centroid monitoring method based on wearable technology.

[0040] Figure 6 This is a flowchart of a multimodal coronal centroid monitoring method based on wearable technology, as described in an embodiment of the present invention.

[0041] The main controller controls a single nine-axis motion sensor and two flexible strain sensors to collect data in real time on the posture of the center of mass in three-dimensional space and the acceleration in the local coordinate system, as well as the changes in strain sensor capacitance caused by bilateral hip joint movements during human walking. Before starting the measurement, all sensors are synchronized, and the synchronization process is repeated at intervals.

[0042] like Figure 6 As shown, the multimodal coronal centroid monitoring method based on wearable technology in this embodiment includes the following steps:

[0043] Step S1: The inertial sensing unit 10 collects motion data of the sacrum during gait. The motion data is fused using an extended Kalman digital filter algorithm to calculate the sacrum's posture relative to the global coordinate system and obtain a rotation matrix. The acceleration data measured in the local coordinate system of the inertial sensor is projected onto the global coordinate system through the rotation matrix to obtain the coronal plane acceleration of the sacrum during human movement.

[0044] Step S2: The flexible strain sensing unit 20 collects motion signals of the coronal plane of the hip joint. Through the peak finding algorithm, it finds the first peak value of the capacitance change of the flexible strain sensor in each gait cycle, which is the maximum value of the coronal plane displacement of the centroid in the mid-support phase, which is also the moment when the motion velocity is zero.

[0045] In step S3, the main control board 30 directly performs a numerical trapezoidal integral on the coronal plane acceleration of the sacrum to obtain the velocity of the center of mass. Combining this with the zero-velocity moment, it corrects the linear drift caused by the direct integration of the velocity, obtaining the corrected velocity result. Specifically, the main control board uses a zero-velocity correction algorithm, based on prior knowledge of the captured zero-velocity moment of the center of mass, to suppress the drift error caused by the integration of attitude calculation results by the inertial sensing unit in each gait cycle.

[0046] In step S4, the main control board performs trapezoidal numerical integration again based on the corrected velocity results to obtain the motion displacement change of the centroid of the coronal plane, and stores the original data and the corrected velocity results locally or uploads them to the computer wirelessly.

[0047] By repeating the above steps, the changes in the coronal plane centroid motion state of the human body during each step forward are calculated, thereby obtaining the variability of the corresponding indicators before and after, realizing a quantitative assessment of the wearer's gait stability and a corresponding early warning of falls or gait abnormalities.

[0048] Figure 7This is a diagram showing the estimated coronal centroid shift during gait.

[0049] like Figure 7 As shown, this is the estimation result of the coronal centroid shift during the gait process obtained based on the above monitoring method steps.

[0050] The role and effect of the embodiments

[0051] The multimodal coronal centroid monitoring device based on wearable technology described in this embodiment includes: an inertial sensing unit fixed to the sacrum to collect motion data of the sacrum during gait, thereby achieving posture calculation and obtaining the centroid acceleration of the human body on the coronal plane in the global coordinate system; a flexible strain sensing unit disposed on the skin on both sides of the hip joints to collect motion signals of the coronal plane of the hip joints to obtain the zero velocity moment during the centroid's forward movement and correct the drift error of the inertial sensing unit; and a main control board that samples the inertial sensing unit and the flexible strain sensing unit at a specified frequency to obtain sensor data, processes and stores the sensor data locally, and calculates the changes in the wearer's coronal centroid motion state.

[0052] Therefore, this embodiment uses only a single inertial measurement unit (IMU) and a flexible strain sensor to measure the position and motion of the human body's center of mass. The flexible strain sensor captures the zero-velocity moment of the coronal plane center of mass motion, correcting for drift errors caused by IMU integration calculations of velocity displacement during each gait cycle. This achieves real-time monitoring of the human body's coronal plane center of mass motion state without range limitations in a low-cost and portable manner.

[0053] Finally, the multimodal coronal centroid monitoring method based on wearable technology described in this embodiment can achieve real-time monitoring of the motion state of the human coronal centroid with lower cost, simpler calculation process and stronger anti-interference ability.

[0054] The above embodiments are preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention.

Claims

1. A multimodal coronal centroid monitoring device based on wearable technology, comprising: An inertial sensing unit, fixed to the sacrum, is used to collect motion data of the sacrum during gait, realize attitude calculation, and then obtain the acceleration of the center of mass of the human body in the coronal plane in the global coordinate system. A flexible strain sensing unit is installed on the skin on both sides of the hip joint to collect motion signals of the coronal plane of the hip joint. Through a peak finding algorithm, the first peak value of the capacitance change of the flexible strain sensor in each gait cycle is found, which is the maximum value of the coronal plane displacement of the centroid in the mid-support phase, i.e. the moment when the motion velocity is zero, and the drift error of the inertial sensing unit is corrected. The main control board samples the inertial sensing unit and the flexible strain sensing unit at a specified frequency to obtain sensor data, processes and stores the sensor data locally, and calculates the changes in the wearer's coronal centroid motion state. The inertial sensing unit is a single nine-axis motion sensor or a six-axis motion sensor, which is attached to the sacrum by strapping it on. The flexible strain sensing unit includes two flexible strain sensors, which are respectively fixed to the two hip joints by straps.

2. The multimodal coronal centroid monitoring device based on wearable technology according to claim 1, characterized in that: in, The motion data are triaxial acceleration, angular velocity, and magnetic field strength in the local coordinate system.

3. The multimodal coronal centroid monitoring device based on wearable technology according to claim 1, characterized in that: in, The main control board performs real-time or post-analysis of data using online or offline methods.

4. A multimodal coronal centroid monitoring method based on wearable technology, characterized in that, The multimodal coronal centroid monitoring device based on wearable technology as described in any one of claims 1 to 3 includes the following steps: Step 1: The inertial sensing unit collects motion data of the sacrum during gait. The motion data is fused using an extended Kalman digital filter algorithm to calculate the sacrum's posture relative to the global coordinate system and obtain a rotation matrix. The acceleration data measured in the local coordinate system of the inertial sensor is projected onto the global coordinate system through the rotation matrix to obtain the coronal plane acceleration of the sacrum during human forward movement. Step 2: The flexible strain sensing unit collects motion signals from the coronal plane of the hip joint. Through the peak finding algorithm, it finds the first peak value of the capacitance change of the flexible strain sensor in each gait cycle, which is the maximum value of the coronal plane displacement of the centroid in the mid-support phase, i.e. the moment when the motion velocity is zero. Step 3: The main control board directly performs numerical trapezoidal integration on the coronal plane acceleration of the sacrum to obtain the velocity of the center of mass. Combining the zero velocity moment, the linear drift caused by the direct integration of the velocity is corrected to obtain the corrected velocity result. Step 4: Based on the corrected velocity results, the main control board performs trapezoidal numerical integration again to obtain the motion displacement change of the coronal centroid. Before starting measurements, all sensors are synchronized, and the synchronization process is repeated periodically. By repeating steps 1 to 4 to calculate the changes in the coronal centroid motion state during each step of the human body's forward movement, the variability of the corresponding indicators before and after can be obtained, thereby achieving a quantitative assessment of the wearer's gait stability and a corresponding early warning of falls or gait abnormalities.

5. The multimodal coronal centroid monitoring method based on wearable technology according to claim 4, characterized in that: in, In step 3, the main control board uses a zero-speed correction algorithm to suppress the drift error caused by the inertial sensing unit integrating the attitude calculation results in each gait cycle, based on the prior knowledge of the zero-speed moment of the captured center of mass motion.

6. The multimodal coronal centroid monitoring method based on wearable technology according to claim 4, characterized in that: in, In step 4, the main control board stores the original data and the corrected speed results locally or uploads them to the computer wirelessly.

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