Patent Publication Number: US-10786719-B2

Title: Swimming posture correction method and swimming posture correction system

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority benefit of Taiwan application no. 108106279, filed on Feb. 25, 2019. The entirety of the above-mentioned patent application is hereby incorporated by reference herein. 
     TECHNICAL FIELD 
     The disclosure relates to an action monitoring method and a system, and also relates to a swimming posture correction method and a swimming posture correction system. 
     BACKGROUND 
     Nowadays, cycling, running and swimming are popularized as sport participation is increased. In general, users typically exercise in their own habits or comfortable postures, but athletes or ordinary exercisers may require correct movements in order to improve their performance. In addition to relying on coaching, they can also utilize electronic equipment as the aid to monitor their movement postures. For example, a swimmer can use a swimming training watch available on the market. The training watch detects the swimmer&#39;s swimming posture through a gravity sensor (G-sensor) and coordinates with a swimming efficiency algorithm, such as SWOLF (Swim-Golf), to calculate the swimming efficiency of the swimmer. 
     Although the swimmer can know the stroke efficiency from the swimming efficiency value, it is impossible to know the posture error when the efficiency is found to be poor, so the posture correction cannot be performed. Incorrect swimming posture is the key to the inability to improve swimming speed, so it is necessary to provide appropriate stroke feedback to the swimmer to assist with posture correction. 
     SUMMARY 
     The embodiments of the disclosure provide a swimming posture correction method. A computing device corrects a swimming posture of a swimmer by using at least two gravity sensors (G-sensors), and the G-sensors are respectively disposed at ends of at least two limbs of the swimmer performing a relative stroke action. The method includes obtaining body parameters of the swimmer to capture a reference index of coordination for implementing a swimming posture suitable for the body parameters, monitoring the stroke action of the limbs by using the G-sensors to obtain a timing diagram of the limbs performing a stroke promotion action, analyzing the timing diagram to calculate the index of coordination of the swimmer, and comparing the calculated index of coordination with the reference index of coordination to prompt for correcting the swimming posture according to the comparison result. 
     The embodiments in the disclosure provide a swimming posture correction system including at least two G-sensors and a computing device, wherein the G-sensors are respectively disposed at end of at least two limbs of the swimmer performing the relative stroke action. The computing device is communicatively connected to the G-sensors for obtaining the body parameters of the swimmer to capture a reference index of coordination for implementing a swimming posture suitable for the body parameters. The G-sensors are used to monitor the stroke action of the limbs to obtain a timing diagram of the limbs performing the stroke promotion action, and then the timing diagram is analyzed to calculate the swimmer&#39;s index of coordination. The calculated index of coordination is compared with the reference index of coordination to prompt for correcting the swimming posture according to the comparison result. 
     Several exemplary embodiments accompanied with figures are described in detail below to further describe the disclosure in details. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram of a swimming posture correction system according to an embodiment of the disclosure. 
         FIG. 2  is a flow chart of a swimming posture correction method according to an embodiment of the disclosure. 
         FIG. 3  is a configuration diagram of a swimming posture correction system according to an embodiment of the disclosure. 
         FIG. 4  is a schematic diagram illustrating performing correction by a gravity sensor according to an embodiment of the disclosure. 
         FIG. 5A  is a schematic diagram illustrating a freestyle stroke action according to an embodiment of the disclosure. 
         FIG. 5B  to  FIG. 5D  are timing diagrams illustrating the stroke promotion action performed by a swimmer performing freestyle stroke action using both hands according to an embodiment of the disclosure. 
         FIG. 6  is a schematic diagram illustrating calculating an index of coordination according to an embodiment of the disclosure. 
         FIG. 7  is a flow chart of a swimming posture correction method according to an embodiment of the disclosure. 
         FIG. 8A  and  FIG. 8B  are schematic diagrams illustrating correction of water flow according to an embodiment of the disclosure. 
         FIG. 9  is a flow chart of a swimming posture correction method according to an embodiment of the disclosure. 
         FIG. 10  is a schematic diagram illustrating a body center axis of a swimmer according to an embodiment of the disclosure. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     In the embodiment of the disclosure, a gravity sensor (G-sensor) is disposed on the swimmer to monitor the stroke action (including the speed, distance, efficiency, etc.) of the swimmer, along with combination of computing methods such as establishing a stroke timing diagram, calculating an index of coordination, comparing with database and so on, it is possible to instantly detect the posture problem of the swimmer, and to prompt the swimmer to correct the swimming posture through a wearing device (e.g., headset, swimming goggles). The embodiment of the disclosure further utilizes flow sensing, detection of body center axis and so on to correct the index value suitable for the water zone with respect to the flow rate of the water zone where the swimmer is located, and to prompt the swimmer to correct the swimming posture according to the deviation of the swimmer&#39;s body center axis. 
       FIG. 1  is a block diagram of a swimming posture correction system according to an embodiment of the disclosure. Referring to  FIG. 1 , a swimming posture correction system  10  of the present embodiment includes a computing device  100  and at least two G-sensors (two G-sensors  112  and  114  are exemplified in the embodiment, but not limited thereto). In this embodiment, the G-sensors  112  and  114  are sensors independent of the computing device  100 , and are connected to a connection device  102  of the computing device  100  to transmit the detected data to the computing device  100 . This configuration allows the swimmer to dispose the G-sensors  112  and  114  flexibly with respect to the coordination of the limb portion to be monitored. For example, the G-sensors  112  and  114  may be disposed on the left and right wrists of the swimmer to monitor the coordination of both hands performing strokes, or the G-sensors  112  and  114  may be disposed on the left wrist and left ankle or right wrist and right ankle to monitor the coordination between the hand performing strokes and the leg performing kicks. 
     In other embodiments, one of the G-sensors  112  and  114  may also be directly disposed within the computing device  100  and integrated with the computing device  100  into a single device (e.g., integrated into a watch or bracelet). This configuration allows omission of additional computing device  100 , thereby preventing hindering the swimmer&#39;s body movement. The embodiments of the disclosure are not limited to the above configuration. 
     The G-sensors  112  and  114 , also known as accelerometers, acceleration sensors, etc., are devices for measuring acceleration, which can measure the acceleration of its own movement in the directions of three axes (X-axis, Y-axis, Z-axis). In other embodiments, the G-sensors  112  and  114  can also be used with a gyroscope to additionally measure the variation of roll, yaw and pitch. The above-described sensors or a combination thereof can assist in monitoring the swimming posture of the swimmer, and the embodiments of the disclosure provide no limitation to the types thereof. 
     The computing device  100  includes, for example, a connection device  102 , a prompt device  104 , and a processor  106 . The connection device  102  is, for example, a device supporting a wireless connection method, and may be a wireless fidelity (Wi-Fi) module, a radio frequency identification (RFID) module, a Bluetooth module, an infrared ray module, a near-field communication (NFC) module or a device-to-device (D2D) module, but not limited thereto. In other embodiments, the connection device  102  may also be a device that supports a wired connection method, but not limited thereto. 
     The prompt device  104  is, for example, a speaker, and can be used to play a voice prompt message such as a voice message, a prompt tone, and an alert tone. The prompt device  104  can also be a display such as a liquid-crystal display (LCD) or a light-emitting diode (LED) display, which can be integrated into swimming goggles or a watch worn by the swimmer, thus prompting the swimmer to correct the swimming posture through visible prompt messages such as a display sign, a graphic or text. In the present embodiment, the prompt device  104  is disposed in the computing device  100 . However, in other embodiments, the prompt device  104  may also be configured independently of the computing device  100  (e.g., configured in swimming goggles), and is connected with the connection device  102  of the computing device  100 , thereby receiving the control instruction of the computing device  100  to play or display the prompt message accordingly. 
     The processor  106  is, for example, a central processing unit (CPU), or other programmable general-purpose or special-purpose microprocessor, a digital signal processor (DSP), a programmable controller, application specific integrated circuits (ASIC) or other similar devices or a combination of these devices. In this embodiment, the processor  106  can load a computer program from a storage device (not shown) such as a memory or a hard drive to perform the swimming posture correction method in the embodiment of the disclosure. 
       FIG. 2  is a flow chart of a swimming posture correction method according to an embodiment of the disclosure. Referring to  FIG. 1  and  FIG. 2 , the method of the present embodiment is adaptable for the swimming posture correction system  10  of  FIG. 1 , and the swimming posture correction method in the disclosure is described in details below with reference to the actuation relationship between the devices in the swimming posture correction system  10 . 
     In step S 202 , the computing device  100  obtains at least one body parameter (e.g., arm length, leg length, etc.) of the swimmer through the processor  106  to capture a reference index of coordination for implementing a swimming posture suitable for the body parameter. In an embodiment, the processor  106  can receive the body parameters input by the swimmer by using an input device such as a button, a touch pad, a touch screen, or the like disposed on the computing device  100 . In other embodiments, the processor  106  can detect the body parameters (e.g., arm length, leg length, etc.) of the swimmer by using a sensor (e.g., G-sensors  112  and  114 ) disposed on the swimmer. Alternatively, the camera can be used to capture the body shape of the swimmer, and to identify the swimmer&#39;s body parameters by using an image identifying technology, or the body parameters of the swimmer can be obtained through any methods, the disclosure is not limited thereto. The above body parameters are, for example, height, weight, palm length, limb length or a combination thereof, but not limited thereto. 
     In addition, in an embodiment, the swimming posture correction system  100  further includes a remote server (not shown). The remote server is, for example, a cloud storage device or a cloud server which, for example, pre-measures the index of coordination under various conditions or a combination thereof with respect to different body shapes (e.g., height, weight), races, ages, swimming modes (e.g., competition, leisure, tutoring), swimming postures (e.g., freestyle, breaststroke, butterfly, backstroke) and so on to be used as reference index of coordination and centrally stored in the database of the remote server for the computing device  100  to make comparisons subsequently. In other embodiments, the database may also be established on the storage device of the computing device  100  itself, thus being accessed by the processor  106  at any time and applied to determining and prompting to correct swimming postures, the disclosure provides no limitation thereto. 
     In step S 204 , the processor  106  monitors the stroke action performed by the swimmer&#39;s limbs through the G-sensors  112  and  114 , thereby obtaining a timing diagram of the limbs performing the stroke promotion action. In an embodiment, the processor  106  uses the G-sensors disposed on the swimmer&#39;s left and right wrists to monitor the stroke actions performed by both hands of the swimmer when the swimmer swims freestyle or backstroke. In an embodiment, the processor  106  uses the G-sensors disposed on the left wrist and left ankle or the right wrist and right ankle of the swimmer to monitor the stroke action performed by the left wrist and left ankle or the right wrist and right ankle of the swimmer when the swimmer swims butterfly or breaststroke. 
     For example,  FIG. 3  is a configuration diagram of a swimming posture correction system according to an embodiment of the disclosure. Referring to  FIG. 1  and  FIG. 3 , the present embodiment shows that the G-sensors  112  and  114  of the swimming posture correction system  10  are respectively disposed on the left and right wrists of the swimmer  30 , and the computing device  100  is disposed on the chest of the swimmer  30 , such that the computing device  100  can monitor the stroke action performed by both hands of the swimmer  30  through the position variation of the left and right wrists detected by the G-sensor  112  and  114 . 
     In an embodiment, the computing device  100 , for example, corrects the position of the G-sensors  112  and  114  prior to monitoring the stroke action of the swimmer&#39;s limbs by using the G-sensors  112  and  114 . For example,  FIG. 4  is a schematic diagram illustrating performing correction by a G-sensor according to an embodiment of the disclosure. Referring to  FIG. 1  and  FIG. 4 , in the present embodiment, for example, the computing device  100  is disposed on the shoulder of the swimmer  40 , and G-sensors  112  and  114  are respectively disposed on the left wrist and the right wrist of the swimmer  40 . The computing device  100 , for example, is provided with a G-sensor (not shown). 
     In step S 402 , the processor  106  uses its own G-sensor as a reference point, prompting the swimmer  40  to lift his/her arm to the swimming forward direction (e.g., the X-axis direction in the figure) to perform an X-axis correction. In step S 404 , the processor  106  prompts the swimmer  40  to lift his/her arm to be right above (e.g., the Y-axis direction in the figure) the reference point to perform a Y-axis correction. In step S 406 , the processor  106  prompts the swimmer  40  to face the swimming forward direction, and his/her hands are opened to be parallel with the body (e.g., the Z-axis direction in the figure) to perform a Z-axis correction. It is assumed that during the above correction process, the position coordinates detected by the G-sensors of the computing device  100  are (X 0 , Y 0 , Z 0 ), the position coordinates detected by the G-sensor  112  are (X 1 , Y 1 , Z 1 ), the position coordinates detected by the G-sensor  114  are (X 2 , Y 2 , Z 2 ), and the position coordinates of the computing device  100  after correction are (0, 0, 0), the position coordinates detected by the G-sensor  112  are (X 1 -X 0 , Y 1 -Y 0 , Z 1 -Z 0 ), and the position coordinates detected by the G-sensor  114  are (X 2 -X 0 , Y 2 -Y 0 , Z 2 -Z 0 ). 
     By the above correction process, the processor  106  can complete the position correction between the computing device  100  and the g-sensors  112  and  114 , and even obtain the arm length of both hands of the swimmer  40 . The processor  106  stores, for example, the correction result in the storage device of the computing device  100  itself as a basis for subsequent correction of the swimming posture. 
     In the present embodiment, the processor  106  detects the position of various limbs by using the G-sensors  112  and  114 , and calculates the time at which the positions of various limbs are lower than the level surface (for instance, water surface) as the time of performing stroke promotion action. Then, the time and sequence of performing stroke promotion action by various limbs are used to establish the timing diagram of the stroke promotion action. 
     For example,  FIG. 5A  is a schematic diagram illustrating a freestyle stroke action according to an embodiment of the disclosure. Referring to  FIG. 5A , this embodiment divides the swimmer&#39;s freestyle actions into four stages: stage I is grabbing water; stage II is holding water; stage III is pushing water; and stage IV is resuming.  FIG. 5B  to  FIG. 5D  are timing diagrams illustrating the stroke promotion action performed by a swimmer performing freestyle stroke action using both hands according to an embodiment of the disclosure. The timing diagram of  FIG. 5B  shows that, after the swimmer completes the water pushing action with right hand (stage III), left hand continues to perform the water grabbing action (stage I), which means that the swimmer performs the stroke promotion actions smoothly one after another with both hands and the stroke efficiency is better. The timing diagram of  FIG. 5C  shows that, after the swimmer completes the water pushing action (stage III) with his/her right hand and before performing the water grabbing action (stage I) with his/her left hand, there is an interval of time length T g , which means that during the interval both of the swimmer&#39;s hands did not perform the stroke promotion action, thus affecting the stroke efficiency. The timing diagram of  FIG. 5D  shows that the swimmer&#39;s left hand performs the water grabbing action (stage I) before completing the water pushing action (stage III) with right hand, and there is an overlap of time length T o , which means that both of the swimmer&#39;s hands perform the stroke promotion action during the overlap, indicating that force is applied repeatedly and stroke efficiency is affected accordingly. 
     This embodiment is directed to the timing diagram described above. In step S 206 , the processor  106  analyzes the timing diagram to calculate the swimmer&#39;s index of coordination. The processor  106 , for example, calculates a time period in which each limb swings a complete circle, and calculates an interval time or an overlapping time (there is no interval time or overlapping time when the stroke promotion action of each limb is performed smoothly one after another) at which the limbs perform the stroke promotion actions respectively, thereby calculating the ratio of the interval time or overlapping time to the time period to be used as an index of coordination. 
     For example,  FIG. 6  is a schematic diagram illustrating calculating an index of coordination according to an embodiment of the disclosure. Referring to  FIG. 6 , in this embodiment, the computing device  100  receives the position coordinates returned by the G-sensors  112  and  114 , and uses the position of the computing device  100  itself as the reference point to calculate the relative position coordinates of the G-sensors  112  and  114  relative to the computing device  100 . The processor  106  of the computing device  100  can calculate the time period T in which the left hand and right hand swing a complete circle according to the variation of the relative position coordinates:
 
 T=Δt|   X≥0,θ     R     =0,Y=0   (1)
 
     Wherein X is the swimming forward direction, and θ R  is an included angle between the relative direction of the right wrist (i.e., G-sensor  114 ) relative to the computing device  100  and the X direction (i.e., the horizontal direction (Y=0)). At is the time required for the left wrist (or right wrist) to swing in a circle from the level surface (θ R =0, Y=0) ahead of the swimmer&#39;s head (X≥0) back to the level surface ahead of the swimmer&#39;s head in a clockwise direction or a counterclockwise direction (depending on the position of the observer). 
     On the other hand, the computing device  100  can calculate the time τ R,prop  for the right hand to perform the stroke promotion action:
 
τ R,prop   =Δt|   Δθ     R     =π,Y&lt;0   =t   2   −t   1   (2)
 
     As shown in the drawings, τ R,prop  represents the time at which the right wrist is below the level surface (Y=0), wherein t 1  represents the time at which the right wrist enters the water, t 2  represents the time at which the right wrist is lifted from the water. Similarly, the computing device  100  can calculate the time τ L,prop  at which the left hand performs the stroke promotion action. 
     Accordingly, the computing device  100  can calculate the reference index of coordination IdC through the following equation:
 
 IdC =(τ R,prop ∩τ L,prop )/ T   (3)
 
     Returning to the flowchart of  FIG. 2 , in step S 208 , the calculated index of coordination is compared with the reference index of coordination by the processor  106  to prompt for correcting the swimming posture according to the comparison result. The processor  106 , for example, calculates an error between the index of coordination and the reference index of coordination, and determines whether the error is greater than a preset value (for example, 5% of the reference index of coordination), so as to prompt for correcting the swimming posture when the error is greater than the preset value. In an embodiment, the processor  106 , for example, sends a control instruction to the prompt device  104 , thereby controlling the prompt device  104  to play or display a prompt message to prompt the user to correct the swimming posture. The prompt message includes a voice message, a prompt tone, an alert tone, a sign, a graphic or text, and the content thereof is, for example, prompting the user to speed up/slow down the stroke action performed by the left hand/right hand, but not limited thereto. 
     By the above method, the swimming posture correction system  10  in the embodiment of the disclosure can determine the error between the stroke action of the swimmer and the stroke action performed by the same group of swimmers by monitoring the stroke action performed by the swimmer, thereby instantly and properly prompting the swimmer to correct the swimming posture. 
     On the other hand, for the flow rate of the water zone in which the swimmer swims, an embodiment of the disclosure further includes providing a pressure sensor (not shown) on the portion (for example, the head or the shoulder) of the swimmer which does not perform the swimming action to detect the water resistance encountered by the swimmer, thereby updating the calculated index of coordination. 
       FIG. 7  is a flow chart of a swimming posture correction method according to an embodiment of the disclosure. Referring to  FIG. 1  and  FIG. 7 , the method of the present embodiment is, for example, performed subsequently after step S 206  of  FIG. 2 , thereby appropriately updating the index of coordination calculated in step S 206  according to the flow rate of the water flow. 
     In step S 702 , the computing device  100  detects the swimming speed of the swimmer by the processor  106  using the G-sensors  112  and  114 . The processor  106  can calculate the swimming speed v of the swimmer according to the variation of the position coordinates detected by the G-sensors  112  and  114  (wherein Δx is the moving distance of the swimmer, and t is the time spent on moving):
 
 v=Δx/t   (4)
 
     In step S 704 , the processor  106  uses the pressure sensor to detect the water resistance encountered by the swimmer. The processor  106  calculates the water resistance f d  according to the pressure value P detected by the pressure sensor and the cross-sectional area A of the pressure sensor:
 
 f   d   =P×A   (5)
 
     In step S 706 , the processor  106  incorporates the swimming speed v and the water resistance f d  calculated in the foregoing steps into the following fluid resistance equation (6), thereby calculating the flow rate ω of the water zone in which the swimmer swims: 
     
       
         
           
             
               
                 
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     Wherein F is the water resistance f d , ρ is the density of the fluid, and C d  is a constant. 
     For example,  FIG. 8A  and  FIG. 8B  are schematic diagrams illustrating correction of water flow according to an embodiment of the disclosure. Referring to  FIG. 8A , in the case of a forward flow (i.e., the swimmer&#39;s advancing direction is the same as the direction of the water flow), the swimmer will be subjected to a water resistance f d (v′) of which the speed is v′, wherein the speed v′=v−ω). The swimming speed v detected by the G-sensor and the water resistance f d (v′) detected by the pressure sensor are incorporated into the fluid resistance equation (6) to calculate the flow rate ω: 
     
       
         
           
             
               
                 
                   
                     
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     Referring to  FIG. 8B , in the case of a backward flow (i.e., the swimmer&#39;s advancing direction is opposite to the direction of the water flow), the swimmer will be subjected to a water resistance f d (v″) of which the speed is v″, wherein the speed v″=v+ω. The swimming speed v detected by the G-sensor and the water resistance f d (v″) detected by the pressure sensor are incorporated into the fluid resistance equation (6) to calculate the flow rate ω: 
     
       
         
           
             
               
                 
                   
                     
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     Returning to the flow chart of  FIG. 7 , in step S 708 , the processor  106  updates the previously calculated index of coordination according to the calculated flow rate. Specifically, in the case of forward flow, the processor  106 , for example, reduces the index of coordination; in the case of backward flow, the processor  106  increases the index of coordination. 
     In addition, for the swimming posture of the swimmer, an embodiment of the disclosure further includes providing a G-sensor on the swimmer&#39;s hands and feet to detect the horizontal axis of the body when the swimmer swims, thereby determining whether the swimming posture is correct according to the degree (angle) at which the body horizontal axis is deviated from the level surface to prompt for correction. 
       FIG. 9  is a flow chart of a swimming posture correction method according to an embodiment of the disclosure. Referring to  FIG. 1  and  FIG. 9 , in an embodiment, the method of the embodiment is applied, for example, in step S 208  of  FIG. 2 , before the processor  106  of the computing device  100  prompts the swimmer to correct the swimming posture by using the prompt device  114 , the degree at which the swimmer&#39;s body horizontal axis is deviated from the level surface is determined first, thereby prompting the swimmer to perform a corresponding posture correction. In other embodiments, the method of the present embodiment can be applied to any step in  FIG. 2  to prompt the swimmer to correct the swimming posture at any time, the disclosure provides no limitation thereto. 
     In step S 902 , the computing device  100  calculates the center point between shoulders and the center point between two feet by the processor  106  through the G-sensors disposed on the swimmer&#39;s shoulders and ankles, and uses the connecting line between the two points as the swimmer&#39;s body center axis vector. In an embodiment, the computing device  100  is disposed, for example, at a position of the swimmer&#39;s chest near the center point of the shoulders, such that the processor  106  can calculate the position coordinate of the center point of the shoulders through the G-sensor (not shown) disposed in the computing device  100 . In addition, the G-sensor is disposed, for example, on the left ankle or right ankle of the swimmer, such that the processor  106  can use the G-sensor to calculate the position coordinate of the center point of the two feet. Accordingly, the processor  106  can calculate the body center axis vector of the swimmer. 
     In step S 904 , the included angle between the body center axis vector and the level surface is calculated by the processor  106 , and in step S 906 , it is determined whether the calculated included angle is greater than a preset value. The preset value is, for example, any value between −30 degrees and 30 degrees, and the disclosure provides no limitation thereto. The included angle is a positive value (ideal value is, for example, less than 20 degrees) when the swimmer breathes, and is a negative value when the swimmer dives into the water. Generally, a larger included angle (−10 degrees to 20 degrees) is generated when the swimmer breathes. When the included angle is close to 0 degree, the resistance encountered by the swimmer will be reduced and the swimming speed of swimming will increase. Accordingly, the swimmer can adjust the preset value as needed to use the prompt of the computing device  100  to assist him/her in improving the swimming speed. 
     In step S 908 , when the processor  106  determines that the calculated included angle is greater than the preset value, it is determined that the inclination of the swimmer&#39;s body at this time will cause the stroke route to increase, and the resistance becomes larger, resulting in decrease of index of coordination. As a result, the prompt device  104  is controlled by prompt the user to correct the swimming posture. For example, the swimmer may be prompted to speed up the kicking speed or reduce the lifting force of the hands to stroke, so that the body can resume to the horizontal standard. 
     For example,  FIG. 10  is a schematic diagram illustrating a body center axis of a swimmer according to an embodiment of the disclosure. Referring to  FIG. 10 , in this embodiment, a G-sensor A is disposed on the shoulder of the swimmer, and a G-sensor B is disposed on the swimmer&#39;s ankle, such that the vector of the body center axis as well as an included angle θ between the body center axis vector and the horizontal vector H (for instance, level surface) can be calculated according to the position coordinates detected by the G-sensor A and the G-sensor B. By determining whether the calculated included angle θ exceeds the preset value (e.g., 15 degrees), and when it is determined that the included angle θ exceeds the preset value, the swimmer is prompted to correct the swimming posture. In this manner, it is possible to remind the swimmer to correct the posture instantly during the swimming process, thereby improving the swimming efficiency. 
     In summary, the swimming posture correction method and system of the embodiments of the disclosure monitor the coordination of the stroke action by configuring the G-sensor on the limbs of the swimmer performing stroke actions, by comparing with the data of the same group in the database, it is possible to instantly detect the posture problem of the swimmer and prompt the swimmer to correct the swimming posture. The method in the disclosure further combines the techniques of flow rate sensing and body center axis detection to assist the swimmer in properly performing posture correction with respect to the flow rate of the water zone where the swimmer is located and body inclination of the swimmer, thereby improving swimming efficiency. 
     It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the disclosed embodiments without departing from the scope or spirit of the disclosure. In view of the foregoing, it is intended that the disclosure cover modifications and variations of this disclosure provided they fall within the scope of the following claims and their equivalents.