Walking test U-turn detection method and device

Abstract

The invention discloses a walking test U-turn detection method and device. The detection method comprises the following steps: acquiring continuous n pieces of first direction angle data of a detected person under a direction meter coordinate system; calculating a first average direction angle, wherein the first average direction angle indicates an instantaneous direction angle of the tested person; whether the difference value between the first average direction angle and a preset reference direction angle is larger than a preset threshold value or not is judged; if yes, determining whether a U-turn action occurs or not, and accumulating the number of U-turn times; if not, the U-turn action does not occur. The U-turn detection provided by the invention does not need human participation, and is high in accuracy, low in complexity, good in performance and few in limiting conditions. The U-turn frequency can be recorded in real time, and the burden of operators is reduced; compared with the prior art, the detection efficiency is improved.

Description

Technical Field

[0001] The invention relates to the technical field of walking test detection, and in particular to a walking test U-turn detection method and device. Background Art

[0002] As a submaximal exercise test, the 6MWT can better replicate the patient's daily physiological state and is widely used in clinical practice to evaluate the patient's exercise capacity, the cardiac function of heart failure patients, the treatment effect and prognosis, etc. According to the American Thoracic Society's "Six-Minute Walk Test Guidelines" (ATS 2002), the test requires recording the number of times the patient walks back and forth on a fixed distance route, and the number of back and forth walks is used as a judgment indicator of the 6MWT.

[0003] The existing method of measuring the number of U-turns of the person to be tested usually adopts manual recording or positioning equipment to record. If the number of U-turns is recorded manually, it is necessary to manually edit the number of U-turns during the entire test cycle, which is time-consuming and labor-intensive. If the positioning equipment is used for recording, every time the fixed distance of the line is adjusted, the positioning signal transmitter needs to be re-arranged at the starting point and end point of the line, which is complicated and has low measurement efficiency.

[0004] Therefore, there is an urgent need for a U-turn detection method that can improve detection efficiency. Summary of the invention

[0005] The invention discloses a walking test U-turn detection method and device to solve the problem of low measurement efficiency in the prior art.

[0006] A first aspect of the present invention provides a walking test U-turn detection method, comprising: Obtaining n consecutive first direction angle data of the measured person in the direction meter coordinate system; Calculating a first average direction angle, wherein the first average direction angle indicates an instantaneous direction angle of the measured person; Determine whether the difference between the first average direction angle and a preset reference direction angle is greater than a preset threshold; If the difference between the average direction angle and the reference direction angle is greater than a preset threshold, it is determined that the person under test has made a U-turn, the number of U-turns is accumulated, and the operation of obtaining n consecutive first direction angle data of the person under test in the direction meter coordinate system is returned; If the difference between the average direction angle and the reference direction angle is not greater than a preset threshold, it is determined that the person being measured has not made a U-turn, and the process returns to executing the operation of obtaining n consecutive first direction angle data of the person being measured in the direction meter coordinate system until the walking test is completed.

[0007] Optionally, calculating a first average direction angle includes: According to the coordinate conversion relationship, the first direction angle data is converted into second direction angle data in the Mardia coordinate system; Calculate the sine mean of the second direction angle data according to the following formula and cosine mean : ; ; in, For the Second direction angle data; The second average direction angle of n second direction angle data is calculated according to the following formula : ; According to the coordinate conversion relationship, the second average direction angle is converted into a first average direction angle in the direction meter coordinate system.

[0008] Optionally, converting the first direction angle data into second direction angle data in a Mardia coordinate system according to a coordinate conversion relationship includes: Determine whether the first direction angle data is greater than 90°; If the first direction angle data is greater than 90°, it is converted according to the following formula: ; If the first direction angle data is not greater than 90°, it is converted according to the following formula: ; in, For the First direction angle data; for The corresponding second direction angle data.

[0009] Optionally, before obtaining n consecutive first direction angle data of the measured person in the direction meter coordinate system, the method further includes: Determine whether a U-turn action occurred in the previous U-turn detection result; If the result of the previous U-turn detection shows that no U-turn action has occurred, it is determined that the current reference direction angle is consistent with the reference direction angle in the previous U-turn detection; If the result of the previous U-turn detection shows that a U-turn action has occurred, the current reference direction angle is changed to the opposite direction of the reference direction angle in the previous U-turn detection.

[0010] Optionally, before obtaining n consecutive first direction angle data of the measured person in the direction meter coordinate system, the method further includes: Obtaining the position of the initial direction angle in the previous U-turn detection, wherein the initial direction angle is the first direction angle data in the first place; According to the preset data interval, the position of the initial direction angle in the current U-turn detection is determined.

[0011] Optionally, obtaining n consecutive first direction angle data of the measured person in the direction meter coordinate system includes: A multi-axis sensor carried by the measured person is used to obtain n consecutive first direction angle data of the measured person in the direction meter coordinate system.

[0012] Optionally, 1 / 5*f≤n<f; wherein f is the frequency of the multi-axis sensor, and the frequency indicates the number of the first direction angle data acquired by the multi-axis sensor in unit time.

[0013] A second aspect of the present invention provides a walking test U-turn detection device, comprising: A first acquisition module is used to acquire n consecutive first direction angle data of the measured person in the direction meter coordinate system; A calculation module, used to calculate a first average direction angle, where the first average direction angle indicates an instantaneous direction angle of the measured person; A first judging module, used to judge whether the difference between the first average direction angle and a preset reference direction angle is greater than a preset threshold; A first determination module is used to determine that the measured person has made a U-turn when the difference between the average direction angle and the reference direction angle is greater than a preset threshold, accumulate the number of U-turns, and return to execute an operation of obtaining n consecutive first direction angle data of the measured person in the direction meter coordinate system; The second determination module is used to determine that the person under test has not made a U-turn when the difference between the average direction angle and the reference direction angle is not greater than a preset threshold, and return to execute the operation of obtaining n consecutive first direction angle data of the person under test in the direction meter coordinate system until the walking test is completed.

[0014] Optionally, the calculation module includes: A first conversion unit, configured to convert the first direction angle data into second direction angle data in a Mardia coordinate system according to a coordinate conversion relationship; The first calculation unit is used to calculate the sine mean of the second direction angle data according to the following formula and cosine mean : ; ; in, For the Second direction angle data; The second calculation unit is used to calculate the second average direction angle of n second direction angle data according to the following formula : ; The second conversion unit is used to convert the second average direction angle into a first average direction angle in the direction meter coordinate system according to a coordinate conversion relationship.

[0015] Optionally, the first conversion unit includes: A judging subunit, used to judge whether the first direction angle data is greater than 90°; The first conversion subunit is used to convert the first direction angle data according to the following formula when the first direction angle data is greater than 90°: ; The second conversion subunit is used for performing conversion according to the following formula when the first direction angle data is not greater than 90°: ; in, For the First direction angle data; for The corresponding second direction angle data.

[0016] It can be seen from the above technical solutions that the present invention obtains the first direction angle data of the person being tested in the walking test, performs coordinate transformation and a series of calculations on the first direction angle data, obtains the first average direction angle, and determines whether a U-turn occurs based on the difference between the first average direction angle and the reference direction angle. The U-turn detection provided by the present invention does not require human participation, has high accuracy, low complexity, good performance, and few restrictions. It can be used to record the number of U-turns in real time and reduce the burden on operators; compared with the prior art, it improves detection efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A working flow chart of a walking test U-turn detection method provided by an embodiment of the present invention; Figure 2 A flowchart of determining a reference direction angle in a walking test U-turn detection method provided by an embodiment of the present invention; Figure 3 An example of a waveform of a difference between a first average direction angle and a reference direction angle and a U-turn detection result diagram provided by an embodiment of the present invention; Figure 4 A schematic structural diagram of a walking test U-turn detection device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] In the present invention, the device for detecting U-turns in walking tests mainly includes a motion sensor acquisition device and a host computer. In an achievable manner, the motion sensor acquisition device is a multi-axis sensor, which can be a 3-axis sensor, a 6-axis sensor, or a 9-axis sensor. A multi-axis sensor is added to the smart device worn by the person to be tested during the test, and the multi-axis sensor collects angular direction data. The host computer obtains and presents the collected angular direction data, and then calculates and records the number of U-turns through the detection method provided by the present invention.

[0020] After the test, the number of U-turns is used to calculate the number of steps in the walking test. If the location where the person being tested stops at the end of the walking test is exactly the starting point or the end point, the walking distance is the full circle distance, which is equal to m*L, where m is the number of U-turns and L is the one-way distance. If the person being tested stops halfway at the end of the walking test, the walking distance is the full circle distance plus the distance walked after the last U-turn.

[0021] refer to Figure 1 As shown in the work flow chart, the embodiment of the present invention provides a walking test U-turn detection method, comprising the following steps: S1. Obtain n consecutive first direction angle data of the measured person in the direction meter coordinate system.

[0022] In the walking test, the person being tested walks back and forth along a pre-set route, and usually, the route is a straight line. In the embodiment of the present invention, the north direction is taken as the positive direction, and the direction angle range of the person being tested is 0~360°. When the person being tested faces the end point at the starting point, the angle between the walking direction of the person being tested and the positive direction is recorded as the current direction angle (for example, if the walking direction coincides with the north direction, the current direction angle of the person being tested is 0°); when the person being tested returns from the end point to face the starting point, the angle between the walking direction of the person being tested and the positive direction is recorded as the reverse angle of the current direction angle (for example, if the walking direction is the south direction, it is recorded as 180°).

[0023] In the embodiment of the present invention, a multi-axis sensor carried by the measured person is used to obtain n consecutive first direction angle data of the measured person in the direction meter coordinate system.

[0024] In this step, 1 / 5*f≤n<f; wherein f is the frequency of the multi-axis sensor, and the frequency indicates the number of the first direction angle data acquired by the multi-axis sensor in a unit time. In the embodiment of the present invention, the unit time is 1S. For example, the frequency can be set to 100S -1 During calculation, the number of data taken is less than the frequency to ensure that the time window corresponding to the data taken is small enough. However, too little data will also affect the accuracy of the result. In another better embodiment, n is selected to be greater than or equal to 1 / 5 of the frequency.

[0025] In this step, before each new walking test U-turn detection is performed, the number of U-turns of the previous time is reset to zero, and then the number of U-turns detected is accumulated to obtain the number of U-turns.

[0026] In a new walking test, the multi-axis sensor continuously outputs directional angle data according to the set frequency. The host computer first determines whether the number of data output by the multi-axis sensor reaches n. If so, it starts the calculation process.

[0027] The present application embodiment is a continuous calculation process, and the data interval is pre-set. In order to reduce the number of calculations and obtain the calculation results in the shortest possible time, the data interval can also be set to n. For example, n is 50, that is, 50 data are set as a group. When the data interval is set to 50, if the first group of data is {x1, x2, ..., x 50}, then the second set of data is {x 51 ,x 12 ,…,x 100}. In order to reduce the error, the data interval is usually set to be smaller than n. For example, n is 50, and the data interval is set to 10. If the first set of data is {x1, x2, …, x 50}, then the second set of data is {x 11 ,x 12 ,…,x 60 The smaller the data interval is, the more accurate the test result is, but it also increases the amount of calculation, resulting in a delay in the calculation result. Therefore, in actual applications, it is sufficient to set an appropriate data interval according to the needs.

[0028] In order to obtain the initial direction angle corresponding to the current calculation process, the following steps need to be performed before each execution of S1: S111, obtaining the position of the initial direction angle in the previous U-turn detection, where the initial direction angle is the first direction angle data in the first place; S112: Determine the position of the initial direction angle in the current U-turn detection according to a preset data interval.

[0029] S2. Calculate a first average direction angle, where the first average direction angle indicates an instantaneous direction angle of the measured person.

[0030] In this step, in order to facilitate calculation, the compass coordinate system is converted into direction angle data in the Mardia coordinate system. The Mardia coordinate system uses points on a unit circle to represent angles.

[0031] In the embodiment of the present invention, calculating the first average direction angle includes the following steps: S210: Convert the first direction angle data into second direction angle data in a Mardia coordinate system according to a coordinate conversion relationship.

[0032] In this step, the coordinate transformation relationship is obtained through the principle of directional data science. In actual execution, the coordinate transformation is performed through the following steps: S211, determining whether the first direction angle data is greater than 90°; S212: If the first direction angle data is greater than 90°, convert according to the following formula: ; S213. If the first direction angle data is not greater than 90°, convert according to the following formula: ; in, For the First direction angle data; for The corresponding second direction angle data.

[0033] S220, calculating the sine mean of the second direction angle data according to the following formula and cosine mean : ; ; in, For the The second direction angle data.

[0034] S230, calculating the second average direction angle of n second direction angle data according to the following formula : .

[0035] In this step, after the calculation using the above formula is completed, in order to make The value ranges from 0 to 360 degrees, and it is also necessary to or The specific conversion method is as follows: First, determine Is it less than 0? Not less than 0, then is the calculated value using the above formula, if <0, Recorded as = +180°; then judge the processed Is it less than 0? If the processed is not less than 0, then the processed This is the second average direction angle finally obtained. If is still less than 0, then Recorded as = +360°; among which, is a calculated value obtained by using the second average direction angle formula in S230.

[0036] S240: Convert the second average direction angle into a first average direction angle in a direction meter coordinate system according to a coordinate conversion relationship.

[0037] The coordinate transformation relationship in S240 is consistent with the transformation relationship in S210. In S240, the second average direction angle is first determined. Is it greater than or equal to 90°? ≥90°, =450- ;if <90°, =90- ;in, is the first average direction angle.

[0038] S3, determining whether the difference between the first average direction angle and a preset reference direction angle is greater than a preset threshold; According to multiple test data, the threshold is set to 135°±5°. When the difference between the first average direction angle and the reference direction angle is greater than the preset threshold, it is considered that the person being measured has made a U-turn, and the operation of S4 is continued; when the difference between the first average direction angle and the reference direction angle is less than or equal to the preset threshold, it is considered that the person being measured has not made a U-turn, and the operation of S5 is continued.

[0039] When the host computer performs each calculation, it first needs to determine the reference direction angle. The reference direction angle is related to whether the person being measured has turned around. In one feasible method, refer to Figure 2 The workflow diagram shown in FIG. 1 further includes the following steps before S1 obtains n consecutive first direction angle data of the measured person in the direction meter coordinate system: S110, determining whether a U-turn action occurred in the previous U-turn detection result; S120, if the result of the previous U-turn detection shows that no U-turn action has occurred, determining that the current reference direction angle is consistent with the reference direction angle in the previous U-turn detection; S130: If the result of the previous U-turn detection shows that a U-turn has occurred, the current reference direction angle is changed to the opposite direction of the reference direction angle in the previous U-turn detection.

[0040] In the compass coordinate system, the range of the direction angle is 0~360°, so in this step, if ≥180°, and < 360°, the current reference direction angle = -180°; if <180°, and ≥ 0°, the current reference direction angle = +180°; It is the reference direction angle in the previous U-turn detection.

[0041] S4. If the difference between the average direction angle and the reference direction angle is greater than a preset threshold, it is determined that the measured person has made a U-turn, the number of U-turns is accumulated, and the operation of obtaining n consecutive first direction angle data of the measured person in the direction meter coordinate system is returned to execute.

[0042] S5. If the difference between the average direction angle and the reference direction angle is not greater than a preset threshold, it is determined that the person under test has not made a U-turn, and the process returns to executing the operation of obtaining n consecutive first direction angle data of the person under test in the direction meter coordinate system until the walking test is completed.

[0043] In this step, before returning to execute S1, a set of first direction angle data to be calculated is obtained according to a preset time interval. If the remaining data is less than n, the calculation is terminated and the number of U-turns is output.

[0044] Figure 3 The figure shows the waveform of the difference between the first average direction angle and the reference direction angle and the U-turn detection result diagram under fast and slow walking conditions. Figure 3 It can be seen that the detection method of the present invention can accurately detect the U-turn behavior and the number of U-turns under fast or slow walking conditions by associating the direction angle data with the point coordinates on the unit circle. Figure 3 It can be seen that under fast walking conditions, the number of U-turns detected is 5 times, and under slow walking conditions, the number of U-turns detected is 2 times. The above number of U-turns is only an example. In actual applications, the number of U-turns is related to the half-circle distance and the situation of the person being tested.

[0045] It can be seen from the above technical solutions that the embodiment of the present invention provides a walking test U-turn detection method, which does not require human participation, has high accuracy, low complexity, good performance, and few restrictions. It can be used to record the number of U-turns in real time and reduce the burden on operators; compared with the prior art, it improves the detection efficiency.

[0046] refer to Figure 4 As shown in the structural schematic diagram, another embodiment of the present invention provides a walking test U-turn detection device, comprising: The first acquisition module 100 is used to acquire n consecutive first direction angle data of the measured person in the direction meter coordinate system; A calculation module 200, configured to calculate a first average direction angle, wherein the first average direction angle indicates an instantaneous direction angle of the measured person; A first judging module 300 is used to judge whether the difference between the first average direction angle and a preset reference direction angle is greater than a preset threshold; A first determination module 400 is used to determine that the measured person has made a U-turn when the difference between the average direction angle and the reference direction angle is greater than a preset threshold, accumulate the number of U-turns, and return to execute an operation of obtaining n consecutive first direction angle data of the measured person in the direction meter coordinate system; The second determination module 500 is used to determine that the person under test has not made a U-turn when the difference between the average direction angle and the reference direction angle is not greater than a preset threshold, and return to execute the operation of obtaining n consecutive first direction angle data of the person under test in the direction meter coordinate system until the walking test is completed.

[0047] Optionally, the calculation module includes: A first conversion unit, configured to convert the first direction angle data into second direction angle data in a Mardia coordinate system according to a coordinate conversion relationship; The first calculation unit is used to calculate the sine mean of the second direction angle data according to the following formula and cosine mean : ; ; in, For the Second direction angle data; The second calculation unit is used to calculate the second average direction angle of n second direction angle data according to the following formula : ; The second conversion unit is used to convert the second average direction angle into a first average direction angle in the direction meter coordinate system according to a coordinate conversion relationship.

[0048] Optionally, the first conversion unit includes: A judging subunit, used to judge whether the first direction angle data is greater than 90°; The first conversion subunit is used to convert the first direction angle data according to the following formula when the first direction angle data is greater than 90°: ; The second conversion subunit is used for performing conversion according to the following formula when the first direction angle data is not greater than 90°: ; in, For the First direction angle data; for The corresponding second direction angle data.

[0049] Optionally, the device further comprises: A second judgment module, used for judging whether a U-turn action occurs in the previous U-turn detection result before the first judgment module; A third determination module is used to determine that the current reference direction angle is consistent with the reference direction angle in the previous U-turn detection when the previous U-turn detection result shows that no U-turn action has occurred; The fourth determination module is used to change the current reference direction angle to the opposite direction of the reference direction angle in the previous U-turn detection when the previous U-turn detection result shows that a U-turn action has occurred.

[0050] Optionally, the device further comprises: A second acquisition module is used to acquire the position of the initial direction angle in the previous U-turn detection before the first judgment module, wherein the initial direction angle is the first direction angle data in the first place; The fifth determination module is used to determine the position of the initial direction angle in the current U-turn detection according to a preset data interval.

[0051] The above are merely embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are included in the scope of the claims of the present invention to be approved.

Claims

1. A walking test U-turn detection method, characterized in that: include: Obtaining n consecutive first direction angle data of the measured person in the direction meter coordinate system; Calculating a first average direction angle, wherein the first average direction angle indicates an instantaneous direction angle of the measured person; Determine whether the difference between the first average direction angle and a preset reference direction angle is greater than a preset threshold; If the difference between the average direction angle and the reference direction angle is greater than a preset threshold, it is determined that the person under test has made a U-turn, the number of U-turns is accumulated, and the operation of obtaining n consecutive first direction angle data of the person under test in the direction meter coordinate system is returned; If the difference between the average direction angle and the reference direction angle is not greater than a preset threshold, it is determined that the person being measured has not made a U-turn, and the process returns to executing the operation of obtaining n consecutive first direction angle data of the person being measured in the direction meter coordinate system until the walking test is completed.

2. A walking test U-turn detection method according to claim 1, characterized in that: Calculate the first average direction angle, including: According to the coordinate conversion relationship, the first direction angle data is converted into second direction angle data in the Mardia coordinate system; Calculate the sine mean of the second direction angle data according to the following formula and cosine mean : ； ； in, For the Second direction angle data; The second average direction angle of n second direction angle data is calculated according to the following formula : ； According to the coordinate conversion relationship, the second average direction angle is converted into a first average direction angle in the direction meter coordinate system.

3. A walking test U-turn detection method according to claim 2, characterized in that: According to the coordinate conversion relationship, the first direction angle data is converted into second direction angle data in the Mardia coordinate system, including: Determine whether the first direction angle data is greater than 90°; If the first direction angle data is greater than 90°, it is converted according to the following formula: ； If the first direction angle data is not greater than 90°, it is converted according to the following formula: ； in, For the First direction angle data; for The corresponding second direction angle data.

4. A walking test U-turn detection method according to claim 1, characterized in that: Before obtaining the n consecutive first direction angle data of the measured person in the direction meter coordinate system, it also includes: Determine whether a U-turn action occurred in the previous U-turn detection result; If the result of the previous U-turn detection shows that no U-turn action has occurred, it is determined that the current reference direction angle is consistent with the reference direction angle in the previous U-turn detection; If the result of the previous U-turn detection shows that a U-turn action has occurred, the current reference direction angle is changed to the opposite direction of the reference direction angle in the previous U-turn detection.

5. The walking test U-turn detection method according to claim 1, characterized in that: Before obtaining the n consecutive first direction angle data of the measured person in the direction meter coordinate system, it also includes: Obtaining the position of the initial direction angle in the previous U-turn detection, wherein the initial direction angle is the first direction angle data in the first place; According to the preset data interval, the position of the initial direction angle in the current U-turn detection is determined.

6. The walking test U-turn detection method according to claim 1, characterized in that: Obtaining n consecutive first direction angle data of the person under test in the direction meter coordinate system, including: A multi-axis sensor carried by the measured person is used to obtain n consecutive first direction angle data of the measured person in the direction meter coordinate system.

7. A walking test U-turn detection method according to claim 6, characterized in that: 1 / 5*f≤n<f; Wherein, f is the frequency of the multi-axis sensor, and the frequency indicates the number of the first direction angle data acquired by the multi-axis sensor in unit time.

8. A walking test U-turn detection device, characterized in that: include: A first acquisition module is used to acquire n consecutive first direction angle data of the measured person in the direction meter coordinate system; A calculation module, used to calculate a first average direction angle, where the first average direction angle indicates an instantaneous direction angle of the measured person; A first judging module, used to judge whether the difference between the first average direction angle and a preset reference direction angle is greater than a preset threshold; A first determination module is used to determine that the measured person has made a U-turn when the difference between the average direction angle and the reference direction angle is greater than a preset threshold, accumulate the number of U-turns, and return to execute an operation of obtaining n consecutive first direction angle data of the measured person in the direction meter coordinate system; The second determination module is used to determine that the person under test has not made a U-turn when the difference between the average direction angle and the reference direction angle is not greater than a preset threshold, and return to execute the operation of obtaining n consecutive first direction angle data of the person under test in the direction meter coordinate system until the walking test is completed.

9. The walking test U-turn detection device according to claim 8, characterized in that: The calculation module comprises: A first conversion unit, configured to convert the first direction angle data into second direction angle data in a Mardia coordinate system according to a coordinate conversion relationship; The first calculation unit is used to calculate the sine mean of the second direction angle data according to the following formula and cosine mean : ； ； in, For the Second direction angle data; The second calculation unit is used to calculate the second average direction angle of n second direction angle data according to the following formula : ； The second conversion unit is used to convert the second average direction angle into a first average direction angle in the direction meter coordinate system according to a coordinate conversion relationship.

10. The walking test U-turn detection device according to claim 9, characterized in that: The first conversion unit comprises: A judging subunit, used to judge whether the first direction angle data is greater than 90°; The first conversion subunit is used to convert the first direction angle data according to the following formula when the first direction angle data is greater than 90°: ； The second conversion subunit is used for performing conversion according to the following formula when the first direction angle data is not greater than 90°: ； in, For the First direction angle data; for The corresponding second direction angle data.

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