A high-precision pedometer method and device based on a flexible pressure sensor

Abstract

The application discloses a high-precision step counting device based on a flexible pressure sensor, which comprises a shoe pad, flexible pressure sensors, a linear voltage conversion circuit, an analog-digital converter, an MCU and a mobile terminal. The shoe pad is provided with a plurality of flexible pressure sensors on the bottom side, which are used for collecting the pressure data of the sole during walking. The flexible pressure sensors are connected with the linear voltage conversion circuit, which is used for converting the resistance change of the flexible pressure sensor into voltage change. The linear voltage conversion circuit is connected with the analog-digital converter, which is used for converting the voltage signal output by the linear voltage conversion circuit into a digital signal. The analog-digital converter is connected with the MCU, which is used for carrying out median filtering on the digital signal to obtain filtered pressure data. The MCU is connected with the mobile terminal, which is used for converting the filtered pressure data into the number of steps through the mobile terminal and displaying the number of steps. The device can accurately judge the movement state of the left and right feet and calculate the step frequency, and can also be used for analyzing the stress distribution of the foot sole, and then high-precision step counting is carried out.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of motion analysis, in particular to a high-precision step counting method and device based on a flexible pressure sensor. BACKGROUND

[0002] In recent years, people have higher and higher demands for health, and various sports software and sports devices have the function of counting steps. However, whether it is sports software or sports devices, they generally achieve the function of counting steps through a three-axis acceleration sensor and a corresponding algorithm. Although this implementation method is relatively common, it still affects the accuracy of the step count due to different human movements. Secondly, the premise for such sports devices to accurately record the movement state is that the user must correctly wear the sports device before movement, otherwise it is easy to cause recording errors. This feature reduces the convenience of use to some extent. Therefore, it is very important to design a high-precision step counting method and device that is convenient to use. SUMMARY

[0003] The present application proposes a high-precision step counting method based on a flexible pressure sensor and its application, which can accurately determine the movement state of the left and right feet and calculate the step frequency, and can also be used to analyze the stress distribution of the foot.

[0004] To solve the above technical problems, the technical scheme of the present application is as follows:

[0005] A high-precision step counting device based on a flexible pressure sensor, comprising an insole, a flexible pressure sensor, a linear voltage conversion circuit, an analog-to-digital converter, an MCU, and a mobile terminal,

[0006] The insole bottom side is provided with a plurality of flexible pressure sensors for collecting foot pressure data during walking;

[0007] The flexible pressure sensor is connected with the linear voltage conversion circuit for converting the resistance change of the flexible pressure sensor into voltage change;

[0008] The linear voltage conversion circuit is connected with the analog-to-digital converter for converting the voltage signal output by the linear voltage conversion circuit into a digital signal;

[0009] The analog-to-digital converter is connected with the MCU for median filtering the digital signal to obtain filtered pressure data;

[0010] The MCU is connected with the mobile terminal for converting the filtered pressure data into step count through the mobile terminal and displaying.

[0011] As preferred, the bottom side of the insole is provided with 4 flexible pressure sensors, two of which are arranged in the forefoot region, and the other two are arranged in the lateral region and the heel region respectively.

[0012] As preferred, the MCU and the mobile terminal transmit data through a wireless transmission system, which is used to pack the filtered pressure data in JSON format, and then publish the packed data to the cloud through the WIFI module, and the mobile terminal can obtain the data in the cloud through the subscription mode by means of the cloud message flow function.

[0013] The application further discloses a high-precision step counting method based on the flexible pressure sensor.

[0014] S1, data acquisition

[0015] The pressure data collected by the high-precision step counting device based on the flexible pressure sensor are applied.

[0016] S2, the data are analyzed, and then the pressure data of four points on each foot are obtained, the pressure data of the left foot are saved by variables L1, L2, L3 and L4 respectively, and the pressure data of the right foot are saved by variables R1, R2, R3 and R4 respectively.

[0017] S3, the left and right foot pressure data of the user in the normal standing condition are obtained by the high-precision step counting device based on the flexible pressure sensor.

[0018] S4, the initial average values PTL=(L1+L2+L3+L4) / 4 and PTR=(R1+R2+R3+R4) / 4 of the data of four points of the left foot and the right foot are calculated respectively, the initial values are saved and named as user 1, and PTL and PTR are set as the left and right foot pressure thresholds of the user.

[0019] S5, the step counting variables Count_left and Count_right are set respectively to save the step counts of the left and right feet, when the user is in motion, if the average pressure of the left foot is greater than the foot pressure threshold PTL, the left foot step counting variable Count_left is increased by 1, and if the average pressure of the right foot is greater than the foot pressure threshold PTR, the right foot step counting variable Count_right is increased by 1.

[0020] As preferred, the threshold determination algorithm adjustment step S6 is further included.

[0021] Set a lag variable Value initial value is set to 0, such as detecting the average pressure of a foot is greater than the foot pressure threshold, then let the lag variable Value increase 1, when the lag variable Value is greater than 3, then make the step variable Count increase 1, and the lag variable Value is assigned to 0.

[0022] The present application has the following characteristics and beneficial effects:

[0023] The flexible pressure sensor with fast response time, high sensitivity and strong recovery ability is combined with the insole, the data of the flexible pressure sensor is collected by the controller unit (MCU), the sensing data is uploaded to the mobile terminal by the wireless transmission module, and the step counting is realized by the corresponding software algorithm, and then high-precision step counting is realized.

[0024] The motion state of the left and right feet can be accurately judged and the step frequency can be calculated, and the force distribution of the foot can also be analyzed. The flexible pressure sensor is combined with the insole, the pressure data collected by the flexible pressure sensor is processed by the MCU, and the pressure data is uploaded to the mobile terminal by the wireless transmission mode, and the step counting is realized by the corresponding software algorithm. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0026] Figure 1 The structure diagram of the flexible pressure sensor combined with the insole in the embodiment of the present application;

[0027] Figure 2 The principle diagram of the data acquisition system in the embodiment of the present application;

[0028] Figure 3 The principle diagram of the wireless transmission system in the embodiment of the present application;

[0029] Figure 4 The step counting display interface of the mobile terminal in the embodiment of the present application.

[0030] Figure 5 The average force waveform diagram of the two feet during exercise in the embodiment of the present application;

[0031] Figure 6 The force distribution diagram of a single foot (left foot) during walking in the embodiment of the present application. DETAILED DESCRIPTION

[0032] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0033] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element indicated must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second" and the like are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" and the like can explicitly or implicitly include one or more of the features. In the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0034] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through intermediate medium, or it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood through specific circumstances.

[0035] The present application provides a high-precision pedometer device based on a flexible pressure sensor, as shown in Figures 1-3 The present application provides a high-precision pedometer device based on a flexible pressure sensor, as shown in

[0036] The insole bottom side is provided with a plurality of flexible pressure sensors for collecting foot pressure data during walking. In this embodiment, a flexible pressure sensor is applied, which is combined with the insole. This flexible pressure sensor has fast response time, high sensitivity and strong recovery ability.

[0037] The flexible pressure sensor is connected with the linear voltage conversion circuit, which is used to convert the resistance change of the flexible pressure sensor into voltage change.

[0038] The linear voltage conversion circuit is connected with the analog-to-digital converter, which is used to convert the voltage signal output by the linear voltage conversion circuit into a digital signal.

[0039] The flexible pressure sensor selected by the design is a piezoresistive sensor, so it is necessary to convert the resistance change of the sensor into voltage change by means of a linear voltage conversion circuit, and then convert the voltage signal into a digital signal by means of an analog-to-digital converter (ADC).

[0040] The analog-to-digital converter is connected with the MCU, and is used for median filtering the digital signal to obtain filtered pressure data; the MCU performs median filtering on the first acquired pressure data to eliminate the pulse noise caused by the sensor, and then obtains the filtered pressure data.

[0041] The MCU is connected with the mobile terminal, and is used for converting the filtered pressure data into steps through the mobile terminal and displaying.

[0042] Specifically, as shown in Figure 1 and Figure 4 The bottom side of the insole is provided with four flexible pressure sensors, two of which are arranged in the forefoot area, and the other two are arranged in the lateral area and the heel area respectively.

[0043] Further, the MCU and the mobile terminal transmit data through a wireless transmission system, and the wireless transmission system is used for data packaging in JSON format, and then publishes the packaged data to the cloud through the WIFI module, and through the function of cloud message flow transfer, the mobile terminal can obtain the data of the cloud through the subscription mode.

[0044] The embodiment also provides a high-precision step counting method based on a flexible pressure sensor. Based on the pressure data collected by the step counting device, the mobile terminal first analyzes the data and then obtains the pressure data of four points on each foot. The pressure data of the left foot are saved by variables L1, L2, L3 and L4 respectively, and the pressure data of the right foot are saved by variables R1, R2, R3 and R4 respectively. Then the user obtains the pressure data of the left and right feet in the normal standing state, and then calculates the initial average values PTL=(L1+L2+L3+L4) / 4 and PTR=(R1+R2+R3+R4) / 4 of the four points of the left and right feet respectively, and saves the initial values as user 1. Then PTL and PTR are set as the left and right foot pressure thresholds of the user. Then the step counting variables Count_left and Count_right are set to save the number of steps of the left and right feet respectively. When the user is moving, if the average pressure of the left foot is greater than the foot pressure threshold PTL, the left foot step counting variable Count_left is increased by 1. Similarly, if the average pressure of the right foot is greater than the foot pressure threshold PTR, the right foot step counting variable Count_right is increased by 1. However, this method has certain disadvantages, that is, when the user does not step down, the pressure generated by the sole on the insole may exceed the threshold pressure due to the movement of the sole, thereby causing misjudgment of the step counting variable. Therefore, the threshold judgment algorithm needs to be further improved: first, set a lag variable Value with an initial value of 0. If the average pressure of a foot is greater than the foot pressure threshold, the lag variable Value is increased by 1. When the lag variable Value is greater than 3, the step counting variable Count is increased by 1, and the lag variable Value is assigned a value of 0. Because the highest transmission rate of the wireless transmission module is as high as 72.2 Mbps, this algorithm does not reduce the real-time performance of step counting, and therefore the accuracy of step counting can be further improved by this method. As known from the above, the change of the step counting variable of the design depends entirely on the number of times the user walks, because the left and right foot pressure thresholds PTL and PTR are obtained in the normal standing state. Only when the user is moving, the gravity will concentrate on a foot, and then the pressure of the foot will be greater than the pressure threshold. In addition, the corresponding software algorithm is added to reduce the misjudgment of the system when obtaining the number of steps, which makes the number of steps obtained by the design achieve very high accuracy.

[0045] It can be understood that, Figure 4 , Figure 5 and Figure 6As shown, under the premise of obtaining high-precision motion counting, the design also proposes several additional functions. First, accurate calculation of step frequency, because the high-precision step count is obtained, then only need to divide the step count by the cumulative motion time to obtain high-precision step frequency data. Second, gait analysis: the foregoing describes the structure diagram of the flexible pressure sensor and the insole, and it is this reasonable structure that enables the collected pressure data to well analyze the force distribution of the sole of each foot during movement and the force center of gravity of each foot. In addition, comparing the average pressure data obtained by the left / right foot with the pressure threshold value thereof can also accurately determine whether each foot is lifted or stepped down.

[0046] The embodiments of the present application are described in detail above with reference to the drawings, but the present application is not limited to the described embodiments. For those skilled in the art, various changes, modifications, replacements and variations of the embodiments including components are made without departing from the principles and spirits of the present application, and still fall within the protection scope of the present application.

Claims

1. A high-precision step counting method based on a flexible pressure sensor, characterized in that, Includes the following steps: S1. Data Acquisition: Apply pressure data collected by a high-precision pedometer based on a flexible pressure sensor; The high-precision pedometer based on a flexible pressure sensor includes an insole, a flexible pressure sensor, a linear voltage conversion circuit, an analog-to-digital converter, an MCU, and a mobile terminal. The insole is equipped with several flexible pressure sensors on the bottom side to collect pressure data of the sole of the foot during walking; The flexible pressure sensor is connected to a linear voltage conversion circuit to convert the resistance change of the flexible pressure sensor into a voltage change. The linear voltage conversion circuit is connected to the analog-to-digital converter and is used to convert the voltage signal output by the linear voltage conversion circuit into a digital signal. The analog-to-digital converter is connected to the MCU and is used to perform median filtering on the digital signal to obtain filtered pressure data. The MCU is connected to the mobile terminal and is used to convert the filtered pressure data into a number of steps and display it through the mobile terminal; The insole has four flexible pressure sensors on its bottom side, two of which are located in the forefoot area, and the other two are located in the outer side area and the heel area, respectively. S2. Analyze the data to obtain the pressure data of four points on each foot. The pressure data of the left foot is stored in variables L1, L2, L3, and L4, and the pressure data of the right foot is stored in variables R1, R2, R3, and R4. S3. Obtain pressure data of the user's left and right feet when standing normally using a high-precision pedometer device based on a flexible pressure sensor; S4. Calculate the initial average values ​​PTL = (L1+L2+L3+L4) / 4 and PTR = (R1+R2+R3+R4) / 4 for the data of the four points of the left and right feet respectively, and save the initial average values ​​as User 1. Set PTL and PTR as the pressure threshold of the left and right feet of this user, and name them Pressure Threshold PTL and Pressure Threshold PTR respectively. S5. Set up step counting variables Count_left and Count_right to store the step count of the left and right feet separately. When the user is exercising, if the average pressure of the left foot is detected to be greater than the left foot pressure threshold PTL, the left foot step counting variable Count_left will be increased by 1. Similarly, if the average pressure of the right foot is detected to be greater than the right foot pressure threshold PTR, the right foot step counting variable Count_right will be increased by 1. S6. Threshold determination algorithm adjustment: Set a hysteresis variable Value with an initial value of 0. If the average pressure of a foot is detected to be greater than the pressure threshold of that foot, the hysteresis variable Value is increased by 1. When the hysteresis variable Value is greater than 3, the step count variable Count is increased by 1, and the hysteresis variable Value is assigned a value of 0.

2. The high-precision step counting method based on a flexible pressure sensor according to claim 1, characterized in that, The MCU and the mobile terminal transmit data via a wireless transmission system. The wireless transmission system is used to package the filtered pressure data in JSON format, and then publish the packaged data to the cloud via the WIFI module. With the help of the cloud message flow function, the mobile terminal can obtain the data from the cloud by subscription.

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