JP5032875B2 - Pedometer - Google Patents

Description

  The present invention relates to a pedometer.

As a conventional pedometer, there is one that counts the number of steps of a wearer by detecting a peak of acceleration (a point at which the inclination of acceleration changes from positive to negative) that is worn on the body or the like and measured by an acceleration sensor. As an example of such a pedometer, Patent Document 1 discloses a technique in which the direction dependency of detection sensitivity is improved by detecting the gravitational acceleration direction based on the output value of the triaxial acceleration sensor.
Japanese Patent Laying-Open No. 2005-157465 (paragraphs 0011 to 0030 and FIG. 1)

  However, since the conventional pedometer includes an offset in the output of the acceleration sensor, there is a problem that the influence of the offset is large in counting the number of steps.

  The present invention has been made in view of the above points, and an object thereof is a pedometer capable of increasing the value of data used for step count counting while reducing the influence of offset included in the output of the acceleration sensor. Is to provide.

According to a first aspect of the present invention, an acceleration sensor, difference calculation means for calculating an absolute value of a difference between the output of the acceleration sensor and the output of the acceleration sensor a predetermined time ago, and the number of steps using the absolute value of the difference are calculated. and a step counting means for counting said predetermined time is the time zone of the past within a predetermined range, said difference calculating means, the absolute value of the difference between the output at each time of the time zone and an output of the acceleration sensor Is calculated, the maximum value of the absolute value of the difference is extracted, and the step counting means counts the number of steps using the maximum value of the absolute value of the difference.

The invention of claim 2 is the invention of claim 1 , further comprising an activity amount calculating means for calculating an activity amount using the output of the acceleration sensor, wherein the step number coefficient section has a plurality of steps according to the size of the activity amount. The walking form is distinguished, and the number of steps is counted for each walking form.

  According to the first aspect of the present invention, the absolute value of the difference from the output before a certain time is calculated, thereby reducing the influence of the offset included in the output of the acceleration sensor and increasing the value of the data used for step count counting. can do.

Further, according to the invention of claim 1, by calculating the maximum value of the absolute value of the difference between the output of each time time zone of a range, while reducing the influence of the offset included in the output of the acceleration sensor The value of data used for counting the number of steps can be further increased.

According to invention of Claim 2 , a walk form can be distinguished according to the magnitude | size of activity amount, and the step count can be counted for every walk form.

(Embodiment 1)
The configuration of the first embodiment will be described with reference to FIGS. As shown in FIG. 1, the pedometer of the present embodiment includes an acceleration sensor 1, an operation input unit 2 having a push button 20 (see FIG. 2) for a user to start / stop device operation, a memory, 3, a timer 4, a display unit 5 for displaying the number of steps and the amount of activity, and the center of the device, input processing of acceleration measured by the acceleration sensor 1, operation information from the operation input unit 2 Power is supplied to each of the units 1 to 6 by an arithmetic unit 6 that performs input processing, information reading / writing processing to the memory 3, startup processing of the timer 4, and display processing on the display unit 5, and a primary battery (for example, a button battery or a coin battery). And a synthetic resin casing 8 (see FIG. 2) that incorporates each of the parts 1 to 7 and exposes the push button 20 to the front surface.

  The acceleration sensor 1 is a three-axis acceleration sensor using a small and low power consumption MEMS (Micro Electro Mechanical Systems), and each acceleration X, Y, Z is measured, and the measured accelerations X, Y, and Z are output to the calculation unit 6 in analog form. The acceleration sensor 1 is not limited to a three-axis acceleration sensor, and may be a one-axis acceleration sensor or a two-axis acceleration sensor.

  The memory 3 stores information on a threshold value L1 described later, activity amount information, and step count information described later, which are set in advance at the time of manufacturing the device or starting the device operation.

  As shown in FIG. 2, the display unit 5 includes a liquid crystal screen 50 exposed on the front surface of the housing 8, and is input when step information and activity amount information described later are input from the calculation unit 6 (see FIG. 1). The number of steps and the amount of activity are displayed on the liquid crystal screen 50 based on the information.

  The arithmetic unit 6 shown in FIG. 1 is composed of a microcomputer. The sampling unit 60 obtains and samples the accelerations X, Y, and Z from the acceleration sensor 1, and the accelerations Xn, Yn, and Zn sampled by the sampling unit 60. Calculating the differences ΔX, ΔY, ΔZ, calculating the acceleration F1 that is the combined value of the differences ΔX, ΔY, ΔZ, and the amount of activity based on the acceleration F1 calculated by the acceleration calculating unit 61 An activity amount calculating unit 62, a step count counting unit 63 that counts the number of times that the acceleration F1 calculated by the acceleration calculating unit 61 exceeds the threshold L1, a display control unit 64 that controls the display unit 5, and an operation input unit 2 and an operation processing unit 65 for processing operation information from 2.

  When each acceleration X, Y, Z is input from the acceleration sensor 1 as an analog signal, the sampling unit 60 samples each analog input acceleration X, Y, Z at a preset sampling frequency such as 10 Hz or more, Each sampled acceleration is output to the acceleration calculation unit 61. Hereinafter, each acceleration sampled n times from the start of sampling is represented by Xn, Yn, Zn (n = 1, 2, 3,...).

  Here, in consideration of the offset of the acceleration sensor 1, each acceleration Xn, Yn, Zn sampled at the nth time can be expressed by the following equation. In the following equation, Xgn, Ygn, and Zgn are true acceleration components on each axis, and Xoffn, Yoffn, and Zoffn are offsets on each axis.

  The acceleration calculation unit 61 includes the accelerations Xn, Yn, and Zn currently sampled (n-th) by the sampling unit 60 and a predetermined past time zone (for example, 0.5 seconds to 0.2 seconds before). .DELTA.X (= Xn-Xn-i), .DELTA.Y (= Yn-Yn-i), differences from the respective accelerations Xn-i, Yn-i, Zn-i sampled at each time of ΔZ (= Zn−Zn−i) is calculated, and the accelerations F1 are calculated using the calculated differences ΔX, ΔY, and ΔZ as shown in the following equations. Here, the fixed time zone is preferably a time zone including a half cycle of each acceleration X, Y, Z so that the differences ΔX, ΔY, ΔZ are as large as possible.

ΔX ² , ΔY ² , ΔZ ² can be expressed by the following equations.

  Here, the offset of the acceleration sensor 1 has power supply voltage dependency, temperature dependency, and the like, but most of them change relatively slowly and do not change greatly in a short time. Therefore, if the sampling interval is short such as a sampling frequency of 10 Hz or more, the offsets can be regarded as almost equal. Therefore, the acceleration F1 can be expressed by the following equation from Equation 2.

  A maximum value is obtained from the plurality of calculated accelerations F1, and this maximum value is set as a corrected acceleration F. FIG. 3 shows the corrected acceleration F (A in FIG. 3). As a comparison, a combined value F2 (Equation 5) of each acceleration Xn, Yn, Zn is also shown (B in FIG. 3). According to FIG. 3, since the offset is removed from the corrected acceleration F, the absolute value is smaller than the combined value F2. However, since the change in the corrected acceleration F is as large as the composite value F2, it is sufficient for the step counting unit 63 described later to count the number of steps.

  As is apparent from the above equation, offsets Xoffn, Yoffn, Zoffn, Xoffn-1, Yoffn-1, and Zoffn-1 in each axis can be removed from the acceleration F1. The accelerations Xn, Yn, Zn and accelerations Xn-i, Yn-i, and Zn-i each contain a gravitational acceleration component, but if the sampling frequency is short such as a sampling frequency of 10 Hz or more, Since the gravitational acceleration component can be regarded as substantially equal, the gravitational acceleration component can be removed from the acceleration F1. As a result, the number of steps can be accurately counted regardless of the direction of the pedometer, and the change in detection sensitivity due to the direction of the acceleration sensor 1 can be reduced.

The activity amount calculation unit 62 calculates the sample variance σ ² from the following equation using the acceleration F1 from the acceleration calculation unit 61 at regular intervals, and calculates the activity amount based on the sample variance σ ² . The calculated activity amount information (activity amount information) is output to the display control unit 64 and stored in the memory 3.

  The step counting unit 63 compares the corrected acceleration F from the acceleration calculating unit 61 with the threshold value L1 stored in the memory 3, and detects the peak of the corrected acceleration F when the corrected acceleration F exceeds the threshold value L1. Then, the number of steps is incremented (increased by 1). Here, the peak of the corrected acceleration F refers to a point where the inclination of the corrected acceleration F changes from positive to negative. On the other hand, if the corrected acceleration F is equal to or less than the threshold value L1, the number of steps is not incremented. By providing the threshold value L1 in this way, it is possible to prevent a peak generated due to body movement or noise other than walking from being counted as the number of steps.

  By the way, the step counting unit 63 distinguishes a plurality of walking forms according to the magnitude of the activity amount measured by the activity amount calculating unit 62, and counts the number of steps for each walking form. Examples of walking modes include “loose walking”, “quick walking”, and “running”. If the amount of activity is less than 2.5Mets, count the number of steps as the walking form “loose walking”, and if the amount of activity is 2.5Mets or more and less than 6Mets, count the number of steps as the walking form “kibiki walking”, If the amount of activity is 6Mets or more, the number of steps as the walking form “running” is counted. Information on the number of steps counted for each walking mode (step count information) is output to the display control unit 64 and stored in the memory 3.

  Based on the activity amount information from the activity amount calculation unit 62 and the step number information for each walking mode from the step number counting unit 63, the display control unit 64 displays the activity amount and the number of steps for each walking mode on the liquid crystal screen 50 (see FIG. 2). The display unit 5 is controlled to display.

  The operation processing unit 65 starts / stops the operation of the device, resets the accumulated total number of steps, displays the number of steps from the start of the step counting to the present time, and stores the accumulated number according to the operation input by the user through the operation input unit 2. It is configured to perform operations required as a pedometer, such as displaying the total number of steps and displaying the amount of activity.

  As described above, according to the present embodiment, by calculating the maximum value of the absolute values of the differences ΔX, ΔY, ΔZ from the accelerations Xn-i, Yn-i, Zn-i in each time in a certain range of time zone, The value of data used for counting the number of steps can be increased while reducing the influence of the offset included in the output of the acceleration sensor 1. Moreover, a walk form can be distinguished according to the magnitude | size of activity amount, and the number of steps can be counted for every walk form.

As a modification of the first embodiment, the acceleration F1 is expressed by Equation 2, but considering the ease of calculation, F1 = ΔX ² + ΔY ² + ΔZ ² may be used without performing route calculation.

  As another modification of the present embodiment, the acceleration calculation unit 61 may calculate the acceleration F3n from the accelerations Xn, Yn, and Zn sampled by the sampling unit 60 as in the following equation.

  Then, the acceleration calculation unit 61 calculates the difference from the acceleration F3n and each acceleration F3n-i in the past fixed time period (for example, 0.5 seconds before to 0.2 seconds before) as shown in the following equation. F4 is calculated.

  Here, considering the offset of the acceleration sensor 1, the accelerations Xn, Yn, Zn acquired at the nth time and the accelerations Xn-i, Yn-i, Zn-i acquired at the nith time are expressed by the following equation (1). be able to.

  Therefore, F4x, F4y, and F4z, which are X, Y, and Z terms in the difference F4, can be expressed by the following equations.

  Here, since the offset of the acceleration sensor 1 can be regarded as almost equal (Xoffn≈Xoffn-i) if the sampling interval is short such as a sampling period of 10 Hz or more, F4x, F4y, and F4z are expressed by the following equations. It can be expressed as

  Therefore, in the case of this modification, the terms Xoffn, Yoffn, and Zoffn remain, and unlike the first embodiment, the offsets Xoffn, Yoffn, Zoffn, Xoffn-1, Yoffn-1, and Zoffn-1 of the acceleration sensor 1 are all removed. Although it is not possible to remove all the square terms of the offset, the influence of the offset can be reduced as compared with the conventional pedometer.

(Embodiment 2)
In the pedometer of the present embodiment, the acceleration calculation unit 61 has a difference between each acceleration Xn, Yn, Zn of the acceleration sensor 1 and each acceleration Xn-i, Yn-i, Zn-i before a predetermined time. The absolute value of ΔX, ΔY, ΔZ is calculated, and the step count counting unit 63 is different from the first embodiment in that the step count is counted using the calculated absolute value of the difference ΔX, ΔY, ΔZ. In addition, about the component similar to Embodiment 1, the same code | symbol is attached | subjected and description is abbreviate | omitted.

The acceleration calculation unit 61 according to the present embodiment is not limited to the accelerations Xn, Yn, and Zn currently sampled (n-th time) by the sampling unit 60 and each time in the past fixed time zone (for example, 0. 0). Differences .DELTA.X, .DELTA.Y, .DELTA.Z from the respective accelerations Xn-i, Yn-i, Zn-i sampled 5 seconds before, etc. are calculated, and the calculated differences .DELTA.X, .DELTA.Y, .DELTA.Z and equations 1 to 3 are calculated. Is used to calculate the acceleration F1 as shown in Equation 4. In the present embodiment, the calculated acceleration F1 is used as the corrected acceleration F as it is. Here, it is preferable that the certain time is about a half cycle of each acceleration X, Y, Z so that the differences ΔX, ΔY, ΔZ are as large as possible.

  The step counting unit 63 of the present embodiment compares the corrected acceleration F with the threshold value L1 stored in the memory 3, and detects the peak of the corrected acceleration F when the corrected acceleration F exceeds the threshold value L1. The number of steps is incremented (increased by 1), and if the corrected acceleration F is equal to or less than the threshold value L1, the number of steps is not incremented.

  As described above, according to the present embodiment, by calculating the absolute values of the differences ΔX, ΔY, ΔZ from the respective accelerations Xn-i, Yn-i, Zn-i before a certain time, each acceleration Xn of the acceleration sensor 1 is calculated. , Yn, and Zn, the value of data used for the step count can be increased while reducing the influence of the offset.

(Embodiment 3)
Pedometer of this embodiment, the acceleration calculation unit 61 in accordance with the magnitude of the activity, the difference [Delta] X, [Delta] Y, the point that determine the predetermined time used to calculate the [Delta] Z, different from the embodiment 2 ing. In addition, about the component similar to Embodiment 2, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  The acceleration calculation unit 61 according to the present embodiment feeds back and acquires the activity amount calculated by the activity amount calculation unit 62, estimates the walking form from the magnitude of the acquired activity amount, and determines the predetermined time. Specifically, if the amount of activity is large, it is determined as “running” and the predetermined time is shortened. On the other hand, if the amount of activity is small, it is determined that “walking slowly” and the predetermined time is lengthened.

  As described above, according to the present embodiment, the walking form can be estimated from the magnitude of the activity amount, and the number of steps counted in consideration of the walking form can be performed. Therefore, the accuracy of the number of steps counting can be improved.

It is a block diagram which shows the structure of Embodiment 1-3. It is an external view same as the above. It is a figure which shows the output of an acceleration sensor same as the above.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Acceleration sensor 6 Calculation part 60 Sampling part 61 Acceleration calculation part 63 Step count part

Claims (2)

An acceleration sensor;
A difference calculating means for calculating an absolute value of a difference between the output of the acceleration sensor and the output of the acceleration sensor a predetermined time ago;
A step counting means for counting the number of steps using the absolute value of the difference ,
The certain period of time is a certain period of time in the past,
The difference calculation means calculates the absolute value of the difference between the output of the acceleration sensor and the output at each time of the time zone, and extracts the maximum value of the absolute value of the difference,
The pedometer characterized in that the step counting means counts the number of steps using the maximum absolute value of the difference . Comprising an activity amount calculating means for calculating an activity amount using an output of the acceleration sensor;
2. The pedometer according to claim 1, wherein the step coefficient unit distinguishes a plurality of walking forms in accordance with the amount of activity and counts the number of steps for each walking form .

Images