JP4913316B2 - Step calculation device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a step count calculation device that is mounted on a human body or the like and measures the number of steps, and more particularly to a step count calculation device that performs step count calculation using an acceleration sensor.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a pedometer, a pedometer (registered trademark), or the like is known as a meter that is attached to a human body or the like and measures the number of steps, for example, to estimate calories consumed.
In general, the pedometer is, for example, a sensor that detects a physical quantity caused by walking and calculates the number of steps based on the detection result.
[0003]
As the physical quantity, the displacement of the weight, the acceleration, or the like is detected, and the displacement of the weight, that is, the method of detecting the number of vibrations of the weight as the number of steps, the detection result of the acceleration sensor is FFT processed, Based on this, it is detected how many times a rhythmic repetitive motion performed at a constant period is performed per unit time (Patent Document 1), and 3 arranged so as to be perpendicular to each other. There has also been proposed a method (Patent Document 2) that uses a single acceleration sensor (hereinafter referred to as a triaxial acceleration sensor) and calculates the number of steps based on the detection results of these acceleration sensors.
[0004]
As a method of calculating the number of steps based on the detection result of the three-axis acceleration sensor, for example, based on the detection result of the three axes of the three-axis acceleration sensor when a pedestrian runs or steps in advance, each axis A method of calculating the number of steps based on the amount of fluctuation and the frequency based on the detection result (Patent Document 3), and the traveling direction acceleration and the vertical direction acceleration are calculated based on the detection results of the three axes. Also proposed is a method in which the number of steps is measured based on the amount of variation and the frequency based on each of them, and it is determined whether the vehicle is traveling on flat ground or the stairs are being lifted (Patent Document 4). ing.
[0005]
[Patent Document 1]
JP-A-10-290854 [Patent Document 2]
JP-A-9-89584 [Patent Document 3]
JP 2001-143048 A [Patent Document 4]
Japanese Patent Laid-Open No. 11-42220
[Problems to be solved by the invention]
When using a method that detects the number of steps based on the amount of displacement of the weight, a mechanism for vibrating the weight is required, which makes it difficult to reduce the size of the step number calculation device. When the acceleration sensor is used, a relatively small size can be achieved.
However, a device incorporating a pedometer as described above has various portable parts or portable directions by a walking body such as a pedestrian, and the portable direction is not constant during walking. It may change arbitrarily every moment.
The acceleration that occurs with walking generally only changes in the vertical direction. For this reason, in the conventional pedometer, when there are only one and two axes of acceleration sensors, if the axes are not oriented in the vertical direction, the acceleration caused by walking cannot be captured, and the number of steps Measurement cannot be performed.
[0007]
In addition, even when a three-axis acceleration sensor is provided (Patent Document 3), if a change in the vertical direction cannot be measured accurately, based on the detection signal of the acceleration sensor corresponding to the vertical direction. Even if the step count calculation is performed, there is a problem that the step count measurement cannot be detected with high accuracy because the error is included. In addition, it is necessary to select which detection signal of the three-axis acceleration sensor is to be referred to as a detection signal for calculating the number of steps, and the detection signal to be referred to is switched indefinitely depending on the change in the carrying direction of the pedometer. As a result, problems remain in terms of calculation accuracy.
[0008]
In the method of detecting vertical and longitudinal accelerations based on the detection results for each axis (Patent Document 4), after converting the coordinates of the output of the triaxial acceleration sensor, the number of steps is calculated again. Therefore, there is a problem that the processing load of the arithmetic processing increases and the arithmetic processing time becomes longer.
Accordingly, the present invention has been made paying attention to the above-mentioned conventional unsolved problems, and an object thereof is to provide a step number calculation device capable of performing step number calculation with higher accuracy and ease.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, a step count calculation apparatus according to claim 1 of the present invention is a step count calculation apparatus including three acceleration sensors arranged so that detection directions are perpendicular to each other.
A sum of squares calculation means that squares detection signals from the three acceleration sensors, and continues to calculate the sum of these as a sum of squares;
By cutting the limit to and frequency threshold value or more ingredients square sum that will be calculated continuously the threshold by the square sum calculating means, the active ingredient extracting means for extracting an effective active ingredient in step arithmetic operation ,
And a step arithmetic operation means for performing a number of steps calculates the active ingredient as one cycle, which is the extracted as one step,
The step count calculation can be performed even when the vertical direction of the walking object carrying the acceleration sensor is different from the detection direction of each acceleration sensor.
[0010]
In the invention according to claim 1, the detection signals from the three acceleration sensors arranged so as to be perpendicular to each other are squared by the square sum calculation means, and these sums are calculated as the sum of squares. Based on the fluctuation state of the sum of squares calculated by the calculation means, the step count calculation is performed by the step count calculation means.
If the direction of each axis of the acceleration sensor deviates from the front, back, left, and right and up and down directions of the step count calculation device, the vertical vibration of the step calculation device is coordinate-converted to the axis direction of each acceleration sensor, Although acceleration components in the vertical direction are dispersed, the sum of squares of detection signals of the respective acceleration sensors is calculated, and the number of steps is calculated based on the sum of squares obtained by combining the detection signal components of the respective acceleration sensors. Therefore, it is possible to improve the accuracy of the step count calculation.
[0011]
In this case, the active component effective step arithmetic operation in step arithmetic operation means by cutting the square sum of the square sum that will be calculated by continuously calculating means limited to the threshold and the frequency threshold or more components extracted is, in step arithmetic operation means performs step arithmetic operation one cycle of intact active ingredients extracted by the effective component extracting means as one step. That is, since the step count calculation means performs the step count calculation based only on the effective component effective for the step count calculation in the sum of squares, the step count calculation can be performed with higher accuracy.
[0012]
Further, in the step calculation device according to claim 2 , the step calculation means includes a counting means for detecting and counting the peak of the effective component , and calculating the step count from the peak number per predetermined time. It is characterized by becoming.
In the invention according to claim 2 , in the step count calculating means, the peak of the active component is detected by the counting means and counted, and the peak number per predetermined time is calculated based on the number of peaks counted by the counting means. By calculating the number of steps, the number of steps is calculated.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a schematic configuration of a step count calculation apparatus 100 according to the present invention.
In FIG. 1, reference numerals 11, 12, and 13 denote acceleration sensors that are arranged so as to be perpendicular to each other, and detect accelerations in three orthogonal directions (hereinafter referred to as X, Y, and Z directions). It is supposed to be. The acceleration sensors 11 to 13 can be applied to any principle of acceleration sensors such as a piezoresistive type and a capacitance type. Further, the detection signals of the acceleration sensors 11 to 13 may be analog values or digital values, and arithmetic processing in the arithmetic processing unit 20 described later is either analog processing or digital processing. Also good.
[0015]
The detection signals in the triaxial directions detected by the acceleration sensors 11 to 13 are input to the arithmetic processing unit 20, where step count calculation is performed. The arithmetic processing unit 20 calculates the sum of squares of the accelerations in the three-axis directions from the acceleration sensors 11 to 13 and calculates a sum G ² thereof. a number of steps effective component extraction unit 22 for extracting a number of steps the active ingredient from the square sum G ^2, a step count unit 23 for counting the number of steps based on the number of steps enable component extraction unit 22 the number of steps have been extracted with the active ingredient, the step count unit And a step count storage unit 24 for storing the number of steps counted at 23.
[0016]
When the detection signals from the acceleration sensors 11 to 13 are Gx, Gy, and Gz, the sum of squares calculation unit 21 calculates the sum of squares G ² according to the following equation (1).
G ² = Gx ² + Gy ² + Gz ² (1)
FIG. 2 shows a typical measurement example of the acceleration change of the walking body. FIG. 2 (a) shows the acceleration in the lateral direction with respect to the traveling direction, and FIG. FIG. 2C shows the acceleration in the front-rear direction, and FIG. 2C shows the acceleration in the vertical direction with respect to the traveling direction, where the horizontal axis represents time and the vertical axis represents acceleration.
[0017]
As can be seen from FIGS. 2 (a) to 2 (c), the acceleration change of the walking body generally occurs only in the vertical direction (up and down direction) although there are individual differences or differences depending on the portable part of the step count calculation device 10. In addition, it can be seen that there is not much occurrence in the horizontal direction (left and right and front and rear directions).
Further, when the acceleration change in the vertical direction is observed, it can be seen that it periodically fluctuates around the acceleration measurement value caused by gravity, that is, every time one step is taken, it vibrates for one cycle.
[0018]
That is, as a parameter that does not depend on the axial direction of the acceleration sensor carried by the walking body, the output result of each component of the acceleration sensor is not used as a calculation target for the step count calculation as it is. As shown in equation (1), the sum of squares G ² of each acceleration component is used as a calculation target for calculating the number of steps. For this reason, even if there is a change in the direction of the acceleration sensor carried by the walking body, it is not necessary to consider the state of the change, and accordingly, the calculation process for calculating the number of steps can be facilitated. In addition, since the calculation processing for the step count calculation is performed based on the value reflecting the value of the detection signal of each acceleration sensor 11 to 13 instead of the detection signal of the acceleration of any one axis, the calculation accuracy of the step count calculation is high. Will improve.
[0019]
The step count effective component extraction unit 22 extracts an effective component for measuring the number of steps based on the square sum G ² calculated by the square sum calculation unit 21, and at this time, the amplitude of the square sum G ² Extraction is performed using clipping as an effective component extraction method in the axial direction and low-pass filter processing as an effective component extraction method in the time axis direction. Specifically, as shown in FIG. 3, the clipping unit 22a, with respect to the square sum G ^2, it limits the value of more than a certain threshold (or thresholds below) to force the threshold. Further, the low-pass filter unit 22b cuts components that are above a certain frequency threshold.
[0020]
Incidentally, the clipping level in the clipping for the square sum G ^2, orders and the like of the cut-off frequency or the low-pass filter in the low-pass filter processing may be set to be optimum in accordance with the purpose or the like of the number of steps measured and pedometer.
Further, as shown in FIG. 4, the step count counting unit 23 sets a threshold value of a peak level for the step count effective component of the square sum G ² extracted by the step count effective component extraction unit 22. And a peak detector 23b that detects a peak that exceeds the threshold of the peak level set by the threshold setting unit 23a by considering that the sum of squares G ² exceeds the threshold due to walking, A peak detection number counting unit 23c that counts the number of peaks per predetermined time for peaks exceeding the threshold detected by the peak detection unit 23b is provided.
[0021]
Note that the threshold of the peak level set by the threshold setting unit 23a may be set to be optimal according to the number of steps to be measured and the purpose of the number of steps measurement.
Further, in the peak detector 23b, an upper peak (maximum value) of the number of steps the active ingredient of the square sum G ² alone, or may be detected only lower peak (minimum value), also detect both You may make it do. When both are detected, the number of steps may be set to 1/2 of the number of detected peaks.
[0022]
Then, if the number of steps is detected by the peak detection number counting unit 23c in this way, it is stored in the step number storage unit 24.
As described above, the arithmetic processing unit 20 calculates the square sum G ² based on the detection signals Gx, Gy, and Gz of the acceleration sensors 11 to 13 in the three-axis directions, and uses this square sum G ² for calculating the number of steps. The number of steps is calculated based on this parameter.
[0023]
Here, when the vertical direction of the walking body and the axial direction of the acceleration sensors 11 to 13 of the number of steps calculating device carried by the walking body coincide with each other, as shown in FIG. In the acceleration detected in, only the acceleration of the acceleration sensor corresponding to the vertical direction is a value centered on the acceleration measurement value caused by gravity, and the acceleration of the acceleration sensor corresponding to the horizontal direction is substantially zero. When the vertical direction of the walking body and the axial direction of the acceleration sensors 11 to 13 of the step count calculation device carried by the walking body are shifted, or the axial direction of the acceleration sensors 11 to 13 changes during walking, As for the acceleration detected by the acceleration sensors 11 to 13, the acceleration components generated in the vertical direction of the walking body are coordinate-converted in the three-axis directions, and the acceleration sensors 11 to 13 detect fluctuations in acceleration. It will be.
[0024]
For this reason, when any of the accelerations detected by these acceleration sensors 11 to 13 is used as a parameter and the number of steps is calculated based on the parameter, the acceleration in the vertical direction of the walking body is divided into three directions. Since the step count calculation is performed based on any one of them, it is easy to include an error, and it is easy to make an erroneous determination, so that the accuracy of the step count calculation is lowered.
[0025]
However, as described above, as a parameter of step arithmetic operation, using the square sum G ² of the acceleration detected by the acceleration sensors 11 to 13, the sum of squares G ² that contains the detected acceleration component in the acceleration sensors 11 to 13 Since the number of steps is calculated using, the number of steps can be calculated with high accuracy even when the vertical direction of the walking body and the axial direction of the acceleration sensor are shifted.
[0026]
In addition, the step count calculation is performed by calculating the square sum G ² of the accelerations detected by the respective acceleration sensors 11 to 13 and counting the peak value. It is possible to reduce the processing load associated with the step count calculation and shorten the processing time.
In addition, because the step count is calculated by counting the peak value, it can be applied to changes in the walking rhythm, that is, the time fluctuation for each step caused by walking, and the step count calculation results are obtained sequentially. can do. For this reason, the convenience as a step count calculation apparatus can be improved.
[0027]
At this time, the step count calculation is not performed using the square sum of acceleration G ² as it is, but the effective component suitable for the step count calculation is extracted from the square sum G ² and the step count is detected based on the extracted effective component. Therefore, it is possible to calculate the number of steps with high accuracy regardless of the individual difference of the walking body or the change of the portable part of the three-axis acceleration sensor carried by the walking body.
In the above embodiment, the step count counting unit 23 explained the case where the step count calculation is performed using the peak detection method for counting the peak value as shown in FIG. The number of steps may be calculated by using other detection methods.
[0028]
For example, instead of the peak detection method, a method of detecting the maximum value of the power spectrum using a Fourier transform method can be applied. In this case, as shown in FIG. 5, the step count unit 23 performs Fourier transform at a predetermined timing on the step count effective component of the square sum G ² from the step count effective component extraction unit 22 per predetermined time. The spectrum calculation unit 23α that performs power spectrum calculation and the maximum spectrum detection that detects the maximum value of the power spectrum from the power spectrum calculated by the spectrum calculation unit 23α and calculates the number of steps based on the frequency corresponding to the detected maximum value Part 23β. In the maximum spectrum detection unit 23β, for example, the number of pulses per predetermined time may be calculated based on the frequency at which the power spectrum becomes maximum, and this may be used as the number of steps.
[0029]
In addition, what is necessary is just to set the predetermined time for performing the said power spectrum calculation so that it may become optimal according to the step measurement object, the purpose of step measurement, etc.
By doing in this way, also in this case, it is possible to obtain the same operational effect as when the peak detection method shown in the above embodiment is used.
In the above embodiment, the case where the sum of squares G ² calculated by the sum of squares computing unit 21 is used as a step count calculation parameter and the number of steps is detected based on the change state of the square sum G ² has been described. However, the present invention is not limited to this, and the square root (G ² ) ^1/2 of the square sum G ² may be calculated and calculated as a step count calculation parameter.
[0030]
Further, in the above embodiment, the case has been described in which the step count effective component is extracted from the square sum G ² calculated by the square sum calculation unit 21 and the step count is detected based on this, but the step count effective component is not necessarily calculated. There is no need to perform extraction, and the number of steps may be arbitrarily changed depending on the required accuracy of the number of steps, processing amount, and the like. For example, when an extremely small amount of calculation processing is required, the number of steps may be counted by passing the square sum G ² or its square root (G ² ) ^1/2 as it is through a comparator.
[0031]
In the above-described embodiment, the case where the present invention is applied to the step count calculation apparatus 100 that performs the step count calculation has been described. However, even if the apparatus is configured to perform predetermined processing based on the step count calculated as described above. Can be applied.
For example, the present invention can be applied to an apparatus that detects a walking distance based on the number of steps. In this case, as shown in FIG. 6, the arithmetic processing unit 20 shown in FIG. 1 further includes a stride measurement / step length setting unit 26 for measuring a stride or setting a stride, and the stride measurement / step stride setting unit 26. A multiplier 27 that multiplies the stride measured or set by step number stored in the step count storage unit 24, and a walking distance storage unit 28 that stores the multiplication result of the multiplier 27 as a walking distance. What should I do?
[0032]
Here, in the above embodiment, the sum of squares computing unit 21 corresponds to the sum of squares calculating means, the step count effective component extracting unit 22 and the step count counting unit 23 correspond to the step count calculating means, and the step count effective component extracting unit 22 is effective. Corresponding to the component extracting means, the step count counting section 23 corresponds to the counting means, and the spectrum calculation section 23α and the maximum spectrum detecting section 23β correspond to the power spectrum maximum value detecting means.
[0033]
【Effect of the invention】
According to the step count calculation apparatus according to claim 1 of the present invention, the step count calculation apparatus calculates the sum of squares of the detection signals of the respective acceleration sensors and performs the step count calculation based on the sum of squares obtained from these sums. The number of steps can be calculated with high accuracy even when the vertical direction of the walking body that carries the vehicle differs from the axial direction of each acceleration sensor.
[0034]
At this time, since a component effective for the conventional step count calculation is extracted from the sum of squares, and the step count calculation is performed based on the extracted effective component, the calculation accuracy of the step count calculation can be further improved.
Further, according to the step count calculating apparatus according to claim 2 , the peak of the effective component of the sum of squares is detected, counted by the counting means, and the number of steps is calculated by obtaining the number of peaks per predetermined time. Can be calculated easily and accurately.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating an example of a step count calculation apparatus according to the present invention.
FIG. 2 is an example of measurement results of acceleration in the left-right direction, the front-rear direction, and the up-down direction with respect to the walking direction.
FIG. 3 is a block diagram illustrating an example of a step count effective component extraction unit 22 in FIG. 1;
4 is a block diagram illustrating an example of a step count counting unit 23 in FIG. 1;
5 is a block diagram showing another example of the step count counting unit 23. FIG.
FIG. 6 is a block diagram showing another example of the step count calculation device.
[Explanation of symbols]
11-13 Acceleration sensor 20 Arithmetic processing unit 21 Sum of squares calculation unit 22 Step count effective component extraction unit 23 Step count count unit 24 Step count storage unit 26 Step length measurement / step length setting unit 27 Multiplier 28 Walk distance storage unit

Claims (2)

In the step number calculation device including three acceleration sensors arranged so that the detection directions are perpendicular to each other,
A sum of squares calculation means that squares detection signals from the three acceleration sensors, and continues to calculate the sum of these as a sum of squares;
By cutting the limit to and frequency threshold value or more ingredients square sum that will be calculated continuously the threshold by the square sum calculating means, the active ingredient extracting means for extracting an effective active ingredient in step arithmetic operation ,
And a step arithmetic operation means for performing a number of steps calculates the active ingredient as one cycle, which is the extracted as one step,
The step number calculating device characterized in that the step number calculation can be performed even when the vertical direction of a walking body in which the acceleration sensor is carried differs from the detection direction of each acceleration sensor. 2. The step count calculating means comprises counting means for detecting and counting the peak of the effective component, and calculating the step count from the number of peaks per predetermined time. step arithmetic operation equipment of.

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