JP4982444B2 - Pedometer - Google Patents

Description

  The present invention relates to an apparatus for measuring the number of steps, and more particularly to a step count measuring apparatus that can stably and accurately measure the number of steps regardless of the mounting position.

  It is no exaggeration to say that the biggest problem for modern Japanese is the health problem. The easiest way to maintain health is so-called walking. Walking is characterized by the fact that it does not place an excessive burden on the body and can be continued even by people with relatively little physical strength.

  However, there is a problem that simply continuing to walk is not interesting and cannot be continued easily. In addition, there is a problem that if you do not know how far you walked, you will not be encouraged.

  Therefore, so-called pedometers are often used. By walking with a pedometer, the number of steps can be measured. For example, walking can be continued by setting a goal for the number of steps per day and walking to achieve the goal. Also, by recording the number of steps taken every day, it can be used for health management.

  Of course, it is desirable that the number of measurements by the pedometer is accurate. However, as described below, there is a problem that it is difficult to accurately measure the number of steps.

  Currently, 2-axis or 3-axis acceleration sensors are often used for pedometers. When a biaxial acceleration sensor is used, if the pedometer is attached to a presumed wearing position, the acceleration during walking can be measured relatively accurately. If the pedometer is placed in a posture different from the assumed posture, for example, walking cannot be counted, and the measurement result of the number of steps becomes totally unreliable. On the other hand, when a triaxial acceleration sensor is used, walking can be counted regardless of the mounting position and posture. However, even in this case, if the pedometer is stored in a bag or pocket, the acceleration sensor does not apply sufficient acceleration, so the step count is greatly reduced, and conversely, the acceleration sensor is excessively accelerated. Therefore, there is a problem that the number of steps is greatly increased and accurate measurement is difficult.

Until now, these problems were not considered as big problems. The use of the pedometer is to measure the number of steps in a steady walk that walks at a certain speed like the above-mentioned walking. In such a use, it is considered that the pedometer is worn at an appropriate position when walking. Because.
JP-A-2005-38018 (paragraphs 0018 to 0022, 0028)

  For example, consider a case where a company employee wants to count daily steps for health management. To do that, you need to have a pedometer every day. If you are a man, don't worry too much about wearing a pedometer on your belt. But women often cannot do that. For this reason, women often keep their pedometers in their bags.

  However, when a pedometer is put in the bag, as described above, acceleration due to walking is absorbed in various places before it is applied to the pedometer, and there is a problem that the pedometer cannot measure accurately. .

  Similar problems can occur when walking slowly and the acceleration itself is small. For example, when a sick patient who has difficulty in walking performs rehabilitation, the walking speed becomes slow. If the number of steps can be accurately measured even with such a weak walk, it will be an encouragement for rehabilitation.

  Patent Document 1 proposes a step count measuring apparatus for solving such a problem. The step count measuring device disclosed in Patent Document 1 uses a triaxial acceleration sensor to synthesize these by taking the sum of squares of triaxial acceleration, and then passes the waveform through a low-pass filter to count the number of steps. Alternatively, frequency analysis is performed on the synthesized acceleration signal, and the number of steps is measured assuming that the frequency of the band having the largest frequency component indicates the number of steps per second.

  However, as described later, when counting the number of steps using a waveform obtained by passing the synthesized acceleration signal through a low-pass filter, the waveform of the synthesized acceleration signal is not stable, and a threshold value for counting is determined. There is a problem that is difficult. Furthermore, since the combined acceleration signal is not stable during measurement, there is a problem that accurate step count measurement is difficult.

  Further, when performing waveform analysis, the step count measuring apparatus described in Patent Document 1 uses an FFT (Fast Fourier Transform). Since a relatively large amount of calculation is required for the FFT calculation, there is a problem that power consumption becomes large both when using hardware and when using a processor. Needless to say, in the case of a product used on a daily basis, such as a step counting device, the smaller the power consumption, the better. In addition, there is a problem that the accuracy cannot be increased very much in the step count measurement using FFT.

  Therefore, an object of the present invention is to provide a step count measuring apparatus capable of accurately measuring the number of steps regardless of the mounting position.

  Another object of the present invention is to provide a step measuring device that can accurately measure the number of steps and consumes less power regardless of the mounting position.

  Still another object of the present invention is to provide a step count measuring apparatus that can accurately measure the number of steps even at a slow walking speed regardless of the mounting position, and that requires less power consumption.

  A step count measuring apparatus according to the first aspect of the present invention includes a three-axis acceleration sensor, acceleration combining means for combining the outputs of the acceleration sensor and outputting a combined acceleration signal, and a plurality of waveforms of the combined acceleration signal. Compare the size of multiple frequency band components extracted by multiple extraction means and multiple extraction means for extracting each frequency band component waveform, and select the waveform of the largest frequency band component By combining, a waveform shaping means for shaping the waveform of the composite acceleration signal, and a counting means for counting the number of steps by comparing the waveform shaped by the waveform shaping means with a predetermined threshold value Including.

  The triaxial acceleration signal output from the acceleration sensor is synthesized by the acceleration synthesis means. A plurality of frequency band component waveforms are extracted from the waveform of the combined acceleration signal by a plurality of extraction means. The waveform shaping means shapes the waveform of the composite acceleration signal by selecting and combining the waveforms of the components in the frequency band having the largest magnitude, that is, the signal level, among these waveforms. The counting means counts the number of steps by comparing the value of the combined acceleration signal after shaping with a threshold value.

  The waveform of the resultant acceleration signal after being shaped by the above-described waveform shaping means draws a smooth curve, and it is easy to determine a threshold value for performing accurate measurement. In addition, since the waveform of the synthetic acceleration signal to be measured is shaped and smoothed even during actual measurement, the comparison with the threshold can be performed stably, the step count can be stabilized, and the reliability can be improved. There is. Furthermore, since the triaxial acceleration signal is synthesized and used for step count measurement, stable step count measurement can be realized regardless of the orientation of the triaxial acceleration sensor. There is no need to execute processing such as FFT, and power consumption is small.

  Preferably, the plurality of extraction means includes a first waveform extraction means for extracting a waveform of a component of the first frequency band from the synthesized acceleration signal, and a second whose center frequency is higher than the center frequency of the first frequency band. And a second waveform extracting means for extracting a waveform in the frequency band from the synthesized acceleration signal.

  The first and second waveform extraction means extract frequency band components of different center frequencies and use them for level comparison during waveform shaping. When the user's walking speed changes, the output of one of the waveform extraction means becomes larger than the other, so the frequency band component corresponding to the walking speed is selected from the synthesized acceleration signal. As a result, even if there is a change in the number of steps, the number of steps can be accurately calculated following the change.

  More preferably, the second frequency band has a portion overlapping the first frequency band.

  According to experiments, when the two bands overlap in this way, the waveform of the combined acceleration signal after shaping becomes smoother than otherwise, and errors in threshold setting and actual measurement occur. Is effective.

  More preferably, the first frequency band may be not less than 0.5 Hz and not more than 1.5 Hz. The second frequency band may be 1.0 Hz or more and 2.0 Hz or less.

  These correspond to the actual walking speed, and the walking speed of about 0.5 to 2 steps per second can be measured with high accuracy and low power consumption.

  Preferably, the plurality of extraction means further include third waveform extraction means for extracting a waveform in a third frequency band having a center frequency higher than the center frequency of the second frequency band from the synthesized acceleration signal.

  By extracting the waveform of the third frequency band in this way and setting the level as a comparison target in waveform shaping, even when the number of steps per second becomes 2 or more, the accuracy of the step speed is maintained. can do.

  Preferably, the third frequency band has a portion overlapping with the second frequency band. More preferably, the third frequency band is 1.5 Hz or more and 2.5 Hz or less.

  As described above, according to the present invention, since the waveform of the composite acceleration signal draws a smooth curve, it is possible to easily determine a threshold value for performing accurate measurement. Since the waveform of the synthetic acceleration signal to be measured is also shaped and smoothed at the time of measurement, the comparison with the threshold can be performed stably, the step count can be stabilized, and the reliability can be improved. Furthermore, since the triaxial acceleration signal is synthesized and used for step count measurement, stable step count measurement can be realized regardless of the orientation of the triaxial acceleration sensor. There is no need to execute processing such as FFT, and power consumption is small.

  As a result, it is possible to provide a step number measuring apparatus that can accurately measure the number of steps and consumes less power regardless of the mounting position. In addition, there is an effect that the number of steps can be accurately measured even at a slow walking speed and power consumption can be reduced.

  In the following description and drawings, the same reference numerals are assigned to the same components. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

[First Embodiment]
<Configuration>
FIG. 1 is an external view of a step count measuring apparatus 20 according to the first embodiment of the present invention. Referring to FIG. 1, the step counting device 20 includes a flat rectangular parallelepiped case 30 and a display unit 32 formed on the front surface of the case 30, both of which are also formed on the front surface of the case 30. A reset button 34, a history switching button 36, and a setting button 38 are included. The reset button 34 is operated when the number of steps is reset to zero. The history switching button 36 is operated when the display on the display unit 32 is switched between the step count display and the daily history display of the step count. The setting button 38 is operated when setting the date and time of the step counting device 20.

  The resetting of steps, history switching, and setting are not directly related to the present invention. Therefore, in the following description, in order to simplify the description and the drawings, detailed description thereof will not be given, and necessary parts thereof will not be illustrated.

  FIG. 2 is a functional block diagram of the step count measuring apparatus 20. Referring to FIG. 2, step count measuring device 20 is fixed in housing 30, and represents acceleration in the coordinate axis directions (the X axis, the Y axis, and the Z axis) fixed to housing 30. A triaxial acceleration sensor 50 that outputs a signal, a triaxial synthesis unit 52 that synthesizes triaxial acceleration by receiving the output of the triaxial acceleration sensor 50 and calculating the sum of squares of the triaxial acceleration, and 3 Bandpass filters that extract components of frequency bands 0.5 to 1.5 Hz, 1.0 to 2.0 Hz, and 1.5 to 2.5 Hz, respectively, from the signal waveform of the combined acceleration output by the shaft combining unit 52. 54, 56 and 58 are connected to receive the outputs of the bandpass filters 54, 56 and 58, respectively, and measure the level of the frequency component of the signal waveform of the resultant acceleration output from the bandpass filters 54, 56 and 58. Output Comprising a Le measuring circuit 80, 90 and 100, receiving the output of the level measuring circuit 80, 90 and 100, and a comparator 60 for outputting a signal identifying the circuit which gives the maximum value of these. Here, the comparator 60 is binary 00 when the output of the low-pass filter 84 is the highest, binary 01 when the output of the low-pass filter 94 is the highest, and binary 10 when the output of the low-pass filter 104 is the highest. Shall be output.

  The pedometer 20 further includes three inputs that receive the outputs of the bandpass filters 54, 56, and 58, respectively, and a control input that receives the output of the comparator 60, and among the outputs of the bandpass filters 54, 56, and 58, , A waveform selection unit 62 that outputs a synthesized acceleration signal shaped by selecting and combining the ones corresponding to the output of the comparator 60, and a waveform of the shaped synthesized acceleration signal outputted from the waveform selection unit 62 with a predetermined threshold. It includes a threshold circuit 64 that binarizes compared to (threshold value), and a counter 66 that adds the number of times that the signal output from the threshold circuit 64 has changed from a low level to a high level. Here, the waveform selection unit 62 selects the output of the band pass filter 54 if the output of the comparator 60 is binary 00, and selects the output of the band pass filter 56 if the output of binary is 01. If so, the output of the bandpass filter 58 is selected.

  Note that the threshold value is set by repeating the experiment in advance. Even in this setting, since the acceleration signal after synthesis is smooth, the threshold can be easily set to an appropriate value.

  The output of the counter 66 is given to the display unit 32 and displayed as the number of steps. The counter 66 is connected to receive a signal from the reset button 34, and resets the count to 0 when a reset signal is given from the reset button 34.

  The level measurement circuit 80 calculates an absolute value of a signal component in the frequency band of 0.5 to 1.5 Hz of the composite acceleration signal output from the bandpass filter 54, and an output of the absolute value circuit 82. And a low-pass filter 84 that extracts and supplies the component up to 0.1 Hz to the comparator 60.

  Both the level measurement circuit 90 and the level measurement circuit 100 have a configuration similar to that of the level measurement circuit 80. Specifically, level measurement circuit 90 includes an absolute value circuit 92 having an input connected to the output of bandpass filter 56 and a low-pass filter 94 having an input connected to the output of absolute value circuit 92. Level measurement circuit 100 includes an absolute value circuit 102 having an input connected to the output of band-pass filter 58 and a low-pass filter 104 having an input connected to the output of absolute value circuit 102. As with the low-pass filter 84, the low-pass filters 94 and 104 both have a cutoff frequency of 0.1 Hz.

<Operation>
At the time of step count measurement, the step count measuring device 20 operates as follows. With reference to FIG. 2, the triaxial acceleration sensor 50 measures the triaxial acceleration of the X axis, the Y axis, and the Z axis, and provides an acceleration signal to the triaxial synthesis unit 52. The triaxial combining unit 52 outputs a combined acceleration signal by calculating the sum of squares of the values of these acceleration signals, and provides the resultant to the bandpass filters 54, 56 and 58.

  FIG. 3A shows an example of the waveform of this combined acceleration signal. FIG. 4A shows a waveform obtained by enlarging the partial waveform 110 in the waveform of the composite acceleration signal shown in FIG. Referring to FIG. 3A, the waveform of the composite acceleration signal has many large and small peaks when viewed in detail, and it is difficult to determine at which point a step (walking) should be detected.

  The band pass filter 54 extracts a component of the frequency band of 0.5 to 1.5 Hz of this synthesized acceleration signal, and supplies it to the absolute value circuit 82 and the first input of the waveform selector 62. The band pass filter 56 extracts the component of the frequency band of 1.0 to 2.0 Hz of the combined acceleration signal and supplies it to the absolute value circuit 92 and the second input of the waveform selector 62. The band pass filter 58 extracts the component of the frequency band of 1.5 to 2.5 Hz of the combined acceleration signal and supplies it to the absolute value circuit 102 and the third input of the waveform selector 62.

  The low-pass filters 84, 94, and 104 provide components (DC components) of 0.1 Hz or less among the outputs of the absolute value circuits 82, 92, and 102 to the first, second, and third inputs of the comparator 60, respectively. . The comparator 60 gives a signal indicating the highest one of these three inputs to the control terminal of the waveform selection unit 62. Specifically, the comparator 60 is binary 00 when the output of the low-pass filter 84 is the highest, 01 is binary when the output of the low-pass filter 94 is the highest, and 10 is binary when the output of the low-pass filter 104 is the highest. , Respectively. The waveform selection unit 62 selects the output of the band pass filter 54 if the output of the comparator 60 is binary 00, selects the output of the band pass filter 56 if the output is binary 01, and selects the output of the band pass filter 56 if the output is binary 10. The output of the pass filter 58 is selected and output. The waveform selection unit 62 selects and outputs the outputs of the bandpass filters 54, 56, and 58 in accordance with the output of the comparator 60 in this way, so that the selected waveforms are sequentially combined, and the shaped combined acceleration signal is converted. can get.

  FIG. 3B shows an example of a waveform after shaping that is obtained at the output of the waveform selection unit 62 based on the waveform shown in FIG. FIG. 4B is a diagram showing a waveform obtained by enlarging the partial waveform 112 in the waveform of the composite acceleration signal shown in FIG. With reference to FIG. 4 (B), the waveform of the synthesized acceleration signal after shaping output from the waveform selection unit 62 is smooth. As a result, it is easy to determine what value is used as the threshold and the measurement result of the number of steps is accurate.

  Referring to FIG. 2 again, the threshold circuit 64 compares the waveform magnitude (value) of the synthesized acceleration signal after shaping output from the waveform selector 62 with a predetermined threshold, thereby reducing the waveform magnitude. When switching from a value smaller than the threshold to a larger value, one pulse is output. The counter 66 counts this pulse and gives the count result to the display unit 32. The display unit 32 displays the given counter value.

  FIG. 8 is a diagram illustrating an error ratio based on the number of steps calculated by the algorithm of the step count measuring apparatus according to the first embodiment and an error ratio when measured by a conventional acceleration sensor pedometer. Referring to FIG. 8, ◯ indicates an error ratio between the number of steps calculated by the algorithm of the step count measuring apparatus according to the first embodiment and a value (actually measured value) obtained by actually counting the number of steps visually. A cross indicates an error ratio between a measurement value obtained by a conventional acceleration sensor pedometer and a value (actual measurement value) obtained by actually measuring the number of steps visually. In FIG. 8, the plus direction on the vertical axis indicates that the number of steps is counted more than the actual measurement value, and the minus direction indicates that the number of steps is counted less than the actual measurement value. The unit of the vertical axis indicates the error rate in percent.

  In the case of the conventional acceleration sensor pedometer as shown by x in FIG. 8, when the walking speed is 40 meters / minute or less, the measurement results are noticeably dispersed, and in particular, only less than half of the actual number of steps is measured. It was observed that there were frequent cases where it was not possible. That is, if the acceleration is weak, the conventional step count measuring device cannot perform the step count measurement with reliability.

  On the other hand, as indicated by a circle in FIG. 8, the algorithm of the step count measuring apparatus 20 according to the present embodiment outputs a step count measurement value with almost no error even when the walking speed is 40 meters / minute or less. We were able to. This is presumably because the shape of the post-synthesis acceleration signal was made smooth by the above-described configuration, and the threshold could be easily set to an appropriate value.

  As described above, according to the present embodiment, the waveform of the combined acceleration signal output from the triaxial combining unit 52 is indefinite and the threshold is difficult to determine as shown in FIGS. 3 (A) and 4 (A). However, the waveform of the signal indicating the composite acceleration output from the waveform selection unit 62 is smoothly shaped as shown in FIGS. 3B and 4B, and the threshold can be easily determined. . As a result, there is an effect that an error in performing the comparison by the threshold circuit 64 is reduced. Further, since the three-axis composition is performed by the three-axis composition unit 52, the number of steps can be stably and accurately measured regardless of the posture of the three-axis acceleration sensor 50, that is, the posture of the step counting device 20. . Therefore, it is possible to accurately measure the number of steps even when the step number measuring device 20 is placed in any mounting position, for example, in a bag or the like. Further, since no FFT is used, the calculation amount is small and the amount of hardware is small. As a result, power consumption can be suppressed.

[Second Embodiment]
The above-mentioned step count measuring apparatus can also be realized by using a processor and software as a part. The step count measuring apparatus according to the second embodiment is such a step count measuring apparatus. FIG. 5 shows a hardware block diagram of the step count measuring apparatus 120 according to the second embodiment.

  Referring to FIG. 5, step count measuring apparatus 120 includes a triaxial acceleration sensor 50, a processor 130 connected to receive the triaxial acceleration from triaxial acceleration sensor 50, and a nonvolatile memory connected to processor 130. In addition, the memory 132 that can be written and read as needed, the reset button 34, the history switching button 36, the setting button 38, the display unit 32, and the output interface of the processor 130 connected to the input interface of the processor 130, respectively. And a driver 134 for driving the display unit 32 in accordance with a signal supplied from the processor 130 and displaying the number of steps and the like. The processor 130 includes a CPU (Central Processing Unit) (not shown) and a memory that can be written and read as needed.

  The memory 132 stores a computer program for measuring the number of steps executed by the processor 130. The processor 130 reads out and executes a program command from an address in the memory 132 specified by a program counter built in the CPU, and processes the output of the three-axis acceleration sensor 50, whereby the processor according to the first embodiment is processed. A step count measuring device 120 having the same function as the step count measuring device 20 is realized.

  FIG. 6 is a flowchart showing a control structure of a computer program for measuring the number of steps executed by the processor 130. Referring to FIG. 6, this program performs initial setting such as clearing all addresses of memory 132 immediately after power-on of pedometer 120, and following step 150, three programs of three-axis acceleration sensor 50 are executed. Step 152 for sampling the acceleration signal of the axis, and calculating the sum of squares of the acceleration signals of the three axes sampled in Step 152, the three-axis acceleration is synthesized, and the resultant acceleration signal is calculated and stored in the memory 132. Step 154. By repeatedly executing this processing as will be described later, the time series of the composite acceleration signal is stored in the memory 132.

  This program further includes steps 156 for calculating the level of the component of 0.5 to 1.5 Hz in the composite acceleration signal after the three-axis synthesis calculated in step 154 and stored in the memory 132, and 1.0 to 2 A step 158 of calculating a level of a component of 0.0 Hz, and a step 160 of calculating a level of a component of 1.5 to 2.5 Hz. In FIG. 6, these three steps are shown to be executed in parallel, but this is for simplifying the drawing, and these steps are executed in order when there is one CPU. Needless to say, the output of each step is stored in the memory 132 or a register in the processor 130.

  Step 156 performs a filtering process on the time series of the composite acceleration signal calculated in Step 154 and stored in the memory 132, and executes a band-pass filtering process for extracting a component of 0.5 to 1.5 Hz. Step 172 for storing the value calculated in Step 170 in the memory 132 or register, Step 174 for calculating the absolute value of the value stored in Step 172 and storing it in the memory 132, and the absolute value calculated in Step 174 And a step 176 of executing a low pass filter process for extracting a component of 0.1 Hz or less by a filtering process for a time series of values.

  Steps 158 and 160 have the same configuration as step 156. Specifically, step 158 includes steps 180, 182, 184 and 186 corresponding to steps 170, 172, 174 and 176 of step 156, respectively. However, in step 180, unlike step 170, a component of 1.0 to 2.0 Hz is extracted from the waveform of the combined acceleration signal. Step 160 includes steps 190, 192, 194 and 196 corresponding to steps 170, 172, 174 and 176 of step 156, respectively. However, in step 190, unlike step 170, a component of 1.5 to 2.5 Hz is extracted from the waveform of the combined acceleration signal.

The program further compares the value stored in the memory 132 as the output of steps 176, 186, and 196, and determines which one has the largest value according to the determination result of step 162 and step 162. When the value obtained at 176 is the largest, the value stored at step 172 is selected. When the value obtained at step 186 is the largest, the value saved at step 182 is selected, and the value obtained at step 196 is selected. When the value is the largest, the value stored in step 192 is selected and stored in the memory 132, and the step count processing is performed based on the time series of the value of the composite acceleration signal thus stored in the memory 132. And step 166 which returns the processing to step 152 after execution.
Since the signal values stored in step 164 are arranged in chronological order, they can be regarded as indicating sequentially synthesized waveforms. Further, the processing of step 152 is not necessarily performed until step 166 is completed. Step 166 may be performed as an interrupt process according to the accumulation state of the waveform data.

  In step 166, the time series of the composite acceleration signal stored in the memory 132 is a value equal to or less than the threshold immediately before, but 1 is added to the number of steps when the latest value becomes larger than the threshold.

  Needless to say, the step counting device 120 according to the second embodiment operates in the same manner as in the first embodiment. Since FFT is not used, the amount of calculation in the processor 130 is relatively small, and power consumption is small.

  It should be noted that when storing the composite acceleration signal in the memory 132 in step 154, it is a problem how many values should be stored as a time series of the composite acceleration signal. Here, the band-pass filter process executed at step 170, 180 and 190, as well as to perform the low-pass filter process executed at step 176 and 186 and 196, depending on whether to store the value of the time series of how much in advance In step 154, the number of values stored as a time series may be determined. In this case, if these values are stored in a format such as a ring buffer, unnecessary values are conveniently deleted automatically in sequence.

  When the processor is used for signal processing as in the second embodiment, it is easy to incorporate the step count measuring device into another portable device. If the portable device has a processor, such as a mobile phone, for example, a three-axis acceleration sensor is incorporated into the portable device and the processor executes the above step count measurement program. Good. Such an example is shown in FIG.

  FIG. 7 shows a mobile phone 220 in which a step count measuring device is incorporated. Mobile phones are usually carried in bags or pockets rather than being worn on a belt. Therefore, even if a conventional step counting device is incorporated, stable measurement cannot be performed. However, with the step count measuring apparatus 120 according to the above-described embodiment of the present invention, the step count can be stably measured regardless of the orientation of the three-axis acceleration sensor, and hence the mobile phone 220. As a result, there is an effect that it becomes unnecessary to carry an independent step counting device in addition to the mobile phone. This is not limited to a mobile phone, and the same applies to a PDA (Personal Digital Assistant).

  As described above, according to the present invention, even when the waveform of the composite acceleration signal is indefinite and it is difficult to determine the threshold, the waveform of the signal indicating the composite acceleration is smoothly shaped, and the threshold can be easily determined. . As a result, it is possible to obtain an effect that an error in performing the comparison by the threshold circuit is reduced. Further, since the output of the triaxial acceleration sensor is synthesized, the number of steps can be stably and accurately measured regardless of the posture of the triaxial acceleration sensor, that is, the posture of the step counting device 20.

  In the above-described embodiment, three bands are used, but this number is not limited to three. If it is two or more, the same effect as the said embodiment can be acquired. In the above embodiment, adjacent bands of the three bands are overlapped by half. However, the present invention is not limited to such an embodiment. The overlapping portion may be smaller than half of each band. Even if there is a non-overlapping portion between adjacent bands, a certain degree of effect can be obtained, but according to experiments, the smoothness of the waveform obtained in this case deteriorates. As a result, it was found that it was somewhat difficult to determine the threshold. However, even in this case, the accuracy of the step count measurement can be greatly improved as compared with the case of using the waveform before shaping.

  In the above-described embodiment, the sum of squares of the acceleration values in the respective axis directions is calculated in order to synthesize the output of the triaxial acceleration. However, the present invention is not limited to such an embodiment. For example, you may use the sum total of the absolute value of the acceleration of each direction, or the route | root of the square sum of the acceleration of each direction. In particular, when the above embodiment is realized by an analog circuit, comparing the case of using the sum of squares and the case of using the root of squares, the method using the root of the sum of squares when the magnitude of acceleration is the same. This is advantageous in terms of circuit mounting and power consumption.

  The embodiment disclosed herein is merely an example, and the present invention is not limited to the above-described embodiment. The scope of the present invention is indicated by each of the claims after taking into account the description of the detailed description of the invention, and all modifications within the meaning and scope equivalent to the wording described therein are intended. Including.

It is a figure which shows the external appearance of the step count measuring apparatus 20 which concerns on the 1st Embodiment of this invention. 2 is a block diagram showing a hardware configuration of a step count measuring device 20. FIG. FIG. 3A is a waveform diagram showing a waveform of a composite acceleration signal after triaxial synthesis, and FIG. 3B is a waveform diagram showing a waveform of the composite acceleration signal after being shaped by the step count measuring device 20. 4A is an enlarged waveform diagram of the partial waveform 110 in FIG. 3A, and FIG. 4B is an enlarged waveform diagram of the partial waveform 112 in FIG. 3B. It is a block diagram which shows the hardware constitutions of the step count measuring apparatus 120 which concerns on the 2nd Embodiment of this invention. It is a flowchart which shows the control structure of the computer program for the step count measurement performed with the processor 130 of the step count measuring device 120. It is a figure which shows the external appearance of the mobile telephone incorporating the step count measuring apparatus which concerns on embodiment of this invention. It is a figure which shows the error ratio of the step count calculated by the algorithm of the step count measuring apparatus 20 which concerns on 1st Embodiment, and a measured value, and the error ratio of the measured value and measured value by the conventional acceleration sensor pedometer.

Explanation of symbols

20, 120 Number of steps measurement device 30 Case 32 Display unit 50 3-axis acceleration sensor 52 3-axis synthesis unit 54, 56, 58 Bandpass filter 60 Comparator 62 Waveform selection unit 64 Threshold circuit 66 Counter 80, 90, 100 Level measurement circuit 82 , 92, 102 Absolute value circuit 84, 94, 104 Low pass filter 130 Processor 132 Memory 220 Mobile phone

Claims (8)

A 3-axis acceleration sensor;
Acceleration combining means for combining the outputs of the acceleration sensors and outputting a combined acceleration signal;
A plurality of extraction means for respectively extracting the waveforms of the components of a plurality of frequency bands of the waveform of the synthetic acceleration signal;
A waveform for shaping the waveform of the composite acceleration signal by comparing the magnitudes of the components of the plurality of frequency bands extracted by the plurality of extracting means, and selecting and combining the waveforms of the components of the largest frequency band Shaping means;
A step count measuring apparatus comprising counting means for counting the number of steps by comparing the waveform shaped by the waveform shaping means with a predetermined threshold value. The plurality of extraction means include
First waveform extraction means for extracting a waveform of a component of a first frequency band from the synthesized acceleration signal;
The step count measuring device according to claim 1, further comprising: a second waveform extracting unit configured to extract, from the synthetic acceleration signal, a waveform in a second frequency band having a center frequency higher than the center frequency of the first frequency band. . The step count measuring apparatus according to claim 2, wherein the second frequency band has a portion overlapping with the first frequency band. The step count measuring device according to claim 2 or 3, wherein the first frequency band is 0.5 Hz or more and 1.5 Hz or less. The step number measuring device according to any one of claims 2 to 4, wherein the second frequency band is 1.0 Hz or more and 2.0 Hz or less. The plurality of extracting means further includes third waveform extracting means for extracting a waveform of a third frequency band having a center frequency higher than a center frequency of the second frequency band from the synthesized acceleration signal. The step counting device according to any one of claims 2 to 5. The step count measuring apparatus according to claim 6, wherein the third frequency band has a portion overlapping the second frequency band. The step count measuring device according to claim 6 or 7, wherein the third frequency band is 1.5 Hz or more and 2.5 Hz or less.

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