TWI480517B - Step count method - Google Patents

Description

Step counter method for electronic sensor

The present invention is related to a step counting method, particularly to a method of calculating the number of steps using an electronic sensing signal.

A pedometer is a small accessory that can be worn on the body to calculate the number of walking steps. It is also a very useful exercise aid. A pedometer usually generates a vibration signal by sensing the up and down vibration of the body when the subject moves or moves, and uses the vibration signal to calculate the step. Generally, it can be divided into a mechanical pedometer and an electronic step. Device.

Conventional mechanical pedometers use mechanical switches to detect the number of steps, such as a C-shaped spring switch, a mercury switch, a ball switch, or a pendulum type switch. When the vibration generated by the subject is sufficient to trigger these mechanical switches, it is counted as one step. However, when the subject moves with less vibration and is not sufficient to effectively trigger the mechanical switch, the accuracy of the step will decrease.

The electronic pedometer is mainly composed of an inertial sensor. When the subject moves, the center of gravity moves up and down slightly, and the inertial sensor detects the up and down movement signal and calculates the number of steps through the algorithm. But this algorithm must overcome the interference of vibration.

Since the mechanical step counting method in the past may be insensitive in the case of low speed, the method of judging the step by the sensor may also have a signal misjudgment. Therefore, in order to provide accurate motion steps in real time, it is still necessary. A more accurate step-by-step method.

It is an object of the present invention to provide an accurate step counting method that makes the step counting more accurate. The algorithm calculates the amplitude of the displacement signal or the acceleration signal of the subject by a conversion relationship and converts the corresponding dynamic time threshold. The dynamic time threshold can be used to limit the number of accumulated steps over a period of time to avoid false positives. To improve accuracy.

Other objects and advantages of the present invention will become apparent from the technical features disclosed herein.

In order to achieve one or a part or all of the above or other objects, an electronic sensor step counting method according to an embodiment of the present invention includes: using an electronic sensor to measure a step movement of a subject And generating a fluctuation signal map along with the step movement process of the subject, wherein the fluctuation signal graph has a plurality of peak points, and the plurality of peak points include an latest peak point, and each of the peak points Corresponding to an amplitude; smoothing the fluctuation signal map; calculating the time difference between the latest peak point and the previous peak point; and calculating the amplitude corresponding to the latest peak point according to a conversion relationship, and obtaining a The latest time threshold; and whether the time difference between the latest peak and its previous peak is greater than the latest time threshold to determine whether to count one step.

In an embodiment, the step of smoothing the fluctuation signal map includes: performing a filtering process on the fluctuation signal map to form a first digital signal; and performing a constant current level removal step on the first digital signal, Forming a second digit signal; and performing a moving average operation on the second digit signal to form a first smoothing signal.

In an embodiment, further zooming in on the first smoothing signal And the step of forming a third digit signal; and performing an integration operation on the third digit signal to form a second smoothing signal.

In one embodiment, the third digit signal comprises a signal less than zero and a signal greater than zero, the amplification processing step comprising: amplifying a signal less than zero by a factor of five; and dividing the signal greater than zero by a square. .

In an embodiment, the conversion relationship has a conversion relationship, and the conversion relationship includes: when the amplitude of the latest peak point is greater than the amplitude corresponding to the previous peak point, the latest time threshold is less than or equal to using the conversion relationship. The time threshold obtained by calculating the amplitude of the previous peak point. And when the amplitude of the latest peak point is smaller than the amplitude corresponding to the previous peak point, the latest time threshold is greater than or equal to the time threshold obtained by calculating the amplitude of the previous peak point using the conversion relationship.

In an embodiment, the step of performing the operation according to the conversion relationship includes: providing a first-step state signal generated by a walking state, and the first-step state signal has a first amplitude; Converting the relational operation to obtain a first time threshold; providing a second gait signal generated by a running state, the second gait signal having a second amplitude greater than the first amplitude; and the The two amplitudes are operated using the conversion relationship to obtain a second time threshold, and the second time threshold is less than the first time threshold.

An important feature of the present invention is a time threshold setting method that can adjust the step counting standard in real time and dynamically in response to the change of the motion state to improve the step counting accuracy under different motion states.

The above and other technical contents, features and effects of the present invention will become more apparent from the following detailed description of the preferred embodiments. The directional terms mentioned in the following embodiments, such as upper, lower, left, right, front or rear, etc., are only used to refer to the directions of the accompanying drawings. Therefore, the directional terms are used for illustration only and are not intended to limit the invention.

The invention is a more accurate step counting method than the prior art. During the walking or running of the subject, an electronic sensor is used to obtain a sensing signal, and the sensing signal passes through a series of After the digital signal processing is smoothed and amplified, the algorithm flow of the embodiment is executed on the processed signal to perform step detection.

As shown in FIG. 1A, the electronic sensor displays the actually measured sensing signal in the form of a wave signal diagram. In this embodiment, the electronic sensor is an accelerometer. The sensing signal provided is an acceleration signal. However, in other embodiments, the electronic sensor is not limited to an accelerometer, and the sensing signal is not limited to other types of signals such as an acceleration signal or a displacement signal. The horizontal axis of Figure 1A is the number of samples; the vertical axis is the value displayed by the accelerometer signal after analog to digital converter conversion. The fluctuation signal diagram of Figure 1A contains a lot of noise and the line shape is not flat. In order to improve the accuracy of the step, a digital signal processing flow is first provided to remove the noise to obtain a smoother line as shown in FIG. 1B. .

As shown in FIG. 2, it is a schematic diagram of a digital signal processing flow. Step S101 is to input the acceleration signal shown in FIG. 1A to the digital signal processing flow. Step S102 filters the acceleration signal with a digital band pass filter. In this embodiment, the characteristic parameter setting of the filter may be, for example, a bandwidth of 0.5 to 2 Hz, a sampling frequency of 360 Hz, and a filter order of 10 steps, and Use a Gaussian window function. Step S103 is to perform a DC level removal step on the filtered acceleration signal. In this embodiment, the acceleration signal is subtracted from the average value of the acceleration signals measured in the first 3 seconds. To remove the DC level of the acceleration signal. Step S104 is to perform a moving average operation on the acceleration signal after the DC level is removed. In this embodiment, a 32-order moving average operation is used, that is, the average number is calculated by 32 signal samples each time. In order to smooth the signal.

Next, in step S105, the smoothed signal is subjected to gain adjustment and signal amplification processing. In order to make the motion signal detected by the accelerometer more obvious, the acceleration signal is divided into a signal smaller than zero and a signal larger than zero for signal amplification processing, and the signal smaller than zero is amplified by 5 times. The signal greater than zero is divided by 10 and then squared. Finally, step S106 performs an integral operation on the acceleration signal after the amplification process, thereby achieving the purpose of smoothing and amplifying again.

As described above, the purpose of the moving average operation (S104) is to perform the first smoothing before the signal amplification processing (S105) to avoid amplifying the noise. The purpose of performing the second smoothing by the integral calculation (S106) is to perform a function of trimming after the signal is amplified (S105).

In the above embodiment, the step of the first smoothing process includes: performing a filtering process on the wave signal pattern provided by the electronic sensor to form a first digital signal; and performing the first bit signal on the first digital signal a bit removing step to form a second digit signal; and performing a moving average operation on the second digit signal to form a first smoothing signal.

The step of the second smoothing process includes: performing an amplification processing step on the first smoothing signal to form a third digit signal; and The bit signal performs an integration operation to form a second smoothed signal.

In an embodiment of the present invention, the digital signal processing flow is not limited to the flow shown in FIG. 2, and a method of removing the noise of the digital signal or a method of smoothing the digital signal pattern may be used. Instead of the procedure of the steps (S102) to (S106) shown in FIG.

FIG. 1B shows the waveform of the acceleration signal after the digital signal processing, which has a smoother waveform and more obvious peaks and troughs, and the lower edge is substantially at the same horizontal line, so that the position of the peak point is easily defined. After the digital signal is processed by the digital signal, it can be identified by an algorithm to determine whether it is a step or a step. The algorithm flow is shown in Figure 3.

Each waveform formed by the acceleration signal shown in FIG. 1A (shown by a dashed box) may also be referred to as a one-step signal, which is performed by an electronic sensor in a process in which the left and right legs of the person alternately step by step. A signal pattern formed by sensing. Referring to FIG. 1B and FIG. 3 simultaneously, step S201 inputs the acceleration signal after the smoothing process into the algorithm of the embodiment. Step S202 is to find a maximum value and a minimum value from the latest gait signal, thereby calculating the amplitude (Pa(i)) of the waveform. Step S203 is to determine whether the location of the maximum value is a newest peak point. If it is the latest peak point, proceed to step S204, otherwise, proceed to step S201. Step S204 is to calculate a time difference (Tp-p(i)) between the latest peak point and its previous peak point.

In particular, step S205 of the embodiment may provide a dynamic time threshold setting method, first calculating the amplitude (Pa(i)) of an latest gait signal, and using a conversion relationship to calculate the amplitude (Pa(i)) It is converted into a time interval, which is called the latest time threshold (Th _Tp-p ), and the corresponding relationship between the amplitude before conversion and the time threshold after conversion is shown in Table 1.

Table 1 shows that the conversion relationship has the following calculation principle: the gait signal generated by the slower walking state has a smaller amplitude relative to the running state, which corresponds to a larger time threshold. Conversely, the gait signal generated by the faster running state has a larger amplitude relative to the walking state, which corresponds to a smaller time threshold.

According to the calculation principle of the conversion relation, when the amplitude of the latest peak point is larger than the amplitude corresponding to the previous peak point, if the amplitude of the latest peak point is calculated by the conversion relation, the latest time threshold obtained will be A time threshold that is less than or equal to the amplitude of its previous peak. When the amplitude of the latest peak point is smaller than the amplitude corresponding to the previous peak point, if the amplitude of the latest peak point is calculated by the conversion relation, the obtained latest time threshold will be greater than or equal to the previous peak point. The time threshold obtained by converting the amplitude. When the amplitude of the latest peak point is equal to the amplitude corresponding to the previous peak point, if the amplitude of the latest peak point is calculated by the conversion relation, the obtained latest time threshold will be equal to the amplitude of the previous peak point. The time threshold obtained by conversion. As such, the time threshold is dynamically set as the amplitude of the most recent peak changes.

Next, in step S206, the time difference between the latest peak point and the previous peak point is compared with the latest time threshold to determine whether the time difference (Tp-p(i)) between the two peak points is greater than the latest. The time threshold, if yes, is counted as one step, otherwise the process proceeds to step S201.

Since the person may change between different movement states such as walking or running at any time during exercise, the time threshold setting method of the embodiment can adjust the step counting standard in real time according to the change of the motion state, thereby Improve step-by-step accuracy under different motion conditions.

Referring to FIG. 4, in summary of the foregoing embodiments, the step counting method of the present invention is generally composed of a digital signal processing flow (S100) and a step detection algorithm (S200). The digital signal processing flow (S100) includes a secondary signal smoothing flow (S110, S120). The first signal smoothing process (S110) includes the processes of steps (S101) to (S104) shown in FIG. 2. The second signal smoothing process (S120) includes the processes of the steps (S105) to (S106) shown in FIG. 2. The step number detecting process (S200) includes the processes of the steps (S201) to (S207) shown in FIG. However, in the step counting method of the present invention, signal smoothing is not limited to two.

Specifically, the step counting method of the present invention includes at least: providing an electronic sensor to a subject; using an electronic sensor to measure the step movement of the subject, and with the subject a step signal moving process generates a wave signal graph, wherein the wave signal graph has a plurality of peak points, wherein the plurality of peak points include a new peak point, and each of the peak points corresponds to an amplitude; The motion signal diagram performs a smoothing process; calculates the time difference between the latest peak point and the previous peak point; calculates the amplitude corresponding to the latest peak point according to a conversion relationship, and obtains a latest time threshold; and judges the latest Whether the time difference between the peak point and its previous peak point is greater than the latest time threshold to determine whether to count it as a step.

In the step counting method of the present invention, the acceleration signal formed by the up and down displacement caused by the walking or running of the subject is processed by the digital signal, and the number of steps of walking or running is identified through a one-step detection algorithm. . The steps of digital signal processing include filtering, DC level removal, moving average operation, gain adjustment, and integration operations. The step detection algorithm converts the amplitude of the acceleration signal into a corresponding dynamic time threshold through a conversion relationship, and the dynamic time threshold can be used to limit the number of step accumulations in the time to avoid misjudgment and improve The accuracy of the step.

The above is only the preferred embodiment of the present invention, and the scope of the invention is not limited thereto, that is, the simple equivalent changes and modifications made by the scope of the invention and the description of the invention are All remain within the scope of the invention patent. In addition, any of the objects or advantages or features of the present invention are not required to be achieved by any embodiment or application of the invention. In addition, the abstract sections and headings are only used to assist in the search of patent documents and are not intended to limit the scope of the invention.

1A is a schematic diagram of sensing signals of an electronic sensor according to an embodiment of the present invention.

FIG. 1B is a schematic diagram of a smoothing sensing signal of an electronic sensor according to an embodiment of the invention.

2 is a schematic diagram of a digital signal processing flow according to an embodiment of the present invention.

FIG. 3 is a schematic flow chart of a step number detection algorithm according to an embodiment of the present invention.

4 is a schematic diagram of a step counting method in accordance with an embodiment of the present invention.

Claims (7)

A step counting method for an electronic sensor, comprising: using an electronic sensor to measure the movement of the step of the subject, and generating a wave signal diagram along with the movement of the step of the subject, wherein The fluctuation signal diagram has a plurality of peak points, wherein the plurality of peak points include a new peak point, and each of the peak points corresponds to an amplitude; and the fluctuation signal map is smoothed; The time difference between the latest peak point and the previous peak point; the amplitude corresponding to the latest peak point is calculated according to a conversion relationship to obtain a latest time threshold; and the latest peak point and its previous peak point are determined Whether the time difference between the time is greater than the latest time threshold to determine whether the cumulative number of steps of the subject movement needs to be increased by one step. The step counting method of the electronic sensor according to claim 1, wherein the step of performing the smoothing process on the wobble signal map comprises: performing a filtering process on the wobble signal map to form a first a digital signal; performing a direct current level removal step on the first digital signal to form a second digital signal; and performing a moving average operation on the second digital signal to form a first smoothed signal. The step-by-step method of the electronic sensor as described in claim 2, further comprising: Performing an amplification processing step on the first smoothing signal to form a third digit signal; and performing an integration operation on the third digit signal to form a second smoothing signal. The step counting method of the electronic sensor of claim 3, wherein the third digit signal comprises a signal less than zero and a signal greater than zero, and the step of amplifying further comprises: The zero signal is amplified by a factor of five; and the signal greater than zero is divided by 10 and then squared. The step counting method of the electronic sensor according to claim 1, wherein the conversion relationship has a conversion relationship, and the conversion relationship includes: when the amplitude of the latest peak point is greater than a previous peak point thereof In the case of amplitude, the latest time threshold is less than or equal to the time threshold obtained by calculating the amplitude of the previous peak using the conversion relation. The step counting method of the electronic sensor according to claim 5, wherein the conversion relationship comprises: when the amplitude of the latest peak point is smaller than the amplitude corresponding to the previous peak point, The latest time threshold is greater than or equal to the time threshold obtained by calculating the amplitude of the previous peak using the conversion relationship. The step of calculating an electronic sensor according to claim 1, wherein the step of performing the operation according to the conversion relationship comprises: providing a first-step state signal generated by the walking state, and the first The gait signal has a first amplitude; Calculating the first amplitude using the conversion relationship to obtain a first time threshold; providing a second gait signal generated by the running state, the second gait signal having a greater than the first amplitude a second amplitude; and calculating the second amplitude using the conversion relationship to obtain a second time threshold, wherein the second time threshold is less than the first time threshold.