CN105962945A - Method and device for calculating step frequency and wearable equipment comprising device - Google Patents
Method and device for calculating step frequency and wearable equipment comprising device Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 33
- 238000001228 spectrum Methods 0.000 claims abstract description 124
- 230000001133 acceleration Effects 0.000 claims abstract description 76
- 238000004364 calculation method Methods 0.000 claims abstract description 15
- 238000000205 computational method Methods 0.000 claims description 14
- 230000000739 chaotic effect Effects 0.000 claims description 7
- 239000008280 blood Substances 0.000 description 5
- 210000004369 blood Anatomy 0.000 description 5
- 230000000386 athletic effect Effects 0.000 description 3
- 238000007405 data analysis Methods 0.000 description 2
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/103—Detecting, measuring or recording devices for testing the shape, pattern, colour, size or movement of the body or parts thereof, for diagnostic purposes
- A61B5/11—Measuring movement of the entire body or parts thereof, e.g. head or hand tremor, mobility of a limb
- A61B5/1118—Determining activity level
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/103—Detecting, measuring or recording devices for testing the shape, pattern, colour, size or movement of the body or parts thereof, for diagnostic purposes
- A61B5/11—Measuring movement of the entire body or parts thereof, e.g. head or hand tremor, mobility of a limb
- A61B5/112—Gait analysis
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/68—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient
- A61B5/6801—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be attached to or worn on the body surface
- A61B5/6802—Sensor mounted on worn items
- A61B5/681—Wristwatch-type devices
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/68—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient
- A61B5/6801—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be attached to or worn on the body surface
- A61B5/6813—Specially adapted to be attached to a specific body part
- A61B5/6829—Foot or ankle
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/72—Signal processing specially adapted for physiological signals or for diagnostic purposes
- A61B5/7203—Signal processing specially adapted for physiological signals or for diagnostic purposes for noise prevention, reduction or removal
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/72—Signal processing specially adapted for physiological signals or for diagnostic purposes
- A61B5/7235—Details of waveform analysis
- A61B5/7253—Details of waveform analysis characterised by using transforms
- A61B5/7257—Details of waveform analysis characterised by using transforms using Fourier transforms
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B2562/00—Details of sensors; Constructional details of sensor housings or probes; Accessories for sensors
- A61B2562/02—Details of sensors specially adapted for in-vivo measurements
- A61B2562/0219—Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches
Abstract
The invention discloses a step frequency calculation method and device and wearable equipment comprising the device, wherein the method comprises the following steps: an acquisition step, which is used for acquiring a PPG signal and an acceleration signal of a user in a motion state; a processing step, which is used for respectively carrying out Fourier processing on the collected PPG signals and acceleration signals to generate PPG frequency spectrums and acceleration frequency spectrums; and a calculating step of calculating a step frequency from the determined peak frequency. According to the step frequency calculation method and device and the wearable device comprising the device, the step frequency does not need to be calculated through the step number, the problem of poor calculated step frequency precision caused by inaccurate step counting is avoided, the step frequency calculation accuracy is improved, and a new step frequency calculation method is also provided.
Description
Technical field
The present invention relates to quantity of motion computing technique field, more particularly, to a kind of cadence computational methods and device and the wearable device comprising this device.
Background technology
Current wearable device (such as intelligent watch, Intelligent bracelet etc.) generally has record step number, the function of cadence, its principle is essentially: be perpendicular to the acceleration of the above-below direction on ground by acceleration transducer detection user, and change of based on this detected value and step number or body kinematics are counted to get step number, then by the cadence of step number correspondence Time Calculation user.Specifically, the mankind walking be one paracycle process, the vibration that human body produces in this process is also quasi-periodic, by sensor detection vibration (acceleration) signal, vibration (acceleration) signal meets a paracycle of certain amplitude (acceleration change) and duration, is then identified as a step and adds up.Then by the time that the step number of statistics is corresponding divided by completing this step number, cadence is i.e. obtained.Obviously, the method for such calculating cadence depends on recorded step number,
But, existing step number computational methods are easily had the situations such as the motion of similar acceleration change rule by noise, cycling etc. to walking to be affected, and during actual motion, take a walk, jog, pace, the acceleration change situation of running etc. is different, and be the most also doped with certain law or erratic noise.Now, just it is difficult to differentiate between the noise of rule and the acceleration change of rule, causes meter step on the high side or leakage meter step number, thus it is also inaccurate for causing calculated cadence.
Accordingly, it would be desirable to additionally find a kind of method calculating cadence, preferably it is not based on step number statistical computation cadence, it is possible to improve the accuracy that cadence calculates.
Summary of the invention
The invention aims to overcome defect present in above-described prior art, it is provided that the method and apparatus of a kind of calculating cadence being different from prior art and the wearable device comprising this device.In order to realize this purpose, the technical solution used in the present invention is as follows.
First aspect according to embodiment of the present invention, it is provided that a kind of cadence computational methods, including: acquisition step, for gathering PPG signal and the acceleration signal of the user being kept in motion；Processing step, for the PPG signal gathered and acceleration signal being carried out respectively Fourier's process, generating PPG frequency spectrum and acceleration frequency spectrum；And calculation procedure, summit in PPG frequency spectrum is set to fundamental frequency frequency peak, if there is frequency peak near the fundamental frequency and two times of frequencies of PPG frequency spectrum, and there is also frequency peak near the corresponding frequency in acceleration frequency spectrum, then utilize the frequency of frequency peak dot near two times of frequencies of PPG frequency spectrum to calculate cadence；Or, there is also frequency peak near frequency peak, and the corresponding frequency in acceleration frequency spectrum if existed near the fundamental frequency and half frequency of PPG frequency spectrum, then utilize the frequency of PPG frequency spectrum fundamental frequency to calculate cadence.
According to an embodiment, in described calculation procedure, if there is not frequency peak near the corresponding frequency in acceleration frequency spectrum, then the summit in acceleration frequency spectrum is set to fundamental frequency frequency peak, if there is frequency peak near the fundamental frequency and two times of frequencies of acceleration frequency spectrum, and there is also frequency peak near the corresponding frequency in PPG frequency spectrum, then utilize the frequency of frequency peak dot near two times of frequencies of PPG frequency spectrum to calculate cadence；Or, there is also frequency peak near frequency peak, and the corresponding frequency in PPG frequency spectrum if existed near the fundamental frequency and half frequency of acceleration frequency spectrum, then utilize the frequency of frequency peak dot near PPG frequency spectrum fundamental frequency to calculate cadence.
According to further embodiment, optionally, described cadence computational methods also include judging step, by motion sensor, judge the most described user is kept in motion.
According to another embodiment, optionally, described cadence computational methods also include reminding step, if be used for can not find corresponding frequency peak in calculation procedure to calculate cadence, remind user's stride frequency chaotic.
According to another embodiment, preferably, after at PPG frequency spectrum and acceleration frequency spectrum, one of them determines fundamental frequency frequency peak, frequency peak near its half frequency and near two times of frequencies should be greater than first predetermined percentage at fundamental frequency peak frequently, and frequency peak near corresponding frequency should occupy the second predetermined percentage of spectrum energy respectively in another frequency spectrum.
According to yet another embodiment, it is preferred that the scope of its intermediate-frequeney point is less than maximum possible cadence.
Second aspect according to embodiment of the present invention, it is provided that a kind of cadence calculates device, including: acquisition module, for gathering PPG signal and the acceleration signal of the user being kept in motion；Processing module, for the PPG signal gathered and acceleration signal carry out Fourier's process respectively, generates PPG frequency spectrum and acceleration frequency spectrum；And computing module, summit in PPG frequency spectrum is set to fundamental frequency frequency peak, if there is frequency peak near the fundamental frequency and two times of frequencies of PPG frequency spectrum, and there is also frequency peak near the corresponding frequency in acceleration frequency spectrum, then utilize the frequency of frequency peak dot near two times of frequencies of PPG frequency spectrum to calculate cadence；Or, there is also frequency peak near frequency peak, and the corresponding frequency in acceleration frequency spectrum if existed near the fundamental frequency and half frequency of PPG frequency spectrum, then utilize the frequency of PPG frequency spectrum fundamental frequency to calculate cadence.
According to an embodiment, if there is not frequency peak near the corresponding frequency in acceleration frequency spectrum, then the summit in acceleration frequency spectrum is set to fundamental frequency frequency peak, if there is frequency peak near the fundamental frequency and two times of frequencies of acceleration frequency spectrum, and there is also frequency peak near the corresponding frequency in PPG frequency spectrum, then utilize the frequency of frequency peak dot near two times of frequencies of PPG frequency spectrum to calculate cadence；Or, there is also frequency peak near frequency peak, and the corresponding frequency in PPG frequency spectrum if existed near the fundamental frequency and half frequency of acceleration frequency spectrum, then utilize the frequency peak dot frequency near PPG frequency spectrum fundamental frequency to calculate cadence.
According to further embodiment, optionally, described cadence calculates device and also includes judge module, is used for judging the most whether user is kept in motion.
According to another embodiment, optionally, described cadence calculates device and also includes prompting module, if when described computing module can not find corresponding frequency peak to calculate cadence during calculating cadence, reminding cadence chaotic.
The 3rd aspect according to embodiment of the present invention, it is provided that a kind of wearable device, calculates device including the cadence described in second aspect according to embodiment of the present invention.
Cadence computational methods according to embodiment of the present invention and device and comprise the wearable device of this device, need not calculate cadence by step number, avoid meter and walk the problem that the inaccurate cadence precision calculated brought is poor, improve the accuracy that cadence calculates, also provide a kind of new method calculating cadence.
Being specifically described the present invention below in conjunction with accompanying drawing and by embodiment, the most identical or essentially identical parts use identical reference instruction.
Accompanying drawing explanation
Fig. 1 is the indicative flowchart of the cadence computational methods according to one embodiment of the invention；
Fig. 2 a and Fig. 2 b is the PPG signal of the user's a period of time being kept in motion the most collected respectively and acceleration signal obtains spectrogram after fast Fourier processes；
Fig. 3 a and Fig. 3 b is the PPG signal of the user's a period of time being kept in motion collected in another example respectively and acceleration signal obtains spectrogram after fast Fourier processes；
Fig. 4 is the schematic block diagram that a kind of cadence calculates device.
Detailed description of the invention
In skin, blood situation follows change with heartbeat, illuminates skin surface by launching green glow, and photoelectric sensor receives the Strength Changes of reflection light, can analyze the heart beating situation of human body.When human body is kept in motion, in skin blood situation except saltus step of following one's inclinations outside the pale of civilization, also change with human motion.Analyzing according to human body behavioural habits, human body is when moving, in addition to lower limb alternately walking produces periodically motion, upper limb consequently also can the swing of generating period, therefore can cause the situation of the blood shake produced due to motion jitter.So, wearable device is worn on hand by user, when user is kept in motion, contains the information of the dermathemia that heartbeat causes and the information of the blood shake of motion jitter generation in the photosignal that photoelectric sensor detects.
The PPG(photoplethaysmography of the information comprising the dermathemia that heartbeat causes and the information of blood that motion jitter produces shake) signal is compared with the PPG signal of the information only comprising the dermathemia that heartbeat causes, distinct feature is that: the peak (peak that peak may be caused for motion or heart rate+motion superposition herein) at heart rate peak periodically occurs being different from, the frequency spectrum obtained after PPG signal is carried out Fourier's process can be distinguished the frequency on the peak periodically occurred in former PPG signal.
After processing the signal Fourier of rule swing arm motion, frequency spectrum there will be one group of spectrum energy Relatively centralized and frequency coordinate becomes the peak of twice relation, such as: fundamental frequency peak and frequency multiplication peak, or half frequency peak and fundamental frequency peak.The most either heart rate signal or such one group of peak all can occur in motor message (superposed signal of motor message+heart rate signal), so by repeatedly compareing peak (fundamental frequency peak and the two frequency multiplication peaks that in PPG frequency spectrum and acceleration frequency spectrum, necessary simultaneous two class frequencys are close, or half frequency peak and fundamental frequency peak), can determine that the used peak calculating cadence is the peak of motor message (superposed signal of motor message+heart rate signal), thus can improve the accuracy calculating cadence.Owing to people is on foot time, frequency of waving is the half of cadence, i.e. wave two steps of once walking, when therefore calculating cadence, the peak point coordinate at peak that one group of peak intermediate-frequeney point coordinate of twice relation is bigger can be become to calculate cadence with PPG frequency spectrum intermediate frequency spectrum energy Relatively centralized and frequency coordinate.
As it is shown in figure 1, be the indicative flowchart of the cadence computational methods according to one embodiment of the invention, specifically include that acquisition step S200, process step S300, and calculation procedure S400；In another embodiment, include the most alternatively judging step S100；In yet another embodiment, include the most alternatively reminding step S500.
Wherein in judging step S100, by motion sensor, judge the most described user is kept in motion.In one embodiment, described motion sensor for example, acceleration transducer (can use same acceleration transducer with following acquisition step), acceleration by continuous collecting user, analyze acceleration change situation, and then judge that the current state of user is non-athletic state or kinestate.In one embodiment, for example, acceleration transducer gathers user's acceleration, if sample rate e.g. 25Hz, it is cumulative and calculate that every 25 pen data carry out one-shot change amount, and adjacent two sampled datas are subtracted each other to take absolute value and then sued for peace, as the sport rank of 1 second.The data of every 1 second, as a unit, are often deposited enough 4 and are taken once average (with nearest 4 calculating), as " nearest 4 seconds sport ranks ".By nearest 4 seconds sport ranks compared with predetermined threshold, if sport rank was more than or equal to predetermined threshold in nearest 4 seconds, then it is assumed that user is kept in motion, and can start to calculate user's stride frequency；Otherwise it is assumed that user is in non-athletic state, do not calculate user's stride frequency.The empirical value that wherein according to predetermined threshold, a large amount of physical activity data analysiss obtain, the most in one embodiment, by actual data analysis, can be set to 200 by this predetermined threshold.
Acquisition step S200 is for gathering PPG signal and the acceleration signal of the user being kept in motion, and such as, by the sustainable PPG signal gathering user of photoelectric sensor, gathers acceleration signal by acceleration transducer.Process step S300 and be used for the PPG signal gathered and acceleration signal are carried out respectively Fourier's process, generate PPG frequency spectrum and acceleration frequency spectrum；The most in one embodiment, described Fourier is processed as fast Fourier transform.
In calculation procedure S400, it is considered to no matter human body is in any kinestate, and cadence always exists a ultimate value, and the cadence exceeding this ultimate value is not generally possible to appearance.So during frequency spectrum takes peak point coordinate and spectrum analysis and calculates cadence, interval restriction can be carried out.Such as, in one embodiment, if setting the limit cadence of people as 300step/min, i.e. 5step/s, then should be limited to interval [0,5] and take peak point coordinate and be analyzed, calculate cadence.
In PPG frequency spectrum, upper certain interval (such as [0 at abscissa (in units of Hz), 5] in), take the peak point coordinate (a at summit in frequency spectrum (i.e. fundamental frequency frequency peak), b), frequency peak has been looked for whether near two times of frequencies or near half frequency, its peak value should be more than first predetermined percentage at fundamental frequency frequency peak, it is set greater than about 30% (the most also this value can be set as 20%, 25%, 35% etc., lower with) of fundamental frequency frequency peak (i.e. summit) the most in one embodiment；Wherein " near " excursion can be set as in one embodiment ± about 0.1 (certainly, be not excluded for the most also can this value being set as ± 0.15 etc., lower same), then, the abscissa at the frequency peak found should fall at interval [2a-0.1,2a+0.1] or interval [0.5a-0.1,0.5a+0.1] in:
If the abscissa that there are the peak point coordinate at a frequency peak in PPG frequency spectrum falls in interval [2a-0.1,2a+0.1], wherein 0≤2a+0.1≤5；And, also frequency peak it has been respectively present near corresponding fundamental frequency and near two times of frequencies in acceleration frequency spectrum, its frequency peak should each occupy the second predetermined percentage of spectrum energy, it is set greater than about 15% (the most also this value can be set as 10%, 20% etc., lower with) of spectrum energy the most in one embodiment；Wherein " near " excursion can be set as in one embodiment ± about 0.2 (certainly, be not excluded for the most also can this value being set as ± 0.15, ± 0.25 etc., lower same), the abscissa of the peak point coordinate that namely there are two peaks respectively falls in interval [a-0.2, a+0.2] (i.e. near fundamental frequency) and [2a-0.2,2a+0.2] in (near i.e. two times frequencies), wherein 0≤2a+0.2≤5；Then, then take the frequency that abscissa in PPG frequency spectrum falls at the frequency peak dot of interval [2a-0.1,2a+0.1] and calculate cadence, if the coordinate of this peak point is (c, d), then cadence=60c(step/min)；It practice, the frequency of the frequency peak dot near two times of frequencies of PPG frequency spectrum is cadence, utilizes its calculating cadence namely described frequency to be multiplied by 60 thus be converted to step number per minute；
If the abscissa that there are the peak point coordinate at a frequency peak in PPG frequency spectrum falls in interval [0.5a-0.1,0.5a+0.1]；And, also frequency peak it has been respectively present near corresponding fundamental frequency and near half frequency in acceleration frequency spectrum, its frequency peak should each occupy the second predetermined percentage of spectrum energy, it is set greater than about the 15% of spectrum energy the most in one embodiment, wherein " near " excursion can be set as ± about 0.2 in one embodiment, the abscissa of the peak point coordinate that namely there are two peaks respectively falls in interval [a-0.2, a+0.2] (i.e. near fundamental frequency) and [0.5a-0.2, 0.5a+0.2] in (near i.e. half frequency), then, then take in PPG frequency spectrum the frequency of fundamental frequency to calculate cadence；As described above, the coordinate of this peak point is (a, b), then cadence=60a(step/min)；It practice, the frequency of PPG frequency spectrum fundamental frequency is cadence, utilizes its calculating cadence namely described frequency to be multiplied by 60 thus be converted to step number per minute.
In the above-described embodiments, when finding an other peak after finding summit, it is desirable to this peak-to-peak value, more than first predetermined percentage (such as 30%) of summit, is the probability including calculating in order to reduce the Interference Peaks caused by noise in, the accuracy calculating cadence is improved.It is obvious peak in spectrogram to ensure found one group peak (fundamental frequency peak and frequency multiplication peak), exclusive PCR peak, improving the discrimination at motion peak (motion+heart rate superposition peak), the fundamental frequency peak found and the peaks demand at frequency multiplication peak each occupy more than second predetermined percentage (such as 15%) of spectrum energy.
In above process, if after determining summit (i.e. fundamental frequency frequency peak) in PPG frequency spectrum, frequency peak is the most there is not near two times of frequencies or near half frequency, when namely can not find corresponding frequency peak to carry out cadence calculating, then according to an embodiment, chaotic by reminding step S500 to prompt the user with cadence.
If after determining summit (i.e. fundamental frequency frequency peak) in PPG frequency spectrum, frequency peak is there are near two times of frequencies or near half frequency, but there is not frequency peak near the corresponding frequency in acceleration frequency spectrum, according to above-described embodiment, namely at the interval [a-0.2 of acceleration frequency spectrum, a+0.2] and [2a-0.2,2a+0.2] or [a-0.2, a+0.2] and [0.5a-0.2,0.5a+0.2] there is not corresponding frequency peak, then according to an embodiment, calculation procedure can proceed to following process:
In acceleration frequency spectrum, upper certain interval (such as [0 at abscissa (in units of Hz), 5] in), take the peak point coordinate (m at summit in frequency spectrum (i.e. fundamental frequency frequency peak), n), having looked for whether a frequency peak near two times of frequencies or near half frequency, its peak value should be set greater than about the 30% of summit the most in one embodiment more than first predetermined percentage at fundamental frequency frequency peak；Wherein " near " excursion can be set as ± about 0.1 in one embodiment, then, the abscissa at the frequency peak found should fall in interval [2m-0.1,2m+0.1] or interval [0.5m-0.1,0.5m+0.1]:
If the abscissa that there are the peak point coordinate at a frequency peak in acceleration frequency spectrum falls at interval [2m
-0.1,2m+0.1] in, wherein 0≤2m+0.1≤5；And, also frequency peak it has been respectively present near corresponding fundamental frequency and near two times of frequencies in PPG frequency spectrum, its frequency peak should each occupy the second predetermined percentage of spectrum energy, it is set greater than about the 15% of spectrum energy the most in one embodiment, wherein " near " excursion can be set as ± about 0.2 in one embodiment, the abscissa of the peak point coordinate that namely there are two peaks respectively falls in interval [m-0.2, m+0.2] (i.e. near fundamental frequency) and [2m-0.2, 2m+0.2] in (near i.e. two times frequencies), wherein 0≤2m+0.2≤5；Then, then take the frequency that abscissa in PPG frequency spectrum falls at the frequency peak dot of interval [2m-0.2,2m+0.2] and calculate cadence, if the coordinate of this peak point is (p, q), then cadence=60p(step/min)；It practice, the frequency of the frequency peak dot near two times of frequencies of PPG frequency spectrum is cadence, utilizes its calculating cadence namely described frequency to be multiplied by 60 thus be converted to step number per minute；
If the abscissa of peak point coordinate that there are a frequency peak in acceleration frequency spectrum fall interval [0.5m-0.1,
0.5m+0.1] in；And, also frequency peak it has been respectively present near corresponding fundamental frequency and near half frequency in PPG frequency spectrum, its frequency peak should each occupy the second predetermined percentage of spectrum energy, it is set greater than about the 15% of spectrum energy the most in one embodiment, wherein " near " excursion can be set as ± about 0.2 in one embodiment, the abscissa of the peak point coordinate that namely there are two peaks respectively falls in interval [m-0.2, m+0.2] and [0.5m-0.2,0.5m+0.2]；Then, then the frequency taking near fundamental frequency in PPG frequency spectrum the frequency peak (in i.e. interval [m-0.2, m+0.2]) calculates cadence, if the coordinate of this peak point is (r, s), then cadence=60r(step/min)；It practice, the peak point frequency at the frequency peak near PPG frequency spectrum fundamental frequency is cadence, utilizes its calculating cadence namely described frequency to be multiplied by 60 thus be converted to step number per minute.
In above process, if after determining summit (i.e. fundamental frequency frequency peak) in acceleration frequency spectrum, frequency peak is the most there is not near two times of frequencies or near half frequency, when namely can not find corresponding frequency peak to carry out cadence calculating, then according to an embodiment, chaotic by reminding step S500 to prompt the user with cadence；If there is not frequency peak near the corresponding frequency in PPG frequency spectrum so that cadence calculates when cannot be carried out, chaotic again by reminding step S500 to prompt the user with cadence.
As shown in Figure 2 a and 2 b, it is the PPG signal of the user's a period of time being kept in motion the most collected respectively and spectrogram that acceleration signal obtains after fast Fourier processes.In two spectrograms, one group peak (fundamental frequency peak, two frequency multiplication peaks) all can be distributed near identical abscissa, this group peak is relevant to motion.On the PPG spectrogram shown in Fig. 2 a, except the peak relevant to motion, also can there is following simple heart rate peak or Interference Peaks.Therefore, in the embodiment in accordance with the invention, it is further added by confirming that the peak found on PPG is the step at the peak that motion causes by acceleration spectrogram auxiliary, confirms that the peak found is motion peak or motion, heart rate superposition peak；It addition, spectrum energy is limited when finding one group of peak of same distribution of another collection of illustrative plates, it is simply that in order to avoid: when having other peaks a large amount of in such as the PPG spectrogram of Fig. 2 a, the peak of non-athletic is screened, minimizing error rate.In this demonstration example, cadence=2.844*60=170.64(step/min).
As shown in Figure 3 a and Figure 3 b shows, it is the PPG signal of the user's a period of time being kept in motion collected in another example respectively and spectrogram that acceleration signal obtains after fast Fourier processes.In two spectrograms, one group peak (fundamental frequency peak, half frequency peak) all can be distributed near identical abscissa, this group peak is relevant to motion.PPG spectrogram as shown in Figure 3 a is relatively cleaner, easily tells such one group of peak, can speculate and think that heart rate is substantially superposition with motion, and the PPG spectrogram of this type is prone to analyze cadence, and the simple PPG spectrogram that passes through just can analyze cadence.But, as the PPG spectrogram of that type shown in Fig. 2 a occurs, in order to improve precision of analysis, need to combine acceleration spectrogram and be analyzed with auxiliary.In this demonstration example, cadence=2.747*60=164.82(step/min).
As shown in Figure 4, it is the schematic block diagram calculating device 400 according to a kind of cadence of one embodiment of the invention, specifically includes that acquisition module 404, processing module 406, and computing module 408；In another embodiment, judge module 402 is included the most alternatively；In yet another embodiment, prompting module 410 is included the most alternatively.These modules can be realized by software, hardware, firmware or a combination thereof.Wherein:
-judge module 402 is used for performing step S100；
-acquisition module 404 is used for performing step S200；
-processing module 406 is used for performing step S300；
-computing module 408 is used for performing step S400；And
-prompting module 410 is used for performing step S500.
Calculate device 400 according to the cadence of above-described embodiment and may be implemented in various wearable device, such as intelligent watch, bracelet, foot ring etc., and can be implemented in combination in the processor in wearable device, acceleration transducer, photoelectric sensor, display, voice playing device etc..
Describe the present invention above by specific embodiment, but the present invention is not limited to these specific embodiments.Those skilled in the art should be understood that, the present invention can also be made various amendment, equivalent, change etc., such as it is divided into two or more steps or module to realize a step in above-described embodiment or module, or contrary, the function of two or more steps in above-described embodiment or module is placed in a step or module and realizes.But, these conversion, all should be within protection scope of the present invention without departing from the spirit of the present invention.It addition, some terms that present specification and claims is used not are to limit, it is only for be easy to describe.Additionally, " embodiment ", " another embodiment " described in above many places etc. represents different embodiments, naturally it is also possible to it is completely or partially combined in one embodiment.
Claims (11)
1. cadence computational methods, it is characterised in that including:
Acquisition step, for gathering PPG signal and the acceleration signal of the user being kept in motion；
Processing step, for the PPG signal gathered and acceleration signal being carried out respectively Fourier's process, generating PPG frequency spectrum and acceleration frequency spectrum；And
Calculation procedure, summit in PPG frequency spectrum is set to fundamental frequency frequency peak, there is also frequency peak near frequency peak, and the corresponding frequency in acceleration frequency spectrum if existed near the fundamental frequency and two times of frequencies of PPG frequency spectrum, then utilize the frequency of frequency peak dot near two times of frequencies of PPG frequency spectrum to calculate cadence；Or, there is also frequency peak near frequency peak, and the corresponding frequency in acceleration frequency spectrum if existed near the fundamental frequency and half frequency of PPG frequency spectrum, then utilize the frequency of PPG frequency spectrum fundamental frequency to calculate cadence.
2. cadence computational methods as claimed in claim 1, it is characterized in that: in described calculation procedure, if there is not frequency peak near the corresponding frequency in acceleration frequency spectrum, then the summit in acceleration frequency spectrum is set to fundamental frequency frequency peak, if there is frequency peak near the fundamental frequency and two times of frequencies of acceleration frequency spectrum, and there is also frequency peak near the corresponding frequency in PPG frequency spectrum, then utilize in PPG frequency spectrum the frequency of frequency peak dot near two times of frequencies to calculate cadence；Or, there is also frequency peak near frequency peak, and the corresponding frequency in PPG frequency spectrum if existed near the fundamental frequency and half frequency of acceleration frequency spectrum, then utilize the frequency peak dot frequency near PPG frequency spectrum fundamental frequency to calculate cadence.
3. cadence computational methods as claimed in claim 1 or 2, it is characterised in that also include:
Judge step, by motion sensor, judge the most whether user is kept in motion.
4. cadence computational methods as claimed in claim 1 or 2, it is characterised in that also include:
Remind step, if be used for can not find corresponding frequency peak in calculation procedure to calculate cadence, remind user's stride frequency chaotic.
5. cadence computational methods as claimed in claim 1 or 2, it is characterized in that: after at PPG frequency spectrum and acceleration frequency spectrum, one of them determines fundamental frequency frequency peak, frequency peak near its half frequency and near two times of frequencies should be greater than first predetermined percentage at fundamental frequency peak frequently, and frequency peak near corresponding frequency should occupy more than the second predetermined percentage of spectrum energy respectively in another frequency spectrum.
6. cadence computational methods as claimed in claim 1 or 2, it is characterised in that: the scope of its intermediate-frequeney point is less than maximum possible cadence.
7. a cadence calculates device, it is characterised in that including:
Acquisition module, for gathering PPG signal and the acceleration signal of the user being kept in motion；
Processing module, for the PPG signal gathered and acceleration signal carry out Fourier's process respectively, generates PPG frequency spectrum and acceleration frequency spectrum；And
Computing module, summit in PPG frequency spectrum is set to fundamental frequency frequency peak, there is also frequency peak near frequency peak, and the corresponding frequency in acceleration frequency spectrum if existed near the fundamental frequency and two times of frequencies of PPG frequency spectrum, then utilize the frequency of frequency peak dot near two times of frequencies of PPG frequency spectrum to calculate cadence；Or, there is also frequency peak near frequency peak, and the corresponding frequency in acceleration frequency spectrum if existed near the fundamental frequency and half frequency of PPG frequency spectrum, then utilize the frequency of PPG frequency spectrum fundamental frequency to calculate cadence.
8. cadence as claimed in claim 7 calculates device, it is characterized in that: if there is not frequency peak near the corresponding frequency in acceleration frequency spectrum, then the summit in acceleration frequency spectrum is set to fundamental frequency frequency peak, if there is frequency peak near the fundamental frequency and two times of frequencies of acceleration frequency spectrum, and there is also frequency peak near the corresponding frequency in PPG frequency spectrum, then utilize the frequency of frequency peak dot near two times of frequencies of PPG frequency spectrum to calculate cadence；Or, there is also frequency peak near frequency peak, and the corresponding frequency in PPG frequency spectrum if existed near the fundamental frequency and half frequency of acceleration frequency spectrum, then utilize the frequency peak dot frequency near PPG frequency spectrum fundamental frequency to calculate cadence.
9. cadence calculates device as claimed in claim 7 or 8, it is characterised in that also include:
Judge module, is used for judging the most whether user is kept in motion.
10. cadence calculates device as claimed in claim 7 or 8, it is characterised in that also include:
Prompting module, if when described computing module can not find corresponding frequency peak to calculate cadence during calculating cadence, reminding user's stride frequency chaotic.
11. 1 kinds of wearable devices, it is characterised in that: include that the cadence as according to any one of claim 7 to 10 calculates device.
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