WO2017193594A1 - Pwm circuit duty ratio adjustment method and system for blood pressure measurement apparatus - Google Patents

Abstract

A PWM circuit duty ratio adjustment method and system for a blood pressure measurement apparatus. The PWM circuit duty ratio adjustment method for a blood pressure measurement apparatus comprises the following steps: when a blood pressure measurement apparatus is used, acquiring a real-time atmospheric pressure in a cuff (S10); calculating a duty ratio of a PWM circuit in the blood pressure measurement apparatus according to the real-time atmospheric pressure and a duty ratio-atmospheric pressure relation model (S20), wherein the duty ratio-atmospheric pressure relation model represents a functional relation between the duty ratio and the atmospheric pressure when a rising velocity of the atmospheric pressure in the cuff is constant; and adjusting a working duty ratio of the PWM circuit according to the duty ratio (S30). The PWM circuit duty ratio adjustment method and system for a blood pressure measurement apparatus are applicable to various kinds or types of blood pressure measurement apparatuses, have a relatively high adjustment effect, and ensure the working stability of a PWM circuit.

Description

Method and system for adjusting PWM circuit duty ratio of blood pressure measuring device Technical field

The present invention relates to the field of electronic technology, and in particular, to a method and system for adjusting a duty cycle of a PWM circuit of a blood pressure measuring device.

Background technique

In a blood pressure measurement device such as a rising blood pressure meter measurement, in order to improve measurement accuracy and stability, it is generally necessary to keep the air pressure increase rate in the cuff of the blood pressure measurement device constant. The constant pressurization speed can reduce the interference of the air pump to the measurement results and obtain a more stable signal. In order to achieve constant speed pressurization, the control of the air pump is particularly important. The driving of the air pump is generally a PWM circuit, and the air pumping power of the air pump can be adjusted by adjusting the duty ratio of the PWM to achieve constant acceleration of the air pressure in the cuff.

In the conventional scheme, the correlation control algorithm can be used to adjust the duty cycle of the PWM circuit according to parameters such as the pressing time. However, different types or different types of blood pressure measuring devices use different control algorithms to make the PWM circuit duty cycle adjustment scheme different. Misalignment, it is easy to affect the adjustment effect of the duty cycle.

Summary of the invention

Based on this, it is necessary to provide a method and system for adjusting the duty ratio of the PWM circuit of the blood pressure measuring device in view of the technical problem that the conventional solution easily affects the duty ratio adjustment effect.

A PWM circuit duty ratio adjustment method for a blood pressure measuring device includes the following steps:

Obtain real-time air pressure in the cuff while the blood pressure measuring device is working;

Calculating a duty cycle of the PWM circuit in the blood pressure measuring device according to the real-time air pressure and duty-pressure relationship model; wherein the duty-pressure relationship model indicates that the duty ratio and the air pressure rising speed in the cuff are constant a functional relationship between pressures;

The duty cycle of the PWM circuit is adjusted according to the duty cycle.

The PWM circuit duty ratio adjustment method of the blood pressure measuring device can determine the duty ratio of the PWM circuit according to the real-time air pressure and the duty-pressure relationship model, and realize the adjustment of the duty ratio of the PWM circuit, wherein the duty ratio is adjusted. Mainly affected by the real-time air pressure in the corresponding cuff, it can be applied to various types or models of blood pressure measuring devices. The higher adjustment effect ensures the stability of the PWM circuit.

In one embodiment, the PWM circuit duty ratio adjustment method of the blood pressure measurement device may further include:

Controlling the PWM circuit to inflate the experimental air volume under a plurality of set duty ratios;

In each process of inflating the experimental gas capacity, the function relationship between the gas pressure rising velocity and the gas pressure in the experimental gas volume is obtained, and a rising velocity-pressure relationship model is obtained;

The relationship between the duty ratio and the air pressure when the air pressure rising speed in the experimental air volume is constant is obtained from the rising speed-pressure relationship model, and the duty ratio-pressure relationship model is obtained.

The PWM circuit duty ratio adjustment method of the blood pressure measuring device obtains a rising speed-pressure relationship model between the air pressure rising speed and the air pressure in the experimental air volume when the PWM circuit inflates the experimental air capacity at different set duty ratios. In order to obtain the corresponding duty cycle-pressure relationship model, the accuracy of the obtained duty cycle-pressure relationship model can be improved.

In one embodiment, the duty cycle-pressure relationship model includes D=a×P+d; wherein P is the air pressure in the cuff, D is the duty cycle of the PWM circuit, and a is the duty cycle-pressure relationship. The first coefficient of the model, d is the second coefficient of the duty cycle-barometric relationship model.

In this embodiment, the duty-pressure relationship model is simplified to a linear relationship model of D=a×P+d, and the efficiency of obtaining the corresponding duty ratio by the above-described duty-pressure relationship model can be improved.

In one embodiment, the PWM circuit duty ratio adjustment method of the blood pressure measurement device may further include:

When the gas pressure rise rate is constant in the experimental gas volume, multiple sets (P _i , D _i ) corresponding to the i-th experimental gas volume are obtained, and D corresponding to the i-th experimental gas volume is determined according to the plurality of sets (P _i , D _i ). _i = a × P _i + d of the first coefficient a _i and the second coefficient d _i ; wherein D _i represents the duty cycle of the PWM circuit corresponding to the i-th experimental gas volume, and P _i represents the duty of the PWM circuit When the ratio is D _i , the pressure in the corresponding experimental gas volume;

The a and d are determined according to the respective a _i and d _i .

In this embodiment, when the gas pressure rising rate in the experimental gas volume is constant, a plurality of sets (P _i , D _i ) corresponding to the plurality of experimental gas contents are respectively obtained, thereby determining the first coefficient and the second coefficient corresponding to the respective experimental gas contents. Further determining the corresponding coefficients of the duty-pressure relationship model according to the plurality of first coefficients and the second coefficients, respectively, can ensure the rationality of the determined coefficients.

As an embodiment, the steps of determining the a and d according to the respective a _i and d _i include:

According to each a _i and formula

Calculate a;

According to each d _i and formula

Calculate d; where i is an integer greater than or equal to 1 and less than or equal to k, and k represents the number of different experimental gas volumes.

In one embodiment, the PWM circuit duty ratio adjustment method of the blood pressure measurement device may further include:

Selecting n times with equal intervals in the set time period;

Obtaining the air pressure P[j] in the cuff at each moment; wherein j is an integer greater than or equal to 1 and less than or equal to n, and P[j] is the air pressure in the cuff at the jth time;

Calculate the air pressure rise speed deviation at the j+1th time according to the air pressure in the cuff at each moment and the formula ΔS[j+1]=S ₀ -(P[j+1]-P[j]); where ΔS[ j+1] is the air pressure rising speed deviation at the j+1th time, P[j+1] is the air pressure in the cuff at the j+1th time, and S ₀ is the preset air pressure rising speed;

According to ΔS[j+1] and formula

Calculate the average boost speed deviation during the set time period;

To set the average boost speed deviation during the time period;

According to ΔS[j+1],

And formula

Calculating a fine adjustment coefficient; wherein Δd is a fine adjustment coefficient, and k _m represents a preset fine adjustment ratio parameter;

The second coefficient is updated to d + Δd according to the trimming coefficient.

In this embodiment, the fine adjustment coefficient is determined according to the air pressure in the cuff at a plurality of times during the use of the blood pressure measuring device and the corresponding air pressure rising speed to update the second coefficient, thereby further improving the accuracy of the determined duty ratio-pressure relationship model.

In one embodiment, after acquiring the real-time air pressure in the cuff, the method further includes:

The real-time air pressure is passed through a low-pass filter to filter out high-frequency signals in the real-time air pressure.

In this embodiment, the high frequency signal in the real-time air pressure can be filtered out, the influence of the noise signal such as the high-frequency signal on the duty cycle acquisition process is reduced, and the accuracy of the obtained duty ratio is improved.

As an embodiment, the low pass filter includes:

P _out [m]=b ₁ ×P _in [m]+b ₂ ×P _in [m-1]+b ₃ ×P _in [m-2]-b ₄ ×P _out [m-1]-b ₅ ×P _out [m-2];

Where P _in [m] is the input air pressure at the current moment of the low-pass filter, P _out [m] is the output air pressure at the current moment of the low-pass filter, and P _in [m-1] is the low-pass filter at the first moment. Enter the air pressure, P _out [m-1] is the output air pressure of the low-pass filter at the first moment, P _in [m-2] is the input air pressure of the low-pass filter at the second moment, P _out [m-2] is the first The output air pressure of the low-pass filter at two times, b ₁ , b ₂ , b ₃ , b ₄ and b ₅ are respectively filter coefficients, the first time is the previous time of the current time, and the second time is the first time The moment before the moment.

In one embodiment, the step of calculating the duty cycle of the PWM circuit in the blood pressure measuring device according to the real-time air pressure and duty-pressure relationship model further includes:

Detecting whether the duty ratio is within a duty cycle interval [D _min , D _max ]; wherein D _min is a duty cycle lower limit value of the PWM circuit, and D _max is a duty cycle upper limit value of the PWM circuit;

If the duty ratio exceeds D _max , the duty ratio is set to D _max ;

If the duty ratio is less than D _min , the duty ratio is set to D _min .

In this embodiment, the excessive duty ratio is set as the duty cycle upper limit value of the PWM circuit, and the excessively small duty ratio is set as the duty cycle lower limit value of the PWM circuit, so that the duty ratio of the PWM circuit can be one. Keeping within the corresponding working range can ensure the safety of the PWM circuit.

As an embodiment, the step of calculating the duty ratio of the PWM circuit in the blood pressure measuring device according to the real-time air pressure and the duty-pressure relationship model further includes:

Obtaining a duty ratio of the first time PWM circuit; wherein the first time is a previous time of the current time;

According to the formula

Updating the duty cycle of the current time; wherein D[m] is the duty cycle after the current time is updated,

The duty ratio of the current duty cycle-pressure relationship model output, D[m-1] is the duty ratio of the first time;

The duty cycle of the PWM circuit is determined based on the updated duty cycle.

In this embodiment, the duty ratio of the corresponding PWM circuit can be updated according to the duty ratio of the previous moment of the current time, so that the duty ratio adjustment is adjusted according to the working state of the PWM circuit at a previous moment, thereby further ensuring the Determine the reasonableness of the duty cycle.

A PWM circuit duty cycle adjustment system for a blood pressure measuring device, comprising:

a first obtaining module, configured to acquire real-time air pressure in the cuff when the blood pressure measuring device works;

a second obtaining module, configured to calculate a blood pressure measuring device according to the real-time air pressure and duty-pressure relationship model a duty cycle of the PWM circuit; wherein the duty cycle-pressure relationship model represents a functional relationship between the duty cycle and the air pressure at which the rate of rise of the air pressure in the cuff is constant;

And a determining module, configured to adjust an operating duty ratio of the PWM circuit according to the duty ratio.

The PWM circuit duty ratio adjusting system of the blood pressure measuring device can determine the duty ratio of the PWM circuit according to the real-time air pressure and the duty-pressure relationship model, thereby realizing the adjustment of the duty ratio of the PWM circuit, wherein the duty ratio is adjusted. Mainly affected by the real-time air pressure in the corresponding cuff, it can be applied to various types or models of blood pressure measuring devices, with high adjustment effect, ensuring the stability of the PWM circuit.

DRAWINGS

1 is a flow chart of a PWM circuit duty cycle adjustment method of a blood pressure measuring device according to an embodiment;

2 is a schematic diagram showing the relationship between experimental gas volume P-T of one embodiment;

3 is a schematic diagram showing the relationship between experimental gas volume W-P of one embodiment;

4 is a schematic diagram of a W-P relationship corresponding to different experimental gas contents of one embodiment;

FIG. 5 is a schematic diagram of comparison of pressure curves before and after filtering according to an embodiment; FIG.

Figure 6 is a schematic diagram showing the analysis of the working data of the blood pressure measuring device of one embodiment;

Fig. 7 is a block diagram showing the structure of a PWM circuit duty ratio adjusting system of a blood pressure measuring device according to an embodiment.

detailed description

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a specific embodiment of a method and system for adjusting a PWM circuit duty ratio of a blood pressure measuring device of the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 1, FIG. 1 is a flow chart of a method for adjusting a PWM circuit duty ratio of a blood pressure measuring device according to an embodiment, comprising the following steps:

S10, obtaining real-time air pressure in the cuff when the blood pressure measuring device is working;

The blood pressure measuring device may generally include an air pump, a pressure sensor, a cuff, a controller, and the like. The air pump can be controlled by a PWM circuit to control the parameters such as the amount of cuff inflation or the inflation speed. The pressure sensor can be The real-time air pressure in the cuff is measured, and the above-mentioned real-time air pressure is sent to the controller, so that the controller obtains the real-time air pressure in the cuff and performs corresponding monitoring and the like. The controller can set or adjust the duty ratio of the PWM circuit to control the driving power of the corresponding air pump to achieve the adjustment of the air pressure rising speed.

S20, calculating a duty ratio of the PWM circuit in the blood pressure measuring device according to the real-time air pressure and duty-pressure relationship model; wherein the duty-pressure relationship model indicates that the duty ratio and the air pressure rising speed in the cuff are constant a functional relationship between the pressures of the time;

The duty cycle-pressure relationship model described above can be used to characterize the duty cycle of the PWM circuit as a function of the real-time air pressure and duty cycle-pressure relationship model when the air pressure rise rate is constant within the cuff. The duty ratio is only affected by the real-time air pressure in the cuff, and can be applied to the adjustment of the duty ratio of the PWM circuit of various blood pressure measuring devices regardless of factors such as the type or model of the blood pressure measuring device.

The cuff of the blood pressure measuring device is an elastic air volume, and the gas capacity can be changed within a certain range (for example, 500 mL to 1500 mL) according to the inflation state, and in order to construct a stable model when the duty ratio-pressure relationship model is obtained. In the working environment, the inelastic gas capacity can be selected as the experimental gas capacity, such as the steel gas capacity. Under certain experimental conditions, the above experimental gas capacity is inflated to obtain the gas pressure, duty cycle and pressure rise during the inflation process. Data such as speed to obtain the above duty cycle-pressure relationship model. For example, the above-described duty-pressure relationship model can acquire the air pressure and the air pressure rising speed in the experimental air volume when the PWM circuit operates at different duty ratios, and then curve the relevant air pressure data and duty cycle characteristics. Processing, drawing analysis, etc.

S30. Adjust an operating duty ratio of the PWM circuit according to the duty ratio.

The PWM circuit duty ratio adjustment method of the blood pressure measuring device provided in this embodiment can determine the duty ratio of the PWM circuit according to the real-time air pressure and the duty-pressure relationship model, thereby realizing the adjustment of the duty ratio of the PWM circuit, wherein The adjustment of the air ratio is mainly affected by the real-time air pressure in the corresponding cuff, and can be applied to various types or models of blood pressure measuring devices, which has a high adjustment effect and ensures the stability of the PWM circuit.

In one embodiment, the PWM circuit duty ratio adjustment method of the blood pressure measurement device may further include:

Controlling the PWM circuit to inflate the experimental air volume under a plurality of set duty ratios;

In each process of inflating the experimental gas capacity, the function relationship between the gas pressure rising velocity and the gas pressure in the experimental gas volume is obtained, and a rising velocity-pressure relationship model is obtained;

The relationship between the duty ratio and the air pressure when the air pressure rising speed in the experimental air volume is constant is obtained from the rising speed-pressure relationship model, and the duty ratio-pressure relationship model is obtained.

The set duty ratio may be set within an effective duty cycle range (between a duty cycle lower limit value and a duty cycle upper limit value) of the PWM circuit, and in order to improve the efficiency of acquiring the above-described rising speed-pressure relationship model, The interval between two adjacent set duty ratios may be set to be equal intervals, for example, setting a plurality of set duty ratios to 16%, 20%, 24%, respectively 28% and 32%, etc., and then the above PWM circuits are sequentially operated under a plurality of set duty ratios.

In this embodiment, when the PWM circuit inflates the experimental gas volume at different set duty ratios, a rising velocity-pressure relationship model between the gas pressure rising velocity and the gas pressure in the experimental gas volume is obtained, thereby obtaining a corresponding duty ratio. - The barometric relationship model can improve the accuracy of the obtained duty cycle-barometric relationship model.

As an embodiment, if the plurality of set duty ratios are respectively set to 16%, 20%, 24%, 28%, and 32%, the PWM circuit may be first inflated to the experimental air volume under the respective duty ratios described above. Obtain the relationship between the air pressure P and the inflation time T (PT relationship) in the experimental air volume when the PWM operates at each duty ratio. The above PT relationship can be as shown in FIG. 2. In FIG. 2, the abscissa can represent time T in units of S (seconds), and the ordinate represents pressure P in units of mmHg (pressure corresponding to 1 mm of mercury), according to the above PT relationship The air pressure rising speed W corresponding to each pressure P in the experimental air volume can be calculated, so that the relationship between the air pressure rising speed W and the pressure P (WP relationship) under each duty ratio can be determined. The WP relationship is fitted to the WP curve corresponding to each duty ratio, as shown in FIG. 3. In FIG. 3, the abscissa indicates the air pressure P in units of mmHg, and the ordinate indicates the air pressure rising speed W in the experimental air volume. The unit is mmHg/S (the pressure corresponding to millimeter mercury per second). According to the WP relationship corresponding to FIG. 3, multiple groups (P, D) corresponding to the gas pressure rising rate in the experimental gas volume can be obtained, for example, the above air pressure. When the ascending speed is 5 mmHg/S, the corresponding multiple sets (P, D) (the intersection of the straight line corresponding to the 5 mmHg/S air pressure rising speed shown in Fig. 3 and each WP curve) can be obtained according to the above multiple groups (P, D). When the gas pressure rise rate is constant in the experimental gas volume, the relationship between the duty ratio and the gas pressure is the above-described duty-pressure relationship model.

According to the WP curve shown in Figure 3, when the adjacent two set duty ratios are equal, and the gas pressure rise rate in the experimental gas volume is constant (such as 4mmHg/S, 5mmHg/S and 6mmHg/S), the adjacent two The air pressure interval between the WP curves is approximately equal. For example, when W=5mmHg/S, the air pressure interval between the WP curve corresponding to the 16% duty ratio and the WP curve corresponding to the 20% duty ratio, 20% duty ratio The pressure interval between the corresponding WP curve and the WP curve corresponding to the 24% duty cycle, and the air pressure interval between the other adjacent two WP curves are equal. It can be seen that the variation of the duty cycle and the experimental gas There is a proportional relationship between the quantitative quantities of the changes in the pressure inside the volume, and the relationship between the duty ratio and the pressure can be approximated as a linear relationship.

In order to further simplify the above-described duty-pressure relationship model, in one embodiment, the above-described duty-pressure relationship model can be set to D=a×P+d; where P is the experimental air volume or cuff The internal pressure, D is the duty cycle of the PWM circuit, a is the first coefficient of the duty cycle-pressure relationship model, and d is the second coefficient of the duty cycle-pressure relationship model.

In this embodiment, the duty-pressure relationship model is simplified to a linear relationship model of D=a×P+d, and the efficiency of obtaining the corresponding duty ratio by the above-described duty-pressure relationship model can be improved. The first coefficient a and the second coefficient d may be obtained by acquiring the duty ratio of the PWM circuit and the corresponding air pressure when the air pressure rising rate in the experimental air volume or the cuff is constant, and substituting the above D=a×P+d for correlation calculation. Determined.

As an embodiment, the PWM circuit duty ratio adjustment method of the blood pressure measurement device may further include:

When the gas pressure rise rate is constant in the experimental gas volume, multiple sets (P _i , D _i ) corresponding to the i-th experimental gas volume are obtained, and D corresponding to the i-th experimental gas volume is determined according to the plurality of sets (P _i , D _i ). _i = a × P _i + d of the first coefficient a _i and the second coefficient d _i ; wherein D _i represents the duty cycle of the PWM circuit corresponding to the i-th experimental gas volume, and P _i represents the duty of the PWM circuit When the ratio is D _i , the pressure in the corresponding experimental gas volume;

The a and d are determined according to the respective a _i and d _i .

The air volume of the cuff in the blood pressure measuring device can be changed within a certain range (the cuff of the cuff is usually between 500mL and 1500mL); in order to construct a relatively stable experimental environment, the steel gas content can be selected. The inelastic gas volume is used as the experimental gas volume, and relevant experiments are carried out to obtain the above-mentioned duty-pressure relationship model. The capacity of the above experimental air volume may be consistent with the range of the cuff gas volume of the blood pressure measuring device, such as 500 mL (ml), 700 mL, 900 mL, 1100 mL, 1300 mL, and 1500 mL, and the like. K may be selected from the above various experimental gas capacities, and when the gas pressure rising rate in the experimental gas volume is constant, the plurality of groups corresponding to the i-th (i=1, 2, . . . , k) experimental gas capacities are obtained (P _i , D _i ), fitting a plurality of sets (P _i , D _i ) corresponding to the i-th experimental gas volume to obtain corresponding first coefficients a _i and second coefficients d _i . After obtaining a plurality of a _i and d _i , a can be determined according to the above a _i , and d is determined according to d _i , for example, after the maximum value and the minimum value between a ₁ and a _k are removed, each remaining a is obtained. The average value of _i is determined as the above average value; or the intermediate value in each a _i is determined as a or the like.

In the above process of determining the first coefficient a and the second coefficient d, the inflation rate to the corresponding experimental air volume can be controlled by the related inflation amount control device to control the air pressure rising speed in the experimental air volume, thereby maintaining the corresponding air pressure rise. The speed is constant and the corresponding P _i , D _{i is obtained} . The above process of obtaining a plurality of sets (P, D) corresponding to each experimental gas volume when the gas pressure rising rate in the experimental gas volume is constant may also include:

The PWM is inflated to each experimental gas volume at a set duty ratio, and the relationship between the air pressure P in the experimental gas volume and the inflation time T (P-T relationship) is obtained when the PWM is operated at each duty ratio;

According to the above P-T relationship, the air pressure rising speed W corresponding to each pressure P in the experimental air volume is calculated, so that the relationship between the air pressure rising speed W and the pressure P under each duty ratio can be determined (W-P relationship);

According to the W-P relationship, when the gas pressure rising rate in the experimental gas volume is constant (the above-mentioned W is constant), the corresponding plurality of groups (P, D) are obtained.

As an embodiment, the steps of determining the a and d according to the respective a _i and d _i may include:

According to each a _i and formula

Calculate a;

According to various, and the equation d _i

Calculate d; where i is an integer greater than or equal to 1 and less than or equal to k, and k represents the number of different experimental gas volumes.

According to the present embodiment determines a plurality of average value of a _i, according to the average value of the plurality of _I d of d determined, the determined can be guaranteed by a and d.

In practical applications, the cuff of the blood pressure measuring device is an elastic air volume, and its gas capacity can vary within a certain range with the inflation state, and the first coefficient and the second coefficient in the duty-pressure relationship model are based on non- Determined by the elastic experimental gas volume, in order to verify the rationality of the determined first coefficient and the second coefficient, in one embodiment, the experimental gas contents of a plurality of different gas volumes may be individually set in multiple duty cycles. The gassing experiment is carried out under specific conditions. For example, the first experimental gas volume and the second experimental gas volume having different gas capacities are sequentially operated at a duty ratio of 16%, 20%, 24%, 28%, and 32% in the PWM circuit. Under the aeration, the WP relationship corresponding to the first experimental gas volume and the second experimental gas volume is fitted to a corresponding curve, as shown in FIG. 4, in FIG. 4, the horizontal coordinate represents the air pressure P, and the unit is mmHg. The coordinates represent the velocity rise velocity W in the experimental gas volume, the unit is mmHg/S, the dotted line is the WP relationship corresponding to the first experimental gas volume, and the solid line is the WP relationship corresponding to the second experimental gas volume; Figure 5 shows that the different gas contents Separately in the same multiple settings The WP relationship obtained by inflating under the condition is not completely the same. However, when the gas pressure rising speed W is constant, the interval between two adjacent WP curves in a set of WP curves corresponding to the same experimental gas volume is Is consistent, or with W, the proportional relationship between the duty cycle change and the corresponding pressure change is constant, visible, for different gas capacity of the gas capacity (different experimental gas capacity, the same cuff) In other words, the first coefficient a in the duty cycle-pressure relationship model D=a×P+d is unchanged, and the second coefficient d is correspondingly changed according to its capacity.

In an embodiment, the PWM circuit duty ratio adjustment method may further include:

Selecting n times with equal intervals in the set time period;

Obtaining the air pressure P[j] in the cuff at each moment; wherein j is an integer greater than or equal to 1 and less than or equal to n, P[j] is the air pressure in the cuff at the jth time;

Calculate the air pressure rise speed deviation at the j+1th time according to the air pressure in the cuff at each moment and the formula ΔS[j+1]=S ₀ -(P[j+1]-P[j]); where ΔS[ j+1] is the air pressure rising speed deviation at the j+1th time, P[j+1] is the air pressure in the cuff at the j+1th time, and S ₀ is the preset air pressure rising speed;

According to ΔS[j+1] and formula

Calculate the average boost speed deviation during the set time period;

To set the average boost speed deviation during the time period;

According to ΔS[j+1],

And formula

Calculating a fine adjustment coefficient; wherein Δd is a fine adjustment coefficient, and k _m represents a preset fine adjustment ratio parameter;

Updating the second coefficient to d + Δd according to the trimming coefficient; the above d is the second coefficient of the pre-update duty-pressure relationship model.

The above set time period can be set to a certain period of time before the current time. For example, during the use of the blood pressure measuring device, within the first 0.5 seconds of the current time, if n=50, that is, 50 equal intervals are taken within 0.5 seconds before the current time. At the time, the first time is the time 0.5 seconds before the current time, and the nth (50)th time is the current time. The preset air pressure rising speed S ₀ is the current air pressure rising speed required by the blood pressure measuring device, so that the real-time air pressure rising speed in the cuff is consistent with S ₀ , and the difference between the two is minimized, and the above can be improved. The measurement effect of the blood pressure measuring device. The above fine adjustment ratio parameter k _m can be set according to the performance characteristics of the corresponding blood pressure measuring device, for example, set to 0.00004 equivalent, so that the fine adjustment coefficient Δd determined according to k _m is correlated with the performance characteristics of the corresponding blood pressure measuring device, further ensuring the determination. The rationality of the fine tuning coefficient Δd.

According to the embodiment, the fine adjustment coefficient is determined according to the air pressure in the cuff at a plurality of times and the corresponding air pressure rising speed during the use of the blood pressure measuring device, thereby improving the accuracy of the determined fine adjustment coefficient, thereby improving the corresponding duty ratio-pressure relationship model. The accuracy.

Since the air volume of the cuff in the blood pressure measuring device is dynamic, the second coefficient of the duty-pressure relationship model D=a×P+d is updated by using the above-mentioned fine adjustment coefficient, so that the updated second coefficient is d+Δd, The updated duty cycle-barometric relationship model is D=a×P+d+Δd, and the above Δd is based on the preset air pressure rising speed and the real-time air pressure rising speed in the cuff. The difference between the two is determined by minimizing the difference between the air pressure rising speed and the preset air pressure rising speed achieved by the duty ratio adjusted by the duty ratio-pressure relationship model described above, and further ensuring the duty ratio according to the above - The accuracy of the duty cycle obtained by the barometric relationship model.

In an embodiment, after acquiring the real-time air pressure in the cuff, the method may further include:

The real-time air pressure is passed through a low-pass filter to filter out high-frequency signals in the real-time air pressure.

In this embodiment, the high frequency signal in the real-time air pressure can be filtered out, and the influence of the noise signal such as the high-frequency signal on the duty cycle acquisition process is reduced, thereby improving the accuracy of the obtained duty ratio.

As an embodiment, the low pass filter may include:

P _out [m]=b ₁ ×P _in [m]+b ₂ ×P _in [m-1]+b ₃ ×P _in [m-2]-b ₄ ×P _out [m-1]-b ₅ ×P _out [m-2];

Where P _in [m] is the input air pressure at the current moment of the low-pass filter, P _out [m] is the output air pressure at the current moment of the low-pass filter, and P _in [m-1] is the low-pass filter at the first moment. Enter the air pressure, P _out [m-1] is the output air pressure of the low-pass filter at the first moment, P _in [m-2] is the input air pressure of the low-pass filter at the second moment, P _out [m-2] is the first The output air pressure of the low-pass filter at two times, b ₁ , b ₂ , b ₃ , b ₄ and b ₅ are respectively filter coefficients, the first time is the previous time of the current time, and the second time is the first time The moment before the moment. In the embodiment, in the process of filtering the real-time air pressure through the low-pass filter, the input air pressure of the low-pass filter can be detected at the set detection frequency, and the output air pressure of the low-pass filter when detecting the input air pressure is recorded, and each The input air pressure detected, the detection time, and the recorded output air pressure are used for adjustment of the corresponding low-pass filter to improve the filtering performance. The first time is the previous detection time of the current time, and the second time is the previous detection time of the first time, that is, the second detection time of the current time. The above detection frequency can be set according to the filtering precision of the low pass filter.

The filter parameters of the low-pass filter may include: a sampling rate of 100 Hz (hertz), a passband cutoff frequency of 0.2 Hz, a stopband cutoff frequency of 0.9 Hz, a maximum attenuation of the passband ripple of 5 dB (decibel), and a stopband attenuation of 10 dB. The values of the above filter coefficients b ₁ , b ₂ , b ₃ , b ₄ and b ₅ may be:

b ₁ =b ₃ =2.413590490419615e-04,

b ₂ =4.827180980839230e-04,

b ₄ =-1.955578240315036,

b ₅ = 0.956543676511203.

The comparison of the barometric pressure curves before and after filtering the real-time barometric pressure using the above-mentioned low-pass filter can be as shown in FIG. 5 In 5, the abscissa represents time, the unit is S, and the ordinate represents other, the unit is mmHg. In Figure 5, the upper irregular curve is the real-time air pressure before filtering, and the lower smooth curve is the filtered real-time air pressure. FIG. 5 can show that after the real-time air pressure is filtered by the low-pass filter, the noise signal such as the high-frequency signal in the real-time air pressure can be effectively cleared.

In an embodiment, the step of calculating the duty ratio of the PWM circuit in the blood pressure measuring device according to the real-time air pressure and the duty-pressure relationship model may further include:

Detecting the duty ratio of the duty is in the interval [D _min, D _max] therein; wherein, D _min is the lower limit value of the duty ratio of the PWM circuit, D _max is the upper limit value of the duty ratio of the PWM circuit;

If the duty ratio exceeds D _max , the duty ratio is set to D _max ;

If the duty ratio is less than D _min , the duty ratio is set to D _min .

When the duty ratio of the PWM circuit to work normally effective duty with a certain range, the effective range of the duty ratio of the duty ratio lower limit value may include a duty ratio duty D _min to an upper limit value D _max between In the ratio interval, if the PWM circuit operates at a duty ratio other than the interval [D _min , D _max ], it may affect the normal operation of the PWM circuit, thereby affecting the measurement effect of the blood pressure measuring device, and the duty ratio of the PWM circuit needs to be adjusted. Corresponding effective duty cycle range to ensure the safety of its work. The above [D _min , D _max ] represents a closed interval between D _min and D _max . The duty ratio lower limit value _Dmin and the duty ratio upper limit value _Dmax described above may be performed in accordance with the performance of the corresponding PWM circuit, for example, _Dmin may be set to 16%, _{Dmax may be} set to 50%, and the like.

As an embodiment, the step of calculating the duty ratio of the PWM circuit in the blood pressure measuring device according to the real-time air pressure and the duty-pressure relationship model may further include:

Obtaining a duty ratio of the first time PWM circuit; wherein the first time is a previous time of the current time;

According to the formula

Updating the duty cycle of the current time; wherein D[m] is the duty cycle after the current time is updated,

The duty ratio of the current duty cycle-pressure relationship model output, D[m-1] is the duty ratio of the first time;

The duty cycle of the PWM circuit is determined based on the updated duty cycle.

In this embodiment, the duty ratio of the corresponding PWM circuit can be updated according to the duty ratio of the previous moment at the current time, so that the duty ratio adjustment can be adjusted according to the working state of the PWM circuit at a previous moment, further ensuring The plausibility of the determined duty cycle.

In one embodiment, the PWM circuit duty ratio adjustment method of the blood pressure measuring device is used to adjust the duty ratio of the blood pressure measuring device PWM circuit in use, and the air pressure and air pressure in the cuff during the operation of the blood pressure measuring device are obtained. The data of the speed and the inflation time are analyzed, and the working data analysis diagram shown in FIG. 6 can be obtained. FIG. 6 includes four data analysis sub-graphs, and the four data analysis sub-graphs are arranged in two rows and two columns in FIG. 6 . The first data analysis subgraph (the first row and the first row) is the original data comparison graph, and the abscissa indicates the inflation time of the cuff, the unit is S, and the ordinate indicates the air pressure in the cuff, and the unit is mmHg, A data analysis subgraph includes two pressure curves of the original air pressure curve measured from the cuff and the filtered air pressure curve filtered by the low pass filter. The first data analysis subgraph can indicate two pressure curves before and after filtering. Coincident, the above low-pass filter can strictly maintain the consistency of the air pressure data after corresponding filtering of the real-time air pressure. The second data analysis subgraph (the first row and the second row) is the air pressure rising speed-time relationship diagram, and the abscissa indicates the inflation time of the cuff, the unit is S, and the ordinate indicates the air pressure rising speed in the cuff, and the unit is mmHg. /S, the second data analysis subgraph shows that in the actual application, the PWM circuit duty ratio adjustment method is adopted to adjust the corresponding duty ratio, so that the air pressure rising speed in the cuff can reach the set target rising speed in a short time. And maintaining the above target rising speed, the measurement effect of the corresponding blood pressure measuring device can be improved. The third data analysis subgraph (the second row and the first one) is the air pressure rising speed-pressure relationship diagram, the abscissa indicates the air pressure in the cuff, the unit is mmHg, and the ordinate indicates the air pressure rising speed in the cuff, and the unit is mmHg. /S, wherein the straight line of the air pressure rising speed W=5 is the above-mentioned speed of the air pressure to be maintained in the cuff, the curve in the figure represents the actual rising speed in the cuff, and the third data analysis subgraph can indicate that the above duty ratio is passed through - The air pressure relationship model D=a×P+d+Δd performs duty cycle control, which can achieve the target ascending speed in the cuff while the air pressure in the cuff is small (ie, the short inflation time), and can maintain the corresponding The target ascending speed is correlated. The fourth data analysis subgraph (the second row and the second row) is a duty cycle-time relationship diagram, the abscissa represents the duty ratio, the unit is 1/1000, and the ordinate represents the inflation time of the cuff, and the unit is S. The fourth data analysis subgraph shows that when the PWM circuit is just starting to work, the corresponding cuff can be quickly inflated with a slightly smaller duty cycle, and the cuff is inflated until the corresponding blood pressure measuring device can start blood pressure measurement. It can be increased at a relatively stable speed to ensure the stability of the corresponding PWM circuit.

Referring to FIG. 7, FIG. 7 is a schematic structural diagram of a PWM circuit duty ratio adjustment system of a blood pressure measuring device according to an embodiment, including:

The first obtaining module 10 is configured to acquire real-time air pressure in the cuff when the blood pressure measuring device works;

a second obtaining module 20, configured to calculate a duty ratio of the PWM circuit in the blood pressure measuring device according to the real-time air pressure and duty-pressure relationship model; wherein the duty-pressure relationship model represents a duty ratio and a sleeve a functional relationship between the pressures at which the rate of rise of the gas pressure in the belt is constant;

The determining module 30 is configured to adjust an operating duty ratio of the PWM circuit according to the duty ratio.

The PWM circuit duty ratio adjusting system of the blood pressure measuring device provided by the present invention corresponds to the PWM circuit duty ratio adjusting method of the blood pressure measuring device provided by the present invention, and the PWM circuit duty ratio adjusting method of the blood pressure measuring device is The technical features set forth in the embodiments and their beneficial effects are all applicable to the embodiment of the PWM circuit duty cycle adjustment system of the blood pressure measuring device, which is hereby declared.

The technical features of the above-described embodiments may be arbitrarily combined. For the sake of brevity of description, all possible combinations of the technical features in the above embodiments are not described. However, as long as there is no contradiction between the combinations of these technical features, All should be considered as the scope of this manual.

The above-described embodiments are merely illustrative of several embodiments of the present invention, and the description thereof is more specific and detailed, but is not to be construed as limiting the scope of the invention. It should be noted that a number of variations and modifications may be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, the scope of the invention should be determined by the appended claims.

Claims (11)

1. A method for adjusting a duty ratio of a PWM circuit of a blood pressure measuring device, comprising the steps of:

   Obtain real-time air pressure in the cuff while the blood pressure measuring device is working;

   Calculating a duty cycle of the PWM circuit in the blood pressure measuring device according to the real-time air pressure and duty-pressure relationship model; wherein the duty-pressure relationship model indicates that the duty ratio and the air pressure rising speed in the cuff are constant a functional relationship between pressures;

   The duty cycle of the PWM circuit is adjusted according to the duty cycle.
2. The PWM circuit duty ratio adjustment method of the blood pressure measurement device according to claim 1, further comprising:

   Controlling the PWM circuit to inflate the experimental air volume under a plurality of set duty ratios;

   In each process of inflating the experimental gas capacity, the function relationship between the gas pressure rising velocity and the gas pressure in the experimental gas volume is obtained, and a rising velocity-pressure relationship model is obtained;

   The relationship between the duty ratio and the air pressure when the air pressure rising speed in the experimental air volume is constant is obtained from the rising speed-pressure relationship model, and the duty ratio-pressure relationship model is obtained.
3. The PWM circuit duty ratio adjusting method of the blood pressure measuring device according to claim 2, wherein the duty-pressure relationship model comprises D = a × P + d; wherein P is a pressure in the cuff D is the duty cycle of the PWM circuit, a is the first coefficient of the duty cycle-barometric relationship model, and d is the second coefficient of the duty cycle-barometric relationship model.
4. The PWM circuit duty ratio adjustment method of the blood pressure measurement device according to claim 3, further comprising:

   When the gas pressure rise rate is constant in the experimental gas volume, multiple sets (P _i , D _i ) corresponding to the i-th experimental gas volume are obtained, and D corresponding to the i-th experimental gas volume is determined according to the plurality of sets (P _i , D _i ). _i = a × P _i + d of the first coefficient a _i and the second coefficient d _i ; wherein D _i represents the duty cycle of the PWM circuit corresponding to the i-th experimental gas volume, and P _i represents the duty of the PWM circuit When the ratio is D _i , the pressure in the corresponding experimental gas volume;

   The a and d are determined according to the respective a _i and d _i .
5. Method PWM duty adjustment circuits blood pressure measurement device according to claim 4, characterized in that, according to various a _{i I} d and the a and d determining comprises the step of:

   According to each a _i and formula

   

   Calculate a;

   According to each d _i and formula

   

   Calculate d; where i is an integer greater than or equal to 1 and less than or equal to k, and k represents the number of different experimental gas volumes.
6. The PWM circuit duty ratio adjustment method of the blood pressure measurement device according to claim 3, further comprising:

   Selecting n times with equal intervals in the set time period;

   Obtaining the air pressure P[j] in the cuff at each moment; wherein j is an integer greater than or equal to 1 and less than or equal to n, and P[j] is the air pressure in the cuff at the jth time;

   Calculate the air pressure rise speed deviation at the j+1th time according to the air pressure in the cuff at each moment and the formula ΔS[j+1]=S ₀ -(P[j+1]-P[j]); where ΔS[ j+1] is the air pressure rising speed deviation at the j+1th time, P[j+1] is the air pressure in the cuff at the j+1th time, and S ₀ is the preset air pressure rising speed;

   According to ΔS[j+1] and formula

   

   Calculate the average boost speed deviation during the set time period;

   

   To set the average boost speed deviation during the time period;

   According to ΔS[j+1],

   

   And formula

   

   Calculating a fine adjustment coefficient; wherein Δd is a fine adjustment coefficient, and k _m represents a preset fine adjustment ratio parameter;

   The second coefficient is updated to d + Δd according to the trimming coefficient.
7. The PWM circuit duty ratio adjusting method of the blood pressure measuring device according to any one of claims 1 to 6, further comprising: after acquiring the real-time air pressure in the cuff, further comprising:

   The real-time air pressure is passed through a low-pass filter to filter out high-frequency signals in the real-time air pressure.
8. The PWM circuit duty ratio adjusting method of the blood pressure measuring device according to claim 7, wherein the low pass filter comprises:

   P _out [m]=b ₁ ×P _in [m]+b ₂ ×P _in [m-1]+b ₃ ×P _in [m-2]-b ₄ ×P _out [m-1]-b ₅ ×P _out [m-2];

   Where P _in [m] is the input air pressure at the current moment of the low-pass filter, P _out [m] is the output air pressure at the current moment of the low-pass filter, and P _in [m-1] is the low-pass filter at the first moment. Enter the air pressure, P _out [m-1] is the output air pressure of the low-pass filter at the first moment, P _in [m-2] is the input air pressure of the low-pass filter at the second moment, P _out [m-2] is the first The output air pressure of the low-pass filter at two times, b ₁ , b ₂ , b ₃ , b ₄ and b ₅ are respectively filter coefficients, the first time is the previous time of the current time, and the second time is the first time The moment before the moment.
9. The PWM circuit duty ratio adjusting method of the blood pressure measuring device according to any one of claims 1 to 6, wherein the calculating the PWM circuit in the blood pressure measuring device according to the real-time air pressure and the duty-pressure relationship model The steps of the duty cycle also include:

   Detecting whether the duty ratio is within a duty cycle interval [D _min , D _max ]; wherein D _min is a duty cycle lower limit value of the PWM circuit, and D _max is a duty cycle upper limit value of the PWM circuit;

   If the duty ratio exceeds D _max , the duty ratio is set to D _max ;

   If the duty ratio is less than D _min , the duty ratio is set to D _min .
10. The PWM circuit duty ratio adjusting method of the blood pressure measuring device according to claim 9, wherein the calculating the duty ratio of the PWM circuit in the blood pressure measuring device according to the real-time air pressure and the duty-pressure relationship model After the step, it also includes:

    Obtaining a duty ratio of the first time PWM circuit; wherein the first time is a previous time of the current time;

    According to the formula

    

    Updating the duty cycle of the current time; wherein D[m] is the duty cycle after the current time is updated,

    

    The duty ratio of the current duty cycle-pressure relationship model output, D[m-1] is the duty ratio of the first time;

    The duty cycle of the PWM circuit is determined based on the updated duty cycle.
11. A PWM circuit duty ratio adjustment system for a blood pressure measuring device, comprising:

    a first obtaining module, configured to acquire real-time air pressure in the cuff when the blood pressure measuring device works;

    a second acquiring module, configured to calculate a duty ratio of the PWM circuit in the blood pressure measuring device according to the real-time air pressure and duty-pressure relationship model; wherein the duty-pressure relationship model represents a duty ratio and a cuff a functional relationship between the pressures at which the internal gas pressure rise rate is constant;

    And a determining module, configured to adjust an operating duty ratio of the PWM circuit according to the duty ratio.

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