1. The utility model provides a little wind speed sensor of fume chamber based on kalman filter algorithm, includes lid (1), base (6) and installs PCB circuit board (3) between lid (1) and base (6) inside, its characterized in that: the top of the cover (1) close to the edges of the two sides is provided with fixing holes (2), the center of the top of the cover (1) is provided with an air through hole (12), the top of the cover (1) is provided with a first screw through hole (11), the center of the top surface inside the cover (1) is fixed with a first connecting circular tube (18), the top surface inside the cover (1) and inside the first connecting circular tube (18) is fixed with a square air inlet channel tube (17), and the top of the square air inlet channel tube (17) is communicated with the air through hole (12);

supporting columns (14) are fixed on the inner bottom surface of the base (6) close to the edges of the two sides, first threaded holes (4) are formed in the two supporting columns (14), three debugging holes (20) are formed in the outer surface of the base (6) at equal intervals, a second connecting circular tube (19) is fixed in the center of the inner bottom surface of the base (6), a placing groove (8) is formed in one side of the base (6), and an air inlet (15) is formed in the center of the bottom of the base (6);

circular through-hole (9) have been seted up to the center department of PCB circuit board (3), one side that the bottom of PCB circuit board (3) is close to circular through-hole (9) is fixed with gentle wind speed sensor (16), the bottom of PCB circuit board (3) is close to one side edge and is fixed with binding post (13), binding post (13) are located the inside of standing groove (8).

2. A fume hood breeze velocity sensor based on kalman filter algorithm, according to claim 1, characterized in that: two second threaded holes (301) and a second screw through hole (5) are respectively formed in the top of the PCB (3) close to the edge.

3. A fume hood breeze velocity sensor based on kalman filter algorithm, according to claim 2, characterized in that: and screws are connected between the second threaded holes (301) and the inner surface wall of the first threaded holes (4) in a threaded manner.

4. A fume hood breeze velocity sensor based on kalman filter algorithm, according to claim 1, characterized in that: the center of the breeze speed sensor (16) is provided with a rectangular through hole (1601), and the inner diameter of the rectangular through hole (1601) is equal to that of the square air inlet channel pipe (17).

5. A fume hood breeze velocity sensor based on kalman filter algorithm, according to claim 2, characterized in that: hexagonal recess (21) have been seted up in one side that the bottom of base (6) is close to air intake (15), threaded connection has screw spike (10) between the interior table wall of first screw via hole (11) and second screw via hole (5), and the bottom of screw spike (10) extends to the inside of hexagonal recess (21).

6. A fume hood breeze speed sensor based on Kalman filtering algorithm as set forth in claim 5, characterized in that: the bottom end of the screw spike (10) is sleeved with a nut (7) in a threaded manner, and the nut (7) is located inside the inner hexagonal groove (21).

7. A fume hood breeze velocity sensor based on kalman filter algorithm, according to claim 1, characterized in that: the micro wind speed sensor (16) is packaged by an SMD patch of a WIN digital anemometer of an MEMS semiconductor chip, and the PCB circuit board (3) comprises an NTC thermistor and an STM32F072CBT6 singlechip.

8. A method for measuring a fume hood micro-wind speed sensor based on a kalman filter algorithm, which is characterized in that the fume hood micro-wind speed sensor based on the kalman filter algorithm of any one of claims 1 to 7 is used, and comprises the following steps:

s1, air with a certain wind speed flows through a speed measuring channel of the breeze speed sensor (16), and the breeze speed sensor (16) sends signals in the form of differential voltage signals after receiving the signals;

s2, processing the voltage signal of the NTC thermistor into a direct current voltage signal in a range of 0-3.3V and then transmitting the direct current voltage signal to the singlechip;

s3, measuring the voltage-wind speed relation in the self-built small wind tunnel, taking multiple groups of data to perform polynomial fitting, and fitting goodness R²Taking the fitted polynomial as a mapping relation of voltage and wind speed as 0.999;

and S4, calibrating for many times at different constant ambient temperatures by controlling the air temperature in the self-built small wind tunnel to obtain a voltage-wind speed relational expression at different temperatures so as to reduce errors caused by temperature changes.

9. The method for measuring a fume hood micro-wind speed sensor based on a kalman filter algorithm according to claim 8, wherein in the operation step of S2, the method further comprises the following steps:

s201, signal processing of environmental temperature: converting the received direct-current voltage signal into an actual temperature through calculation of a calculation formula of the NTC thermistor;

s202, wind speed signal processing: calculating the received direct current voltage signal through a voltage-wind speed relational expression to obtain the corresponding wind speed;

s203, according to the calibrated relational expression, selecting a voltage-wind speed relational expression corresponding to the environmental temperature to map the voltage signal into wind speed;

s204, collecting micro differential pressure signals of an ambient temperature and micro wind speed sensor (16) chip, establishing a state equation and an observation equation of Kalman filtering under a nonlinear dynamic system, and establishing a Kalman filtering model according to the state equation and the observation equation of the Kalman filtering;

s205, determining the initialization state of the nonlinear dynamic system, namely determining the initial value of the state parameter of the initial epoch, the initial value of the variance matrix and the initial variance matrix of the dynamic noise;

s206, filtering the initial value of the state parameter, the initial value of the variance matrix and the dynamic noise variance matrix by a Kalman filtering recursion equation based on the state equation and the observation equation of the initial epoch to obtain a new filtering value;

and S207, calculating to obtain the current optimal wind speed according to the current measured wind speed and the predicted wind speed and error at the previous moment, and predicting the wind speed at the next moment.

Background

The micro wind speed sensor is used for measuring micro wind speed of 0-1.0 m/s. The main application scenario is to measure the speed of air flowing in a biological laboratory fume hood. The breeze speed sensor adopts a scheme of multi-sensor fusion. The traditional micro wind speed sensor mostly adopts a PT20 resistor to detect micro wind speed, and an NTC thermistor detects ambient temperature; in addition, the singlechip is adopted to receive the voltage signal, and the feedback voltage is processed and output through the singlechip program. Principle of micro wind speed sensor: the air flow with a certain wind speed passes through the micro wind speed sensor to take away the heat of PT20 in a speed measuring channel of the micro wind speed sensor, and in order to keep the temperature constant, the heat needs to be increased, so that the change of voltage can be detected, and the wind speed is measured by using a voltage-wind speed relational expression.

However, in the prior art, the existing micro wind speed sensor has the following disadvantages in use:

1. when the environmental temperature changes, the measurement error is increased; such as when the ambient temperature rises by 4 c, the resulting error is about 30% of full scale.

The reason is as follows: the PT20 resistor works normally depending on temperature, and when the ambient temperature changes, the normal output current of the PT20 resistor is influenced, so that errors are generated in the measured value.

2. Under the environmental conditions of constant wind speed and constant temperature, the voltage signal is interfered, and the deviation is about 5% of the full scale.

The reason is as follows: the circuit has noise, so that voltage signals received by the single chip microcomputer are inaccurate, measurement errors of wind speed are generated, filtering processing of traditional products is simple, and test results caused by normally distributed random signal noise cannot be effectively processed to be unstable.

3. The chip PT20 used for measuring the micro-wind speed generates heat seriously, and the temperature of the chip reaches more than 70 ℃ under the condition of normal work, so that the NTC thermistor for measuring the environmental temperature needs to be placed at a place far away from a speed measuring channel, and the difference between the measured temperature and the actual environmental temperature is large.

The reason is as follows: the problems arising from the principles of the prior art solutions.

Disclosure of Invention

The invention aims to: the method is characterized in that the breeze speed is measured by adopting a multi-sensor fusion mode, an SMD (surface mounted device) patch packaging type of WIN series digital anemometer based on an MEMS (micro-electromechanical system) semiconductor chip is selected as a breeze speed sensor for measuring the wind speed, an NTC (negative temperature coefficient) thermistor scheme is selected as a temperature scheme for measuring the ambient temperature, an STM32F072CBT6 single chip microcomputer is adopted for signal processing, and a filter part of a voltage signal converted from an analog quantity to a digital quantity uses Kalman filtering to reduce the influence caused by noise.

The technical scheme adopted by the invention is as follows: a ventilation cabinet micro-wind speed sensor based on a Kalman filtering algorithm comprises a cover, a base and a PCB (printed Circuit Board) arranged between the cover and the base, wherein the top of the cover is provided with fixing holes close to edges of two sides, the center of the top of the cover is provided with an air through hole, the top of the cover is provided with a first screw through hole, a first connecting circular pipe is fixed at the center of the inner top surface of the cover, a square air inlet channel pipe is fixed at the inner part of the first connecting circular pipe on the inner top surface of the cover, and the top of the square air inlet channel pipe is communicated with the air through hole;

support columns are fixed on the inner bottom surface of the base close to the edges of the two sides, first threaded holes are formed in the two support columns, three debugging holes are formed in the outer surface of the base at equal intervals, a second connecting circular pipe is fixed at the center of the inner bottom surface of the base, a placing groove is formed in one side of the base, and an air inlet is formed in the center of the bottom of the base;

the PCB is characterized in that a circular through hole is formed in the center of the PCB, a breeze speed sensor is fixed on one side, close to the circular through hole, of the bottom of the PCB, a wiring terminal is fixed on one side edge, close to one side edge, of the bottom of the PCB, and the wiring terminal is located inside the placing groove.

Two second threaded holes and a second screw through hole are respectively formed in the top of the PCB close to the edge.

And screws are connected between the second threaded holes and the inner surface wall of the first threaded holes in a threaded manner.

The center of the micro-wind speed sensor is provided with a rectangular through hole, and the inner diameter of the rectangular through hole is equal to that of the square air inlet channel pipe.

The bottom of the base is close to one side of the air inlet, an inner hexagonal groove is formed in the bottom of the base, a screw spike is connected between the inner surface walls of the first screw via hole and the second screw via hole in a threaded mode, and the bottom end of the screw spike extends to the inside of the inner hexagonal groove.

The bottom end of the screw spike is sleeved with a nut, and the nut is located inside the inner hexagonal groove.

The micro-wind speed sensor is packaged by an SMD (surface mounted device) patch of a WIN (wind turbine system) digital anemometer of an MEMS (micro-electromechanical system) semiconductor chip, and the PCB (printed circuit board) comprises an NTC (negative temperature coefficient) thermistor and an STM32F072CBT6 singlechip.

A method for measuring a fume hood micro-wind speed sensor based on a Kalman filtering algorithm comprises the following steps:

s1, air with a certain wind speed flows through a speed measuring channel of the breeze speed sensor, and the breeze speed sensor sends signals in the form of differential voltage signals after receiving the signals;

s2, processing the voltage signal of the NTC thermistor into a direct current voltage signal in a range of 0-3.3V and then transmitting the direct current voltage signal to the singlechip;

s3, measuring the voltage-wind speed relation in the self-built small wind tunnel, taking multiple groups of data to perform polynomial fitting, and fitting goodness R²Taking the fitted polynomial as a mapping relation of voltage and wind speed as 0.999;

and S4, calibrating for many times at different constant ambient temperatures by controlling the air temperature in the self-built small wind tunnel to obtain a voltage-wind speed relational expression at different temperatures so as to reduce errors caused by temperature changes.

Wherein, in the operation step of S2, the method further includes the following steps:

s201, signal processing of environmental temperature: converting the received direct-current voltage signal into an actual temperature through calculation of a calculation formula of the NTC thermistor;

s202, wind speed signal processing: calculating the received direct current voltage signal through a voltage-wind speed relational expression to obtain the corresponding wind speed;

s203, according to the calibrated relational expression, selecting a voltage-wind speed relational expression corresponding to the environmental temperature to map the voltage signal into wind speed;

s204, collecting micro differential pressure signals of the ambient temperature and the micro wind speed sensor chip, establishing a state equation and an observation equation of Kalman filtering under a nonlinear dynamic system, and establishing a Kalman filtering model according to the state equation and the observation equation of the Kalman filtering;

s205, determining the initialization state of the nonlinear dynamic system, namely determining the initial value of the state parameter of the initial epoch, the initial value of the variance matrix and the initial variance matrix of the dynamic noise;

s206, filtering the initial value of the state parameter, the initial value of the variance matrix and the dynamic noise variance matrix by a Kalman filtering recursion equation based on the state equation and the observation equation of the initial epoch to obtain a new filtering value;

and S207, calculating to obtain the current optimal wind speed according to the current measured wind speed and the predicted wind speed and error at the previous moment, and predicting the wind speed at the next moment.

In summary, due to the adoption of the technical scheme, the invention has the beneficial effects that:

1. according to the invention, the adopted breeze speed sensor is less influenced by the ambient temperature and humidity, the error caused by temperature change can be further reduced through temperature calibration, and Kalman filtering is used for filtering the acquired voltage signal in the singlechip, so that the interference of noise in a circuit to the voltage signal is effectively inhibited and prevented, the output result is more accurate, and the disturbance is very small.

2. In the invention, the adopted micro-wind speed sensor chip has smaller heat productivity, and the influence on the environment temperature can be almost ignored under the condition of the background technology, so that the NTC thermistor can be placed at a position closer to a speed measuring channel of the micro-wind speed sensor, the measurement on the environment temperature is more accurate, the precision is high, the error is small, the stability is good, and the defect that the influence of the environment temperature on the traditional wind speed sensor is large is effectively solved.

3. In the invention, the speed measuring channel of the breeze speed sensor is reduced, so that the speed measuring channel is more sensitive to the change of the breeze speed, and the transition curved surface of the breeze speed sensor facing the speed measuring channel is increased, so that the air flowing through the speed measuring channel is more stable.

Drawings

FIG. 1 is an exploded view of the present invention;

FIG. 2 is a perspective view of the present invention;

FIG. 3 is a perspective view of the present invention;

FIG. 4 is a perspective view of the present invention;

FIG. 5 is a perspective view of a PCB circuit board of the present invention;

FIG. 6 is a perspective view of the lid of the present invention;

FIG. 7 is a perspective view of the lid of the present invention;

FIG. 8 is a perspective view of the base of the present invention;

FIG. 9 is a perspective view of the base of the present invention;

the labels in the figure are: 1. a cover; 2. a fixing hole; 3. a PCB circuit board; 301. a second threaded hole; 4. a first threaded hole; 5. a second screw via hole; 6. a base; 7. a nut; 8. a placement groove; 9. a circular through hole; 10. a screw spike; 11. a first screw via hole; 12. an air passage port; 13. a wiring terminal; 14. a support pillar; 15. an air inlet; 16. a breeze speed sensor; 1601. a rectangular via hole; 17. a square intake passage pipe; 18. a first connecting circular tube; 19. a second connecting circular tube; 20. debugging the hole; 21. and an inner hexagonal groove.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Referring to FIGS. 1-9: a micro-wind speed sensor of a fume hood based on a Kalman filtering algorithm comprises a cover 1, a base 6 and a PCB (printed Circuit Board) 3 arranged between the cover 1 and the base 6, wherein fixing holes 2 are respectively formed in the top of the cover 1 close to the edges of two sides, the fixing holes 2 are hole sites fixedly used in practical use, an air through hole 12 is formed in the center of the top of the cover 1, the air through hole 12 is a channel through which air passes in measurement, a first screw through hole 11 is formed in the top of the cover 1, the first screw through hole 11 and a second screw through hole 5 are screw through holes fixedly used up and down between the cover 1 and the base 6, a first connecting circular tube 18 is fixed in the center of the top of the inside of the cover 1, a square air inlet channel tube 17 is fixed in the inside of the first connecting circular tube 18, and the top of the square air inlet channel tube 17 is communicated with the air through hole 12, the square air inlet passage pipe 17 is a passage through which air passes during measurement;

the inner bottom surface of the base 6 is fixed with support columns 14 near the edges of two sides, the two support columns 14 are used for supporting and installing the position of the PCB 3, the inner parts of the two support columns 14 are both provided with first threaded holes 4, the outer surface of the base 6 is provided with three debugging holes 20 at equal intervals, the two support columns can be connected into the inner part after being integrally assembled through the debugging holes 20, the center of the inner bottom surface of the base 6 is fixed with a second connecting circular tube 19, a convex block (shown in figure 5) is arranged on the first connecting circular tube 18, a clamping port (shown in figure 8) is arranged on the second connecting circular tube 19, when the cover 1 and the base 6 are butt-jointed and installed, the convex block on the first connecting circular tube 18 can be clamped and connected with the clamping port of the second connecting circular tube 19, the installation is convenient, a placement groove 8 is arranged on one side of the base 6, the placement groove 8 is used for installing and placing the position of the wiring terminal 13, an air inlet 15 is arranged at the center of the bottom of the base 6, the air inlet 15 is a channel through which air passes during measurement and is subjected to guide surface treatment;

circular through-hole 9 has been seted up to the center department of PCB circuit board 3, is used for first connecting pipe 18 and the butt joint of passing of second connecting pipe 19 through circular through-hole 9, and one side that the bottom of PCB circuit board 3 is close to circular through-hole 9 is fixed with gentle wind speed sensor 16, and one side edge department is close to in the bottom of PCB circuit board 3 is fixed with binding post 13, and binding post 13 is located the inside of standing groove 8.

Two second threaded holes 301 and a second screw via hole 5 are respectively arranged at the top of the PCB circuit board 3 close to the edge.

Screws are connected between the second threaded holes 301 and the inner surface wall of the first threaded holes 4 in a threaded mode, and the screws penetrate through the first threaded holes 4 and the second threaded holes 301, so that the position of the PCB circuit board 3 can be installed and fixed.

The center of the breeze speed sensor 16 is provided with a rectangular through hole 1601, and the inner diameter of the rectangular through hole 1601 is equal to the inner diameter of the square air inlet channel pipe 17, so that the breeze can pass through the rectangular through hole.

Hexagonal recess 21 has been seted up in one side that the bottom of base 6 is close to air intake 15, and threaded connection has screw spike 10 between the interior table wall of first screw via hole 11 and second screw via hole 5, and the bottom of screw spike 10 extends to the inside of hexagonal recess 21 in, thereby passes first screw via hole 11 and second screw via hole 5 through screw spike 10 screw thread and can install lid 1 and base 6.

The bottom end thread cover of the screw spike 10 is provided with a nut 7, and the nut 7 is positioned in the inner hexagonal groove 21, so that the screw spike 10 can be fastened through the nut 7.

The micro-wind speed sensor 16 adopts an SMD (surface mounted device) patch packaging type of WIN series digital anemometer of an MEMS (micro-electromechanical system) semiconductor chip, the PCB circuit board 3 comprises an NTC thermistor and an STM32F072CBT6 singlechip, the temperature scheme for measuring the ambient temperature selects the NTC thermistor scheme, the STM32F072CBT6 singlechip is adopted for signal processing, and Kalman filtering is used for a filtering part of a voltage signal to reduce the influence caused by noise.

A method for measuring a fume hood micro-wind speed sensor based on a Kalman filtering algorithm comprises the following steps:

firstly, air with a certain wind speed flows through a speed measuring channel of a micro wind speed sensor 16, the micro wind speed sensor 16 receives the air and sends a signal in the form of a differential voltage signal, and the differential signal is converted into a direct current voltage signal of 0-3.3V and transmitted to a single chip microcomputer after being processed by a circuit;

step two, processing the voltage signal of the NTC thermistor into a direct-current voltage signal in a range of 0-3.3V and then transmitting the direct-current voltage signal to the singlechip;

measuring the voltage-wind speed relation in the self-built small wind tunnel, taking multiple groups of data to perform polynomial fitting, and fitting goodness of fit R²Multiple to fit to 0.999The polynomial is used as a mapping relation of voltage and wind speed;

and step four, calibrating for many times under different constant environmental temperatures by controlling the air temperature in the self-built small wind tunnel to obtain a voltage-wind speed relational expression under different temperatures so as to reduce errors caused by temperature changes.

In the operation step of the second step, the method further comprises the following steps:

1) and signal processing of the ambient temperature: converting the received direct-current voltage signal into actual temperature (unit: DEG C) through calculation of a calculation formula of the NTC thermistor;

2) and processing the wind speed signal: calculating the received direct current voltage signal through a voltage-wind speed relational expression to obtain the corresponding wind speed;

3) according to the calibrated relational expression, selecting a voltage-wind speed relational expression corresponding to the ambient temperature to map the voltage signal into wind speed;

4) acquiring micro differential pressure signals (T, V) of a sensor 16 chip of the ambient temperature and the micro wind speed, establishing a state equation and an observation equation of Kalman filtering under a nonlinear dynamic system, and establishing a Kalman filtering model according to the state equation and the observation equation of the Kalman filtering;

5) determining the initialization state of the nonlinear dynamic system, namely determining the initial value of the state parameter of the initial epoch, the initial value of the variance matrix and the initial variance matrix of the dynamic noise;

6) filtering the initial value of the state parameter, the initial value of the variance matrix and the dynamic noise variance matrix by a Kalman filtering recursion equation based on the state equation and the observation equation of the initial epoch to obtain a new filtering value;

7) and calculating to obtain the current optimal wind speed according to the current measured wind speed and the predicted wind speed and error at the previous moment, and then predicting the wind speed at the next moment.

In the invention, the adopted breeze speed sensor 16 is less influenced by the ambient temperature and humidity, and the error caused by the temperature change can be further reduced by temperature calibration, the collected voltage signal is filtered by Kalman filtering in a single chip microcomputer, the interference of noise in a circuit to the voltage signal is effectively inhibited and prevented, the output result is more accurate, the disturbance is very small, the heat productivity of the chip of the adopted breeze speed sensor 16 is smaller, and the influence on the ambient temperature can be almost ignored under the background technical condition, therefore, the NTC thermistor can be placed at a position closer to a speed measuring channel of the breeze speed sensor 16, the measurement on the ambient temperature is more accurate, the speed measuring channel of the breeze speed sensor 16 is reduced, the speed measuring channel is more sensitive to the change of the breeze speed, and the transition curved surface of the breeze speed measuring channel of the breeze speed sensor 16 is increased, the invention has the advantages of high precision, small error and good stability, and effectively solves the defect that the environmental temperature has great influence on the traditional wind speed sensor.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.