CN113567498B - Dew point meter integrating video and optical detection and control method - Google Patents
Dew point meter integrating video and optical detection and control method Download PDFInfo
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Abstract
The invention relates to a dew point meter integrating video and optical detection and a control method thereof, comprising a temperature measuring module, a refrigerating module, a main control module, a video module and an optical module; the temperature measuring module comprises a four-wire platinum resistor PT1000, and the four-wire platinum resistor PT1000 is embedded into the cold mirror to measure the temperature; the refrigerating module adopts a three-stage semiconductor refrigerating sheet, is stuck to the back surface of the cold mirror through heat-conducting silica gel and is used for controlling the temperature of the mirror surface; the main control module comprises an STM32 microprocessor, an H-bridge driving circuit and a communication circuit, and is used for completing the work of detection, control, processing, communication and the like; the video module consists of a camera and a laser, and is used for collecting video of the mirror surface; the optical module consists of a lens and a photoelectric sensor and detects the reflectivity of the mirror surface; the invention combines image recognition and optical detection, and has the advantages of improving the measurement accuracy of the system, and the like.
Description
Technical Field
The invention relates to a dew point meter integrating video and optical detection and a control method thereof, belonging to the technical field of meteorological detection.
Background
The dew point meter in the prior art receives the reflected light of the cold mirror through the photoelectric sensor, detects the dew point temperature by judging whether the mirror surface of the cold mirror is dewed or not, and also detects the dew point temperature through video image recognition dewed.
Disclosure of Invention
The invention provides a dew point meter integrating video and optical detection and a control method thereof, which have the capabilities of data fusion and alternate dew point detection and high detection precision.
The technical scheme adopted for solving the technical problems is as follows:
the dew point meter integrating video and optical detection comprises a cold mirror dew point meter body, which comprises a cold mirror, a temperature measuring module, a refrigerating module, a main control module, a video module and an optical module, wherein the main control module is electrically connected with the temperature measuring module, the refrigerating module, the video module and the optical module at the same time,
the temperature measuring module comprises a platinum resistor which is embedded in the center of the cold mirror and is used for reading the temperature of the mirror surface of the cold mirror and transmitting the temperature to the main control module;
the video module comprises a camera and a laser, the camera is suspended on the cold mirror surface, the transmitting end of the laser is aligned to the mirror surface, and the main control module acquires a mirror surface image shot by the camera;
the optical module comprises a lens and a photoelectric sensor, the lens and the photoelectric sensor are both positioned on the cold mirror surface, and the main control module obtains a mirror reflection signal through the optical module;
the control module controls the refrigerating sheet to heat and cool and transmits the temperature to the cold mirror;
as a further preferred aspect of the present invention, the chilled mirror dew point meter body further comprises a first case and a second case, wherein the bottom of the first case is mounted on the top of the second case, and the bottom of the first case is communicated with the top of the second case;
the cold mirror is embedded at the bottom of the second box body, the camera and the optical module are arranged in the first box body, and the camera and the optical module are arranged opposite to the mirror surface at the communication position of the first box body and the second box body;
the laser is arranged on the side wall of the second box body, and the emitting end of the laser stretches into the second box body to be aligned with the mirror surface;
the top of the first box body is provided with a signal transmission interface for transmitting detection data of the camera and the optical module, and the side edge of the second box body is provided with a pipeline for introducing gas to be detected into the second box body;
as a further preferable mode of the invention, the contact surface of the cold mirror and the refrigerating sheet is coated with heat-conducting silicone grease;
as a further preferred aspect of the present invention, the main control module includes an STM32 processor, an H-bridge driving circuit, a communication circuit and an a/D conversion circuit,
the STM32 processor is electrically connected with the refrigerating sheet through the H-bridge driving circuit, and the STM32 processor controls the temperature rise and fall of the refrigerating sheet through outputting PWM to drive the H-bridge circuit;
the STM32 processor is communicated with the cloud server through a communication circuit and transmits received data to the cloud server;
the STM32 processor is communicated with the temperature measuring module through an A/D conversion circuit;
as a further preferred mode of the invention, an analog-to-digital conversion chip in the A/D conversion circuit is an ADS1232 chip, a communication module in the communication circuit is an ESP8266 module, the model of the camera is OV7670, and a platinum resistor is a four-wire platinum resistor PT1000;
as a further preferred aspect of the present invention, a heat dissipating device is installed at the bottom of the refrigeration module, and the heat dissipating device dissipates heat of the refrigeration module in a combination manner of air cooling and water cooling;
the control method of the dew point meter based on the fusion of the video and the optical detection specifically comprises the following steps:
step S1: starting a laser, emitting a wide laser beam to a mirror surface, starting a camera, collecting a mirror image, transmitting the collected mirror image to a main control module for calculation to obtain an image entropy, and defining the image entropy as S;
step S2: when a camera is started to acquire a mirror image, a photoelectric sensor receives laser emitted by a mirror, and a main control module obtains the reflectivity of the mirror through laser detection processing, and the reflectivity is defined as R;
step S3: through multiple experiments, an image entropy change critical value delta S and a reflectivity change critical value delta R before and after mirror surface condensation are obtained, and after the cold mirror dew point meter body is started, an image entropy and a reflectivity of the mirror surface when the mirror surface is not condensed are combined, and a dynamic image entropy set value S 'and a dynamic reflectivity set value R' are obtained;
step S4: the dynamic PID parameter is determined by experiments according to the deviation between the image entropy and S ', the deviation between the reflected light and R' and the deviation between the measured temperature and the target dew point temperature, which are detected in real time, by taking the image entropy set value S ', the reflectivity set value R' and the set temperature of minus 100 ℃ as targets
In the formula (1), u (k) Is the output adjustment amount at the time of k, u (k-1) Is the output adjustment amount at the time of k-1, es Is the error amount of image entropy at the time of k, k-1 and k-2, er Is the error amount of reflectivity at the time of k, k-1 and k-2, et Is the error amount of temperature at the time of k, k-1 and k-2, ps, pr and Pt are proportional coefficients, is, ir and It are integral coefficients, and Ds, dr and Dt are differential coefficients;
step S5: starting PID control cooling, when one of a preset image entropy set value or a reflectivity set value is reached, reading a corresponding temperature value, then taking the other set value which is not reached as a target value, setting PID parameters of the reached target value and target temperature to be zero, continuing cooling until the set value is reached, and obtaining the temperature value again, thereby obtaining two corresponding dew point temperatures Ts and Tr;
step S6: the dew point temperature Ts and Tr which are respectively read out are calculated to obtain the dew point temperature measured value after data fusion, and the calculation formula is as follows
Td＝k*Ts+(1-k)*TrTd (2)
In the formula (2), k is a weight coefficient, k=s Tr /(s Ts +s Tr )，s Ts Standard deviation of Ts, s Tr Is the standard deviation of Tr;
step S7: the image entropy set value S and the reflectivity set value R are used as set values for control in a circulating mode, and the temperature value is measured continuously to obtain the dew point temperature;
as a further preferred aspect of the present invention, in step S1, the step of calculating the image entropy by the main control module includes:
step S11: denoising the acquired mirror image, and then calculating to obtain the comprehensive characteristics reflecting the gray value of a certain pixel and the gray distribution of surrounding pixels, wherein the calculation formula is as follows
In the formula (3), selecting a neighborhood gray average value of the mirror image as a space feature quantity of gray distribution, forming a feature binary group with pixel gray of the mirror image, and marking the feature binary group as (i, j), wherein i represents a gray value (i is more than or equal to 0 and less than or equal to 255) of the pixel, j represents a neighborhood gray average value (i is more than or equal to 0 and less than or equal to 255), f (i, j) is a frequency of occurrence of the feature binary group (i, j), and N is a scale of the image;
step S12: calculating to obtain texture feature value reflecting the gray information of pixel position in the image and the comprehensive feature of gray distribution in the pixel field, namely image entropy S, wherein the calculation formula is
As a further preferred aspect of the present invention, in step S3, when the two-dimensional entropy of the image obtained by denoising the image collected in real time, that is, the image entropy S, exceeds a threshold, the image entropy S indicates mirror condensation;
in a further preferred aspect of the present invention, in step S5, when the reflectance set value or texture characteristic value reaches the set threshold value, it is determined that the measured gas has reached the critical dew point value, and the voltage R across the platinum resistor at that time is read t 、R 0 Calculating the resistance of the platinum resistor, wherein the calculation formula is as follows
R t ＝R 0 *(1+At+Bt 2 ) (5)
In the formula (5), A, BAre all index constants of 3.9083 ×10 respectively -3 、-5.775×10 -7 The temperature value is measured using the temperature relation of equation (5).
Through the technical scheme, compared with the prior art, the invention has the following beneficial effects:
1. according to the invention, a camera can shoot a mirror image, and whether the mirror surface is dewed or not is judged according to the change of the shot picture pixels;
2. the invention combines the traditional reflection detection method, and can improve the accuracy and reliability of dew point detection.
Drawings
The invention will be further described with reference to the drawings and examples.
FIG. 1 is a schematic diagram of the connection relationship of the various modules of the present invention;
FIG. 2 is a schematic view of the structure of a preferred embodiment provided by the present invention;
FIG. 3 is a side view of a preferred embodiment provided by the present invention;
fig. 4 is a top view of a preferred embodiment provided by the present invention.
In the figure: 1 is a first box body, 2 is a second box body, 3 is a cold mirror, 4 is a refrigerating sheet, 5 is a platinum resistor, 6 is a laser, 7 is a heat radiating device, 8 is a camera, and 9 is an optical module.
Detailed Description
The invention will now be described in further detail with reference to the accompanying drawings. In the description of the present application, it should be understood that the terms "left," "right," "upper," "lower," and the like indicate orientations or positional relationships based on the orientation or positional relationships shown in the drawings, and are merely for convenience in describing the present invention and simplifying the description, rather than indicating or implying that the apparatus or element being referred to must have a specific orientation, be configured and operated in a specific orientation, and that "first," "second," etc. do not represent the importance of the components and therefore should not be construed as limiting the present invention. The specific dimensions adopted in the present embodiment are only for illustrating the technical solution, and do not limit the protection scope of the present invention.
In the prior art, whether dew point is formed on the mirror surface of the cold mirror is judged only by receiving reflected light of the cold mirror by the photoelectric sensor, or whether the mirror surface is formed on the dew point is judged only by video image recognition, and finally the dew point temperature is detected.
The cold mirror dew point meter body is used as a basis and mainly comprises a temperature measuring module, a refrigerating module, a main control module, a video module and an optical module 9, wherein the main control module is connected with other modules to control the modules as shown in fig. 1, and the cold mirror dew point meter body comprises a first box body 1 and a second box body 2 as shown in a structural schematic diagram of fig. 2; the cold mirror 3 is embedded at the bottom of the second box body, the temperature measuring module comprises a platinum resistor 5, the platinum resistor is a four-wire platinum resistor PT1000, and the platinum resistor is embedded at the center of the cold mirror and is used for reading the temperature of the mirror surface and transmitting the temperature to the main control module; the refrigeration module comprises a refrigeration sheet 4 which is arranged at the bottom of the cold mirror; the video module comprises a camera 8 and a laser 6, the camera and the optical module are arranged in a first box body, the camera and the optical module are suspended on a cold mirror surface at the communication position of the first box body and a second box body, the laser is arranged on the side wall of the second box body as shown in fig. 3, and the transmitting end of the laser extends into the second box body to be aligned with the mirror surface; here, the camera selects OV7670, which has high sensitivity, low voltage, standard SCCB interface, compatible IIC interface, supporting automatic exposure control, automatic gain control, automatic white balance, automatic elimination of light stripes, automatic black level calibration and other automatic control functions.
The main control module comprises an STM32 processor, an H-bridge driving circuit, a communication circuit and an A/D conversion circuit, wherein the STM32 processor is electrically connected with the refrigerating sheet through the H-bridge driving circuit, heat conduction silicone grease is coated on the contact surface of the refrigerating sheet and the refrigerating sheet, the STM32 processor controls the refrigerating sheet to rise and fall through outputting PWM (pulse width modulation) to drive the H-bridge circuit, and the temperature is transferred to the refrigerating sheet in the gas to be tested through the heat conduction silicone grease; in order to better control the temperature of the refrigerating sheets, a heat dissipation device 7 shown in fig. 4 is arranged at the bottom of the refrigerating sheets, and mainly uses a mode of combining air cooling and water cooling to dissipate heat of the three-stage refrigerating sheets; the STM32 processor is communicated with the temperature measuring module through the A/D conversion circuit, and when the main control module receives the mirror image transmitted by the video module and the reflection signal obtained through the optical module, the temperature measuring module reads out the dew point temperature value corresponding to the instant dew condensation of the cold mirror surface after judging whether the mirror surface is condensed. In the application, an ADS1232 chip is selected as an analog-to-digital conversion chip of the A/D conversion circuit, and the chip has the advantages of low power consumption, high integration level, low-noise programmable gain amplifier and the like; the voltage stabilizing chip AMS1117-5.0 supplies power through 5V to form a reference voltage of 2.5V, and provides a reference for the ADS1232 chip, so that the reliability and stability of the operation of the voltage stabilizing chip AMS1117-5.0 are improved.
The STM32 processor is communicated with the cloud server through a communication circuit, the communication module selected in the communication circuit is an ESP8266 module, RX and TX of the ESP8266 module are connected with TX and RX of the microprocessor, the microprocessor is connected with the ESP8266 module, and data are displayed on the LCD screen; ESP8266 module transmits the data received to cloud server through WIFI, and mobile phone APP calls the API interface that cloud server provided through Java sentence, and data that will store in the server is shown on the mobile phone for the user to look over, and the chart interface on the APP with the data that will read is recorded.
In the application, after the gas to be detected enters through the pipeline of the second box body, the main control module controls the refrigerating sheet to rapidly refrigerate, and the temperature of the mirror surface is reduced along with the reduction of the temperature of the refrigerating sheet, and when the temperature reaches the critical temperature of condensation, for example, the gas to be detected contacts the mirror surface, water in the gas can condense on the mirror surface to form dew; when the laser emits a wide laser beam to irradiate the mirror surface, the optical module detects the reflectivity of the mirror surface, and compared with a dynamic reflectivity set value, the wide laser beam is realized by adjusting the lens to make the laser beam divergent.
The applicant then presents a control method for a dew point meter with fusion of video and optical detection, comprising in particular the following steps:
step S1: starting a laser, emitting a wide laser beam to a mirror surface, starting a camera, collecting a mirror image, transmitting the collected mirror image to a main control module for calculation to obtain an image entropy, and defining the image entropy as S;
the main control module calculates the image entropy:
step S11: denoising the acquired mirror image, and then calculating to obtain the comprehensive characteristics reflecting the gray value of a certain pixel and the gray distribution of surrounding pixels, wherein the calculation formula is as follows
In the formula (3), selecting a neighborhood gray average value of the mirror image as a space feature quantity of gray distribution, forming a feature binary group with pixel gray of the mirror image, and marking the feature binary group as (i, j), wherein i represents a gray value (i is more than or equal to 0 and less than or equal to 255) of the pixel, j represents a neighborhood gray average value (i is more than or equal to 0 and less than or equal to 255), f (i, j) is a frequency number of occurrence of the feature binary group (i, j) (namely, the frequency number of occurrence of pixel gray of a certain point in the mirror image, namely, the field gray of the pixel gray is equal to i and j), and N is a scale of the image (the number of rows and the number of the selected mirror image);
step S12: calculating to obtain texture feature value reflecting the gray information of pixel position in the image and the comprehensive feature of gray distribution in the pixel field, namely image entropy S, wherein the calculation formula is
The texture characteristic value is calculated as two-dimensional entropy of the image, the dew point identification is carried out by carrying out image preprocessing on dew point images acquired in real time, namely carrying out median filtering on each mirror image, determining the entropy value of the filtered image, and judging the image as a dew condensation image when the texture characteristic value (entropy) of the calculated real-time image is compared with a set standard value to exceed a threshold value.
Step S2: when the camera is started to collect the mirror image, the photoelectric sensor receives laser emitted by the mirror, and the main control module obtains the reflectivity of the mirror through the laser detection processing, and the reflectivity is defined as R.
Step S3: through multiple experiments, an image entropy change critical value delta S and a reflectivity change critical value delta R before and after mirror surface dew condensation are obtained, and after the cold mirror dew point meter body is started, the image entropy and the reflectivity of the mirror surface when the mirror surface is not dew condensation are combined, and a dynamic image entropy set value S 'and a dynamic reflectivity set value R' are obtained.
Step S4: the dynamic PID parameter is determined by experiments according to the deviation between the image entropy and S ', the deviation between the reflected light and R' and the deviation between the measured temperature and the target dew point temperature, which are detected in real time, by taking the image entropy set value S ', the reflectivity set value R' and the set temperature of minus 100 ℃ as targets
In the formula (1), u (k) Is the output adjustment amount at the time of k, u (k-1) Is the output adjustment amount at the time of k-1, es Is the error amount of image entropy at the times of k, k-1, k-2, er Is the error amount of reflectivity at the times of k, k-1, k-2, et Is the error amount of temperature at the times of k, k-1, k-2, ps, pr, pt are proportional coefficients, is, ir, it Is an integral coefficient, ds, dr, dt are differential coefficients.
Step S5: starting PID control cooling, when one of a preset image entropy set value or a reflectivity set value is reached, reading a corresponding temperature value, then taking the other set value which is not reached as a target value, setting PID parameters of the reached target value and target temperature to be zero, continuing cooling until the set value is reached, and obtaining the temperature value again, thereby obtaining two corresponding dew point temperatures Ts and Tr; by the method, the temperature is controlled to fluctuate within a small range, the stability of the whole system is improved, and the measurement accuracy of the system is further improved;
in this step, the temperature value is read based on the detected reflectance set value or texture characteristic valueWhen the set threshold is reached, the detected gas can be judged to reach the critical dew point value, and the voltage R at two ends of the platinum resistor at the moment can be read out t 、R 0 Calculating the resistance of the platinum resistor, wherein the calculation formula is as follows
R t ＝R 0 *(1+At+Bt 2 ) (5)
In the formula (5), A and B are index constants of 3.9083 ×10 respectively -3 、-5.775×10 -7 The temperature value is measured using the temperature relation of equation (5).
Step S6: the dew point temperature Ts and Tr which are respectively read out are calculated to obtain the dew point temperature measured value after data fusion, and the calculation formula is as follows
Td＝k*Ts+(1-k)*TrTd (2)
In the formula (2), k is a weight coefficient, k=s Tr /(s Ts +s Tr )，s Ts Standard deviation of Ts, s Tr Is the standard deviation of Tr;
step S7: the image entropy set value S and the reflectivity set value R are used as set values for control in a circulating mode, and the temperature value is measured continuously to obtain the dew point temperature; wherein the continuous measurement of the temperature value is realized by reducing the refrigeration current and even adding reverse voltage to heat the three-stage refrigeration piece.
Through setting forth the dew point meter structure and setting forth the control method that this application provided, can know this application during operation, main control module control video module gathers mirror image and denoising handles and obtain image two-dimensional entropy, detect the specular reflectivity through optical module simultaneously, input image entropy and reflectivity into the PID controller, control tertiary refrigeration piece refrigeration to the target value, through image entropy and reflectivity alternating control dew point critical point and detect corresponding dew point temperature, obtain final dew point temperature after the data fusion, this application combines reflection detection method with the picture pixel change that the camera was shot, can accurately judge the dew condition of mirror surface, improve dew point detection's degree of accuracy and reliability.
It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
The meaning of "and/or" as referred to in this application means that each exists alone or both.
As used herein, "connected" means either a direct connection between elements or an indirect connection between elements via other elements.
With the above-described preferred embodiments according to the present invention as an illustration, the above-described descriptions can be used by persons skilled in the relevant art to make various changes and modifications without departing from the scope of the technical idea of the present invention. The technical scope of the present invention is not limited to the description, but must be determined according to the scope of claims.
Claims (4)
1. A control method of a dew point meter integrating video and optical detection is characterized by comprising the following steps:
the dew point meter comprises a cold mirror (3) dew point meter body, which comprises the cold mirror (3), a temperature measuring module, a refrigerating module, a main control module, a video module and an optical module (9), wherein the main control module is electrically connected with the temperature measuring module, the refrigerating module, the video module and the optical module (9) at the same time,
the temperature measuring module comprises a platinum resistor (5) which is embedded in the center of the cold mirror (3) and is used for reading the temperature of the mirror surface of the cold mirror (3) and transmitting the temperature to the main control module;
the video module comprises a camera (8) and a laser (6), the camera (8) is suspended on the mirror surface of the cold mirror (3), the transmitting end of the laser (6) is aligned to the mirror surface, and the main control module acquires a mirror surface image shot by the camera (8);
the optical module (9) comprises a lens and a photoelectric sensor, the lens and the photoelectric sensor are both positioned on the mirror surface of the cold mirror (3), and the main control module acquires a mirror reflection signal through the optical module (9);
the refrigerating module comprises a refrigerating sheet (4) which is arranged at the bottom of the cold mirror (3), and the control module controls the refrigerating sheet (4) to rise and fall and transmits the temperature to the cold mirror (3);
the cold mirror (3) dew point meter body further comprises a first box body (1) and a second box body (2), wherein the bottom of the first box body (1) is arranged at the top of the second box body (2), and the bottom of the first box body (1) is communicated with the top of the second box body (2);
the cold mirror (3) is embedded at the bottom of the second box body (2), the camera (8) and the optical module (9) are arranged in the first box body (1), and the camera (8) and the optical module (9) are arranged at the joint of the first box body (1) and the second box body (2) relative to the mirror surface;
the laser (6) is arranged on the side wall of the second box body (2), and the emitting end of the laser (6) extends into the second box body (2) to be aligned with the mirror surface;
the top of the first box body (1) is provided with a signal transmission interface for transmitting detection data of the camera (8) and the optical module (9), and the side edge of the second box body (2) is provided with a pipeline for introducing gas to be detected into the second box body (2); the contact surface of the cold mirror (3) and the refrigerating sheet (4) is coated with heat-conducting silicone grease;
the main control module comprises an STM32 processor, an H-bridge driving circuit, a communication circuit and an A/D conversion circuit,
the STM32 processor is electrically connected with the refrigerating sheet (4) through the H-bridge driving circuit, and the STM32 processor controls the refrigerating sheet (4) to be heated and cooled through outputting PWM to drive the H-bridge driving circuit;
the STM32 processor is communicated with the cloud server through a communication circuit and transmits received data to the cloud server;
the STM32 processor is communicated with the temperature measuring module through an A/D conversion circuit;
an analog-to-digital conversion chip in the A/D conversion circuit adopts an ADS1232 chip, a communication module in the communication circuit adopts an ESP8266 module, the model of the camera (8) adopts an OV7670, and a platinum resistor (5) adopts a four-wire platinum resistor (5) PT1000;
a heat dissipation device (7) is arranged at the bottom of the refrigeration module, and the heat dissipation device dissipates heat of the refrigeration module in an air cooling and water cooling combined mode;
the control method specifically comprises the following steps:
step S1: starting a laser (6), emitting a wide laser beam to a mirror surface, starting a camera (8), collecting a mirror surface image, transmitting the collected mirror surface image to a main control module for calculation to obtain an image entropy, and defining the image entropy as S;
step S2: when a camera (8) is started to collect a mirror image, the photoelectric sensor receives laser emitted by the mirror, and the main control module obtains the reflectivity of the mirror through the laser detection processing, and is defined as R;
step S3: through multiple experiments, an image entropy change critical value delta S and a reflectivity change critical value delta R before and after mirror surface condensation are obtained, and after the cold mirror (3) dew point meter body is started, the image entropy and the reflectivity of the mirror surface when the mirror surface is not condensed are combined, and a dynamic image entropy set value S 'and a dynamic reflectivity set value R' are obtained;
step S4: the dynamic PID parameter is determined by experiments according to the deviation between the image entropy and S ', the deviation between the reflected light and R' and the deviation between the measured temperature and the target dew point temperature, which are detected in real time, by taking the image entropy set value S ', the reflectivity set value R' and the set temperature of minus 100 ℃ as targets
u(k)＝u(k-1)+Ps*(es(k)-es(k-1)+Is*es(k)+Ds(es(k)-2*es(k-1)+es(k-2))+Pr*(er(k)-er(k-1))+Ir*er(k)+Dr(er(k)-2*er(k-1)+er(k-2))+Pt*(et(k)-et(k-1))+It*et(k)+Dt(et(k)-2*et(k-1)+et(k-2)) (1)
In the formula (1), u (k) Is the output adjustment amount at the time of k, u (k-1) Is the output adjustment amount at the time of k-1, es Is the error amount of image entropy at the time of k, k-1 and k-2, er Is the error amount of reflectivity at the time of k, k-1 and k-2, et Is the error amount of temperature at the time of k, k-1 and k-2, ps, pr and Pt are proportional coefficients, is, ir and It are integral coefficients, and Ds, dr and Dt are differential coefficients;
step S5: starting PID control cooling, when one of a preset image entropy set value or a reflectivity set value is reached, reading a corresponding temperature value, then taking the other set value which is not reached as a target value, setting PID parameters of the reached target value and target temperature to be zero, continuing cooling until the set value is reached, and obtaining the temperature value again, thereby obtaining two corresponding dew point temperatures Ts and Tr;
step S6: the dew point temperature Ts and Tr which are respectively read out are calculated to obtain the dew point temperature measured value after data fusion, and the calculation formula is as follows
Td＝ k*Ts+(1-k)*TrTd (2)
In the formula (2), k is a weight coefficient, k=s Tr /(s Ts +s Tr )，s Ts Standard deviation of Ts, s Tr Is the standard deviation of Tr;
step S7: and the circulation is controlled by taking the image entropy set value S and the reflectivity set value R as set values, and the temperature value is continuously measured to obtain the dew point temperature.
2. The method for controlling a dew point meter with video and optical detection fusion according to claim 1, wherein: in step S1, the step of calculating the image entropy by the main control module includes:
step S11: denoising the acquired mirror image, and then calculating to obtain the comprehensive characteristics reflecting the gray value of a certain pixel and the gray distribution of surrounding pixels, wherein the calculation formula is as follows
In the formula (3), selecting a neighborhood gray average value of the mirror image as a space feature quantity of gray distribution, forming a feature binary group with pixel gray of the mirror image, wherein i is equal to or more than 0 and equal to or less than 255 of the pixel gray value, j is equal to or less than 0 and equal to or less than 255 of the neighborhood gray average value, f (i, j) is the frequency of occurrence of the feature binary group (i, j), and N is the scale of the image;
step S12: calculating to obtain texture feature value reflecting the gray information of pixel position in the image and the comprehensive feature of gray distribution in the pixel field, namely image entropy S, wherein the calculation formula is
3. The method for controlling a dew point meter with video and optical detection fusion according to claim 2, wherein: in step S3, when the two-dimensional entropy of the image obtained by denoising the image acquired in real time, that is, the image entropy S, exceeds a threshold, the image entropy S indicates mirror condensation.
4. A method of controlling a video and optical detection fused dew point meter according to claim 3, wherein: in step S5, if the detected reflectivity set value or texture characteristic value reaches the set threshold value, it can be judged that the detected gas reaches the critical dew point value, and the voltage R at the two ends of the platinum resistor (5) at the moment is read t 、R 0 The resistance value of the platinum resistor (5) is calculated, and the calculation formula is as follows
R t ＝R 0 *(1+At+Bt 2 ) (5)
In the formula (5), A and B are index constants of 3.9083 ×10 respectively -3 、-5.775×10 -7 The temperature value is measured using the temperature relation of equation (5).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110856504.3A CN113567498B (en) | 2021-07-28 | Dew point meter integrating video and optical detection and control method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN202110856504.3A CN113567498B (en) | 2021-07-28 | Dew point meter integrating video and optical detection and control method |
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| CN113567498A CN113567498A (en) | 2021-10-29 |
| CN113567498B true CN113567498B (en) | 2023-05-09 |
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