An automatic calibration method and device for a sensor

Abstract

The present invention relates to an automatic calibration method and device for a sensor. The method includes: obtaining the code value of the sensor at zero load and the code value at rated load; selecting N calibration points between the zero load and the rated load of the sensor, where N is an integer greater than or equal to 1; obtaining the code value parameters of the sensor at each calibration point; establishing a calibration equation based on the code value parameters of each calibration point, and the calibration equation is used to characterize the corresponding relationship between the sensor detection value and the code value parameter. After calibrating the sensor by the calibration method of the present invention, the accuracy of the output data of the sensor can be ensured.

Description

Technical Field

[0001] The present invention relates to the field of sensors, and particularly to an automatic calibration method and device for a sensor. Background Art

[0002] The informatization of railway engineering based on railway BIM technology can record the data of the entire life cycle of railway engineering design, construction, and operation and maintenance, and has been widely applied in railway engineering construction projects. The informatization of railway engineering requires the real-time upload of process construction inspection data to achieve collaborative management of railway engineering construction. The automatic equipment for data upload usually uses sensors as the data acquisition method, so it is necessary to ensure the accuracy of the sensors during use to guarantee the construction quality of railway engineering. Sensors generally use the method of periodic calibration to ensure the accuracy of their output data. Usually, the calibration of sensors is carried out manually, and due to human factors, the accuracy of the calibration data of sensors cannot be ensured. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to propose an automatic calibration method and device for a sensor, which can improve the accuracy of the output data of the sensor.

[0004] The first embodiment of the present invention provides an automatic calibration method for a sensor, and the method includes: obtaining the code value of the sensor at zero load and the code value at rated load; selecting N calibration points between the zero load and the rated load of the sensor, where N is an integer greater than or equal to 1; obtaining the code value parameters of the sensor at each calibration point; establishing a calibration equation according to the code value parameters at each calibration point, and the calibration equation is used to characterize the corresponding relationship between the sensor detection value and the code value parameter.

[0005] In some embodiments, the obtaining the code value parameters of the sensor at each calibration point includes: obtaining multiple code values of the sensor at each calibration point; calculating the average value of the multiple code values of the sensor at each calibration point, and taking the average value as the code value parameter.

[0006] In some embodiments, after taking the average value as the code value parameter, it further includes: calculating the repeatability error of the sensor at each calibration point; sending an abnormal alarm when the repeatability error is greater than a predetermined value.

[0007] In some embodiments, obtaining the code value parameters of the sensor at each calibration point includes: applying a load to the sensor; calculating a plurality of forward difference values of the code value of the sensor during the application of the load; calculating the average value of the obtained plurality of forward difference values; calculating the variance of the plurality of forward difference values; determining the loading and holding state of the sensor according to the variance; and obtaining the code value parameters of the sensor when the sensor is in the holding state.

[0008] In some embodiments, the load applied to the sensor is a linear load.

[0009] The second embodiment of the present invention provides an automatic calibration device for a sensor. The device includes: a serial port communication module for connecting to the sensor; a storage module; and a control module configured to perform the following steps: obtaining the code value of the sensor at zero load and the code value at rated load; selecting N calibration points between the zero load and the rated load of the sensor, where N is an integer greater than or equal to 1; obtaining the code value parameters of the sensor at each calibration point; and establishing a calibration equation according to the code value parameters of each calibration point, where the calibration equation is used to characterize the correspondence between the sensor detection value and the code value parameters.

[0010] In some embodiments, the calibration device of the sensor further includes: an alarm module; and a remote communication module; the control module is further configured to upload the code value parameters of the sensor to the status monitoring server through the remote communication module, and, in response to receiving an alarm instruction, control the alarm module to alarm.

[0011] In some embodiments, the remote communication module includes a wireless transmission module and an Ethernet communication module. The control module is configured to connect to the status monitoring server through the wireless transmission module, and the control module is further configured to connect to other control systems through the Ethernet communication module or the serial port communication module.

[0012] In some embodiments, the device further includes a display screen.

[0013] In some embodiments, the serial port communication module is an RS485 serial port communication module. The RS485 serial port communication module includes six communication serial ports. One serial port of the RS485 serial port communication module is used to connect to the display screen, another serial port of the RS485 serial port communication module is used to connect to the wireless transmission module, the RS485 serial port communication module communicates with other control systems for data, and the other three serial ports of the RS485 serial port communication module are used to connect to the sensor.

[0014] The calibration method and calibration device of the embodiments of the present invention can ensure the accuracy of the data output by the sensor. Description of the Drawings

[0015] Through the following description of the embodiments of the present invention with reference to the accompanying drawings, the above and other objects, features, and advantages of the present invention will become clearer. In the drawings:

[0016] Figure 1 Schematic diagram of the steps of the calibration method according to the first embodiment of the present invention;

[0017] Figure 2 Schematic diagram of a sub-step of the calibration method according to the first embodiment of the present invention;

[0018] Figure 3 Schematic diagram of another sub-step of the calibration method according to the first embodiment of the present invention;

[0019] Figure 4 Schematic diagram of another sub-step of the calibration method according to the first embodiment of the present invention;

[0020] Figure 5 Schematic diagram of the internal structure connection of the calibration device according to the second embodiment of the present invention;

[0021] Figure 6 Schematic diagram of the information interaction of the calibration device according to the second embodiment of the present invention. Detailed implementation manners

[0022] The following describes the present invention based on embodiments, but the present invention is not limited to these embodiments. In the following detailed description of the present invention, some specific details are described in detail. Those skilled in the art can fully understand the present invention without the description of these details. In order to avoid obscuring the essence of the present invention, well-known methods, processes, procedures, elements, and circuits are not described in detail.

[0023] In addition, those of ordinary skill in the art should understand that the accompanying drawings provided herein are for illustrative purposes only, and the drawings are not necessarily drawn to scale.

[0024] At the same time, it should be understood that in the following description, a "circuit" refers to a conductive loop formed by at least one element or sub-circuit through electrical connection or electromagnetic connection. When an element or circuit is said to be "connected to" another element or when an element / circuit is said to be "connected between" two nodes, it can be directly coupled or connected to another element or there may be intermediate elements, and the connection between the elements can be physical, logical, or a combination thereof. On the contrary, when an element is said to be "directly coupled to" or "directly connected to" another element, it means that there are no intermediate elements between the two.

[0025] Unless the context clearly requires otherwise, the words "including", "comprising" and similar words in the specification shall be construed in an inclusive sense rather than an exclusive or exhaustive sense; that is, it is the meaning of "including but not limited to".

[0026] In the description of the present invention, it should be understood that the terms "first", "second", etc. are only used for descriptive purposes and cannot be construed as indicating or implying relative importance. In addition, in the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more than two.

[0027] As Figure 1 shown Figure 1 is a schematic diagram of the steps of a calibration method for a sensor according to the first embodiment of the present invention. The method includes:

[0028] S101, obtaining the code value D0 of the sensor at zero load and the code value D of the sensor at rated load N ;

[0029] S102, selecting N calibration points between the zero load and the rated load of the sensor;

[0030] S103, obtaining the code value parameter D of the sensor at each calibration point i ;

[0031] S104, establishing a calibration equation according to the code value parameter D of each calibration point i

[0032] Wherein, N is an integer greater than or equal to 1. i is the ith calibration point among the N calibration points, that is, i ∈ [1, N], and i ∈ {Z}.

[0033] In the following description, taking the sensor as a force sensor as an example:

[0034] The sensor can be a digital sensor. After purchasing the sensor, it is necessary to calibrate the sensor first before it can be put into use. And when the sensor is in use, it also needs to be calibrated periodically to ensure its stability. The calibration of the sensor can be carried out in a third-party institution, generally completed step by step through the loading and holding of a force standard machine. The output of the sensor is a code value, and there is a corresponding relationship between the code value and the force value applied by the force standard machine (that is, the input of the sensor). In addition, the manufacturer of the sensor can provide information such as the number, rated load, accuracy level, repeatability error, number of calibration points, and load at each calibration point of the sensor.

[0035] In step S101, the code value D0 of the sensor at zero load, that is, the output value of the sensor when no load is applied to the sensor, can be directly obtained. The code value D of the sensor at rated load N ​That is, the output value of the sensor when a rated load is applied to the sensor, which can be obtained by applying the rated load to the sensor by a force standard machine. Among them, the rated load is provided by the sensor manufacturer.

[0036] In step S102, the selection of N calibration points can be divided according to the calibration point information provided by the sensor manufacturer. At the same time, the load information of each calibration point can be set through a program in the force standard machine, so that the force standard machine can apply the predetermined load corresponding to the calibration point to the sensor at each calibration point.

[0037] In step S103, the code value parameter D of the sensor at each calibration point i can be realized by the force standard machine loading and holding the load on the sensor. Among them, loading means applying a load, and holding means maintaining the current load. Specifically, each calibration point corresponds to a load value. The force standard machine sequentially loads the sensor to the load corresponding to the i-th calibration point and holds the load for a predetermined time, and records the code value D output by the sensor at this calibration point i , and then unloads to zero, that is, removes the load on the sensor, and then loads the sensor to the load corresponding to the next calibration point, holds the load, and records the code value D of this calibration point i , and so on, until the code value D of each calibration point i is recorded. For example, taking the number N of calibration points as 10 as an example, then i is also 10. The force standard machine first loads the sensor to the load corresponding to the first calibration point, and records the code value D1 output by the sensor after holding the load for a predetermined time; then the force standard machine unloads to zero, and then loads the sensor to the load corresponding to the second calibration point, and records the output code value D2 of the sensor after holding the load for a predetermined time; and so on, sequentially recording the output code values D3, D4, D5... D 10 of the sensor at the 3rd, 4th, 5th... until the 10th calibration point.

[0038] Among them, in an optional implementation manner, the holding time of each stage can be 30 seconds. Generally, the sensor can reach stability within 30 seconds after being loaded, and the code value D of this calibration point can be recorded after reaching stability i . Of course, in some other optional implementation manners, the holding time can also be other times, such as longer or shorter than 30 seconds, which can be adjusted according to the performance of the sensor, the force standard machine, etc. or the actual requirements, and this embodiment does not limit this.

[0039] For some sensors with elastomeric elements as sensitive elements, the force standard machine and the sensor can be preheated before formal calibration. In an alternative implementation, before step S103, the following steps can be performed: The sensor is pressed to the rated load on the force standard machine and unloaded to zero load 3 times. And, after each unloading, it is necessary to maintain for more than 30 seconds (the purpose is to provide time for the elastomeric element to recover and buffer). Additionally, the sensor can also be a sensor in other sensitive element forms. For sensor types where the sensitive element is not an elastomeric element, the preheating step can be omitted before formal calibration.

[0040] In step S104, according to the code value parameters D of each calibration point i A calibration equation is established. The establishment of the equation can be executed through a preset program in the calibration device. There are N calibration points between the zero load and the rated load of the sensor, where the 1st point is the calibration point of the rated load. It is easy to understand that the N calibration points divide the entire interval into N sub-intervals. A calibration equation is established between each adjacent calibration point. Therefore, the number of calibration equations obtained is N. And, each calibration equation is a linear equation. Thus, when a force is input to the sensor, a corresponding code value can be obtained according to the calibration point interval to which the force belongs and the calibration equation of that interval, and the sensor can output this code value. The reason for doing this is that for a digital sensor, the relationship between the input force value and the output code value is usually not a linear correspondence. Moreover, the input value of the digital sensor can be a continuously changing input, while the output code value is a discrete value. Therefore, it is necessary to determine a corresponding relationship so that when the sensor has an input value, a corresponding output code value can be determined. When dividing the N calibration points, according to the calibration point load information provided by the sensor manufacturer, the division of the calibration points can make the corresponding relationship between each adjacent calibration point a linear correspondence. Therefore, after establishing a calibration equation between each adjacent calibration point, when a force value is input to the sensor, find the calibration point interval corresponding to this force value, and a corresponding code value can be determined through the calibration equation of that interval, and the sensor can output this code value. In this case, the corresponding relationship between the input value and the output value of the sensor is determined, and the output value of the sensor is accurate.

[0041] As Figure 2 shown, in some embodiments, after obtaining the code value parameters of the sensor at each calibration point, it may further include:

[0042] S201, obtaining multiple code values of the sensor at each calibration point;

[0043] S202, taking the average of the multiple code values of the sensor at each calibration point.

[0044] In step S201, it can be achieved by calibrating the sensor multiple times. Specifically, when using a force standard machine to sequentially obtain the code value D for each calibration point of the sensor i after that, the first set of calibration data is obtained. Then, use the force standard machine to obtain the code value for each calibration point of the sensor again to obtain the second set of calibration data. This process can be repeated two or more times, which can be determined according to the actual situation. Thus, multiple code value data regarding each calibration point can be obtained at each calibration point.

[0045] In step S202, calculate the average value of the multiple code values for each of the above calibration points, and use the average value as the code value parameter, and a calibration equation can be established between each adjacent calibration point according to step S104 through the code value parameter.

[0046] By obtaining the code value multiple times at a single calibration point and calculating the average value, the calibration of the sensor can be made more accurate.

[0047] As Figure 3 shown, in some embodiments, after using the average value as the code value parameter, it may further include:

[0048] S301, calculate the repeatability error of the sensor at each calibration point;

[0049] S302, issue an abnormal alarm when the repeatability error is greater than a predetermined value.

[0050] In step S301, the repeatability error at each calibration point can be calculated through the multiple code values at this calibration point and the average value of the multiple code values.

[0051] In step S302, the predetermined value of the repeatability error can be provided by the manufacturer of the sensor. By comparing the calculated repeatability error at each calibration point with the standard value of the repeatability error at this calibration point, it can be known whether the repeatability error of the sensor at this calibration point meets the standard. When it does not meet the standard, the calibration device can issue an abnormal alarm.

[0052] As Figure 4 shown, in some embodiments, obtaining the code value parameter of the sensor at each calibration point includes:

[0053] S401, apply a load to the sensor;

[0054] S402, calculate multiple forward difference values of the code value of the sensor during the process of applying the load;

[0055] S403, calculate the average value of the multiple obtained forward difference values;

[0056] S404. Calculate the variance of multiple forward difference values;

[0057] S405. Determine the loading and holding state of the sensor according to the variance;

[0058] S406. When the sensor is in the holding state, obtain the code value parameter of the sensor.

[0059] In step S401, a load is applied to the sensor, and the output code value of the sensor is D i . Preferably, considering that the upper and lower limits of the output code values of sensors from different manufacturers are different, therefore, the output code value of the sensor can be normalized. The normalization method is as follows:

[0060]

[0061] where F(i) is the normalized sensor code value, D i , D0, D N are the current load output code value, zero load output code value, and rated load output code value of the sensor respectively. 180000 is related to the performance of the sensor, and the normalized code value F(i) ∈ [0, 180000]. In this way, it can be ensured that the sensor resolution is above 16 bits. For sensor types with higher resolution, the value 180000 can be appropriately increased.

[0062] In step S402, the calculation domain of the forward difference value can be 2 seconds. That is to say, during loading, the normalized sensor code values F(i) within the most recent 2 seconds are forward differenced to obtain the first-order differential signal X(n). Let the normalized code value of the sensor at a certain moment during the loading process be F(i), and let the normalized code value of the sensor 2 seconds before the said moment be F(i - 1). Then:

[0063] X(n) = F(i) - F(i - 1).

[0064] In step S403, calculate the average value of the multiple forward difference values obtained. In other words, it can be to calculate the mean μ of the differential signal within 2 seconds. Then:

[0065]

[0066] where T is the number of differential signals X(n) obtained within 2 seconds.

[0067] In step S404, calculate the variance of the multiple forward difference values. In other words, it can be to calculate the variance σ of the differential signal within 2 seconds 2 , then:

[0068]

[0069] In step S405, a variance threshold σ0 can be preset. 2 , the variance threshold σ0 2 can be provided by the manufacturer information of the sensor or set according to the performance of the sensor. When the sensor is in the loading state, the load value continuously increases, and the normalized code value F(i) of the sensor has a large degree of dispersion, and the variance σ of the differential signal of the sensor 2 is large; when the sensor is in the holding state, the load value is stable, the normalized code value F(i) of the sensor has a small degree of dispersion, and the variance σ of the differential signal of the sensor 2 is small. When σ 2 < σ0 2 , it can be determined that the sensor is in the holding state at the current moment.

[0070] In step S406, as described above, the holding time can be 30 seconds. Preferably, after it is determined that the sensor is in the holding state, the code value D corresponding to the current load can be obtained at the 27th second of the holding i . Generally, the output value of the sensor obtained at this time is stable and accurate. Of course, in some other alternative implementation manners, the output value of the sensor can also be obtained at other times within 30 seconds of the holding, for example, it can be the 20th second of the holding, or the 28th second of the holding, etc., which can be set according to the actual situation.

[0071] In addition, in some embodiments, the following method can be used to determine whether the sensor has completed the calibration process, or rather, after step S406, there is also step S407 (not shown):

[0072] S407, after obtaining the code value parameter of a certain calibration point each time, compare this code value with the code value parameter at the previous holding. If the code value at the current moment is lower than 80% of the previous code value, it is determined that the holding at the last calibration point ends, then the force standard machine can unload the load, and the primary calibration process of the sensor ends. For example, during the calibration process, if the code value obtained at a certain calibration point is 10000, the code value obtained at the next calibration point is 18000, and the code value obtained at the next calibration point is 24000, then it is not difficult to understand that the sensor is in the loading state during this process. Further, if after obtaining the code value of 24000, the next code value obtained is 12000, that is, less than 80% of the previous code value of 24000, then it is not difficult to understand that the load does not continue to increase, and it can be determined that the calibration point with the code value of 24000 is the last calibration point, and this calibration can end. When multiple calibrations are required to take the average value, a new calibration can be started after this process ends, and so on, until a predetermined number of calibration data is obtained.

[0073] Among them, the value of 80% is a commonly used value under normal circumstances. This value can also be 75%, 85% or other values, which can be adjusted according to the actual situation.

[0074] In some embodiments, when the force standard machine applies a load to the sensor, it applies the load linearly, which can make the loading process smoother and the output display of the sensor can stabilize faster.

[0075] In addition, in this embodiment, the input signal received by the calibration device from the digital sensor is a digital signal. If the input sensor is an analog sensor, the analog sensor can also output a digital signal to the calibration device through A / D conversion.

[0076] As Figure 5 shown, Figure 5 is a schematic diagram of a calibration device according to the second embodiment of the present invention. The calibration device of this embodiment can be used to perform the calibration method described in the first embodiment. The calibration device includes a control module 501, a serial communication module 502, and a storage module 504.

[0077] Among them, the control module 501 is used to execute the calibration method, and the serial communication module 502 is used to connect the sensor. The storage module 504 is used to store information. The information stored in the storage module 504 may include: the factory information of the sensor (including information such as the sensor number, manufacturer code, rated load, accuracy grade, repeatability error, calibration points, loads at each calibration point, etc.), the code value parameters of each calibration point obtained during the calibration process, other data obtained during the calibration process, and the calibration equation determined according to the code value parameters of adjacent calibration points.

[0078] After the automatic calibration is completed, the calibration information is automatically encrypted and saved to the storage module 504 to prevent users from modifying the calibration data. Currently, secondary instruments generally have an interface for modifying calibration parameters, which is convenient for users to re-correct calibration parameters during calibration. After the sensor is calibrated, manually modifying the data will result in the authenticity of its calibration parameters not being guaranteed. Therefore, after the calibration information of the sensor is encrypted and stored in the storage module 504, it can effectively avoid manual data tampering and ensure the authenticity of the sensor output data. In addition, the sensor should be calibrated regularly to ensure the accuracy of the data. Thus, both the authenticity and accuracy of the sensor output data can be guaranteed.

[0079] As Figure 5 and Figure 6As shown, in some embodiments, the calibration device may further include an alarm module 503 and remote communication modules 506, 507. The control module 501 is further configured to upload the code value parameters of the sensor to the status monitoring server 605 through the remote communication modules 506, 507, and, in response to receiving an alarm instruction, control the alarm module 503 to give an alarm.

[0080] Among them, the main functions of the status monitoring server 605 include parsing the sensor information and calibration parameters uploaded by the calibration device 601, capturing data and storing it, providing query indexes, calls and other related data services for the application server and the mobile server. And intelligent analysis can also be performed on the uploaded calibration parameters and captured data, and when the sensor has an abnormality, it can give a timely feedback. The server side can send the abnormal status to the calibration device 601 through the remote communication modules 506, 507. At the same time, the user can access the status monitoring server 605 through a computer and a mobile terminal.

[0081] The code value parameters uploaded by the control module 501 to the status monitoring server 605 refer to that after obtaining the corresponding code value parameters at each calibration point of the sensor, they can be uploaded to the status monitoring server 605. When multiple code values are obtained at the same calibration point and the average value is taken to obtain the code value parameters, they can also be uploaded to the status monitoring server 605. The status monitoring server 605 can judge whether the repeatability error of each calibration point meets the standard, and can send an abnormal signal when it does not meet the standard.

[0082] As Figure 5 As shown, in some embodiments, the calibration device may further include a display screen 505. The calibration device can work in a calibration mode or a display mode. When the calibration device works in the calibration mode, as described above, it can execute the calibration method. When the calibration device works in the display mode, it can display the data information of the sensor in real time through the display screen 505. When the calibration device switches from the calibration mode to the display mode, the calibration device can automatically read out the calibration parameters stored in the storage module 504 and send them to the status monitoring server 605. The status monitoring server 605 compares with the historical calibration parameters of the sensor with this number, and only after they are consistent can the sensor be allowed to be used, otherwise the calibration device will be prohibited from working in the display mode, so as to ensure the authenticity and accuracy of the sensor output data.

[0083] In addition, the status monitoring server 605 can also calculate the upper and lower limit deviations of the zero point value of the sensor during calibration, and judge whether the zero point drift meets the requirements. If the zero point drift does not meet the requirements, it can also send an abnormal signal. When the calibration device works in the display mode, it automatically sends the zero point code value of the sensor to the status monitoring server 605. The status monitoring server 605 compares with the historical zero point records of the sensor with the same number to judge whether the zero point drift meets the requirements.

[0084] When the calibration device operates in the display mode, the calibration device can also randomly capture the code value and the corresponding displayed load value during the use of the sensor, and send them to the status monitoring server 605. The status monitoring server 605 calculates the force value corresponding to the code value by retrieving the historical calibration data of the sensor with the same number, so as to verify whether the load value calculated by the status monitoring server 605 is consistent with the load value at the sensor end. If they are inconsistent, calculate whether the difference exceeds a predetermined threshold (this threshold can be obtained from the factory information of the sensor). If it exceeds the predetermined threshold, an abnormal signal is sent.

[0085] When the status monitoring server 605 as described above sends an abnormal signal, the calibration device controls the alarm module 503 to alarm in response to the received abnormal signal, so as to remind the user to maintain the sensor in time. At the same time, the calibration device can also control the sensor to stop in response to the received abnormal signal, so that the sensor cannot continue to be used temporarily. The user can access the status monitoring server through a computer and a mobile terminal device to query in time whether the used sensor has an abnormal status.

[0086] As Figure 5 and Figure 6 shown, in some embodiments, the remote communication modules 506, 507 include a wireless transmission module 507 and an Ethernet communication module 506. The control module 501 is configured to be connected to the status monitoring server 605 through the wireless transmission module 507. The control module 501 is also configured to be connected to other control systems 606 through the Ethernet communication module 506 or the serial communication module 502.

[0087] In some embodiments, the serial communication module 502 can be an RS485 serial communication module. The RS485 serial communication module includes six communication serial ports. Among them, one serial port of the RS485 serial communication module is used to connect to the display screen 505, another serial port of the RS485 serial communication module is used to connect to the wireless transmission module 507, and another serial port of the RS485 serial communication module is used for data communication with other control systems 606. The other three serial ports of the RS485 serial communication module are used to connect to the sensor. The communication baud rate of the RS485 serial communication module is adjustable and can be used for data sending and receiving.

[0088] In some embodiments, the control module 501 can be an ARM microcontroller STM32F407VET6 chip. This chip supports multi-channel serial communication, with a maximum support of up to 6 channels, and supports 1-channel Ethernet communication. Multi-channel communication can realize the simultaneous access and display of multiple sensors of the calibration device. The data of multiple sensors are merged by framing, and finally the data is sent through the serial port and the network port.

[0089] As Figure 5and Figure 6 As shown, in this embodiment, the calibration device 601 accesses three sensors through the RS485 serial communication module, namely the first sensor 602, the second sensor 603, and the third sensor 604. When the calibration device operates in the display mode, the calibration device reads the corresponding calibration parameters and sensor information according to the serial port to which the sensor is connected, and uploads them to the status monitoring server 605 for verification. After the status monitoring server 605 verifies that the data is correct, it processes the sensor code value parameters.

[0090] In some embodiments, the alarm module 503 may include an indicator light (not shown) and a buzzer (not shown). When the calibration device receives an abnormal signal, it can control the indicator light to flash and / or control the buzzer to sound, thereby reminding the user.

[0091] In some embodiments, the core chip of the storage module 504 may be a 16K non-volatile memory FM24CL16 manufactured by ferroelectric technology. Ferroelectric random access memory FRAM has fast read and write speeds, low power consumption, and long data retention time when power is off. In this embodiment, the calibration data of the first sensor 602, the second sensor 603, and the third sensor 604 can be saved to the storage module 504 according to the serial port number.

[0092] In some embodiments, the display screen 505 may be a resistive touch screen, which is used to complete human-machine interface interaction and data display. The resistive touch screen can transplant the functions of a physical button keyboard into software to complete, with a simple circuit, realizing human-machine interaction and convenient and flexible operation.

[0093] As Figure 6 shown, in this embodiment, the Ethernet communication module 506 can be used to frame and send the data of the first sensor 602, the second sensor 603, and the third sensor 604 to other control systems 606, and the other control systems 606 can select the communication method as needed.

[0094] The calibration method and calibration device of the embodiments of the present invention can effectively ensure the authenticity and accuracy of the sensor output data. Among them, by executing the calibration method through an automatic calibration device, compared with manual calibration, the calibration data is more accurate. And after calibration, the calibration data is automatically encrypted and stored in the storage module of the calibration device, which can avoid human tampering with the data and effectively guarantee the authenticity of the data.

[0095] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An automatic calibration method for a sensor, characterized in that, The method includes: Obtaining the code value of the sensor at zero load and the code value at rated load; Selecting N calibration points between the zero load and the rated load of the sensor, where N is an integer greater than or equal to 1; Obtaining the code value parameters of the sensor at each calibration point; Establishing a calibration equation based on the code value parameters of each calibration point, where the calibration equation is used to characterize the correspondence between the sensor detection value and the code value parameters; Wherein, the obtaining of the code value parameters of the sensor at each calibration point includes: Applying a load to the sensor; Calculating multiple forward difference values of the code value of the sensor during the application of the load; Calculating the average value of the multiple obtained forward difference values; Calculating the variance of the multiple forward difference values; Judging the loading and holding state of the sensor according to the variance; When the sensor is in the holding state, obtaining the code value parameters of the sensor; Wherein, the obtaining of the code value parameters of the sensor at each calibration point further includes: After obtaining the code value parameters of a certain calibration point each time, comparing the code value parameters with the code value parameters at the previous holding; In response to the code value parameters at the current moment being lower than 75% or 80% or 85% of the code value parameters at the previous time, determining the calibration point of the previous holding as the last calibration point and ending the holding.

2. The automatic calibration method of the sensor according to claim 1, characterized in that, The obtaining of the code value parameters of the sensor at each calibration point includes: Obtaining multiple code values of the sensor at each calibration point; Calculating the average value of the multiple code values of the sensor at each calibration point, and taking the average value as the code value parameter.

3. The automatic calibration method of the sensor according to claim 2, characterized in that, After taking the average value as the code value parameter, it further includes: Calculating the repeatability error of the sensor at each calibration point; Issuing an abnormal alarm when the repeatability error is greater than a predetermined value.

4. The automatic calibration method of the sensor according to claim 1, characterized in that, The load applied to the sensor is a linear load.

5. An automatic calibration device for a sensor, characterized in that, The device includes: A serial communication module for connecting to the sensor; A storage module; and A control module configured to perform the following steps: Obtaining the code value of the sensor at zero load and the code value at rated load; Selecting N calibration points between the zero load and the rated load of the sensor, where N is an integer greater than or equal to 1; Obtaining the code value parameters of the sensor at each calibration point; Establishing a calibration equation based on the code value parameters of each calibration point, where the calibration equation is used to characterize the correspondence between the sensor detection value and the code value parameters; Wherein, the obtaining of the code value parameters of the sensor at each calibration point includes: Applying a load to the sensor; Calculating multiple forward difference values of the code value of the sensor during the application of the load; Calculating the average value of the multiple obtained forward difference values; Calculating the variance of the multiple forward difference values; Judging the loading and holding state of the sensor according to the variance; When the sensor is in the holding state, obtaining the code value parameters of the sensor; Wherein, the obtaining of the code value parameters of the sensor at each calibration point further includes: After obtaining the code value parameters of a certain calibration point each time, comparing the code value parameters with the code value parameters at the previous holding; In response to the code value parameter at the current moment being lower than 75% or 80% or 85% of the previous code value parameter, determine that the calibration point of the previous holding load is the last calibration point and end the holding load.

6. The automatic calibration device of the sensor according to claim 5, characterized in that The calibration device of the sensor further includes: an alarm module; and a remote communication module; The control module is further configured to upload the code value parameter of the sensor to the status monitoring server through the remote communication module, and in response to receiving an alarm instruction, control the alarm module to give an alarm.

7. The automatic calibration device of the sensor according to claim 6, characterized in that The remote communication module includes a wireless transmission module and an Ethernet communication module. The control module is configured to connect to the status monitoring server through the wireless transmission module. The control module is further configured to connect to other control systems through the Ethernet communication module or the serial communication module.

8. The automatic calibration device of the sensor according to claim 7, characterized in that, The device further includes a display screen.

9. The automatic calibration device of the sensor according to claim 8, characterized in that, The serial communication module is an RS485 serial communication module. The RS485 serial communication module includes six communication serial ports. Among them, one serial port of the RS485 serial communication module is used to connect to the display screen, another serial port of the RS485 serial communication module is used to connect to the wireless transmission module, another serial port of the RS485 serial communication module is used for data communication with other control systems, and the other three serial ports of the RS485 serial communication module are used to connect to the sensor.

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