Temperature excursion compensation test system and temperature excursion compensation test method of capacitive sensor

Abstract

The invention discloses a temperature drift compensation test system and a temperature drift compensation test method for a capacitive sensor. The test system comprises a test incubator and at least one capacitive sensor, wherein each capacitive sensor at least comprises a temperature detection module; the analog switch and the digital potentiometer are used for replacing the thermistor of the temperature detection module in the temperature drift compensation test process; the control module is used for controlling the test environment of the test temperature box, controlling the analog switch to adjust the resistance value of the digital potentiometer and communicating with the capacitive sensor; the control module is configured to adjust the resistance value of the digital potentiometer in the temperature drift compensation test process until the analog-to-digital conversion values of the capacitive sensor obtained by sampling based on the preset detection distance in different preset test environments of the test temperature box are all located in a target analog-to-digital conversion value range. The problems that in a traditional temperature drift compensation scheme, a resistor needs to be manually adjusted, a test incubator needs to be repeatedly started, and data is inaccurate in the incomplete glue filling state are solved.

Description

Technical Field

[0001] This application relates to the technical field of sensors, and particularly to a temperature drift compensation test system and method for a capacitive sensor. Background Art

[0002] The performance of a capacitive proximity sensor is susceptible to environmental temperature changes. Therefore, temperature drift compensation has become a key technology to ensure its stability. Usually, a capacitive sensor relies on a method that combines a thermistor and a fixed resistor for temperature drift compensation. The resistance values of the thermistor and the fixed resistor are obtained through testing. However, the traditional temperature drift compensation test scheme has significant defects.

[0003] Specifically, the traditional temperature drift compensation scheme is to use a thermistor and a fixed resistor to construct a temperature detection module of a capacitive sensor, and then place the capacitive sensor in a test temperature chamber for temperature drift compensation testing. This process requires manual modification of the fixed resistor or the thermistor resistance repeatedly until the required resistance parameters are tested. However, this scheme requires frequent opening and closing of the test temperature chamber, which not only consumes a large amount of time but also easily causes external air to enter the test temperature chamber, increasing the humidity inside the test temperature chamber and thus affecting the test accuracy.

[0004] In addition, for the traditional temperature drift compensation scheme to facilitate the modification of resistance parameters, usually only partial potting is performed on the sensor at the initial stage to partially seal the sensor. After determining the optimal resistance value, the sensor needs to be fully potted and sealed, and the sensor needs to be placed back in the temperature chamber for verification. However, the data obtained in the state of incomplete potting has a large error compared with the data obtained in the state of complete potting, resulting in additional R & D cycle and cost increase. Summary of the Invention

[0005] In view of the above problems, this application provides a temperature drift compensation test system and method for a capacitive sensor to solve the above technical problems.

[0006] In a first aspect, this application provides a temperature drift compensation test system for a capacitive sensor, including: A test temperature chamber and at least one capacitive sensor. At least one of the capacitive sensors is placed in the test temperature chamber for temperature drift compensation testing. Each capacitive sensor includes at least a temperature detection module formed by a voltage-dividing resistor and a thermistor connected in parallel; An analog switch and a digital potentiometer. The analog switch and the digital potentiometer are connected. The analog switch and the digital potentiometer are used to replace the thermistor of the temperature detection module during the temperature drift compensation testing; A control module, connected to the test incubator, the analog switch, the digital potentiometer and at least one of the capacitive sensors, respectively, for controlling the test environment of the test incubator, for controlling the analog switch to adjust the resistance of the digital potentiometer, and for communicating with the capacitive sensor; The control module is configured to adjust the resistance of the digital potentiometer during a temperature drift compensation test to control an equivalent resistance value of the voltage divider resistor and the digital potentiometer in parallel, until the analog-to-digital conversion values ​​sampled by the capacitive sensor based on a preset detection distance under different preset test environments of the test temperature chamber are all within a target analog-to-digital conversion value range.

[0007] In a second aspect, the present application provides a temperature drift compensation test method for a capacitive sensor, which is applied to the temperature drift compensation test system for the capacitive sensor as described in the first aspect, and the temperature drift compensation test method for the capacitive sensor includes: Replace the thermistor of the temperature detection module of the capacitive sensor by an analog switch and a digital potentiometer, and set the resistance value of the voltage divider resistor of the temperature detection module to a preset initial voltage divider value; The capacitive sensor is placed in a test incubator, and the analog switch is controlled by a control module to adjust the resistance value of the digital potentiometer, so that the analog-to-digital conversion value obtained by the capacitive sensor based on the preset detection distance sampling under each preset test environment is within the target analog-to-digital conversion value range; The equivalent resistance values ​​of the voltage divider resistor and the digital potentiometer in parallel under each of the preset test environments are respectively obtained, a resistor combination that meets the parallel condition is determined based on each of the equivalent resistance values, and two resistors in the resistor combination are respectively used as pre-selected results of the voltage divider resistor and the thermistor.

[0008] The present application provides a temperature drift compensation test system and a temperature drift compensation test method for a capacitive sensor. The temperature drift compensation test method is applied to the temperature drift compensation test system. By using an analog switch and a digital potentiometer to dynamically replace the thermistor in the temperature detection module, and automatically adjusting the equivalent resistance value under different preset test environments until the target analog-to-digital conversion value range is met, the problems of frequent manual adjustment of resistance, repeated opening of the test temperature chamber, and inaccurate data in the incompletely glued state in the traditional temperature drift compensation scheme are effectively solved, and the test efficiency and data accuracy are significantly improved.

[0009] Specifically, the control module can control the resistance adjustment of the analog switch and the digital potentiometer throughout the entire testing process, thereby avoiding errors and time losses caused by frequent manual resistance adjustment. In addition, since there is no need to repeatedly open the test incubator for adjustment, the influence of humidity changes caused by the entry of external air into the test environment can be reduced, further improving the accuracy of the test. Finally, because the resistance value does not need to be manually adjusted during the testing process, the capacitive sensor can remain in a fully potted state throughout the process, ensuring the consistency between the testing stage and the subsequent verification stage, reducing data deviation caused by packaging differences, and reducing the additional R & D cycle and cost.

[0010] These aspects or other aspects of the present application will be more clearly understood in the following description of the embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0012] Figure 1 FIG. shows a schematic block diagram of a temperature drift compensation test system for a capacitive sensor provided by an embodiment of the present application.

[0013] Figure 2 FIG. shows another schematic block diagram of a temperature drift compensation test system for a capacitive sensor provided by an embodiment of the present application.

[0014] Figure 3 FIG. shows a flowchart of a temperature drift compensation test method for a capacitive sensor provided by an embodiment of the present application.

[0015] Figure 4 FIG. shows another flowchart of a temperature drift compensation test method for a capacitive sensor provided by an embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0016] In order to enable those skilled in the art to better understand the solutions of the present application, the following will clearly and completely describe the technical solutions in the embodiments of the present application in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, rather than all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present application.

[0017] Moreover, the term "comprising", "including" or any other variation thereof is intended to cover non-exclusive inclusion, such that a process, method, article or apparatus comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or apparatus. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or apparatus comprising said element.

[0018] In addition, "a plurality of" in the embodiments of the present application means two or more. In view of this, "a plurality of" in the embodiments of the present application can also be understood as "at least two". "At least one" can be understood as one or more, for example, understood as one, two or more. For example, including at least one means including one, two or more, and does not limit which ones are included. For example, including at least one of A, B and C, then what can be included are A, B, C, A and B, A and C, B and C, or A, B and C.

[0019] It should be noted that "connection" in the embodiments of the present application can be understood as electrical connection, and the connection of two electrical components can be a direct or indirect connection between the two electrical components. For example, the connection between A and B can be either a direct connection between A and B or an indirect connection between A and B through one or more other electrical components.

[0020] The embodiments of the present application provide a temperature drift compensation test system for a capacitive sensor. Figure 1 The module schematic diagram of the temperature drift compensation test system for the capacitive sensor provided by the embodiments of the present application is shown, as Figure 1 shown, the temperature drift compensation test system for the capacitive sensor includes: A test temperature chamber and at least one capacitive sensor. The at least one capacitive sensor is placed in the test temperature chamber for temperature drift compensation testing. Each capacitive sensor includes at least a temperature detection module formed by a voltage-dividing resistor and a thermistor connected in parallel.

[0021] An analog switch and a digital potentiometer. The analog switch and the digital potentiometer are connected. The analog switch and the digital potentiometer are used to replace the thermistor of the temperature detection module during the temperature drift compensation test.

[0022] A control module, which is respectively connected to the test temperature chamber, the analog switch, the digital potentiometer and at least one capacitive sensor, and is used to control the test environment of the test temperature chamber, and is used to control the analog switch to adjust the resistance value of the digital potentiometer, and is used to communicate with the capacitive sensor.

[0023] The control module is configured to: during the temperature drift compensation test, adjust the resistance value of the digital potentiometer to control the equivalent resistance value of the parallel connection of the voltage dividing resistor and the digital potentiometer until the analog-to-digital conversion values sampled by the capacitive sensor based on the preset detection distance in different preset test environments of the test incubator are all within the target analog-to-digital conversion value range.

[0024] It can be understood that the specific structure of the control module in the embodiments of the present application is not limited. It uses existing electronic control technologies and communication protocols to interact with the test incubator, analog switch, and digital potentiometer.

[0025] In the temperature drift compensation test system of the capacitive sensor provided by the embodiments of the present application, the control module adjusts the resistance value of the digital potentiometer during the temperature drift compensation test to control the equivalent resistance value of the parallel connection of the voltage dividing resistor and the digital potentiometer, so that the analog-to-digital conversion values sampled by the capacitive sensor based on the preset detection distance in different preset test environments of the test incubator are all within the target analog-to-digital conversion value range. At this time, the equivalent resistance value of the parallel connection of the voltage dividing resistor and the digital potentiometer in different preset test environments can be obtained, and the resistance value of the digital potentiometer is the value closest to the resistance value of the thermistor. Furthermore, the voltage dividing resistor and thermistor that meet the conditions can be calculated according to the principle of resistance voltage division. The embodiments of the present application avoid the errors and time losses caused by frequent manual adjustment of resistors, and since there is no need to repeatedly open the test incubator for adjustment, the influence of humidity changes caused by the entry of external air into the test environment can be reduced, further improving the accuracy of the test. In addition, since the resistance value does not need to be manually adjusted during the test process, the capacitive sensor can maintain a fully potted state throughout the process, ensuring the consistency between the test stage and the subsequent verification stage, reducing the errors caused by potting differences, and reducing the additional R & D cycle and cost. Finally, since the resistance value does not need to be manually adjusted during the test process, synchronously testing multiple capacitive sensors during the test process does not increase the labor cost, further improving the test efficiency.

[0026] It should be clear that the purpose of the embodiments of the present application is to test the resistance values of the thermistor and voltage dividing resistor of the temperature detection module of the capacitive sensor. Therefore, the other part structures of the capacitive sensor are not limited, as long as the capacitive sensor to be tested has a corresponding temperature detection module. Among them, the detection principle of the capacitive sensor is that the capacitive sensor generates an oscillation signal according to the internal capacitance change, then performs circuit processing such as filtering and amplification on the oscillation signal, and converts the processed signal into an analog-to-digital conversion value, and judges whether there is a target object within its detection range according to the analog-to-digital conversion value.

[0027] In some embodiments, Figure 2 shows another module schematic diagram of the temperature drift compensation test system of the capacitive sensor provided by the embodiments of the present application, as Figure 2As shown, the temperature drift compensation test system of the capacitive sensor further includes: A host computer, connected to the control module, is configured to communicate with the control module, determine a resistor combination that meets the parallel condition based on each equivalent resistance value, and use two resistors in the resistor combination as the preliminary selection results of the voltage-dividing resistor and the thermistor respectively.

[0028] It can be understood that in the embodiments of the present application, there is no limitation on the way the host computer obtains the resistor combination. For example, the host computer can use the exhaustive method to calculate the resistor combination that meets the parallel condition. Since the number of existing resistor specifications is limited, the host computer can, based on the principle of resistor voltage division, test the resistor combination that meets the parallel condition through the exhaustive method.

[0029] Based on the temperature drift compensation test system of the capacitive sensor provided in the above embodiments, the embodiments of the present application also provide a temperature drift compensation test method for the capacitive sensor. Specifically, the temperature drift compensation test method for the capacitive sensor is applied to the temperature drift compensation test system of the capacitive sensor provided in the above embodiments. Figure 3 The flowchart of the temperature drift compensation test method for the capacitive sensor provided in the embodiments of the present application is shown. As Figure 3 shown, the temperature drift compensation test method includes: Step S100: Replace the thermistor of the temperature detection module of the capacitive sensor with a analog switch and a digital potentiometer, and set the resistance value of the voltage-dividing resistor of the temperature detection module to a preset initial voltage-dividing value. Optionally, compared with the resistance value of the thermistor that changes with temperature, the voltage-dividing resistor is a resistor with a fixed resistance value in the temperature detection module. In the embodiments of the present application, there is no limitation on the source of the initial voltage-dividing value of the voltage-dividing resistor. For example, the initial voltage-dividing value can be set according to the empirical values of past tests. For another example, the designer can also calculate a suitable initial voltage-dividing value or a reasonable range in combination with the specific circuit parameters of the capacitive sensor.

[0030] Step S200: Place the capacitive sensor in a test incubator, and control the analog switch through the control module to adjust the resistance of the digital potentiometer, so that the analog-to-digital conversion values ​​sampled by the capacitive sensor based on the preset detection distance under each preset test environment are all within the target analog-to-digital conversion value range. Optionally, the preset detection distance is usually selected as the maximum detection distance of the capacitive sensor, and the target analog-to-digital conversion value range is usually selected as less than half of the analog-to-digital conversion range of the capacitive sensor. For example, when the maximum detection range of the capacitive sensor is 8mm and its analog-to-digital conversion range is 4095, the preset detection distance can be set to 8mm, and the target analog-to-digital conversion value range can be set to 1350~1650, and then the test environment of the test incubator is adjusted to each preset test environment in turn. Under different preset test environments, the resistance value of the digital potentiometer is adjusted so that the analog-to-digital conversion value obtained by the capacitive sensor based on the detection distance of 8mm reaches the range of 1350~1650. The purpose of setting the target analog-to-digital value range is to provide an error range. If the target analog-to-digital conversion value is preferably 1500, a 10% deviation can be set. At this time, the target analog-to-digital conversion value range including the deviation is 1350~1650.

[0031] Step S300: Obtain the equivalent resistance value of the voltage divider resistor and the digital potentiometer in parallel under each preset test environment, determine the resistor combination that meets the parallel condition based on each equivalent resistance value, and use the two resistors in the resistor combination as the pre-selected results of the voltage divider resistor and the thermistor. Optionally, under each preset test environment, the resistance value of the voltage divider resistor is a preset initial voltage divider value, and the resistance value of the digital potentiometer is obtained through step S200. The equivalent resistance value of the voltage divider resistor and the digital potentiometer after the two are connected in parallel can be obtained according to the parallel principle. Then, based on each equivalent resistance value, determine the resistor combination that meets the parallel condition. Specifically, each equivalent resistance value must meet the same parallel condition, that is, satisfy the formula , where R represents the equivalent resistance value, R1 and R2 represent the resistance values ​​of the two resistors in the resistor combination respectively. Finally, the two resistors in the resistor combination are used as the pre-selected results of the voltage divider resistor and the thermistor respectively.

[0032] As an implementation mode, the resistor combination satisfying the parallel connection condition determined based on each equivalent resistance value includes multiple resistor combinations. At this time, the designer can select any resistor combination, or test all resistor combinations to obtain the optimal resistor combination.

[0033] The temperature drift compensation test system and method for a capacitive sensor provided by an embodiment of the present application. The temperature drift compensation test method is applied to the temperature drift compensation test system. By using an analog switch and a digital potentiometer to dynamically replace the thermistor in the temperature detection module, and automatically adjusting the equivalent resistance value until the requirements of the target analog-to-digital conversion value range are met in different preset test environments, it effectively solves the problems in the traditional temperature drift compensation scheme, such as the need to frequently manually adjust the resistance, repeatedly open the test temperature chamber, and inaccurate data in the state of incomplete potting. It significantly improves the test efficiency and data accuracy. And because the resistance value does not need to be manually adjusted during the test process, multiple capacitive sensors can be tested synchronously during the test process, and the labor cost is not increased, further improving the test efficiency.

[0034] It can be understood that the embodiment of the present application does not limit the specific implementation manner of the control module to control the digital potentiometer through the analog switch. For example, the control module can increase the resistance of the digital potentiometer and decrease the resistance of the digital potentiometer by transmitting a rising electrical signal or a falling electrical signal to the analog switch respectively. Another example is that the control module can also introduce a binary coding signal to adjust the resistance value of the digital potentiometer. Specifically, the number of binary coding signals is determined according to the resistance gear of the digital potentiometer. For example, a 7-bit binary coding signal can adjust a digital potentiometer with up to 128 resistance gears at most.

[0035] In some embodiments, in the temperature drift compensation test method for a capacitive sensor provided by the embodiment of the present application, step S100: The step of replacing the thermistor of the temperature detection module of the capacitive sensor with an analog switch and a digital potentiometer, and setting the resistance value of the voltage-dividing resistor of the temperature detection module to a preset initial voltage-dividing value further includes: Pot the capacitive sensor to seal the capacitive sensor.

[0036] The temperature drift compensation test method for a capacitive sensor provided by the embodiment of the present application directly controls the analog switch by the control module to adjust the resistance value of the digital potentiometer. Compared with the traditional temperature drift compensation test method, there is no need to manually adjust the resistance value. Therefore, in the test stage of the embodiment of the present application, the capacitive sensor including the digital potentiometer and the analog switch can be fully potted to seal the capacitive sensor, thereby preventing the influence of external factors such as dust and moisture pollutants in the test temperature chamber on the sensor during the test stage.

[0037] In some embodiments, in the temperature drift compensation test method for a capacitive sensor provided by the embodiment of the present application, step S300: The step of respectively obtaining the equivalent resistance values of the parallel connection of the voltage-dividing resistor and the digital potentiometer in each preset test environment includes: When the average analog-to-digital conversion value obtained by performing average filtering on all the analog-to-digital conversion values continuously sampled by the capacitive sensor based on a preset detection distance for a preset time is within the target analog-to-digital conversion value range, the equivalent resistance value of the parallel connection of the voltage-dividing resistor and the digital potentiometer is obtained. Optionally, for each preset test environment, the embodiments of the present application perform average filtering on the analog-to-digital conversion values continuously sampled by the capacitive sensor to obtain an average analog-to-digital conversion value, thereby making the data under the corresponding preset test environment more stable. The preset time is set according to design requirements. For example, the preset time can be set to 30 minutes, so that the capacitive sensor performs average filtering on all the analog-to-digital conversion values continuously sampled based on the preset detection distance for 30 minutes.

[0038] In some embodiments, in the temperature drift compensation test method of the capacitive sensor provided by the embodiments of the present application, the test environment further includes temperature and humidity. Optionally, the temperatures of the respective preset test environments are different from each other. Since the test chamber is a sealed environment, the humidity of the respective preset test environments needs to be the same to stabilize the test environment.

[0039] It can be understood that the specific temperature and specific humidity of each preset test environment are determined by the designer. For example, if the working environment of the capacitive sensor is between -25°C and 75°C, five preset test environments can be set, and the temperatures of the five preset test environments are -25°C, 0°C, 25°C, 50°C, and 75°C respectively, and the humidity is 50% for all. Also, the errors of humidity and temperature should be considered, such as the temperature error is ±1°C and the humidity error is ±5%.

[0040] In some embodiments, Figure 4 shows another flowchart of the temperature drift compensation test method of the capacitive sensor provided by the embodiments of the present application. As Figure 4 shown, in the temperature drift compensation test method of the capacitive sensor provided by the embodiments of the present application, after step S300: respectively obtaining the equivalent resistance values of the parallel connection of the voltage-dividing resistor and the digital potentiometer under each preset test environment, determining a resistor combination that satisfies the parallel condition based on the respective equivalent resistance values, and using the two resistors in the resistor combination as the preliminary selection results of the voltage-dividing resistor and the thermistor respectively, the method further includes: Step S400: Set the temperature detection module of the capacitive sensor according to the preliminary selection results. Specifically, the resistance values of the two resistors in the resistor combination used as the preliminary selection results are respectively used as the resistance value of the voltage-dividing resistor and the resistance value of the thermistor, and a temperature detection module is formed using the voltage-dividing resistor and the thermistor of the corresponding specifications.

[0041] Step S500: Place the capacitive sensor in a test incubator, and respectively obtain the analog-to-digital conversion values sampled by the capacitive sensor based on a preset detection distance under each preset test environment. Specifically, after testing the resistance values of the voltage-dividing resistor and the thermistor through an analog switch and a digital potentiometer, further verify the tested resistance values of the voltage-dividing resistor and the thermistor.

[0042] Step S600: When the analog-to-digital conversion values sampled by the capacitive sensor based on a preset detection distance under at least one preset test environment do not fall within the target analog-to-digital conversion value range, set a temperature compensation coefficient between every two adjacent preset test environments, so that the capacitive sensor performs temperature compensation on the sampled analog-to-digital conversion values according to the temperature compensation coefficient. Specifically, when the analog-to-digital conversion values obtained by the capacitive sensor under at least one preset test environment do not conform to the target analog-to-digital conversion value range, temperature compensation is set for the capacitive sensor, that is, a temperature compensation coefficient is set between every two adjacent preset test environments, so that the capacitive sensor performs temperature compensation on the obtained analog-to-digital conversion values under the corresponding preset test environment, so that the compensated analog-to-digital conversion values reach the target analog-to-digital conversion values.

[0043] In some embodiments, in the temperature drift compensation test method of the capacitive sensor provided by the embodiments of the present application, the temperature compensation coefficient between every two adjacent preset test environments is: where K represents the temperature compensation coefficient between two adjacent preset test environments, AD2 and AD1 respectively represent the analog-to-digital conversion values sampled by the capacitive sensor based on a preset detection distance under two adjacent preset test environments, and T1 and T2 respectively represent the temperatures of two adjacent preset test environments; The capacitive sensor performs temperature compensation on the sampled analog-to-digital conversion values according to the temperature compensation coefficient, including: When the temperature drops between two adjacent preset test environments, increase the analog-to-digital conversion value obtained by the capacitive sensor; When the temperature rises between two adjacent preset test environments, decrease the analog-to-digital conversion value obtained by the capacitive sensor; T represents the temperature change value between two adjacent preset test environments.

[0044] Exemplarily, for example, the temperatures of each preset test environment are -25°C, 0°C, 25°C, 50°C, and 75°C respectively, the humidity is 50% for all, the temperature error is ±1°C, the humidity error is ±5%, and the target analog-to-digital conversion value range of the capacitive sensor is 1350 - 1650, that is, 1500 ± 10%. Assuming that under each preset test environment, the analog-to-digital conversion values obtained by the capacitive sensor based on the preset detection distance are 1200, 1300, 1480, 1520, and 1580 respectively. That is, at this time, the analog-to-digital conversion values corresponding to -25°C and 0°C do not meet the target analog-to-digital conversion value range. Then, a temperature compensation coefficient needs to be set between every two adjacent preset test environments. For -25°C to 0°C, its temperature compensation coefficient is: K = (1300 - 1200) / (0 - (-25)) = 4, which means that during the process of the temperature decreasing from 0°C to -25°C, for every 1°C decrease in temperature, the AD value is increased by 4 through software, so that the analog-to-digital conversion value corresponding to -25°C is equal to or close to the analog-to-digital conversion value corresponding to 0°C. For 0°C to 25°C, its temperature compensation coefficient is: K = (1480 - 1300) / (25 - 0) = 7.2, which means that during the process of the temperature decreasing from 25°C to 0°C, for every 1°C decrease in temperature, the AD value is increased by 7.2 through software, so that the analog-to-digital conversion value corresponding to 0°C is equal to or close to the analog-to-digital conversion value corresponding to 25°C. For 50°C to 25°C, its temperature compensation coefficient is: K = (1520 - 1480) / (50 - 25) = 1.6, which means that during the process of the temperature increasing from 25°C to 50°C, for every 1°C increase in temperature, the AD value is decreased by 1.6 through software, so that the analog-to-digital conversion value corresponding to 50°C is equal to or close to the analog-to-digital conversion value corresponding to 25°C. For 75°C to 50°C, its temperature compensation coefficient is: K = (1580 - 1520) / (75 - 50) = 2.4, which means that during the process of the temperature increasing from 50°C to 75°C, for every 1°C increase in temperature, the AD value is decreased by 2.4 through software, so that the analog-to-digital conversion value corresponding to 75°C is equal to or close to the analog-to-digital conversion value corresponding to 50°C.

[0045] In some embodiments, in the temperature drift compensation test method of the capacitive sensor provided by the embodiments of the present application, step S300: Determining the resistor combinations that meet the parallel conditions based on each equivalent resistance value includes: Calculating the resistor combinations that meet the parallel conditions by the exhaustive method. Optionally, because the number of existing resistor specifications is limited, the embodiments of the present application can test the resistor combinations that meet the parallel conditions by the exhaustive method based on the resistor voltage division principle.

[0046] In some embodiments, in the temperature drift compensation test method of the capacitive sensor provided by the embodiments of the present application, step S300: Determining the resistor combinations that meet the parallel conditions further includes: When the resistor combinations that meet the parallel conditions cannot match the specifications of the actually existing resistor components, select the two actual resistor components that are closest to the resistor combination as the resistor combination.

[0047] The above content is a further detailed description of the present application in combination with specific implementation manners. It cannot be determined that the specific implementation of the present application is only limited to these descriptions. For those of ordinary skill in the technical field to which the present application belongs, without departing from the concept of the present application, several simple deductions or substitutions can still be made, which should all be regarded as the protection scope of the present application.

Claims

1. A temperature drift compensation test system for a capacitive sensor, characterized in that: include: A test temperature box and at least one capacitive sensor, at least one of the capacitive sensors is placed in the test temperature box for temperature drift compensation testing, each of the capacitive sensors at least comprises a temperature detection module formed by a voltage divider resistor and a thermistor connected in parallel; At least one analog switch and at least one digital potentiometer, each of the analog switches is connected to one of the digital potentiometers, and the analog switch and the digital potentiometer are used to replace the thermistor of the temperature detection module during the temperature drift compensation test; A control module, connected to the test incubator, at least one of the analog switches, at least one of the digital potentiometers and at least one of the capacitive sensors, respectively, for controlling the test environment of the test incubator, for controlling the analog switch to adjust the resistance of the digital potentiometer, and for communicating with the capacitive sensor; The control module is configured to adjust the resistance of the digital potentiometer during a temperature drift compensation test to control an equivalent resistance value of the voltage divider resistor and the digital potentiometer in parallel, until the analog-to-digital conversion values ​​sampled by the capacitive sensor based on a preset detection distance under different preset test environments of the test temperature chamber are all within a target analog-to-digital conversion value range.

2. The temperature drift compensation test system of a capacitive sensor as claimed in claim 1, characterized in that: Also includes: A host computer is connected to the control module, and is configured to: communicate with the control module, determine a resistor combination that meets the parallel condition based on each of the equivalent resistance values, and use two resistors in the resistor combination as pre-selected results of a voltage divider resistor and a thermistor, respectively.

3. A temperature drift compensation test method for a capacitive sensor, characterized in that: The temperature drift compensation test system for the capacitive sensor according to any one of claims 1 to 2, wherein the temperature drift compensation test method for the capacitive sensor comprises: Replace the thermistor of the temperature detection module of the capacitive sensor by an analog switch and a digital potentiometer, and set the resistance value of the voltage divider resistor of the temperature detection module to a preset initial voltage divider value; The capacitive sensor is placed in a test incubator, and the analog switch is controlled by a control module to adjust the resistance value of the digital potentiometer, so that the analog-to-digital conversion value obtained by the capacitive sensor based on the preset detection distance sampling under each preset test environment is within the target analog-to-digital conversion value range; The equivalent resistance values ​​of the voltage divider resistor and the digital potentiometer in parallel under each of the preset test environments are respectively obtained, a resistor combination that meets the parallel condition is determined based on each of the equivalent resistance values, and two resistors in the resistor combination are respectively used as pre-selected results of the voltage divider resistor and the thermistor.

4. The temperature drift compensation test method of a capacitive sensor as claimed in claim 3, characterized in that: The step of replacing the thermistor of the temperature detection module of the capacitive sensor by the analog switch and the digital potentiometer, and setting the resistance value of the voltage divider resistor of the temperature detection module to a preset initial voltage divider value, further includes: The capacitive sensor is filled with glue to seal the capacitive sensor.

5. The temperature drift compensation test method of a capacitive sensor as claimed in claim 3, characterized in that: The step of respectively obtaining the equivalent resistance value of the voltage divider resistor and the digital potentiometer in parallel under each of the preset test environments comprises: When all analog-to-digital conversion values ​​obtained by continuous sampling of the capacitive sensor for a preset time based on a preset detection distance are averaged and filtered, the average analog-to-digital conversion value obtained is within the target analog-to-digital conversion value range, and the equivalent resistance value of the voltage divider resistor and the digital potentiometer in parallel is obtained.

6. The temperature drift compensation test method of a capacitive sensor as claimed in claim 3, characterized in that: The test environment of the test incubator includes temperature and humidity.

7. The temperature drift compensation test method of a capacitive sensor as claimed in claim 5, characterized in that: After the steps of respectively obtaining the equivalent resistance values ​​of the voltage divider resistor and the digital potentiometer in parallel under the preset test environments, determining a resistor combination that meets the parallel condition based on each of the equivalent resistance values, and using two resistors in the resistor combination as pre-selected results of the voltage divider resistor and the thermistor, the method further includes: Setting a temperature detection module of the capacitive sensor according to the preselected result; The capacitive sensor is placed in the test incubator, and analog-to-digital conversion values ​​obtained by sampling the capacitive sensor based on the preset detection distance under each of the preset test environments are respectively obtained; When the analog-to-digital conversion value sampled by the capacitive sensor based on the preset detection distance under at least one of the preset test environments fails to fall within the target analog-to-digital conversion value range, a temperature compensation coefficient is set between every two adjacent preset test environments so that the capacitive sensor performs temperature compensation on the sampled analog-to-digital conversion value according to the temperature compensation coefficient.

8. The temperature drift compensation test method of a capacitive sensor as claimed in claim 7, characterized in that: The temperature compensation coefficient between each two adjacent preset test environments is: Wherein, K represents the temperature compensation coefficient between two adjacent preset test environments, AD2 and AD1 respectively represent the analog-to-digital conversion values ​​obtained by sampling the capacitive sensor based on the preset detection distance under two adjacent preset test environments, and T2 and T1 respectively represent the temperatures of two adjacent preset test environments; The capacitive sensor performs temperature compensation on the sampled analog-to-digital conversion value according to the temperature compensation coefficient, comprising: When the temperature between the two adjacent preset test environments drops, the analog-to-digital conversion value obtained by the capacitive sensor is increased by ; When the temperature between the two adjacent preset test environments rises, the analog-to-digital conversion value obtained by the capacitive sensor is reduced ; The T represents the temperature change value between two adjacent preset test environments.

9. The temperature drift compensation test method of a capacitive sensor as claimed in claim 3, characterized in that: The determining of a resistor combination satisfying the parallel connection condition based on each of the equivalent resistance values ​​comprises: The resistor combination satisfying the parallel connection condition is calculated by exhaustive method.

10. The temperature drift compensation test method of a capacitive sensor according to claim 9, characterized in that: The determining of the resistor combination satisfying the parallel connection condition based on each of the equivalent resistance values ​​further includes: When the resistance combination satisfying the parallel connection condition cannot match the specification of the actually existing resistance element, two actual resistance elements closest to the resistance combination are selected as the resistance combination.

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