Temperature sampling calibration method, tooling and temperature sampling system

Abstract

This application discloses a temperature sampling calibration method, tooling, and temperature sampling system, applied in the field of temperature measurement technology, to solve the problem of poor accuracy in existing temperature sampling calibration methods. Specifically, it involves: obtaining the temperature range to be measured; determining at least two corresponding calibration resistor values ​​based on the temperature range; sampling based on each calibration resistor value to obtain the sampled value corresponding to each calibration resistor value; determining a resistance correction model for temperature sampling based on each calibration resistor value and the corresponding sampled value; storing the resistance correction model; in subsequent temperature sampling, correcting the real-time sampled value according to the resistance correction model to obtain the target resistance value; determining the current temperature value based on the target resistance value; and replacing the method of independently calibrating the excitation current and sampling voltage separately with direct calibration of the resistance domain, thus avoiding the superposition of measurement errors introduced by the voltage and current channels respectively, and improving the accuracy of calibration.

Description

Technical Field

[0001] This application relates to the field of temperature measurement technology, and in particular to a temperature sampling calibration method, tooling, and temperature sampling system. Background Technology

[0002] RTD (Resistance Temperature Detector) is widely used in temperature measurement scenarios in the medium and low temperature range (-200℃ to 850℃) due to its high accuracy, good linearity and long-term stability, such as power equipment monitoring, environmental temperature control, medical instruments and industrial process control.

[0003] Temperature sampling systems typically employ constant current source excitation sensors. The resistance value is calculated by measuring the voltage drop across the sensor and combining this with the known excitation current, then converted to temperature based on the resistance-temperature characteristic curve. To ensure measurement accuracy, conventional practice requires independent calibration of the excitation current source and voltage measurement channel. This involves connecting a high-precision standard resistor at the current output to inversely deduce the actual excitation current, and applying a standard voltage signal at the voltage input to calibrate the analog-to-digital converter gain and offset. However, this calibration method requires complex hardware circuitry and multi-stage signal conditioning circuitry, resulting in complex calibration wiring and cumbersome operation. More importantly, the system errors introduced by the voltage and current calibration stages create nonlinear coupling in subsequent temperature calculations, and the errors from each stage add up, significantly reducing the overall calibration accuracy of the system and affecting the accuracy of the temperature measurement results. Summary of the Invention

[0004] This application provides a temperature sampling calibration method, tooling, and temperature sampling system to solve the problem of poor accuracy in existing temperature sampling calibration methods.

[0005] The technical solution provided in this application is as follows: On the one hand, this application provides a temperature sampling calibration method, including: Obtain the temperature range to be measured; Determine at least two corresponding calibration resistor values ​​based on the temperature range to be measured; Samples are taken based on each calibration resistor value to obtain the sampled value corresponding to each calibration resistor value; The resistance correction model for temperature sampling is determined based on each calibration resistor value and its corresponding sample value. The resistance correction model is stored. In subsequent temperature sampling, the real-time sampled value is corrected according to the resistance correction model to obtain the target resistance value, and the current temperature value is determined according to the target resistance value.

[0006] Optionally, at least two calibration resistor values ​​are determined based on the temperature range to be measured, including: Based on the resistance-temperature characteristics of the temperature acquisition device, the range of resistance to be measured corresponding to the range of the temperature to be measured is determined. Determine at least two calibration resistor values ​​based on the range of the resistor to be measured and the resistance value of the preset resistor.

[0007] Optionally, a resistance correction model for temperature sampling is determined based on each calibration resistor value and its corresponding sampled value, including: Each calibration resistor value is matched with its corresponding sampled value to form multiple data points; Determine the current fitting strategy based on the distribution characteristics of each data point; Based on the current fitting strategy, each data point is fitted to obtain a resistance correction model for temperature sampling.

[0008] Optionally, the current fitting strategy can be determined based on the distribution characteristics of each data point, including: A linear reference line is obtained by performing linear fitting on each data point; Determine the deviation of each data point from the linear reference line; When the deviation of each data point meets the deviation constraint, the current fitting strategy is determined to be linear fitting; When the deviation of each data point does not meet the deviation constraint, each data point is divided into at least two sub-intervals according to the deviation of each data point, and the sub-fitting strategy of each sub-interval is determined. The sub-fitting strategy is either linear fitting or polynomial fitting.

[0009] Optionally, based on the current fitting strategy, each data point is fitted to obtain a resistance correction model for temperature sampling, including: When the current fitting strategy is linear fitting, the linear reference line is used as the resistance correction model; When the current fitting strategy is a sub-fitting strategy for each sub-interval, each sub-interval is fitted according to the corresponding sub-fitting strategy to obtain the data fitting line for each sub-interval, and a resistance correction model is constructed based on the data fitting line for each sub-interval.

[0010] Optionally, after determining the current temperature value based on the target resistance value, the following steps are also included: If the current temperature value exceeds the preset temperature range, it is determined whether the real-time sampled value is within the range of the resistance to be measured corresponding to the temperature range to be measured. If the real-time sampled value is within the range of the resistance to be measured, the resistance correction model is determined to be invalid, and the resistance correction model is redefined. If the real-time sampled value is outside the range of the resistor under test, the sampling function is determined to be abnormal, and a fault message is output.

[0011] On the other hand, this application provides a temperature sampling calibration fixture, including: a main resistor module and an adjustable resistor module; The main resistor module and the adjustable resistor module are respectively connected between the first terminal and the second terminal of the fixture; the first terminal and the second terminal of the fixture are connected to the external sampling module; the control terminal of the adjustable resistor module is connected to the external control module. The main resistor module is used to connect a resistor with a fixed resistance value between the first terminal and the second terminal of the fixture. The adjustable resistor module is used to connect an adjustable resistor between the first terminal and the second terminal of the fixture, and adjust the resistance value under the control of an external control module.

[0012] Optionally, the main resistor module includes: a main standard resistor; The main standard resistor is connected between the first terminal and the second terminal of the tooling. The adjustable resistor module includes: multiple parallel resistor branches; Each resistor branch is connected between the first terminal and the second terminal of the fixture. Each resistor branch includes a controllable switch and an auxiliary standard resistor connected in series. The control terminal of each controllable switch is connected to an external control module.

[0013] Optionally, the wiring between the first terminal of the tooling and the external sampling module and the wiring between the second terminal of the tooling and the external sampling module have the same wire length and wire diameter specifications.

[0014] On the other hand, this application provides a temperature sampling system, including: a sampling module, a control module, and the above-mentioned temperature sampling calibration fixture; The first and second terminals of the temperature sampling calibration fixture are connected to the sampling module via wiring lines, and the control terminal of the temperature sampling calibration fixture is connected to the control module; the temperature sampling calibration fixture is used to provide calibration resistance values ​​to the sampling module. The output of the sampling module is connected to the control module; the sampling module is used to sample based on the calibration resistor value and output the sampled value corresponding to the calibration resistor value. The control module is used to execute the temperature sampling calibration method described above.

[0015] The beneficial effects of this application are as follows: In this application, by obtaining the temperature range to be measured and determining at least two corresponding calibration resistor values ​​based on the temperature range, a mapping from temperature domain range requirements to resistance domain calibration operations is achieved. This ensures that the selection of calibration resistor values ​​directly corresponds to the actual operating temperature range, avoiding redundant calibration within invalid ranges and improving calibration efficiency and specificity. By directly sampling based on each calibration resistor value and obtaining the corresponding sampled value, an original correspondence between known standard resistance values ​​and the actual response of the sampling link is established. Direct calibration in the resistance domain replaces the traditional method of independently calibrating the excitation current and sampling voltage in RTD temperature sampling systems. This eliminates the need to arrange independent leads and conditioning circuits for milliampere-level current sampling and voltage sampling, simplifying hardware configuration and avoiding the superposition of measurement errors introduced by the voltage and current channels, thus improving the convenience and accuracy of calibration. By determining the resistance correction model for temperature sampling based on each calibration resistor value and the corresponding sampled value, a quantitative characterization of the sampling link system error is achieved. By storing the resistance correction model and correcting the real-time sampled value according to the resistance correction model in subsequent temperature sampling to obtain the target resistance value, continuous reuse of calibration results is achieved, effectively improving the temperature measurement accuracy and stability across the entire range.

[0016] Other features and advantages of this application will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the application. The objectives and other advantages of this application may be realized and obtained by means of the structures particularly pointed out in the written description, claims, and drawings. Attached Figure Description

[0017] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a schematic diagram of the system framework of the temperature sampling system in the embodiments of this application; Figure 2 This is a schematic diagram of the first functional structure of the temperature sampling and calibration fixture in the embodiments of this application; Figure 3 This is a schematic diagram of the second functional structure of the temperature sampling calibration fixture in the embodiments of this application; Figure 4 This is a schematic diagram outlining the temperature sampling calibration method in the embodiments of this application; Figure 5 This is a schematic diagram illustrating the specific process of establishing the resistance correction model in the embodiments of this application; Figure 6 This is a schematic diagram illustrating the specific process of the temperature anomaly handling method in the embodiments of this application.

[0018] Icons: 100 - Temperature sampling system; 110 - Sampling module; 120 - Control module; 130 - Temperature sampling calibration fixture; 131 - Main resistor module; 132 - Adjustable resistor module; 133 - Main standard resistor; 134 - Controllable switch; 135 - Auxiliary standard resistor. Detailed Implementation

[0019] To make the objectives, technical solutions, and beneficial effects of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0020] This application provides a temperature sampling system applicable to resistance temperature detector (RTD) type temperature sensors. RTD type temperature sensors sense temperature based on the physical property that the resistance of a metallic conductor changes with temperature; a definite functional relationship exists between their resistance and temperature. Therefore, the sampling calibration method and temperature sampling system based on calibration resistance values ​​provided in this application are only applicable to temperature sampling systems using RTD type temperature sensors as temperature acquisition devices. If thermocouples, thermistors, or other non-RTD principle temperature sensors are used, their output signal type or resistance-temperature characteristics differ fundamentally from those of RTD type temperature sensors, and therefore they are not within the scope of protection of this application.

[0021] For details, please refer to Figure 1 As shown, the temperature sampling system 100 provided in this application embodiment includes at least: a sampling module 110, a control module 120, and a temperature sampling calibration fixture 130; The first and second terminals of the temperature sampling calibration fixture 130 are connected to the sampling module 110 via wiring lines, and the control terminal of the temperature sampling calibration fixture 130 is connected to the control module 120. The temperature sampling calibration fixture 130 is used to provide calibration resistance values ​​to the sampling module 110. The output of the sampling module 110 is connected to the control module 120; the sampling module 110 is used to sample based on the calibration resistor value and output the sampled value corresponding to the calibration resistor value. The control module 120 is used to perform the temperature sampling calibration method.

[0022] In practical applications, for a temperature sampling system 100 using an RTD-type temperature sensor, the input terminal of the sampling module 110 is typically configured with an interface matching a specific wiring method, including but not limited to two-wire, three-wire, and four-wire systems. When the temperature sampling calibration fixture 130 is connected to the sampling module 110 via the fixture's first and second terminals, the wiring method must be consistent with the wiring method of the RTD-type temperature sensor used in subsequent actual temperature measurements. For example, if a three-wire wiring method is used to connect the fixture's first and second terminals and the sampling module 110 during the calibration phase, then after calibration, when connecting the RTD-type temperature sensor to the sampling module 110, the exact same three-wire wiring method must also be used, ensuring that the length, wire diameter, and connection topology of each wiring line are consistent with those during the calibration phase. The temperature sampling calibration fixture 130 provides the sampling module 110 with a calibration resistor value to simulate the theoretical resistance output of the RTD-type temperature sensor at a specific temperature point, so that the sampling module 110 can complete the static calibration of the entire sampling link without the need for intervention in the real temperature environment.

[0023] The sampling module 110 may contain a constant current source excitation circuit, a signal conditioning circuit, and an analog-to-digital converter circuit. When the calibration resistor value is connected to the sampling circuit, the constant current source excitation circuit applies a constant excitation current to the calibration resistor, the signal conditioning circuit amplifies, filters, and levels the response voltage across the calibration resistor, and the analog-to-digital converter circuit converts the analog voltage signal into a digital sample value and outputs it to the control module 120.

[0024] The control module 120 has different functions in the calibration and real-time measurement phases, respectively. In the calibration phase, the control module 120 acquires the temperature range to be measured and determines at least two corresponding calibration resistor values ​​based on this range. Based on each calibration resistor value, it outputs a gating control signal to the temperature sampling calibration fixture 130, sequentially connecting each calibration resistor value to the sampling loop of the sampling module 110. After receiving the sampled values ​​output by the sampling module 110, it matches each calibration resistor value with its corresponding sampled value to form data points. Based on the distribution characteristics of each data point, it determines the current fitting strategy and performs fitting processing on each data point based on the current fitting strategy to construct a resistance correction model. In the real-time measurement phase, the control module 120 stores the resistance correction model in non-volatile memory. In the subsequent real-time temperature measurement phase, it calls the resistance correction model to correct the real-time sampled values ​​to the target resistance value and, based on the resistance-temperature characteristics of the RTD-type temperature sensor, retrieves the target resistance value back to the current temperature value. Furthermore, when the current temperature value exceeds the preset temperature range, the control module 120 initiates bidirectional diagnostics to determine whether the real-time sampled value is within the range of the resistance being measured. If it is within the range, the resistance correction model is deemed to have failed and recalibration is triggered. If it is outside the range, the sampling function is deemed abnormal and a fault indication is output. The fault indication can be output through audible and visual alarms, communication interface reporting, or display interface prompts, prompting maintenance personnel to check hardware connections or replace faulty components.

[0025] Based on the above embodiments, this application provides a temperature sampling and calibration fixture, see below. Figure 2 As shown, the temperature sampling calibration fixture 130 provided in this embodiment includes at least: a main resistor module 131 and an adjustable resistor module 132; The main resistor module 131 and the adjustable resistor module 132 are respectively connected between the first terminal A and the second terminal B of the fixture; the first terminal A and the second terminal B of the fixture are connected to the external sampling module; the control terminal of the adjustable resistor module 132 is connected to the external control module 120. The main resistor module 131 is used to connect a resistor with a fixed resistance value between the first terminal A and the second terminal B of the fixture. The adjustable resistor module 132 is used to connect an adjustable resistor between the first terminal A and the second terminal B of the tooling, and adjust the resistance value under the control of the external control module 120.

[0026] In practical applications, the temperature sampling calibration fixture 130 integrates the main resistor module 131, which provides a fixed resistance value, and the adjustable resistor module 132, which provides an adjustable resistance value, into the same fixture housing, forming an integrated standard calibration accessory. The fixture's first terminal A and second terminal B serve as a unified external electrical interface. Both the fixed resistance value output by the main resistor module 131 and the adjustable resistance value output by the adjustable resistor module 132 are fed to the external sampling module through this set of terminals, thus simplifying the interface design on the external sampling module side and eliminating the need to configure multiple input ports for different resistance value sources.

[0027] Specifically, the temperature sampling calibration fixture has four wires leading out, that is, two independent wires are led out from the first terminal A and the second terminal B of the fixture, for a total of four terminals, so that the temperature sampling calibration fixture can be adapted to the calibration requirements of two-wire, three-wire and four-wire RTD. In the two-wire RTD calibration mode, the two wires from terminal A of the first terminal of the fixture and the two wires from terminal B of the second terminal of the fixture are shorted in pairs and then connected to the sampling module to form a single-loop excitation and detection path. In the three-wire RTD calibration mode, one of the two wires from terminal A of the first terminal of the fixture is used as the excitation line and the other as the detection line. One of the two wires from terminal B of the second terminal of the fixture is used as the excitation return line and the other is shared with the detection line, thus using the symmetrical lead structure to offset the line resistance error. In the four-wire RTD calibration mode, the two wires from terminal A of the first terminal of the fixture are used independently as the excitation line and the detection line, respectively. The two wires from terminal B of the second terminal of the fixture are used independently as the excitation return line and the detection return line, respectively. Through the physical separation of the current loop and the voltage detection loop, the sampling module can directly detect the voltage across the calibration resistor without being affected by the voltage drop across the lead resistance, thereby completely eliminating the measurement error caused by the lead resistance and improving the calibration accuracy.

[0028] The fixed-value resistors output by the main resistor module 131 undergo precise selection and aging treatment, exhibiting extremely low temperature drift coefficients and long-term stability. This module is always connected after the external sampling module is connected to the tooling, providing the system with at least one highly reliable reference calibration point for quickly verifying the reference accuracy of the external sampling module, or directly serving as the calibration basis in scenarios requiring only single-point verification. The adjustable resistor module 132 achieves digital adjustment of its resistance value through remote control by the external control module 120. During actual calibration, the external control module 120 sends corresponding selection commands to the adjustable resistor module 132 based on the determined calibration resistor value. When the required calibration resistance value exactly matches the nominal resistance value of a certain auxiliary standard resistor 135, the external control module 120 controls the controllable switch 134 of the corresponding branch to conduct, connecting the auxiliary standard resistor 135 to the circuit alone. When the required calibration resistance value is between two adjacent auxiliary standard resistors 135, the external control module 120 can control multiple branches to conduct simultaneously, using the parallel combination of multiple auxiliary standard resistors 135 to obtain the equivalent target resistance value, thereby expanding the precision of the resistance value coverage without increasing the number of physical resistors. This resistance value generation method, which combines fixed resistors with parallel combinations, balances calibration accuracy and hardware cost, enabling a limited number of auxiliary standard resistors 135 to cover a wide range of resistances to be measured.

[0029] Furthermore, the main resistor module 131 and the adjustable resistor module 132 are connected to the first terminal A and the second terminal B of the fixture respectively via internal wiring, and are arranged with thermal isolation distance to prevent the micro-heating effect of the controllable switch 134 in the adjustable resistor module 132 from interfering with the temperature characteristics of the high-precision resistor in the main resistor module 131. A status indicator unit can also be configured on the fixture housing to display the current switch-on status or fault information of the adjustable resistor module 132, allowing on-site operators to intuitively grasp the calibration process.

[0030] In one possible implementation, see [reference] Figure 3 As shown, the main resistor module includes: a main standard resistor 133; The main standard resistor 133 is connected between the first terminal A and the second terminal B of the tooling. The adjustable resistor module includes: multiple parallel resistor branches; Each resistor branch is connected between the first terminal A and the second terminal B of the tooling. Each resistor branch includes a controllable switch 134 and an auxiliary standard resistor 135 connected in series. The control terminal of each controllable switch 134 is connected to the external control module 120.

[0031] In practical applications, the main standard resistor 133, as the core reference element inside the temperature sampling calibration fixture 130, typically corresponds to the characteristic calibration point of an RTD-type temperature sensor or the upper limit of the measured resistance range. The main standard resistor 133 is always connected across the first terminal A and the second terminal B of the fixture, in parallel with the adjustable resistor module. Its resistance constitutes the maximum equivalent resistance that the fixture can output. Therefore, the resistance value of the main standard resistor 133 should be greater than or equal to the upper limit of the measured resistance range to ensure that when all auxiliary standard resistors 135 are disconnected, the equivalent resistance presented at the fixture output is the resistance value of the main standard resistor 133, thus covering the upper limit of the range. By selectively activating one or more auxiliary standard resistors 135 branches, connecting them in parallel with the main standard resistor 133, a smaller equivalent resistance value is obtained, achieving downward coverage of the entire measured resistance range. The main standard resistor 133 does not pass through any controllable switch 134 device. The current flows directly through its body to form a path, avoiding the influence of switch contact resistance and conduction voltage drop on the resistance accuracy, eliminating the additional error sources introduced by the switching device, and providing a highly reliable reference point for the entire calibration process.

[0032] The adjustable resistor module consists of multiple parallel resistor branches, each independently connected between the first terminal A and the second terminal B of the fixture. This parallel structure allows the auxiliary standard resistor 135 of any single branch to act as a calibration resistor in the main circuit when any single branch is conducting. When multiple branches are conducting simultaneously, the auxiliary standard resistors 135 of each conducting branch are combined in parallel, and the equivalent resistance is calculated according to the parallel resistance formula, thus expanding the precision of the resistance value coverage without increasing the number of physical resistors. The branches are electrically isolated from each other and do not affect each other; changes in the switching state of one branch will not alter the inherent resistance characteristics of other branches.

[0033] Within each resistor branch, the controllable switch 134 and the auxiliary standard resistor 135 are connected in series. Current must flow sequentially through the controllable switch 134 and the auxiliary standard resistor 135 to form a complete circuit. The controllable switch 134 is located on the side of the branch closest to the first terminal A or the second terminal B of the fixture, facilitating unified layout and wiring within the fixture. The nominal resistance values ​​of the auxiliary standard resistors 135 are configured according to a specific sequence, such as a precision resistor sequence or standard resistance values ​​corresponding to different temperature points. The accuracy class of each auxiliary standard resistor 135 is consistent with that of the main standard resistor 133, ensuring that the output resistance values ​​all have equal calibration reliability. Each controllable switch 134 has an independent control terminal, and each control terminal is led out to the control terminal of the adjustable resistor module via independent control leads within the fixture. The external control module 120 can individually control each controllable switch 134. The control signal can be a digital level signal, which is applied to the drive terminal of the controllable switch 134 after passing through the internal drive circuit of the fixture. By outputting an effective level to the corresponding control terminal, the external control module 120 can connect the corresponding auxiliary standard resistor 135 to the sampling circuit. By simultaneously outputting effective levels to multiple control terminals, multiple auxiliary standard resistors 135 can be combined in parallel to generate the corresponding equivalent resistance value. Through independent control and parallel combination mechanisms, the adjustable resistor module, under the digital instructions of the external control module 120, achieves discrete or combined adjustable resistance values ​​to cover any target resistance value within the range of the resistor to be measured.

[0034] The nominal resistance values ​​of each auxiliary standard resistor 135 are configured according to the precision resistor sequence, and their resistance values ​​are much greater than the on-state resistance of the corresponding branch controllable switch 134. When the controllable switch 134 is turned on, the series equivalent resistance of this branch is the sum of the on-state resistance of the controllable switch 134 and the nominal resistance value of the auxiliary standard resistor 135. The internal resistance of the controllable switch 134 accounts for a very small proportion of the total series resistance, making the equivalent resistance of this branch approximately equal to the nominal resistance value of the auxiliary standard resistor 135. This can greatly eliminate the resistance error caused by the internal resistance of the controllable switch 134 and ensure the output accuracy of the calibration resistance value.

[0035] In one possible implementation, the wiring between the first terminal of the tooling and the external sampling module and the wiring between the second terminal of the tooling and the external sampling module have the same wire length and wire diameter specifications.

[0036] Specifically, the first and second terminals of the fixture serve as a unified electrical interface for the temperature sampling calibration fixture to output calibration resistance values ​​to the external sampling module. Each terminal is connected to its corresponding input port on the external sampling module via independent wiring lines. The wiring lines are either part of the fixture itself or dedicated connecting wires included with the fixture. The line length refers to the actual distance the conductor travels from the fixture terminal to the input terminal of the sampling module, and the wire diameter refers to the standard cross-sectional area or diameter of the copper conductor constituting the line. By setting the line length and wire diameter of both wiring lines to be identical, the two lines maintain strict symmetry in their physical structure. The conductor materials of the two wiring lines are also set to be the same.

[0037] Assuming identical conductor materials, lines of equal length and diameter will theoretically have equal DC resistances, and their resistance drift with ambient temperature will also be synchronized. Furthermore, identical line length and diameter ensure consistent distributed inductance and capacitance parameters, maintaining symmetrical transmission delays and impedance matching characteristics when the external sampling module uses AC excitation or high-speed sampling. For temperature sampling systems employing RTD (Resistive Temperature Detector) type temperature sensors, the external sampling module typically uses a constant current source to apply excitation current to the connected resistive element and detects the response voltage across the resistor to calculate its resistance. By maintaining strictly identical line lengths and diameters, the DC resistances of the two lines are equal, and their temperature drift is synchronized. When the external sampling module performs differential voltage detection or bridge measurements, the additional impedance introduced by the two lines is symmetrically distributed. The common-mode component can be canceled out by the differential structure of the sampling circuit, and the differential-mode component approaches zero, ensuring that the transmission path from the tooling terminals to the sampling module input terminals does not introduce additional asymmetric errors.

[0038] In this way, by controlling the consistency of line length and wire diameter specifications, the additional resistance introduced by the line and its drift can be suppressed to a negligible level, ensuring that the calibration resistance value maintains its nominal accuracy during transmission to the external sampling module. Furthermore, the consistency requirement for line length and wire diameter specifications provides a reproducible connection method for subsequent actual temperature measurement stages. After calibration, when connecting the RTD-type temperature sensor to the external sampling module, as long as the sensor leads are arranged with the same line length and wire diameter specifications as the tooling wiring, it can be ensured that the line error components calibrated during the calibration stage completely match the line error components during the actual measurement stage. This allows the line symmetry assumptions covered by the resistance correction model to continue in actual operating conditions, avoiding model mismatch caused by changes in line parameters.

[0039] Based on the above embodiments, this application provides a temperature sampling calibration method, applied in the control module of the above temperature sampling system, see reference. Figure 4As shown, the general flow of the temperature sampling calibration method provided in this application embodiment is as follows: Step 401: Obtain the temperature range to be measured.

[0040] In practical applications, the temperature range to be measured refers to the operating temperature range within which the temperature sampling system needs to perform precise measurements in the actual application scenario. The lower and upper limits of the temperature range define the physical range boundaries that subsequent calibration operations need to cover. The control module obtains the temperature range to be measured by reading system configuration parameters, receiving user input commands, or based on preset operating condition logic. For example, in industrial heat treatment scenarios, the temperature range to be measured can be set to 0℃ to 500℃; in cold chain storage and transportation scenarios, the temperature range to be measured can be set to -40℃ to 10℃. Obtaining the temperature range to be measured provides clear physical boundary constraints for subsequent resistance mapping, calibration point selection, and the applicable range of the resistance correction model, avoiding redundant calibration within invalid ranges, reducing calibration resource consumption, and ensuring the characterization accuracy of the resistance correction model within the effective range.

[0041] Step 402: Determine at least two corresponding calibration resistor values ​​based on the temperature range to be measured.

[0042] In practical applications, the control module determines the range of resistance to be measured corresponding to the temperature range collected by the RTD-type temperature sensor, based on the correspondence between the temperature and resistance values. It then determines at least two calibration resistance values ​​based on this range. Determining the calibration resistance values ​​ensures that the calibration operation covers the actual operating range of the RTD-type temperature sensor, guaranteeing consistency between the calibration results and actual measurement conditions.

[0043] Step 403: Sample based on each calibration resistor value to obtain the sampled value corresponding to each calibration resistor value.

[0044] In practical applications, the control module controls the temperature sampling calibration fixture to sequentially connect each calibration resistor value to the sampling module. The sampling module performs a sampling operation on each calibration resistor value, converting the resistance value into a corresponding sampled value and outputting it to the control module. The sampled value represents the impedance value of the currently connected resistor. The sampled value can be the resistance measurement directly output by the sampling module, or it can be the equivalent impedance value calculated by the control module based on the excitation parameters and response signal of the sampling module after the sampling module outputs a voltage or current signal. The sampled value incorporates system errors introduced by the sampling module and the connecting lines.

[0045] Step 404: Determine the resistance correction model for temperature sampling based on each calibration resistor value and the corresponding sampled value.

[0046] In practical applications, the control module establishes a mapping relationship between sampled values ​​and true resistance values ​​based on each calibrated resistor value and its corresponding sampled value, and determines the resistance correction model according to the mapping relationship. The calibrated resistor value is the known true resistance value, and the sampled value is the measured response value output by the sampling link. The resistance correction model is used to characterize the conversion law between the sampled value and the true resistance value, so as to compensate for the systematic error introduced by the sampling link and realize the correction conversion from the error-contaminated sampled value to the accurate resistance value.

[0047] Step 405: Store the resistance correction model. In subsequent temperature sampling, correct the real-time sampled value according to the resistance correction model to obtain the target resistance value, and determine the current temperature value according to the target resistance value.

[0048] In practical applications, the control module stores the resistance correction model to ensure the continuous availability of calibration results during system operation. In the subsequent real-time measurement phase, an RTD-type temperature sensor is connected to the sampling module. The sampling module samples the real-time resistance value of the RTD-type temperature sensor and outputs a real-time sampled value. This real-time sampled value is the measured response quantity after the RTD-type temperature sensor's true resistance value has been transformed by the sampling link, incorporating system errors introduced by the sampling link. The real-time sampled value can be the resistance measurement directly output by the sampling module, or it can be the equivalent impedance value calculated by the control module based on the sampling module's excitation parameters and response signal after the sampling module outputs a voltage or current signal. The control module calls the stored resistance correction model, using the real-time sampled value as input. Through the mapping relationship represented by the resistance correction model, it obtains the target resistance value, which is the accurate resistance value after eliminating the system errors of the sampling link. Based on the resistance-temperature characteristics of the RTD-type temperature sensor, the control module looks up the corresponding temperature value from the target resistance value to determine the current temperature value. By calling and calculating the resistance correction model during the real-time measurement stage, full-range digital compensation for the sampling link system error is achieved, ensuring that the final output current temperature value can accurately reflect the true temperature state of the measured environment.

[0049] In this way, by obtaining the temperature range to be measured and determining at least two corresponding calibration resistor values ​​based on the temperature range, the mapping from temperature domain range requirements to resistance domain calibration operations is realized. This allows the selection of calibration resistor values ​​to be directly anchored to the actual operating temperature range, avoiding redundant calibration within invalid ranges and improving calibration efficiency and specificity. By directly sampling based on each calibration resistor value and obtaining the corresponding sampled value, the original correspondence between known standard resistance values ​​and the actual response of the sampling link is established. Direct calibration in the resistance domain replaces the traditional method of independently calibrating the excitation current and sampling voltage in RTD temperature sampling systems. This eliminates the need to arrange independent leads and conditioning circuits for milliampere-level current sampling and voltage sampling, simplifying hardware configuration and avoiding the superposition of measurement errors introduced by the voltage and current channels, thus improving the convenience and accuracy of calibration. By determining the resistance correction model for temperature sampling based on each calibration resistor value and the corresponding sampled value, a quantitative characterization of the sampling link system error is achieved. By storing the resistance correction model and correcting the real-time sampled value according to the resistance correction model in subsequent temperature sampling to obtain the target resistance value, continuous reuse of calibration results is realized, effectively improving the temperature measurement accuracy and stability across the entire range.

[0050] In one possible implementation, at least two calibration resistor values ​​are determined based on the temperature range to be measured, including: First, based on the resistance-temperature characteristics of the temperature acquisition device, the range of resistance to be measured corresponding to the range of the temperature to be measured is determined.

[0051] Then, based on the range of the resistor to be measured and the resistance value of the preset resistor, at least two calibration resistor values ​​are determined.

[0052] In practical applications, the preset resistors are known resistance elements configured in the temperature sampling calibration fixture, including the main standard resistor in the main resistor module and the auxiliary standard resistor in the adjustable resistor module. The control module compares the range of the resistance to be measured with the resistance values ​​of the preset resistors and selects at least two calibration resistor values ​​from the preset resistors. The selection of at least two calibration resistor values ​​follows the range coverage principle, that is, at least two calibration resistor values ​​should include resistance values ​​corresponding to the lower and upper limits of the range of the resistance to be measured, to ensure that subsequent calibration operations can cover the full operating range of the RTD type temperature sensor.

[0053] Specifically, if the resistance value of the primary standard resistor falls within the range of the resistor under test, it is directly designated as one of the calibration resistance values, with the primary standard resistor providing a reference calibration point due to its high stability. For boundary points or intermediate points within the range of the resistor under test that are not covered by the primary standard resistor, a resistor with a matching resistance value is selected from the auxiliary standard resistors, or multiple auxiliary standard resistors are combined to obtain an equivalent resistance value to reproduce the target resistance value required for the range of the resistor under test, thus determining these as the remaining calibration resistance values. In another selection method, if the resistance value of the primary standard resistor does not fall within the range of the resistor under test, at least two calibration resistance values ​​are selected or combined from the auxiliary standard resistors, corresponding to the lower and upper limits of the range of the resistor under test, respectively. Through the above selection methods, at least two calibration resistance values ​​cover the key boundaries of the range of the resistor under test in terms of resistance distribution, providing sufficient calibration samples for the subsequent establishment of a full-range resistance correction model.

[0054] In one possible implementation, see [reference] Figure 5 As shown, the resistance correction model for temperature sampling is determined based on each calibration resistor value and its corresponding sampled value, including: Step 501: Match each calibration resistor value with its corresponding sample value to form multiple data points.

[0055] In practical applications, the control module pairs each set of calibration resistor values ​​with its corresponding sampled values ​​to form a data point. In this data point, the calibration resistor value represents the actual resistance value, and the sampled value represents the actual electrical response of the sampling link to that actual resistance value. By matching multiple sets of calibration resistor values ​​with their corresponding sampled values ​​one by one to form multiple data points, a discrete correspondence between the actual resistance value and the measured response is established.

[0056] Step 502: Determine the current fitting strategy based on the distribution characteristics of each data point.

[0057] In practical applications, multiple data points are discretely distributed in a two-dimensional coordinate space. Their distribution pattern reflects the response characteristics of the sampling link across its entire range. The control module analyzes the distribution patterns of these data points in the coordinate space to obtain the distribution characteristics of each data point. These characteristics include the overall trend of the data points, local density, and curvature variation. These characteristics reflect whether the actual response of the sampling link to the input resistance tends to be linear or nonlinear. Based on these distribution characteristics, the control module selects a fitting strategy that accurately describes the distribution pattern as the current fitting strategy. When the distribution characteristics indicate that the data points tend to be distributed along a straight line, a linear fitting strategy is adopted to simplify the model complexity and reduce computational overhead. When the distribution characteristics indicate that the data points exhibit a curved distribution trend, a nonlinear fitting strategy is adopted to improve the model's accuracy in representing the nonlinear response of the sampling link. By adaptively determining the fitting strategy based on the actual distribution characteristics of the data points, the resistance correction model can accurately match the actual transmission characteristics of the sampling link, avoiding model mismatch problems caused by a fixed fitting method.

[0058] Step 503: Fit each data point based on the current fitting strategy to obtain the resistance correction model for temperature sampling.

[0059] In practical applications, fitting is performed using mathematical algorithms to find the optimal functional relationship that accurately describes the correspondence between sampled values ​​and true resistance values. The result of fitting is the resistance correction model, which characterizes the transmission characteristics of the sampling link from the input resistance value to the output sampled value and supports the reverse deduction of the corresponding true resistance value from the sampled value. The control module stores the resistance correction model for later retrieval during real-time measurement.

[0060] In one possible implementation, the current fitting strategy is determined based on the distribution characteristics of each data point, including: First, a linear fit is performed on each data point to obtain a linear reference line.

[0061] In practical applications, the control module directly uses the calibration resistance value at each data point as the independent variable and the corresponding sampled value as the dependent variable, and performs linear fitting using the least squares method. By minimizing the sum of squared residuals from each data point to the fitted line, a linear reference line is obtained. The linear reference line characterizes the global trend of the sampled value as a function of the calibration resistance value under the assumption of ideal linearity.

[0062] Then, determine the deviation of each data point from the linear reference line.

[0063] In practical applications, for each data point consisting of a calibration resistor value and its corresponding sampled value, the control module searches for the corresponding theoretical sampled value on the linear reference line based on the calibration resistor value at that data point, and calculates the difference between the actual sampled value and the theoretical sampled value at that data point. This difference is taken as the deviation between the data point and the linear reference line. For example, when the actual sampled value of the data point corresponding to a 100Ω calibration resistor value is the first sampled value, and the theoretical sampled value corresponding to the linear reference line at 100Ω is the second sampled value, the deviation is the difference between the first and second sampled values. The magnitude of the deviation directly reflects the degree to which the actual response of the sampling link deviates from the ideal linearity at the resistance point corresponding to the calibration resistor value. The smaller the deviation, the better the linearity of the sampling link in that range; the larger the deviation, the more significant the nonlinear distortion of the sampling link in that range. By calculating the deviation of each data point, a quantitative evaluation of the linear response characteristics of the sampling link at each calibration resistance point is achieved, providing a data basis for subsequent judgment on whether a nonlinear fitting strategy needs to be adopted.

[0064] Finally, when the deviation of each data point meets the deviation constraint, the current fitting strategy is determined to be linear fitting; when the deviation of each data point does not meet the deviation constraint, each data point is divided into at least two sub-intervals according to the deviation of each data point, and the sub-fitting strategy for each sub-interval is determined. The sub-fitting strategy is either linear fitting or polynomial fitting.

[0065] In practical applications, the deviation constraint condition refers to the deviation of each data point from the linear reference line being within a preset allowable range. If the deviation of all data points satisfies the deviation constraint condition, it indicates that the difference between the actual sampled value of each data point and the theoretical value of the linear reference line is within the allowable range, and the response of the sampling link within the range of the resistor under test can be considered linear. In this case, the current fitting strategy is determined to be linear fitting to simplify the model structure and reduce the complexity of subsequent correction calculations. If the deviation of some data points does not satisfy the deviation constraint condition, the control module divides each data point into at least two sub-intervals based on the magnitude and distribution of the deviation. For sub-intervals with small deviations and a linear distribution, the corresponding sub-fitting strategy is determined to be linear fitting; for sub-intervals with large deviations and a curvature distribution, the corresponding sub-fitting strategy is determined to be polynomial fitting to improve the correction accuracy of local intervals through higher-order curves.

[0066] Specifically, the control module iterates through the data points according to the magnitude of the calibration resistor values, calculates the difference in deviation between adjacent data points, and obtains the deviation gradient. When the deviation gradient exceeds a preset gradient threshold, the corresponding adjacent positions are used as the boundaries for dividing sub-intervals. After the iteration is complete, each data point is divided into at least two sub-intervals. For each sub-interval, if the deviation of all data points within the sub-interval meets the deviation constraint condition and the deviation gradient does not exceed the preset gradient threshold, then the sub-fitting strategy for that sub-interval is determined to be linear fitting. If there are data points within the sub-interval whose deviation does not meet the deviation constraint condition, or whose deviation gradient exceeds the preset gradient threshold, then the sub-fitting strategy for that sub-interval is determined to be polynomial fitting.

[0067] In one possible implementation, the data points are fitted based on the current fitting strategy to obtain a resistance correction model for temperature sampling, including: When the current fitting strategy is linear fitting, the linear reference line is used as the resistance correction model; When the current fitting strategy is a sub-fitting strategy for each sub-interval, each sub-interval is fitted according to the corresponding sub-fitting strategy to obtain the data fitting line for each sub-interval, and a resistance correction model is constructed based on the data fitting line for each sub-interval.

[0068] In practical applications, when the current fitting strategy is linear fitting, it indicates that the global mapping relationship between the calibration resistance values ​​and sampled values ​​corresponding to all data points can be accurately described by a linear equation. The control module directly uses the linear reference line as the resistance correction model. At this time, the resistance correction model is a global linear model, and the one-to-one correspondence represented by the linear reference line is the conversion rule between the sampled value and the true resistance value. Subsequently, the true resistance value can be directly deduced from the real-time sampled value based on this linear reference line.

[0069] When the current fitting strategy is a sub-fitting strategy for each sub-interval, it indicates that the data points in different intervals exhibit differentiated distribution characteristics. The control module performs corresponding fitting processing on each sub-interval. For sub-intervals with a linear fitting strategy, the control module establishes a linear equation of the form y=ax+b for the data points within the sub-interval, where x is the calibration resistance value and y is the corresponding sampled value. The least squares method is used to solve for the coefficients a and b, minimizing the sum of squared vertical residuals from each data point in the sub-interval to the linear equation, thus obtaining the linear data fitting line for the sub-interval. For sub-intervals with a polynomial fitting strategy, the control module establishes a polynomial equation of the form y=anxn+…+a1x+a0 for the data points within the sub-interval, where x is the calibration resistance value, y is the corresponding sampled value, and n is the polynomial order. The least squares method is used to solve for the coefficients an,…,a1,a0, minimizing the sum of squared vertical residuals from each data point in the sub-interval to the polynomial equation, thus obtaining the curve data fitting line for the sub-interval. After each sub-interval is fitted, a data fitting line for each sub-interval is obtained. The control module integrates the data fitting lines of each sub-interval and their corresponding sub-interval boundary information to construct a piecewise composite resistance correction model. The resistance correction model records the interval range of each sub-interval and the expression of the data fitting line within that interval. Subsequently, based on the real-time sampled values, it determines the sub-interval to which it belongs and calls the corresponding data fitting line for correction calculation.

[0070] In one possible implementation, see [reference] Figure 6 As shown, after determining the current temperature value based on the target resistance value, the process also includes: Step 601: When the current temperature value exceeds the preset temperature range, determine whether the real-time sampled value is within the range of the resistance to be measured corresponding to the temperature range to be measured.

[0071] Specifically, after determining the current temperature value based on the target resistance value, the control module compares the current temperature value with the temperature range to be measured. The temperature range to be measured is the actual operating temperature range of the temperature sampling system obtained in step 401, and the current temperature value is the final output result obtained after correction by the resistance correction model. When the current temperature value exceeds the temperature range to be measured, it indicates that the output of the temperature sampling system has deviated abnormally. At this time, the control module does not directly determine it as an over-temperature fault or trigger blind recalibration, but instead starts a bidirectional diagnostic mechanism to obtain real-time sampled values ​​and determine whether they are within the resistance range to be measured. The real-time sampled value is the raw response of the sampling module to the currently connected RTD-type temperature sensor, and the resistance range to be measured is the theoretical resistance range determined in step 402 based on the temperature range to be measured and the resistance-temperature characteristics of the RTD-type temperature sensor. By tracing the abnormal temperature domain back to the original resistance domain data before correction, a basis for judgment is provided to distinguish the root cause of the abnormality.

[0072] Step 602: If the real-time sampled value is within the range of the resistance to be measured, the resistance correction model is determined to be invalid, and the resistance correction model is re-determined; if the real-time sampled value is outside the range of the resistance to be measured, the sampling function is determined to be abnormal, and a fault prompt is output.

[0073] Specifically, if the real-time sampled value is within the range of the resistance to be measured, it indicates that the current resistance of the RTD-type temperature sensor is within the theoretical resistance boundary corresponding to the temperature range to be measured, meaning the hardware function of the sampling link is normal and the real-time sampled value itself has physical rationality. In this case, the original sampled value is reasonable, but after correction by the resistance correction model, an abnormal temperature value exceeding the temperature range to be measured is obtained. This phenomenon indicates that the resistance correction model can no longer correctly describe the actual transmission characteristics of the current sampling link, which may be caused by factors such as aging of the RTD-type temperature sensor, accumulation of temperature drift in the sampling link, changes in the operating environment, or deviation of model parameters due to long-term operation. At this time, the control module determines that the resistance correction model has failed and automatically triggers the process of re-determining the resistance correction model, that is, re-executes the steps of determining the calibration resistance value, acquiring the sampled value, and constructing the resistance correction model to update the correction model adapted to the current operating conditions.

[0074] If the real-time sampled value is outside the range of the resistance being measured, it indicates that the original sampled value itself has exceeded the physical resistance range that an RTD-type temperature sensor should have within the measured temperature range. This situation is usually caused by a sampling hardware failure, such as a broken wire in the RTD-type temperature sensor causing the resistance to approach infinity, a short circuit causing the resistance to approach zero, or a failure of the constant current source inside the sampling module, or saturation of the analog-to-digital conversion circuit. In this case, even if the resistance correction model is redefined, the hardware-level anomaly cannot be resolved. The control module determines that the sampling function is abnormal and outputs a fault message to prompt maintenance personnel to check the physical connection status of the RTD-type temperature sensor or replace the faulty component, rather than performing an invalid recalibration operation.

[0075] Taking an industrial heat treatment scenario as an example, the temperature sampling system uses a PT100 RTD temperature sensor, with the temperature range to be measured set to 0℃~200℃. Based on the resistance-temperature characteristics of the PT100, the control module determines the range of resistance to be measured corresponding to the temperature range to be measured to be 100Ω (0℃)~175.84Ω (200℃).

[0076] The temperature sampling calibration fixture is equipped with a main standard resistor and an adjustable resistor module controlled by a relay. The resistance value of the main standard resistor constitutes the maximum equivalent resistance that the fixture can output. Its resistance value should be greater than or equal to the upper limit of the range of the resistor being measured to ensure that the entire range of the resistor being measured can be covered by the parallel auxiliary standard resistors. Based on the above principle, a 200Ω precision foil resistor is selected as the main standard resistor, directly connected between the first and second terminals of the fixture as the upper limit reference point of the range; the 200Ω resistance value is greater than the upper limit of the range of the resistor being measured by 175.84Ω, ensuring that the calibration requirements around 200℃ can be covered when all auxiliary standard resistors are disconnected. The adjustable resistor module contains three parallel resistor branches, each consisting of a relay connected in series with an auxiliary standard resistor, with auxiliary standard resistors of 200Ω, 300Ω, and 600Ω respectively. The relays are small signal relays with a typical contact internal resistance of approximately 50mΩ.

[0077] Because the resistance of the auxiliary standard resistor is much greater than the on-resistance of the relay, with a ratio of over 4000:1, the series impedance error introduced when the relay contacts are on accounts for less than 0.025%, which is negligible compared to the nominal accuracy (±0.01%) of the auxiliary standard resistor. This ensures that the equivalent resistance output of the adjustable resistor module is mainly determined by the auxiliary standard resistor and is not affected by relay contact aging, oxidation, or changes in contact pressure, significantly improving the long-term stability and calibration accuracy of the resistance output.

[0078] The calibration process is as follows: Step 1: The control module acquires the temperature range to be measured from 0℃ to 200℃ and determines the corresponding resistance range to be measured as 100Ω to 175.84Ω. Based on the circuit characteristic that the main standard resistor of 200Ω is always connected in parallel, the selection strategy for the calibration resistor value is determined: when all auxiliary standard resistors are disconnected, the main standard resistor of 200Ω is output (corresponding to approximately 519℃, serving as the upper limit of the range); by connecting different auxiliary standard resistor branches in parallel with the main standard resistor, the equivalent resistance value covering the lower range is obtained.

[0079] Step two: The control module controls the temperature sampling calibration fixture to sequentially connect each calibration resistor value to the sampling module. Each relay is independently controlled by an external control module, which can either individually activate a single auxiliary standard resistor branch or simultaneously activate multiple auxiliary standard resistor branches to achieve a wider range of equivalent resistance combinations. For the 200Ω calibration point, all relays remain open, and the main standard resistor outputs 200Ω directly. This resistance value is greater than the upper limit of the range of the resistor under test, 175.84Ω, for redundant coverage of the upper limit of the range.

[0080] For the 171.43Ω calibration point, the control module outputs a turn-on command to the relay connected in series with a 1200Ω auxiliary standard resistor, while the other relays remain open; the main standard resistor of 200Ω and the auxiliary standard resistor of 1200Ω are connected in parallel, with an equivalent resistance of 171.43Ω, which is close to the upper limit of the 175.84Ω range.

[0081] For the 133.33Ω calibration point, the control module outputs a turn-on command to the relay connected in series with a 400Ω auxiliary standard resistor, while the other relays remain open; the main standard resistor of 200Ω and the auxiliary standard resistor of 400Ω are connected in parallel, with an equivalent resistance of 133.33Ω, serving as an intermediate characteristic point.

[0082] For the 120Ω calibration point, the control module simultaneously outputs a conduction command to the relay connected in series with a 400Ω auxiliary standard resistor and the relay connected in series with a 1200Ω auxiliary standard resistor; the main standard resistor 200Ω is connected in parallel with the 400Ω and 1200Ω resistors, where the 400Ω and 1200Ω resistors in parallel are equivalent to 300Ω, which is then connected in parallel with the 200Ω resistor to obtain 120Ω, serving as a supplementary intermediate point.

[0083] For the 100Ω calibration point, the control module outputs a turn-on command to the relay connected in series with a 200Ω auxiliary standard resistor, while the other relays remain open; the 200Ω main standard resistor and the 200Ω auxiliary standard resistor are connected in parallel, with an equivalent resistance of 100Ω, corresponding to the lower limit of the range.

[0084] Through the aforementioned independent control and multi-channel combination mechanism, the temperature sampling calibration fixture can output multiple calibration resistance values, including 200Ω, 171.43Ω, 133.33Ω, 120Ω, and 100Ω, covering the critical boundaries and intermediate sections of the resistance range to be measured, from 100Ω to 175.84Ω. During the input of each calibration resistance value, the sampling module performs a sampling operation and outputs the corresponding sampled value. Since the internal resistance of the relay is extremely small compared to the auxiliary standard resistor, the deviation between the parallel equivalent resistance value and the theoretical calculated value is negligible, ensuring the accuracy of the calibration reference.

[0085] Step 3: The control module matches the calibration resistor values ​​of 200Ω, 171.43Ω, 133.33Ω, 120Ω, and 100Ω with the corresponding sampled values ​​to form five data points. A two-dimensional coordinate distribution is established with each calibration resistor value as the independent variable and the corresponding sampled value as the dependent variable.

[0086] The control module uses the least squares method to perform linear fitting on the five data points to obtain a linear reference line, which represents the global linear trend of the sampled value as the calibration resistor value changes.

[0087] The control module determines the deviation between each data point and the linear reference line. Specifically, for the 100Ω calibration point, it obtains the first deviation between its actual sampled value and the linear reference line's sampled value at 100Ω; for the 120Ω calibration point, it obtains the second deviation; for the 133.33Ω calibration point, it obtains the third deviation; for the 171.43Ω calibration point, it obtains the fourth deviation; and for the 200Ω calibration point, it obtains the fifth deviation.

[0088] The control module compares the first, second, third, fourth, and fifth deviations with the deviation constraints. In this embodiment, the control module determines whether the deviation of each data point meets the deviation constraints. The deviation constraints refer to the rules for determining whether the deviation of each data point relative to the linear reference line is within a preset allowable range. Taking the first and second deviations as examples where the first and second deviations are both within the preset allowable range, but the third, fourth, and fifth deviations exceed the preset allowable range, it indicates that the response of the sampling link tends to be linear in the low-resistance range of 100Ω to 120Ω, and there is nonlinear distortion in the high-resistance range of 133.33Ω to 200Ω.

[0089] At this point, the control module iterates through the data points according to the magnitude of the calibration resistor values, calculating the difference in deviation between adjacent data points to obtain the gradient of deviation change. When the gradient of the third deviation relative to the second deviation exceeds a preset gradient threshold, the adjacent positions between 120Ω and 133.33Ω are used as the boundary for dividing the sub-interval. After the iteration is complete, each data point is divided into two sub-intervals: the data points corresponding to 100Ω and 120Ω are assigned to the first sub-interval, with a resistance range of 100Ω to 120Ω; the data points corresponding to 133.33Ω, 171.43Ω, and 200Ω are assigned to the second sub-interval, with a resistance range of 133.33Ω to 200Ω.

[0090] For the first sub-interval, the control module determines the sub-fitting strategy as linear fitting, and uses the least squares method to perform linear fitting on two data points in the sub-interval to obtain the linear data fitting line of the first sub-interval.

[0091] For the second sub-interval, the control module determines the sub-fitting strategy as polynomial fitting, and uses the least squares method to perform polynomial fitting on the three data points in the sub-interval to obtain the curve data fitting line of the second sub-interval.

[0092] Finally, the control module integrates the linear data fitting line of the first sub-interval, the curve data fitting line of the second sub-interval, and the corresponding resistance range of each sub-interval to construct a piecewise composite resistance correction model. The resistance correction model records the linear expression for the first sub-interval, the polynomial expression for the second sub-interval, and the interval boundaries of each sub-interval. These are used to subsequently determine the sub-interval to which a sub-interval belongs based on real-time sampled values ​​and to call the corresponding data fitting line for correction calculations.

[0093] Step four: The control module stores the resistance correction model. In the subsequent real-time measurement stage, the PT100 temperature sensor is connected to the sampling module. The control module calls the resistance correction model to correct the real-time sampled value, obtains the target resistance value, and then looks up the temperature value to achieve high-precision temperature measurement within the range of 0℃ to 200℃.

[0094] It should be noted that although several units or sub-units of the device have been mentioned in the detailed description above, this division is merely exemplary and not mandatory. In fact, according to embodiments of this application, the features and functions of two or more units described above can be embodied in one unit. Conversely, the features and functions of one unit described above can be further divided and embodied by multiple units.

[0095] Furthermore, although the operations of the method of this application are described in a specific order in the accompanying drawings, this does not require or imply that these operations must be performed in that specific order, or that all the operations shown must be performed to achieve the desired result. Additionally or alternatively, certain steps may be omitted, multiple steps may be combined into one step, and / or one step may be broken down into multiple steps.

[0096] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0097] Obviously, those skilled in the art can make various modifications and variations to the embodiments of this application without departing from the spirit and scope of the embodiments of this application. Therefore, if these modifications and variations to the embodiments of this application fall within the scope of the claims of this application and their equivalents, this application also intends to include these modifications and variations.

Claims

1. A temperature sampling calibration method, characterized in that, include: Obtain the temperature range to be measured; Determine at least two corresponding calibration resistor values ​​based on the temperature range to be measured; Based on the calibration resistor values, sample values ​​are obtained corresponding to each calibration resistor value; The resistance correction model for the temperature sampling is determined based on each of the calibration resistor values ​​and the corresponding sampled values. The resistance correction model is stored. In subsequent temperature sampling, the real-time sampled value is corrected according to the resistance correction model to obtain the target resistance value, and the current temperature value is determined according to the target resistance value.

2. The temperature sampling calibration method as described in claim 1, characterized in that, The step of determining at least two corresponding calibration resistance values ​​based on the temperature range to be measured includes: Based on the resistance-temperature characteristics of the temperature acquisition device, the range of resistance to be measured corresponding to the range of temperature to be measured is determined. Based on the range of resistance to be measured and the resistance value of the preset resistor, at least two calibration resistance values ​​are determined.

3. The temperature sampling calibration method as described in claim 1, characterized in that, The determination of the resistance correction model for the temperature sampling based on each of the calibration resistor values ​​and the corresponding sampled values ​​includes: Each calibration resistor value is matched with its corresponding sampled value to form multiple data points; Determine the current fitting strategy based on the distribution characteristics of each data point; The current fitting strategy is used to fit each data point to obtain the resistance correction model for the temperature sampling.

4. The temperature sampling calibration method as described in claim 3, characterized in that, The process of determining the current fitting strategy based on the distribution characteristics of each data point includes: A linear reference line is obtained by performing linear fitting on each data point; Determine the deviation of each data point from the linear reference line; When the deviation of each data point meets the deviation constraint, the current fitting strategy is determined to be linear fitting; When the deviation of each data point does not meet the deviation constraint, each data point is divided into at least two sub-intervals according to the deviation of each data point, and a sub-fitting strategy is determined for each sub-interval. The sub-fitting strategy is linear fitting or polynomial fitting.

5. The temperature sampling calibration method as described in claim 4, characterized in that, The process of fitting each data point based on the current fitting strategy to obtain the resistance correction model for the temperature sampling includes: When the current fitting strategy is linear fitting, the linear reference line is used as the resistance correction model; When the current fitting strategy is a sub-fitting strategy for each sub-interval, each sub-interval is fitted according to the corresponding sub-fitting strategy to obtain the data fitting line for each sub-interval, and the resistance correction model is constructed based on the data fitting line for each sub-interval.

6. The temperature sampling calibration method according to any one of claims 1-5, characterized in that, After determining the current temperature value based on the target resistance value, the method further includes: When the current temperature value exceeds the preset temperature range, it is determined whether the real-time sampled value is within the range of the resistance to be measured corresponding to the temperature range to be measured. If the real-time sampled value is within the range of the resistance to be measured, then the resistance correction model is determined to be invalid, and the resistance correction model is re-determined. If the real-time sampled value is outside the range of the resistor under test, the sampling function is determined to be abnormal, and a fault prompt is output.

7. A temperature sampling and calibration fixture, characterized in that, include: Main resistor module and adjustable resistor module; The main resistor module and the adjustable resistor module are respectively connected between the first terminal and the second terminal of the fixture; the first terminal and the second terminal of the fixture are connected to an external sampling module; the control terminal of the adjustable resistor module is connected to an external control module. The main resistor module is used to connect a resistor with a fixed resistance value between the first terminal and the second terminal of the tooling. The adjustable resistor module is used to connect an adjustable resistor between the first terminal and the second terminal of the tooling, and to adjust the resistance value under the control of the external control module.

8. The temperature sampling and calibration fixture as described in claim 7, characterized in that, The main resistor module includes: a main standard resistor; The main standard resistor is connected between the first terminal and the second terminal of the tooling. The adjustable resistor module includes: multiple parallel resistor branches; Each of the resistor branches is connected between the first terminal and the second terminal of the tooling. Each of the resistor branches includes a controllable switch and an auxiliary standard resistor connected in series. The control terminal of each controllable switch is connected to the external control module.

9. The temperature sampling and calibration fixture as described in claim 7, characterized in that, The wiring between the first terminal of the tooling and the external sampling module and the wiring between the second terminal of the tooling and the external sampling module have the same wire length and wire diameter specifications.

10. A temperature sampling system, characterized in that, include: The sampling module, the control module, and the temperature sampling calibration fixture as described in any one of claims 7-9; The first and second terminals of the temperature sampling calibration fixture are respectively connected to the sampling module via wiring lines, and the control terminal of the temperature sampling calibration fixture is connected to the control module; the temperature sampling calibration fixture is used to provide calibration resistance values ​​to the sampling module. The output of the sampling module is connected to the control module; the sampling module is used to sample based on the calibration resistor value and output the sampled value corresponding to the calibration resistor value. The control module is used to execute the temperature sampling calibration method as described in any one of claims 1-6.

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