Calibration method based on miniature wireless temperature measuring device and array calibration tool

Abstract

The invention relates to the technical field of temperature detection, in particular to a calibration method based on a miniature wireless temperature measuring device and an array calibration tool. The calibration method comprises the following steps: calibrating unconnected temperature sensors to obtain an R-T contrast relationship; putting a plurality of connected micro wireless temperature measuring devices into a water bath cavity in the array calibration tool, and monitoring the true value temperature Tstand of the water bath cavity in real time; reading an original temperature reading Traw output by the micro-control unit; the system error delta T = Traw-Tstand of each miniature wireless temperature measuring device at each temperature point is calculated, and a function model delta T = f (Traw) with Traw as an independent variable and a compensation value delta T as a dependent variable is established for each miniature wireless temperature measuring device. According to the method, the problems that calibration of an existing sensor before leaving a factory is inaccurate, and only one sensor can be calibrated at a time in a traditional method are solved.

Description

Technical Field

[0001] This application relates to the field of temperature detection technology, and in particular to a calibration method and array calibration fixture based on a miniature wireless temperature measuring device. Background Technology

[0002] In the field of precision temperature measurement, whether it is a traditional wired sensor or an emerging temperature measurement unit, calibration before leaving the factory is the core link to ensure its measurement accuracy.

[0003] Current sensor calibration methods typically involve a single-level calibration of the sensor probe itself using a high-precision temperature-controlled bath to obtain the RT meter. This method completely ignores the systematic errors introduced by subsequent circuits (ADC reference voltage, MCU temperature drift) under real-world operating conditions, ultimately leading to inaccurate calibration.

[0004] For temperature measurement units, existing technologies typically use this method directly, treating the entire unit as a "black box" placed in a constant temperature bath, and calibrating the relationship between its final output digital temperature value T_output and the true temperature field value T_standard. However, while existing calibration methods are mature, they reveal many inherent flaws when facing next-generation miniaturized, wireless, system-level temperature measurement units, failing to meet high-precision requirements. For example, severe thermal crosstalk leads to calibration distortion: the temperature measurement unit is a highly integrated system. During "black box" calibration, the heat from the constant temperature bath must pass through the unit's outer shell to reach the internal NTC probe. The internal MCU, ADC, and other components generate heat during operation, becoming internal heat sources and creating a complex internal thermal field. This causes a difference between the temperature sensed by the NTC probe and the external ambient temperature (i.e., the true calibration value), known as "thermal crosstalk." This, in turn, leads to distorted calibration data and a systematically higher actual measurement value.

[0005] Furthermore, calibration efficiency and consistency are difficult to guarantee when using either traditional wired sensors or emerging temperature sensing units in a constant temperature bath. Traditional methods can only calibrate one probe or temperature sensing unit at a time, resulting in low efficiency. For temperature sensing networks requiring large-scale deployment (such as high-voltage switchgear with a dozen or so temperature sensing points), calibrating each temperature sensing unit individually is extremely time-consuming. More importantly, factors such as the parameter dispersion of internal components, differences in patch stress, and slight variations in the thermal conductivity of potting compounds within different temperature sensing units can lead to inconsistent system error characteristics for each unit. Traditional single-unit calibration cannot effectively assess and correct these consistency differences between temperature sensing units, resulting in non-negligible deviations in the measured values ​​of different temperature sensing units under the same temperature field. Summary of the Invention

[0006] The purpose of this application is to provide a calibration method and array calibration fixture based on a miniature wireless temperature measurement device, thereby solving the problems of inaccurate calibration (calibration) of existing sensors before they leave the factory and the fact that traditional methods can only calibrate one sensor at a time.

[0007] According to a first aspect of this application, a calibration method based on a miniature wireless temperature measuring device is provided. The miniature wireless temperature measuring device includes a housing and a temperature sensor, an ADC chip, and a microcontroller unit encapsulated inside the housing. The ADC chip converts the analog signal corresponding to the ambient temperature collected by the temperature sensor into a digital signal and transmits the digital signal to the microcontroller unit. The microcontroller unit converts the digital signal into temperature data. The calibration method includes: Probe-level calibration: The temperature sensor that has not yet been connected is calibrated to obtain the RT comparison relationship, and the RT comparison relationship is written into the microcontroller unit. System-level combined calibration: Multiple connected miniature wireless temperature measuring devices are placed in a water bath chamber inside the array calibration fixture, and kept warm at multiple temperature points. The true temperature T_standard of the water bath chamber is monitored in real time using a standard thermometer. Read the raw temperature reading T_raw output by the microcontroller, where T_raw is the voltage value read by the microcontroller through the ADC chip and the result calculated by combining it with the RT meter; Calculate the system error ΔT=T_raw-T_standard for each miniature wireless temperature measuring device at each temperature point, and establish a function model ΔT=f(T_raw) with T_raw as the independent variable and the compensation value ΔT as the dependent variable for each miniature wireless temperature measuring device, and write the function model ΔT=f(T_raw) into the microcontroller unit; When performing core compensation, T_raw is substituted into the model function f(T_raw) to calculate the system error compensation value ΔT corresponding to the current temperature point. The final output is T_final = T_raw – ΔT.

[0008] In any of the above technical solutions, further, in the probe-level calibration step, in a metrology-level constant temperature liquid bath, the temperature sensor and standard thermometer that have not yet been connected are placed together, and the temperature is kept at multiple temperature points. The resistance value R of the temperature sensor at each temperature point is recorded, and the RT comparison relationship is obtained.

[0009] In any of the above technical solutions, further, in the system-level combined calibration step, the function model ΔT = aT_raw² + bT_raw + c.

[0010] In any of the above technical solutions, further, in the system-level combined calibration step, after placing multiple connected miniature wireless temperature measuring devices into the water bath cavity inside the array calibration fixture, the array calibration fixture is placed in a high-precision environmental test chamber, which can provide a stable and uniform temperature field.

[0011] In any of the above technical solutions, the calibration method further includes: Simulated environment verification and calibration: The miniature wireless temperature measuring device, after system-level combined calibration, is installed in an environmental simulation test chamber that simulates actual working conditions. The output of the miniature wireless temperature measuring device is compared with the reading of the standard thermometer arranged in the environmental simulation test chamber for final verification and fine-tuning. The final output is T_final+d.

[0012] In any of the above technical solutions, the miniature wireless temperature measuring device further includes a Bluetooth chip encapsulated inside the housing. The micro control unit converts the digital signal into temperature data and sends it to the Bluetooth chip, so that the Bluetooth chip can wirelessly transmit the temperature data. In the system-level integrated calibration step, the raw temperature reading T_raw output by the microcontroller unit is read through the interface of the Bluetooth chip.

[0013] In any of the above technical solutions, the miniature wireless temperature measurement device further includes a circuit board; the temperature sensor, the ADC chip, the microcontroller unit, and the Bluetooth chip are all integrated on the circuit board; the temperature sensor includes a thermistor and a metal pillar; the head of the metal pillar passes through the housing and is exposed outside the housing; the thermistor is encapsulated in the metal pillar to achieve thermal coupling with the end of the metal pillar.

[0014] In any of the above technical solutions, the temperature sensor and the microcontroller unit are further arranged on the front and back sides of the circuit board, respectively; along the thickness direction of the circuit board, the temperature sensor and the microcontroller unit have no overlapping area.

[0015] According to a second aspect of this application, an array calibration fixture is provided for use in the calibration method described above; the array calibration fixture includes a base, a top cover, and a standard thermometer; the top cover is sealed to the base to form the water bath chamber; the base is provided with a plurality of mounting slots for fixing the miniature wireless temperature measuring device, and the base is provided with mounting holes for fixing the standard thermometer.

[0016] In any of the above technical solutions, further, there are 4 installation slots, arranged at intervals along the same direction; or, there are 16 installation slots, arranged in a matrix.

[0017] The calibration method of this application includes: Probe-level calibration: The temperature sensor that has not yet been connected is calibrated to obtain the RT comparison relationship, and the RT comparison relationship is written into the microcontroller unit. System-level combined calibration: Multiple connected miniature wireless temperature measuring devices are placed in a water bath chamber inside the array calibration fixture, and kept warm at multiple temperature points. The true temperature T_standard of the water bath chamber is monitored in real time using a standard thermometer. Read the raw temperature reading T_raw output by the microcontroller, where T_raw is the voltage value read by the microcontroller through the ADC chip and the result calculated by combining it with the RT meter; Calculate the system error ΔT=T_raw-T_standard for each miniature wireless temperature measuring device at each temperature point, and establish a function model ΔT=f(T_raw) with T_raw as the independent variable and the compensation value ΔT as the dependent variable for each miniature wireless temperature measuring device, and write the function model ΔT=f(T_raw) into the microcontroller unit; When performing core compensation, T_raw is substituted into the model function f(T_raw) to calculate the system error compensation value ΔT corresponding to the current temperature point. The final output is T_final = T_raw – ΔT.

[0018] Based on the above technical features, the beneficial effects of this application are as follows: This application calibrates the entire miniature wireless temperature measurement device as a complete measuring instrument. The compensation model directly corrects the internal errors of each miniature wireless temperature measurement device, thereby improving the temperature measurement accuracy of the miniature wireless temperature measurement device to the mK level, meeting the extreme requirements of scientific research and high-end industrial monitoring. Furthermore, by simultaneously calibrating multiple miniature wireless temperature measurement devices, calibration efficiency is greatly improved. More importantly, in system-level combined calibration, the differences between each miniature wireless temperature measurement device can be accurately quantified, and independent compensation algorithms can be used to make the outputs of all miniature wireless temperature measurement devices tend to be consistent, greatly improving the consistency level of batch products.

[0019] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 A schematic flowchart illustrating a calibration method based on a miniature wireless temperature measuring device according to an embodiment of this application is shown. Figure 2 This diagram shows the structure of the array calibration fixture according to the first embodiment of this application; Figure 3 Show Figure 2 Partial structural diagram; Figure 4 This diagram shows a schematic of the array calibration fixture according to the second embodiment of this application; Figure 5 Show Figure 4 Partial structural diagram; Figure 6 A schematic diagram illustrating the principle of a miniature wireless temperature measurement device according to an embodiment of this application is shown. Figure 7 A schematic diagram of the overall structure of a miniature wireless temperature measurement device according to an embodiment of this application is shown; Figure 8 Show Figure 7 A schematic diagram of the structure after the outer shell is hidden; Figure 9 Show Figure 8 Another structural diagram from another perspective; Figure 10 A schematic diagram illustrating the effect of a miniature wireless temperature measurement device according to an embodiment of this application is shown.

[0022] Icons: 1-Miniature wireless temperature measurement device; 10-Thermistor; 11-Metal pillar; 20-Differential amplifier; 30-Filter module; 40-Bluetooth chip; 50-Microcontroller unit; 60-Memory chip; 70-Constant current source; 80-Analog-to-digital converter; 90-Housing; 100-Circuit board; 200-Array calibration fixture; 201-Base; 202-Top cover; 203-Standard thermometer. Detailed Implementation

[0023] The following detailed embodiments are provided to help the reader gain a comprehensive understanding of the methods, apparatus, and / or systems described herein. However, various changes, modifications, and equivalents of the methods, apparatus, and / or systems described herein will be apparent after understanding the disclosure of this application. For example, the order of operations described herein is merely illustrative and is not limited to the order set forth herein; changes that will be apparent after understanding the disclosure of this application are possible, except for operations that must occur in a specific order. Furthermore, for clarity and brevity, descriptions of features known in the art may be omitted.

[0024] The features described herein may be implemented in different forms and should not be construed as being limited to the examples described herein. Rather, the examples described herein have been provided merely to illustrate some of the many feasible ways of implementing the methods, apparatus, and / or systems described herein that will be apparent upon understanding the disclosure of this application.

[0025] Throughout the specification, when an element (such as a layer, region, or substrate) is described as being "on" another element, "connected to" another element, "bonded to" another element, "on" another element, or "covering" another element, it may be directly "on" another element, "connected to" another element, "bonded to" another element, "on" another element, or "covering" another element, or there may be one or more other elements in between. In contrast, when an element is described as being "directly on" another element, "directly connected to" another element, "directly bonded to" another element, "directly on" another element, or "directly covering" another element, there may be no other elements in between.

[0026] As used herein, the term “and / or” includes any one of the relevant items listed and any combination of any two or more items.

[0027] Although terms such as “first,” “second,” and “third” may be used herein to describe individual components, assemblies, regions, layers, or parts, these components, assemblies, regions, layers, or parts are not limited by these terms. Rather, these terms are used only to distinguish one component, assembly, region, layer, or part from another. Therefore, without departing from the teachings of the examples described herein, the first component, assembly, region, layer, or part referred to as the second component, assembly, region, layer, or part may also be referred to as the second component, assembly, region, layer, or part.

[0028] For ease of description, spatial relation terms such as “above,” “upper,” “below,” and “lower” are used herein to describe the relationship between one element and another, as shown in the accompanying drawings. Such spatial relation terms are intended to include not only the orientation depicted in the drawings but also different orientations of the device during use or operation. For example, if the device in the drawings is flipped, an element described as being “above” or “upper” relative to another element will subsequently be “below” or “lower” relative to that other element. Therefore, the term “above” includes both “above” and “below” orientations depending on the spatial orientation of the device. The device may also be positioned in other ways (e.g., rotated 90 degrees or in other orientations), and the spatial relation terms used herein will be interpreted accordingly.

[0029] The terminology used herein is for the purpose of describing various examples only and is not intended to limit this disclosure. Unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. The terms “comprising,” “including,” and “having” enumerate the stated features, quantities, operations, components, elements, and / or combinations thereof, but do not exclude the presence or addition of one or more other features, quantities, operations, components, elements, and / or combinations thereof.

[0030] Variations in the shapes shown in the accompanying drawings may occur due to manufacturing techniques and / or tolerances. Therefore, the examples described herein are not limited to the specific shapes shown in the accompanying drawings, but include changes in shape that may occur during manufacturing.

[0031] The features of the examples described herein can be combined in various ways that will be apparent upon understanding the disclosure of this application. Furthermore, although the examples described herein have a wide variety of constructions, other constructions are possible, as will be apparent upon understanding the disclosure of this application.

[0032] This application provides a calibration method and array calibration fixture based on a miniature wireless temperature measurement device, thereby solving the problems of inaccurate pre-shipment calibration of existing sensors and the fact that traditional methods can only calibrate one sensor at a time. See below for reference. Figure 1 The calibration method for the miniature wireless temperature measurement device according to some embodiments of this application is described, with reference to Figures 2 to 5 This application describes an array calibration fixture according to some embodiments. (Refer to...) Figures 6 to 9 This application describes a miniature wireless temperature measurement device according to some embodiments.

[0033] like Figures 6 to 9As shown, the miniature wireless temperature measurement device of this application includes a housing 90, a circuit board 100, and a temperature measurement sub-circuit and a microcontroller 50 integrated on the circuit board 100; the circuit board 100, the temperature measurement sub-circuit, and the microcontroller 50 are all encapsulated inside the housing 90. The temperature measurement sub-circuit includes a temperature sensor, a differential amplifier 20, and an analog-to-digital converter 80; part of the sensing end of the temperature sensor is exposed outside the housing 90; the input end of the differential amplifier 20 is connected to both ends of the temperature sensor; the first input end of the analog-to-digital converter 80 is connected to the output end of the differential amplifier 20, and the output end of the analog-to-digital converter 80 is connected to the first communication interface of the microcontroller 50; the temperature measurement sub-circuit collects the analog signal corresponding to the ambient temperature of the environment and converts the analog signal into a digital signal, transmits the digital signal to the microcontroller 50, and the microcontroller 50 converts the digital signal into temperature data.

[0034] By employing this design, this application eliminates the wired transmission via shielded or unshielded twisted-pair cables, which can stretch for meters or even tens of meters, between the temperature sensor and the microcontroller 50 in existing technologies. This application integrates all communication (electrical) connections onto the circuit board 100; that is, the communication (electrical) connections between the temperature sensor, differential amplifier 20, analog-to-digital converter 80, and microcontroller 50 are all routed on the circuit board 100. Furthermore, by encapsulating the temperature-measuring subcircuit and the microcontroller 50 within the miniature space of the housing 90, miniaturization and integration of temperature measurement are achieved, allowing it to be easily pasted or embedded into previously inaccessible slits, much like a "stamp." This addresses the aforementioned technical problems inherent in wired contact-based temperature measurement solutions in existing technologies.

[0035] Furthermore, such as Figure 6 , Figure 8 and Figure 9 As shown, in the embodiments of this application, the miniature wireless temperature measuring device may further include a Bluetooth chip 40 integrated on the circuit board 100, which is encapsulated inside the housing 90. The second communication interface of the microcontroller 50 is connected to the Bluetooth chip 40, and the microcontroller 50 can send the converted temperature data to the Bluetooth chip 40, enabling the Bluetooth chip 40 to wirelessly transmit the temperature data to an external host computer. With this configuration, compared to the prior art, the miniature wireless temperature measuring device of this application also eliminates the wired connection between the microcontroller 50 and the host computer.

[0036] Specifically, the temperature detection sub-circuit acquires an analog signal to reflect the ambient temperature, converts the analog signal into a digital signal through analog-to-digital conversion, and then sends it to the microcontroller 50 through the first communication interface of the microcontroller 50. After receiving the digital signal, the first communication interface of the microcontroller 50 analyzes the temperature data from the digital signal, including the ambient temperature value, and sends the ambient temperature to the Bluetooth chip 40 through the second communication interface of the microcontroller 50. The Bluetooth chip 40 sends the received temperature data to the gateway in real time to realize wireless transmission of temperature data.

[0037] The microcontroller unit is configured to execute an ultra-low power management strategy, controlling the entire micro wireless temperature measurement device to be in deep sleep mode most of the time, and only waking it up at preset time intervals or triggered by external interrupts. After waking up, it will power on the temperature sensor, ADC chip, and Bluetooth chip 40 in an orderly manner within a very short time window, and immediately cut off the power to each module and re-enter deep sleep mode after completing the measurement, processing and communication tasks.

[0038] In the embodiments of this application, as an example, such as Figures 7 to 9 As shown, the temperature sensor includes a thermistor 10 and a metal post 11. The first end of the metal post 11 passes through the bottom of the housing 90 and is exposed outside the housing 90. This application designs a convex metal post 11 made of a high thermal conductivity material at the bottom of the housing 90, which directly contacts the surface of the object being measured. During installation, the high-precision thermistor 10 (NTC probe) is directly mounted and stored inside the metal post 11, and good thermal coupling is achieved with the end of the metal post 11 through thermally conductive grease and adhesive. This allows the heat from the object being measured to be efficiently transferred to the thermistor 10 through the metal post 11, reducing the thermal response time. The two ends of the thermistor 10 are connected to the input terminals of the differential amplifier 20.

[0039] Furthermore, in the embodiments of this application, the temperature measuring sub-circuit also includes a filtering module 30; one end of the filtering module 30 is connected to the output terminal of the differential amplifier 20, and the other end is connected to the first input terminal of the analog-to-digital converter 80.

[0040] In the embodiments of this application, the input terminal of the differential amplifier 20 is connected to both ends of the thermistor 10 to detect the voltage value across the thermistor 10 and amplify the voltage value. The amplified voltage value is then transmitted to the filter module 30 through the output terminal of the differential amplifier 20. The filter module 30 filters the amplified voltage value and then transmits the filtered voltage value to the first input terminal of the analog-to-digital converter 80. The analog-to-digital converter 80 performs analog-to-digital conversion on the filtered voltage value to obtain the digital signal corresponding to the voltage value across the thermistor 10, and then sends the digital signal to the first communication interface of the microcontroller unit 50.

[0041] In other words, the temperature detection sub-circuit amplifies, filters, and converts the voltage across the thermistor 10 sequentially, and then outputs the processed digital signal to the first communication interface of the microcontroller 50. Thus, the first communication interface of the microcontroller 50 receives the digital signal containing the voltage across the thermistor 10.

[0042] For example, the differential amplifier 20 can be any existing differential amplifier circuit, and the filter module 30 can be any existing amplification and filtering circuit; this application does not impose any restrictions on this. The differential amplifier 20 can be an operational amplifier with ultra-low noise and low drift, and the filter circuit can be a low-pass filter circuit, thereby conditioning the weak voltage signal across the thermistor 10 to maximize the signal-to-noise ratio.

[0043] Furthermore, in the embodiments of this application, such as Figure 6 As shown, the temperature sensing sub-circuit also includes a constant current source 70. One end of the thermistor 10 is grounded to GND, and the other end is connected to the constant current source 70. Specifically, the constant current source 70 is used to provide a stable input power supply to the temperature sensing sub-circuit. By selecting the constant current source 70, measurement errors caused by excitation current fluctuations are avoided, thereby providing a more stable analog signal. Based on this, this application provides a stable voltage required for temperature detection by directly connecting the temperature sensing sub-circuit to the constant current source 70, and converts the detected high-precision analog signal into a digital signal. The microcontroller unit 50 then converts the digital signal into temperature data and transmits it to the Bluetooth chip 40, enabling the Bluetooth chip 40 to transmit the temperature data wirelessly, thus achieving the technical effect of improving temperature measurement accuracy.

[0044] Additionally, in the embodiments of this application, such as Figure 6 As shown, the constant current source 70, differential amplifier 20, filter module 30, and analog-to-digital converter 80 can be integrated onto a single ADC chip. The microcontroller unit 50 also includes a control interface, where the ADC chip connects to the control interface of the microcontroller unit 50 to receive control signals from the microcontroller unit 50 indicating the operating mode. Specifically, the microcontroller unit 50 sends control signals to the ADC chip through its control interface, and the ADC chip operates according to the operating mode indicated by the control signals. In other words, the control signals indicate the operating mode of the ADC chip, and the operating mode indicates the magnitude of the output constant current source 70.

[0045] Furthermore, in the design of the temperature detection sub-circuit in this application, the accuracy of the physical signal sensing level is ensured by providing a stable constant current source 70 to the thermistor 10. By designing and selecting a low-pass filter circuit, an ultra-low noise and low drift operational amplifier, a 24-bit analog-to-digital converter 80, and a low-drift reference voltage source, the accuracy of the entire process of converting analog signals into digital signals is determined. This provides high-quality raw data for subsequent algorithm processing by the microcontroller unit 50 and provides a hardware foundation for achieving milliKelvin (mk) level temperature measurement accuracy.

[0046] Furthermore, in the embodiments of this application, such as Figure 6 As shown, the miniature wireless temperature measurement device also includes a memory chip 60 integrated on the circuit board 100, which is encapsulated inside the housing 90. The transmission interface of the memory chip 60 is connected to the third communication interface of the microcontroller 50, enabling the microcontroller 50 to transmit temperature data to the memory chip 60.

[0047] The storage chip 60 includes an SPI Flash memory (serial flash memory). The third communication interface of the microcontroller 50 transmits the temperature data calculated by the microcontroller 50 via digital signals to the storage chip 60. The microcontroller 50 can also send each temperature data point transmitted to the Bluetooth chip 40 to the storage chip 60 for local storage backup.

[0048] Specifically, the microcontroller unit 50 is configured to: receive status signals transmitted by the Bluetooth chip 40, the status signals including a first status signal indicating that the Bluetooth chip 40 has successfully connected or a second status signal indicating that the Bluetooth chip 40 has failed to connect; when the status signal is the second status signal, transmit the temperature data to the storage chip 60; when the status signal is the first status signal, transmit the temperature data stored in the storage chip 60 to the Bluetooth chip 40.

[0049] In other words, the Bluetooth chip 40 also sends its own status signal to the microcontroller unit 50. This status signal indicates whether the Bluetooth chip 40's wireless connection was successful or failed. When the status signal is the first status signal, it means the Bluetooth chip 40 has successfully uploaded the temperature data to the gateway. When the status signal is the second status signal, it means the Bluetooth chip 40 was unable to upload the temperature data to the gateway. Furthermore, when the microcontroller unit 50 receives the second status signal, it means the Bluetooth chip 40's upload failed. At this point, the temperature data is transmitted to the storage chip 60 for storage. When the microcontroller unit 50 receives the first status signal again, it means the Bluetooth chip 40 has successfully connected to the gateway, and can then transmit the temperature data stored in the storage chip 60 (when the upload failed) to the Bluetooth chip 40, enabling the Bluetooth chip 40 to transmit the temperature data to the gateway.

[0050] Therefore, the microcontroller unit 50 can send all temperature data to both the Bluetooth chip 40 and the storage chip 60, or it can choose to send only the temperature data that failed to upload via the Bluetooth chip 40 to the storage chip 60 for storage. In this way, the storage chip 60 can store all the temperature data, or only cache the temperature data that failed to upload.

[0051] In other words, when the microcontroller unit 50 receives temperature data, it uploads the temperature data to the Bluetooth chip 40 and the storage chip 60. If the Bluetooth chip 40 sends a first status signal to the microcontroller unit 50, the microcontroller unit 50 knows that the Bluetooth chip 40 has successfully uploaded the temperature data to the gateway. If the Bluetooth chip 40 sends a second status signal to the microcontroller unit 50, the microcontroller unit 50 knows that the Bluetooth chip 40 failed to upload the temperature data. The microcontroller unit 50 records the temperature data identifier that was last sent to the storage chip 60. Thus, when the microcontroller unit 50 receives the first status signal again, it retrieves the temperature data corresponding to the temperature data identifier from the storage chip 60 and sends this temperature data to the Bluetooth chip 40.

[0052] Alternatively, when the microcontroller unit 50 receives temperature data, it only uploads the temperature data to the Bluetooth chip 40. If the Bluetooth chip 40 sends a first status signal to the microcontroller unit 50, the microcontroller unit 50 knows that the Bluetooth chip 40 has successfully uploaded the temperature data to the gateway and therefore does not transmit the temperature data to the storage chip 60. If the Bluetooth chip 40 sends a second status signal to the microcontroller unit 50, then the microcontroller unit 50 transmits the temperature data to the storage chip 60. When the microcontroller unit 50 receives the first status signal again, it retrieves all the temperature data cached in the storage chip 60 and sends them to the Bluetooth chip 40 sequentially. The storage chip 60 can periodically delete the cached temperature data, or it can clear the storage chip 60 after the microcontroller unit 50 retrieves the temperature data from it.

[0053] Furthermore, this application enables seamless switching between real-time transmission and breakpoint resume of temperature data, fundamentally solving the problem of data loss during wireless transmission in complex industrial environments and ensuring the integrity of the data link.

[0054] As an example, the miniature wireless temperature measurement device of this application is woken up at preset intervals (such as every 1 second or every 10 seconds). After measuring the temperature, it prioritizes sending data packets to a nearby gateway or smart terminal via Bluetooth chip. This mode provides a real-time data stream.

[0055] Storage protection mode: The miniature wireless temperature measuring device of this application will no longer attempt to transmit the measured data, but will write it into the local storage chip in real time.

[0056] Data Resume Mode: When the wireless connection is restored (e.g., when the cabinet door is opened and signal strength is restored), the microcontroller unit will detect this change and automatically read the temporarily stored historical data from the storage chip, retransmitting it to the gateway in chronological order to complete the data resume transmission. After completion, the corresponding buffer area will be cleared.

[0057] As stated above, this application perfectly solves the pain points of signal instability and intermittent interruptions that wireless transmission may face in complex industrial environments. It retains all the convenience of wireless technology while adding an extra layer of "safety" to ensure the integrity of the temperature data link, which is crucial for applications such as fault diagnosis and prediction based on big data.

[0058] As an example, the microcontroller unit 50 of this application employs an ultra-low-power microcontroller (MCU) with a built-in high-precision ADC (24-bit). This MCU is responsible for controlling the entire unit's workflow, signal acquisition, data processing, and algorithm execution. The Bluetooth chip 40 uses a low-power Bluetooth system-on-chip (SoC) supporting the BLE 5.0 protocol. BLE 5.0 achieves an optimal balance between power consumption, transmission rate, and distance (theoretically exceeding 15m), making it ideal for short-range wireless data transmission in industrial environments. Power is provided by a rechargeable micro-pouch battery, coupled with a high-efficiency power management chip (PMIC) for voltage conversion and power management.

[0059] The interior of the casing 90 of this application is formed into a miniature space of 22*22*11mm³. To achieve the ultra-small size of 22*22*11mm³, this application adopts a 0402 / 0201 micro-component layout, using a large number of passive components (resistors, capacitors, inductors) in 0402 (1.0mm x 0.5mm) or even smaller 0201 (0.6mm x 0.3mm) packages for high-density layout; at the same time, it makes full use of the Z-axis space of the circuit board 100, and realizes vertical connection between different signal layers through blind vias and buried vias, which greatly saves horizontal wiring space.

[0060] This application adopts a three-dimensional integrated heterogeneous design to carry out a multi-layer stacked circuit board 100 design (FR4 substrate, layer thickness 0.8mm). Through 0402 micro component layout optimization and vertical interconnection technology, the four major modules of sensing, processing, communication and storage are integrated into a micro space of 22*22*11mm³.

[0061] This highly integrated design allows a complete, fully functional temperature measurement system to be encapsulated within a tiny 22*22*11mm³ housing. It can be easily glued, embedded, or fixed in narrow spaces such as slits, achieving true in-situ, embedded measurement. This eliminates external wiring and bulky main unit, resolving deployment challenges and safety hazards.

[0062] As an example, the housing 90 of this application is made of high-temperature resistant, highly insulating, and thermally conductive engineering plastic (PMMA), which ensures electrical safety while allowing heat to be transferred to the interior.

[0063] In addition, such as Figures 7 to 9 As shown, the temperature sensor and microcontroller unit 50 of this application are respectively arranged on the front and back sides of the circuit board 100. Along the thickness direction of the circuit board 100, the temperature sensor and microcontroller unit 50 have no overlapping area. That is, this application adopts a thermal isolation design; the internal layout of the housing 90 has been optimized through thermal simulation, placing heat-generating components (such as the microcontroller unit 50) in an area far away from the thermistor 10. Simultaneously, the thermal resistance path between the heat source and the thermistor 10 is increased as much as possible structurally. Furthermore, this application strictly selects low-power, low-heat-generating chips and optimizes the operating rhythm in software to minimize its own heat generation. The constant current source 70, differential amplifier 20, filter module 30, and analog-to-digital converter 80 can be integrated onto a single ADC chip. The ADC chip can be arranged on the back side of the circuit board 100, near the microcontroller unit 50, but is not shown in the figure.

[0064] This design ensures that the thermistor 10 primarily senses heat from the external object being measured, rather than the self-heating of the chip inside the unit, greatly reducing thermal crosstalk. This is a key mechanical structural innovation for achieving high-precision measurement.

[0065] Furthermore, the present application provides multiple miniature wireless temperature measuring devices, which are arranged at multiple contact positions in a switch cabinet, or at multiple cell gap positions in a battery pack, or at multiple bearing seats in mechanical equipment.

[0066] This setup, as in existing technologies, represents single-point wired measurement. This application achieves wireless connectivity and allows for easy network formation. It integrates BLE 5.0 wireless communication and local storage capabilities, enabling a single Bluetooth gateway to easily receive data from dozens of such temperature measurement units. Users can flexibly deploy multiple miniature wireless temperature measurement devices within the device, constructing a high-density temperature monitoring network to map the internal temperature distribution of the equipment, providing unprecedentedly rich data for thermal management and fault early warning. Wireless connectivity makes this multi-array deployment extremely simple and low-cost.

[0067] The calibration method of this application includes: S1 Level 1 Calibration, Probe-Level Calibration: Independent calibration is performed on unconnected temperature sensors (thermometers) in a high-precision thermostat bath. A batch of unconnected temperature sensors (thermometers) and standard thermometers (second-class standard platinum resistance thermometers) are placed together. Multiple points (no fewer than 7) are selected within the target temperature range (e.g., 18°C ​​to 40°C) for thorough temperature maintenance and measurement. The resistance value R of each sensor at each temperature point is recorded, and the RT correlation is obtained, i.e., the RT characteristic parameters (Steinhart-Hart equation coefficients). This step ensures the accuracy of the temperature sensing source and establishes a reliable absolute benchmark for subsequent calibration.

[0068] Improvement effect: It eliminates the manufacturing discreteness error of the temperature sensor (probe) itself from the source, and provides a known and accurate sensor model for subsequent system-level assembly calibration.

[0069] S2 second-level calibration, system-level combined calibration (ensuring consistency and eliminating system errors).

[0070] Based on the first-level calibration, S21 inserts the welded miniature wireless temperature measuring devices (4 or 16 per group) into the water bath chamber inside a specially designed array calibration fixture 200. Then, the array calibration fixture 200 is placed in a high-precision environmental test chamber, which provides a stable and uniform temperature field. Simultaneously, temperature maintenance is performed at multiple temperature points, and the following processes are also conducted: Reference measurement: Use a calibrated precision thermometer (such as Fluke 1529) with a standard platinum resistance thermometer to accurately monitor the true temperature T_standard of the water bath chamber in real time.

[0071] S22 Output Acquisition: Simultaneously reads the raw output value T_raw (i.e., the uncompensated temperature calculated by the microcontroller unit based on the first-level RT relationship) of all tested miniature wireless temperature measuring devices via wireless or wired means. For example, it reads the raw temperature reading T_raw output by the microcontroller unit through the Bluetooth chip interface. Here, T_raw is the voltage value read by the microcontroller unit through the ADC chip and the result calculated in conjunction with the RT meter.

[0072] S23 Data Processing and Compensation: For each miniature wireless temperature measuring device, calculate its systematic error ΔT = T_raw - T_standard at each temperature point, and establish a function model ΔT = f(T_raw) for each miniature wireless temperature measuring device, with T_raw as the independent variable and the compensation value ΔT as the dependent variable. Write the function model ΔT = f(T_raw) into the microcontroller unit (preferably, ΔT = aT_raw² + bT_raw + c). This model incorporates the unique temperature drift characteristics introduced by all internal circuits (ADC, MCU, etc.) of the miniature wireless temperature measuring device. Write the parameters a, b, and c of this model into the microcontroller unit of the miniature wireless temperature measuring device.

[0073] When S24 performs core compensation, it substitutes T_raw into the model function f(T_raw) to calculate the system error compensation value ΔT corresponding to the current temperature point, and then finally outputs T_final=T_raw–ΔT.

[0074] Improvements: ① Elimination of system errors: The compensation model directly corrects the internal errors of each miniature wireless temperature measuring device, improving accuracy from the "probe level" to the "system level". ② Ensuring consistency: By synchronously calibrating a group of miniature wireless temperature measuring devices, the differences between each device can be accurately quantified, and independent compensation algorithms ensure that the outputs of all devices are consistent, greatly improving the consistency level of batch products.

[0075] S3 simulation environment verification and calibration (ensuring operational reliability).

[0076] The miniature wireless temperature measurement device, after system-level calibration, is installed in an environmental simulation test chamber that simulates actual working conditions (such as a chamber simulating a switchgear structure, containing conductors, insulators, and a current-carrying chamber that generates Joule heating). Realistic environmental conditions, including temperature gradients, airflow, and electromagnetic interference, are created within the chamber. The output of the miniature wireless temperature measurement device is then compared with the readings of a standard thermometer placed within the environmental simulation test chamber for final verification and fine-tuning, ultimately outputting T_final+d.

[0077] Improvement results: Verifying the performance of the miniature wireless temperature measurement device in real-world application environments ensures the effectiveness of the first two calibration results under complex actual conditions, greatly improving the reliability of the final product.

[0078] It is also worth mentioning that existing calibration typically uses a universal fixture to fix one miniature wireless temperature measuring device at a time, which cannot achieve synchronous and isothermal comparison calibration of multiple miniature wireless temperature measuring devices.

[0079] In view of this, a second aspect of this application provides an array calibration fixture 200, which is applied to the calibration method described above.

[0080] like Figures 2 to 5 As shown, the array calibration fixture 200 of this application includes a base 201, a top cover 202, and a standard thermometer 203. The base 201 is a substrate made of a high thermal conductivity metal and precision-machined. The top cover 202 is sealed to the base 201 to form a water bath chamber. The array calibration fixture 200 integrates mounting holes for the standard thermometer 203 (such as NTC or PT1000), the positions of which have been optimized through thermal simulation to accurately reflect the overall temperature of the fixture.

[0081] like Figure 3 As shown, the base 201 is provided with 16 mounting slots for fixing the miniature wireless temperature measuring device 1, which are used to embed the miniature wireless temperature measuring device 1. The 16 slots for fixing the miniature wireless temperature measuring device 1 are arranged in a matrix.

[0082] like Figure 5 As shown, the base 201 is provided with 4 mounting slots for fixing the miniature wireless temperature measuring device 1, which are used to embed the miniature wireless temperature measuring device 1. The 4 slots are arranged at intervals along the same direction for the miniature wireless temperature measuring device 1.

[0083] The array calibration fixture 200 of this application is designed to ensure that all mounting slots have excellent thermal balance and consistency, and when placed in a temperature field, it can ensure that all calibrated miniature wireless temperature measuring devices are at the same highly consistent temperature.

[0084] Improvement effect: This tooling enables parallel, synchronous, and isothermal calibration of multiple miniature wireless temperature measurement devices, greatly improving calibration efficiency (4 times or 16 times higher). More importantly, it provides a crucial and fair comparison platform for consistency between evaluation and correction units in the second-level calibration, which is the physical basis for achieving high consistency.

[0085] In summary, this application calibrates the entire miniature wireless temperature measurement device as a complete measuring instrument. The compensation model directly corrects the internal errors of each miniature wireless temperature measurement device, thereby improving the temperature measurement accuracy to the mK level, meeting the extreme requirements of scientific research and high-end industrial monitoring. Furthermore, by simultaneously calibrating multiple miniature wireless temperature measurement devices, calibration efficiency is greatly improved. More importantly, in system-level combined calibration, the differences between individual miniature wireless temperature measurement devices can be accurately quantified, and independent compensation algorithms can make the outputs of all miniature wireless temperature measurement devices tend to be consistent, greatly improving the consistency level of batch products.

[0086] like Figure 10 As shown, Channel 1 (orange curve) represents real-time data collected by the miniature wireless temperature measuring device, while Channel 2 (blue curve) represents real-time data collected by the reference resistor. After two hours of continuous data collection, the temperature curves remained largely consistent, with the maximum temperature difference being less than 3 mK.

[0087] In summary, this application has the following advantages: (1) Improved temperature measurement accuracy: Through three-level calibration and dynamic compensation, the system accuracy of the miniature wireless temperature measurement device is improved from the traditional ±0.1~0.5°C to the metrological level of ±0.005°C (±5mK), which meets the most demanding application requirements.

[0088] (2) Improved deployment convenience of this application: The miniaturized, wireless, and integrated design makes the deployment of the miniature wireless temperature measurement device as simple as "sticking on a stamp". Several or even dozens of measurement points can be quickly and flexibly deployed inside the device to build a high-density temperature sensing network without having to consider wiring issues.

[0089] (3) The reliability of the system in this application is enhanced: the fault links such as wires and their connection points are eliminated; the dual-mode data protection mechanism ensures that the data is never lost; the overall packaging design improves the ability to resist vibration and impact.

[0090] (4) The overall cost of this application is reduced: Although the cost of a single miniature wireless temperature measurement device is high, it eliminates the expensive multi-channel data acquisition unit, a large number of cables and construction costs. In multi-point measurement applications, the total cost of ownership over the entire life cycle may be significantly reduced.

[0091] (5) Significantly improved consistency: Based on the system-level calibration of the array calibration fixture 200, the output deviation of the same batch of miniature wireless temperature measuring devices under the same temperature field is extremely low, and the consistency is greatly improved, laying the foundation for building a highly reliable distributed temperature measuring network.

[0092] (6) Enhanced reliability: The third-level operating condition simulation calibration ensures the performance of the product in the actual environment, eliminates the industry pain point of "good laboratory data, but off-target field data", and greatly improves the field reliability of the product.

[0093] Finally, it should be noted that the above-described embodiments are merely specific implementations of this application, used to illustrate the technical solutions of this application, and not to limit them. The protection scope of this application is not limited thereto. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the scope of the technology disclosed in this application, or make equivalent substitutions for some of the technical features. Such modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be covered within the protection scope of this application.

Claims

1. A calibration method based on a miniature wireless temperature measuring device, characterized in that, The miniature wireless temperature measurement device includes a housing and a temperature sensor, an ADC chip, and a microcontroller unit encapsulated inside the housing. The ADC chip converts the analog signal corresponding to the ambient temperature collected by the temperature sensor into a digital signal and transmits the digital signal to the microcontroller unit, which then converts the digital signal into temperature data. The calibration method includes: Probe-level calibration: The temperature sensor that has not yet been connected is calibrated to obtain the RT comparison relationship, and the RT comparison relationship is written into the microcontroller unit. System-level combined calibration: Multiple connected miniature wireless temperature measuring devices are placed in a water bath chamber inside the array calibration fixture, and kept warm at multiple temperature points. The true temperature T_standard of the water bath chamber is monitored in real time using a standard thermometer. Read the raw temperature reading T_raw output by the microcontroller, where T_raw is the voltage value read by the microcontroller through the ADC chip and the result calculated by combining it with the RT meter; Calculate the system error ΔT=T_raw-T_standard for each miniature wireless temperature measuring device at each temperature point, and establish a function model ΔT=f(T_raw) with T_raw as the independent variable and the compensation value ΔT as the dependent variable for each miniature wireless temperature measuring device, and write the function model ΔT=f(T_raw) into the microcontroller unit; When performing core compensation, T_raw is substituted into the model function f(T_raw) to calculate the system error compensation value ΔT corresponding to the current temperature point. The final output is T_final = T_raw – ΔT.

2. The calibration method based on a miniature wireless temperature measuring device according to claim 1, characterized in that, In the probe-level calibration step, the temperature sensor and standard thermometer, which are not yet connected, are placed together in a metrology-grade constant temperature bath and kept at multiple temperature points. The resistance value R of the temperature sensor at each temperature point is recorded, and the RT comparison relationship is obtained.

3. The calibration method based on a miniature wireless temperature measuring device according to claim 1, characterized in that, In the system-level combinatorial calibration step, the function model is ΔT = aT_raw² + bT_raw + c.

4. The calibration method based on a miniature wireless temperature measuring device according to claim 1, characterized in that, In the system-level combined calibration step, after placing multiple connected miniature wireless temperature measuring devices into the water bath chamber inside the array calibration fixture, the array calibration fixture is placed in a high-precision environmental test chamber, which can provide a stable and uniform temperature field.

5. The calibration method based on a miniature wireless temperature measuring device according to claim 1, characterized in that, The calibration method further includes: Simulated environment verification and calibration: The miniature wireless temperature measuring device, after system-level combined calibration, is installed in an environmental simulation test chamber that simulates actual working conditions. The output of the miniature wireless temperature measuring device is compared with the reading of the standard thermometer arranged in the environmental simulation test chamber for final verification and fine-tuning. The final output is T_final+d.

6. The calibration method based on a miniature wireless temperature measuring device according to claim 1, characterized in that, The miniature wireless temperature measuring device also includes a Bluetooth chip encapsulated inside the housing. The microcontroller converts the digital signal into temperature data and sends it to the Bluetooth chip, so that the Bluetooth chip can wirelessly transmit the temperature data. In the system-level integrated calibration step, the raw temperature reading T_raw output by the microcontroller unit is read through the interface of the Bluetooth chip.

7. The calibration method based on a miniature wireless temperature measuring device according to claim 6, characterized in that, The miniature wireless temperature measurement device also includes a circuit board; The temperature sensor, the ADC chip, the microcontroller unit, and the Bluetooth chip are all integrated on the circuit board; The temperature sensor includes a thermistor and a metal column; The first end of the metal pillar passes through the housing and is exposed outside the housing; the thermistor is encapsulated inside the metal pillar to achieve thermal coupling with the end of the metal pillar.

8. The calibration method based on a miniature wireless temperature measuring device according to claim 7, characterized in that, The temperature sensor and the microcontroller unit are respectively arranged on the front and back sides of the circuit board; along the thickness direction of the circuit board, the temperature sensor and the microcontroller unit have no overlapping area.

9. An array calibration fixture, characterized in that, The calibration method applicable to any one of claims 1-8; The array calibration fixture includes a base, a top cover, and a standard thermometer; The upper cover is sealed to the base to form the water bath cavity; The base is provided with multiple mounting slots for fixing the miniature wireless temperature measuring device, and the base is provided with mounting holes for fixing the standard thermometer.

10. The array calibration fixture according to claim 9, characterized in that, There are four mounting slots, arranged at intervals along the same direction; Alternatively, there are 16 mounting slots arranged in a matrix.

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