An in-situ composite calibration method to improve the accuracy of spacecraft on-orbit temperature measurement system

Abstract

The present invention discloses an in-situ composite calibration method for improving the accuracy of a spacecraft's on-orbit temperature measurement system, comprising: screening the consistency of temperature sensors to be carried on the spacecraft; arranging a reference temperature source on the spacecraft; performing absolute calibration on the temperature sensor and its temperature measurement circuit in the on-board reference temperature source; designing a standard resistor on the satellite and performing precise temperature control on the standard resistor to prevent its temperature drift; measuring the resistance value of the standard resistor in each temperature measurement channel, calibrating the measurement deviation of each channel, and achieving absolute calibration of the measurement deviation and consistency of each channel; utilizing the drift characteristics of the temperature sensor in the reference temperature source to perform relative calibration on the remaining temperature sensors on the satellite. The present invention solves the problem that the deviation of on-orbit temperature measurement of a spacecraft gradually increases over time, thereby ensuring the accuracy and consistency of the temperature measurement system during the long life cycle of the spacecraft; and timely discovering and diagnosing abnormally drifting sensors on the satellite through cross-calibration between similar sensors.

Description

Technical Field

[0001] The present invention relates to the technical field of calibration of temperature measurement circuits and temperature measurement sensors during the on-orbit operation of a spacecraft, and in particular to an in-situ composite calibration method for improving the accuracy of an on-orbit temperature measurement system of a spacecraft. Background Art

[0002] With the continuous development of aerospace technology, the requirements for the stability and reliability of various spacecraft systems are becoming increasingly higher. Among them, the temperature measurement system is a key component, and its accuracy and reliability are directly related to the safe operation of the spacecraft.

[0003] In the industrial field, traditional temperature measurement calibration techniques typically rely on calibrated high-precision temperature sensors to indirectly calibrate the target temperature sensor. However, this indirect calibration method is prone to the accumulation of multiple errors in practical applications. This accumulation of errors can seriously affect the accuracy and reliability of temperature measurements, especially in complex spacecraft temperature measurement systems.

[0004] To overcome the limitations of indirect calibration, existing technologies have proposed methods for directly calibrating temperature sensors using a reference temperature source. However, when a spacecraft is in orbit, temperature sensors are distributed in various key locations, and these locations are often difficult to directly access ground-based calibration equipment. Therefore, it is not possible to adopt ground-based calibration (i.e., regular calibration by operation and maintenance personnel by placing the temperature sensor to be measured in a reference temperature source) to compare each temperature sensor with the reference source one by one. This limitation makes the direct calibration method proposed in the existing technology unable to meet the special needs of on-orbit calibration of spacecraft temperature measurement systems.

[0005] In summary, existing calibration methods for temperature sensors and temperature measurement circuits are relatively simple, relying primarily on higher-precision temperature sensors or temperature reference sources obtained through precise temperature control. Alternatively, they require operators to place the temperature sensor under test within a reference temperature source for calibration, which is limited by the operator's expertise and operational experience. Therefore, this method, which relies on high-precision equipment and specialized personnel, is clearly impractical in the on-orbit environment of a spacecraft. Summary of the Invention

[0006] In view of this, the present invention proposes an in-situ composite calibration method for improving the accuracy of the spacecraft's on-orbit temperature measurement system, so as to solve the problems commonly faced in the existing technology of spacecraft temperature measurement system calibration, such as the accumulation of indirect calibration errors, the impracticability of direct calibration, and the limited temperature measurement calibration due to high dependence on calibration resources.

[0007] The specific technical solutions of the present invention are as follows:

[0008] An in-situ composite calibration method for improving the accuracy of a spacecraft on-orbit temperature measurement system is characterized by comprising the following steps:

[0009] Step 1: During the ground phase, the temperature sensors to be carried on the spacecraft are screened for consistency. The consistency of their raw materials, production, and packaging processes is strictly controlled. Resistor groups with the same drift coefficients are selected to obtain temperature sensors with relatively consistent long-term resistance drift patterns.

[0010] Step 2: Arrange a reference temperature source on the spacecraft. The reference temperature source includes an active temperature control device, a packaging shell, a thermal insulation layer, a temperature sensor, a support structure, and temperature fixed point materials.

[0011] Step 3: Perform absolute calibration on the temperature sensor and its temperature measurement circuit in the onboard reference temperature source. The resistance deviation of the temperature sensor and the measurement circuit output is determined by the deviation between the fixed point temperature of the reference temperature source and the measured value of its internal temperature sensor.

[0012] Step 4: Design a standard resistor onboard the satellite and precisely control its temperature to prevent temperature drift. By switching the switch, each temperature measurement channel measures the resistance of the standard resistor to calibrate the measurement deviation of each channel, thus achieving absolute calibration of the measurement deviation and consistency of each channel.

[0013] Step 5: Based on the temperature measurement system deviation value obtained in step 3 minus the measurement circuit deviation value obtained in step 4, the drift characteristics of the temperature sensor in the reference temperature source are obtained, and the drift characteristics of at least one temperature sensor in the reference temperature source are used to perform relative calibration on the remaining temperature sensors on the satellite;

[0014] Step 6: If an abnormal drift is found in a temperature sensor on the satellite, resulting in a deviation in the measurement results, the temperature measurement results are cross-checked using temperature sensors arranged in similar positions or the same area, through heat transfer relationship calculation or temperature field reconstruction, to check and eliminate abnormal data.

[0015] Specifically, in step 1, the reference temperature source uses the phase transition temperature fixed point of a metal or non-metallic pure substance as the reference point for temperature calibration, including but not limited to the triple point of water, the melting point of gallium, and the eutectic phase transition temperature point of a gallium-based alloy.

[0016] Specifically, step 5 includes: first, determining the on-orbit drift pattern of sensors in the same batch through the average measurement results of the temperature drift of the temperature sensors in the reference temperature source, and then performing relative calibration on the remaining temperature sensors on the satellite based on this.

[0017] Specifically, in step 2, the reference temperature source is precisely temperature-controlled by an active heater and a semiconductor cooler to ensure that the temperature in the reference temperature source remains at a temperature plateau.

[0018] Specifically, in step 3, the temperature sensor and measurement circuit in the reference temperature source are calibrated by calculating their resistance deviation, and the resistance deviation is obtained based on the temperature-resistance function relationship of the temperature sensor and the deviation of the temperature measurement result from the reference temperature of the standard temperature source.

[0019] Specifically, in step 4, the resistance of the standard resistor remains almost unchanged during the calibration process. By comparing the resistance measured by each temperature measurement channel with the resistance of the standard resistor, the measured resistance deviation of each channel is calculated, thereby achieving absolute calibration of the measurement deviation and consistency of each channel.

[0020] Specifically, in step 4, during the calibration process, switch switching technology is used to achieve uninterrupted switching between channels to ensure that the calibration process does not interrupt the temperature monitoring of the target being measured.

[0021] Specifically, step 5 includes: obtaining the on-orbit drift law, after the spacecraft enters the predetermined orbit, continuously monitoring the changes in the temperature measurement results of the temperature sensor in the reference temperature source, inversely calculating and regularly recording the resistance value through the temperature-resistance function relationship, subtracting the absolute deviation of the measurement circuit, obtaining the drift amount of the temperature sensor in the reference temperature source, and obtaining the drift law of the same batch of sensors operating on orbit.

[0022] Specifically, in step 5, the relative calibration step includes: correcting the resistance drift of the temperature sensor outside the on-board reference temperature source according to the on-orbit drift law of the temperature sensor in the reference temperature source, and calculating the true resistance value of the on-board sensor during on-orbit operation.

[0023] The beneficial effects of the present invention are:

[0024] 1. Establishment of an absolute temperature reference: Using the measurement results of the temperature sensor within the temperature reference source, the deviations of the on-orbit temperature sensor and measurement circuit are absolutely calibrated to ensure that the spacecraft can obtain an accurate absolute temperature reference when operating on-orbit, thus solving the problem of the spacecraft's on-orbit absolute temperature reference.

[0025] 2. Compensation for measurement circuit deviation: The measurement results of the standard resistors in each measurement channel are used to perform absolute calibration of the measurement circuit, effectively compensating for the deviation of the spacecraft's on-orbit measurement circuit and improving the accuracy and stability of the measurement circuit.

[0026] 3. Optimization of distributed sensor calibration: Based on the consistency characteristics of sensors screened on the ground, the present invention uses the drift value of the temperature sensor in the reference source to calibrate other temperature sensors on the satellite, solving the calibration problem of distributed sensors on the satellite and ensuring the accuracy and consistency of the measurement results between sensors.

[0027] 4. Diagnosis of abnormal drift sensors: Through cross-calibration between nearby sensors, the present invention can promptly detect and diagnose abnormal drift sensors on the satellite, thereby improving the reliability and maintainability of the temperature measurement system.

[0028] 5. Formation of an in-situ composite calibration system: The combination of the aforementioned absolute, relative, and cross-calibration methods forms a complete in-situ composite calibration system. This system significantly improves the accuracy of spacecraft temperature measurement systems over their long on-orbit lifecycle, effectively addressing the issue of increasing on-orbit temperature measurement deviations over time.

[0029] In summary, the in-situ composite calibration method for the on-orbit temperature measurement system proposed in the present invention not only improves the accuracy and consistency of the spacecraft temperature measurement system, but also enhances the reliability and maintainability of the system by optimizing the calibration of distributed sensors and the diagnosis of abnormal sensors, providing a strong technical guarantee for the long-term stable operation of the spacecraft. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments or descriptions of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0031] Figure 1 A simple schematic diagram of the in-situ composite calibration method for improving the accuracy of the spacecraft on-orbit temperature measurement system in the present invention;

[0032] Figure 2 Schematic diagram of the structure of the reference temperature source in the present invention;

[0033] Figure 3 It is a simple schematic diagram of the absolute calibration method of the standard resistor in the present invention. DETAILED DESCRIPTION

[0034] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0035] Spacecraft typically use resistance-based temperature measurement, using temperature sensors such as thermistors and platinum resistors to measure temperature. During a spacecraft's on-orbit lifecycle, which can span years or even decades, thermistors, as core components of the temperature measurement system, can experience significant performance impacts from ambient temperature fluctuations. This impact is primarily manifested in the thermistor's zero-point instability: its resistance at zero degrees (or a certain reference temperature) can drift over time and temperature. Furthermore, the temperature measurement channel, a crucial bridge connecting the temperature sensor and the measurement circuit, can also suffer from inherent physical properties and environmental factors that can lead to deviations in measurement results.

[0036] To address this issue, we face the following challenges:

[0037] 1. Since temperature sensors are located in various key locations on spacecraft, such as the engine compartment, solar panels, and thermal insulation layers, they are numerous and widely distributed, making it impossible to compare them one by one with the reference source, thus limiting the applicability of traditional calibration methods.

[0038] 2. The temperature measurement circuit’s measurement deviation lacks a unified benchmark for calibration. This means that there may be differences in accuracy between different measurement circuits, thus affecting the accuracy of the entire temperature measurement system.

[0039] 3. Temperature sensor drift is uncertain. During spacecraft operation, sensor performance may change due to environmental factors, material aging, and other factors, leading to deviations in measurement results. However, the lack of effective means to identify and calibrate this abnormal drift makes the problem difficult to resolve.

[0040] To address these issues, this paper proposes an in-situ composite calibration method to improve the accuracy of spacecraft on-orbit temperature measurement systems. This method combines absolute calibration of a reference source, relative calibration between temperature sensors, and cross-calibration of temperature measurement channels, aiming to enhance the accuracy and reliability of the temperature measurement system.

[0041] The principle of the temperature measurement system is to obtain and output the resistance value of the temperature sensor at the temperature to be measured through the measurement circuit. From the hardware perspective, the system can be divided into two parts: the temperature sensor and the measurement circuit. The drift of the sensor resistance and the measurement circuit accuracy can introduce deviations in the output resistance value, as shown in the following formula.

[0042] ΔE s =R output -R true =ΔE R +ΔE c (1)

[0043] Where, ΔE s is the total deviation of the output resistance signal of the temperature measurement system, Routput is the output resistance value of the measurement system, R true is the true value of resistance corresponding to the actual temperature to be measured, ΔE R is the deviation caused by the resistance drift of the thermistor sensor, ΔE c The measurement deviation is caused by the drift of the measurement circuit accuracy.

[0044] like Figure 1 As shown, the method of the present invention comprises the following steps:

[0045] Step 1: Absolute calibration of the reference temperature source: First, start the reference temperature source and wait for it to reach a stable state. Then, use precision measuring equipment to continuously and accurately measure the output of the temperature sensor and temperature measurement circuit in the reference temperature source to obtain the ΔE of the temperature measurement link in the reference source. s Through this process, the accuracy of the temperature measurement link within the reference source can be established, providing a benchmark for subsequent calibration.

[0046] Step 2: Absolute calibration of standard resistors: Connect a standard resistor of known value to the measurement circuit and record the voltage or current signal output by the measurement circuit. Use signal processing algorithms to calculate the deviation between the actual output and the theoretical output, thereby obtaining the measurement deviation ΔE of each measurement circuit. R This process ensures the precision and accuracy of the measurement circuit.

[0047] Step 3: Relative calibration of temperature sensors: Based on the strict control and screening of the ground production process, it is believed that the on-board temperature sensors have extremely high consistency. The on-orbit drift of the temperature sensor in the reference source is used as a reference to obtain the resistance drift deviation ΔE of other temperature measurement sensors outside the on-board reference source. R ′.

[0048] Step 4, cross-calibration of temperature measurement channels: By comparing the measurement data between adjacent temperature sensors on board and the data between different measurement channels, the accuracy of the measurement results is verified and potential error sources are identified. Based on the results of the cross-calibration, the deviation ΔE of the actual measurement values ​​of different temperature sensors on orbit is obtained. R ”, it can eliminate temperature sensors that have abnormal drift on orbit and ensure the accuracy and reliability of the entire temperature measurement system.

[0049] To facilitate tracking and managing the status and performance of each temperature sensor, the present invention numbers the temperature sensors and measurement circuits within the reference temperature source as 1, 2, ..., j, ..., N (where j specifically refers to the sensor and circuit within the reference temperature source). All temperature sensors onboard the satellite are numbered 1, 2, ..., i, ..., n (where i represents the number of the temperature sensor onboard).

[0050] The steps involved in the method of the present invention are specifically as follows:

[0051] Step 1: Perform absolute calibration on the temperature sensor and its temperature measurement circuit in the onboard reference temperature source.

[0052] Step 1.1, set the reference temperature source.

[0053] (1) Select a suitable location on the spacecraft to place the reference temperature source. The reference temperature source is a specially designed device with the following structure: Figure 2 As shown, it usually includes active temperature control equipment, packaging shell, thermal insulation layer, temperature sensor, support structure and temperature fixed point material.

[0054] (2) Temperature fixed point materials are key components used to determine a series of known and stable temperature points, which are determined based on the phase transition temperatures of pure metals and non-metallic substances.

[0055] (3) The reference temperature source is based on the ITS-90 International Temperature Scale, which defines reference points and algorithms for temperature measurement. To provide accurate temperature reference points, the reference temperature source uses a series of fixed phase transition temperature points of pure metals and non-metallic substances as reference points for temperature calibration, such as the triple point of water, the melting point of gallium, and the eutectic phase transition temperature of gallium-based alloys.

[0056] Step 1.2, precise temperature control.

[0057] Active heaters and semiconductor coolers are used to precisely control the temperature of the reference temperature source. These devices can precisely adjust the heating and cooling power to ensure that the temperature inside the reference temperature source is stable within a very small range.

[0058] Step 1.3, temperature sensor measurement.

[0059] (1) Place at least one temperature sensor inside the reference temperature source to monitor the temperature of the reference temperature source in real time. This temperature sensor can be a thermistor, platinum resistance resistor, etc., depending on application requirements and design considerations.

[0060] (2) By calculating the fixed point temperature T of the reference temperature source r The deviation of the internal temperature sensor's measured value, T(i), (determined by the phase transition temperature) from the measured value, T(i), can be used to determine the temperature sensor's temperature drift during on-orbit operation. Temperature drift refers to the shift in the temperature sensor's measured value over time and changing environmental conditions.

[0061] ΔE T，j =T(j)-T r (2)

[0062] Where T(j) is the measured temperature of the jth temperature measurement channel in the reference temperature source (unit: K); ΔET，j is the temperature measurement deviation of the jth temperature sensor and the measurement circuit in the reference temperature source (unit: K); T r is the reference temperature of the standard temperature source (unit: K).

[0063] Step 1.4, obtain resistance deviation.

[0064] (1) Given the type of temperature sensor and the functional relationship between temperature and resistance, R(j) = f(T(j)), this functional relationship describes how temperature affects the resistance of the temperature sensor.

[0065] (2) Temperature measurement deviation ΔE obtained by absolute calibration of the reference temperature source T，j , combined with the temperature-resistance function relationship of the temperature sensor, through the error transfer principle, the resistance deviation ΔE of the temperature sensor and the measurement circuit at a given temperature can be calculated s , as shown below:

[0066]

[0067] (3) Resistance deviation reflects the difference between the resistance value of the temperature sensor and its measurement circuit in the reference temperature source at a specific temperature and the actual value.

[0068] Step 2: Perform absolute calibration on the measurement channel of the onboard temperature measurement circuit. Figure 3 shown.

[0069] Step 2.1, design standard resistor and control temperature.

[0070] (1) Design a standard resistor R on the satellite r , the resistance of this resistor is known and stable.

[0071] (2) To ensure that the resistance value of the standard resistor is not affected by temperature changes during the calibration process, it is necessary to precisely control its temperature. This is usually achieved through active heaters and temperature sensors to ensure that the temperature of the standard resistor is maintained at a constant level, thereby preventing temperature drift of the standard resistor.

[0072] Step 2.2, channel switching and measurement.

[0073] (1) During the calibration process, switch switching technology is used to enable each temperature measurement channel to be connected to the standard resistor in turn.

[0074] (2) When a temperature measurement channel is connected to a standard resistor, the channel will measure the resistance of the standard resistor and record the measured value. This process will be repeated until all temperature measurement channels have completed the resistance measurement of the standard resistor.

[0075] Step 2.3, calculate the measurement deviation.

[0076] The actual resistance value of the standard resistor is known. By comparing the resistance value measured by each temperature measurement channel with the actual resistance value of the standard resistor, the measured resistance deviation of each channel can be calculated, thereby achieving absolute calibration of the measurement deviation and consistency of each channel.

[0077] ΔE c，i =R(i)-R r (4)

[0078] Where R(i) is the measured resistance of the i-th temperature measurement channel on the satellite (unit: Ω); ΔE c，i is the measured resistance deviation of the i-th temperature measurement channel on the satellite (unit: Ω); R r is the resistance value of the standard resistor (unit: Ω).

[0079] Step 2.4, regular calibration and uninterrupted switching.

[0080] (1) According to the calibration requirements, each channel can be calibrated regularly with reference source and standard resistor. This helps to maintain the long-term stability and accuracy of the temperature measurement system.

[0081] (2) During the calibration process, switching technology is used to achieve uninterrupted switching between channels. This means that while one channel is being calibrated, the other channels can still operate normally, without interrupting the temperature monitoring of the target. After calibration is completed, each temperature measurement channel will be reconnected to the temperature measurement circuit of the target to perform normal temperature measurement.

[0082] Step 3: Perform relative calibration on the remaining temperature sensors on the satellite using the temperature sensor in the reference source.

[0083] Temperature sensor drift is a complex phenomenon, primarily influenced by two factors: zero-point instability caused by temperature fluctuations; and resistance drift caused by component aging during long-term on-orbit operation. Because temperature sensors are discretely mounted within a spacecraft, it is impossible to directly compare sensors external to a reference source with a temperature reference. To address this issue, this paper proposes a method for relative calibration of the remaining onboard temperature sensors based on the drift characteristics of the temperature sensor within the reference source.

[0084] Step 3.1, ground stage screening and consistency control.

[0085] (1) During the ground stage, the raw materials, production and packaging processes of the sensors are strictly controlled to ensure their consistency.

[0086] (2) Screening of sensors. For example, short-term high-temperature aging tests are conducted on NTC thermistors from the same batch to simulate the environmental conditions of on-orbit operation.

[0087] (3) The long-term drift characteristics of each thermistor are evaluated by formula (5), and resistor groups with the same drift coefficients a and b are selected. The temperature sensors in these resistor groups will have a more consistent long-term resistance drift law.

[0088]

[0089] Where R0 is the initial resistance value, R t is the resistance value at time t, t is the usage time of the thermistor, a is the intercept at t=1, and b is the slope of the resistance change per decade.

[0090] Step 3.2: Obtain the on-orbit drift law.

[0091] After the spacecraft enters its intended orbit, the resistance changes of the temperature sensors within the reference temperature source are continuously monitored. By regularly recording the resistance of these sensors and calculating their drift, the drift pattern of the same batch of sensors during on-orbit operation can be determined. This drift pattern will serve as a benchmark for subsequent relative calibration.

[0092] Step 3.3, relative calibration.

[0093] After obtaining the on-orbit drift law of the temperature sensor in the reference temperature source, the remaining temperature sensors on the satellite can be relatively calibrated.

[0094] First, it is necessary to obtain the total deviation of the temperature measurement link within the reference temperature source according to the absolute calibration of the reference temperature source in step 1, and obtain the measurement deviation of all temperature measurement circuits on the satellite according to the absolute calibration of the standard resistor in step 2.

[0095] These differences can then be corrected based on the on-orbit drift of the temperature sensor within the reference temperature source. In other words, by calculating the resistance difference between the onboard sensor and the reference sensor and combining it with the drift of the reference sensor, the true resistance of the onboard sensor during on-orbit operation can be inferred.

[0096] Specifically, the drift of the remaining sensors on the satellite is relatively calibrated by averaging the temperature drift measurements of N (N≥1) temperature sensors in the reference temperature source. The drift of each temperature sensor in the reference temperature source can be measured by the absolute calibration result ΔE of the measurement system. s，j Subtract the absolute calibration result ΔE of the measurement circuit c，j We can get the following formula:

[0097] ΔE R，j =ΔE s，j -ΔE c，j (6)

[0098] Under the condition that there is no abnormal drift in the reference temperature source, the drift pattern of the on-orbit sensors of the same batch is obtained by averaging the resistance drift of the temperature sensors in the reference source.

[0099]

[0100] Step 4: Cross-calibrate multiple temperature sensors.

[0101] When a temperature sensor on a satellite (assuming it is the i-th) experiences abnormal drift, causing its measurement results to deviate significantly from the normal value, in order to ensure the accuracy and reliability of the temperature measurement system, a cross-calibration method is needed to identify and correct this anomaly.

[0102] Cross-check process:

[0103] 1. Heat Transfer Relationship and Temperature Field Analysis: First, we conduct an in-depth analysis of the heat transfer relationship between on-orbit measurement point i and the remaining measurement points. These measurement points may be located in close proximity or within the same region, and the heat transfer relationship between them can be determined through theoretical calculations or simulations. Based on these relationships, we construct a temperature field model that describes the theoretical functional relationship between the temperature values ​​at each measurement point.

[0104] 2. Comparison of actual measured values ​​with theoretical values: Compare the actual measured value at measurement point i on track with the theoretical value obtained based on the temperature field model. If the actual measured value is far outside the theoretically predicted deviation range, it means that the sensor at measurement point i may have abnormal drift.

[0105] 3. Abnormal data processing: Once abnormal drift is found at measurement point i, the data from that point will be immediately removed from subsequent measurements to avoid its impact on the overall temperature measurement system. At the same time, this abnormality will be recorded and further investigated and analyzed.

[0106] Specifically, temperature sensors placed in similar locations or in the same area can be used to perform cross-checks on the temperature measurement results through simple heat transfer relationship calculations or precise temperature field reconstruction, to identify abnormal sensor locations and calibrate the measurement results. For example, by analyzing the heat transfer relationship between the on-orbit measurement point i and the remaining measurement points, the theoretical functional relationship T(i) between the temperature values ​​can be obtained. * =f(T1, T2, ..., T n ), and compare it with the actual measurement value T(i) of the i measuring point

[0107] ΔE″ R =T(i)-T(i) * =T(i)-f(T1,T2,…,T n ) (8)

[0108] If ΔE″R When the deviation far exceeds the prediction of the thermal model, it is considered that the i measurement point has an abnormal drift, and the abnormal data is eliminated in the measurement.

[0109] In summary, through a series of absolute calibration of reference temperature source, absolute calibration of standard resistor, relative calibration between sensors and cross calibration, the deviation of the output resistance value of the temperature measurement system is calibrated, and the temperature result T of the external temperature measurement point of the on-board reference source after calibration is obtained. call (i) Make the temperature measurement value as close to the true value as possible.

[0110] T call (i)-f(R call )-f(R(i)-ΔE s,l ) (9)

[0111] Among them, T call (i) is the temperature value obtained after calibration, ∫ is the functional relationship between temperature and resistance, R call is the resistance value obtained after calibration, R(i) is the resistance value actually measured by the system, ΔE s,l is the total deviation of the output resistance. According to the above, the total deviation ΔE of the i-th sensor and the measurement circuit on the satellite s,l It can be calculated by the following formula:

[0112]

[0113] Where ΔE s,j is the total deviation between the sensor and the measurement channel in the reference temperature source, ΔE c，i is the measurement deviation of the corresponding circuit of the sensor in the reference temperature source, j and N represent the number and quantity of the temperature sensor in the reference temperature source respectively, ΔE c，i is the measurement deviation of the i-th measurement circuit. Combining formulas (9) and (10), the calibration results of the temperature measurement system are as follows.

[0114]

[0115] The present invention proposes an in-situ composite calibration method for an on-orbit temperature measurement system, which has the following beneficial effects:

[0116] First, the deviation of the on-orbit temperature sensor and measurement circuit is absolutely calibrated through the measurement results of the temperature sensor in the temperature reference source, ensuring the accuracy of the absolute temperature reference when the spacecraft is in orbit, thereby effectively solving the problem of the absolute temperature reference of the spacecraft on orbit.

[0117] Secondly, the measurement results of the standard resistors in each measurement channel are used to perform absolute calibration on the measurement circuit, achieving accurate compensation for the deviation of the spacecraft's on-orbit measurement circuit and solving the deviation compensation problem of the on-orbit measurement circuit.

[0118] Furthermore, based on the consistency characteristics of sensors screened on the ground, the present invention uses the drift value of the temperature sensor in the reference source to calibrate the drift of other on-board temperature sensors, successfully solving the calibration problem of distributed sensors on the satellite and improving the overall performance of the distributed sensor system.

[0119] In addition, through cross-calibration between adjacent sensors, the present invention can timely discover and diagnose sensors with abnormal drift on the satellite, thereby improving the reliability and robustness of the entire temperature measurement system.

[0120] In summary, this invention combines absolute, relative, and cross-calibration methods to form a complete in-situ composite calibration system, significantly improving the measurement accuracy of spacecraft temperature measurement systems throughout their long on-orbit lifecycle. This method not only addresses the problem of increasing on-orbit temperature measurement deviations over time, but also ensures the accuracy and consistency of the temperature measurement system throughout the spacecraft's lifecycle, providing a strong guarantee for the safe and stable operation of the spacecraft.

[0121] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An in-situ composite calibration method for improving the accuracy of a spacecraft on-orbit temperature measurement system, characterized in that: The following steps are involved: Step 1: During the ground phase, the temperature sensors to be carried on the spacecraft are screened for consistency. The consistency of their raw materials, production, and packaging processes is strictly controlled. Resistor groups with the same drift coefficients are selected to obtain temperature sensors with relatively consistent long-term resistance drift patterns. Step 2: Arrange a reference temperature source on the spacecraft. The reference temperature source includes an active temperature control device, a packaging shell, a thermal insulation layer, a temperature sensor, a support structure, and temperature fixed point materials. Step 3: Perform absolute calibration on the temperature sensor and its temperature measurement circuit in the onboard reference temperature source. The resistance deviation of the temperature sensor and the temperature measurement circuit output is determined by the deviation between the fixed point temperature of the reference temperature source and the measured value of its internal temperature sensor. Step 4: Design a standard resistor onboard the satellite and precisely control its temperature to prevent temperature drift. By switching the switch, each temperature measurement channel measures the resistance of the standard resistor to calibrate the measurement deviation of each temperature measurement channel, thus achieving absolute calibration of the measurement deviation and consistency of each channel. Step 5: Based on the resistance deviation of the temperature sensor and the temperature measurement circuit output obtained in Step 3, minus the measurement deviation of each temperature measurement channel obtained in Step 4, the drift characteristics of the temperature sensor in the reference temperature source are obtained. The drift characteristics of at least one temperature sensor in the reference temperature source are used to perform relative calibration on the remaining temperature sensors on the satellite. Step 6: If an abnormal drift is found in a temperature sensor on the satellite, resulting in a deviation in the measurement results, the temperature measurement results are cross-checked using temperature sensors arranged in similar positions or the same area, through heat transfer relationship calculation or temperature field reconstruction, to check and eliminate abnormal data.

2. The in-situ composite calibration method according to claim 1, characterized in that: In step 1, the reference temperature source uses a fixed phase transition temperature point of a metal or non-metallic pure substance as a reference point for temperature calibration, including but not limited to the triple point of water, the melting point of gallium, and the eutectic phase transition temperature point of a gallium-based alloy.

3. The in-situ composite calibration method according to claim 1, wherein: The step 5 includes: first, determining the on-orbit drift pattern of sensors in the same batch through the average measurement results of the temperature drift of the temperature sensors in the reference temperature source, and then performing relative calibration on the remaining temperature sensors on the satellite based on the average measurement results.

4. The in-situ composite calibration method according to claim 1, wherein: In step 2, the reference temperature source is precisely temperature-controlled by an active heater and a semiconductor cooler to ensure that the temperature in the reference temperature source remains at a temperature plateau.

5. The in-situ composite calibration method according to claim 1, characterized in that: In step 3, the temperature sensor and temperature measurement circuit in the reference temperature source are calibrated by calculating their resistance deviation, and the resistance deviation is obtained based on the temperature-resistance function relationship of the temperature sensor and the deviation of the temperature measurement result from the reference temperature of the standard temperature source.

6. The in-situ composite calibration method according to claim 1, characterized in that: In step 4, the resistance of the standard resistor remains almost unchanged during the calibration process. By comparing the resistance measured by each temperature measurement channel with the resistance of the standard resistor, the measured resistance deviation of each channel is calculated, thereby achieving absolute calibration of the measurement deviation and consistency of each channel.

7. The in-situ composite calibration method according to claim 1, wherein: In step 4, during the calibration process, switch switching technology is used to achieve uninterrupted switching between channels to ensure that the calibration process does not interrupt the temperature monitoring of the target being measured.

8. The in-situ composite calibration method according to claim 1, wherein: The step 5 includes: obtaining the on-orbit drift law, after the spacecraft enters the predetermined orbit, continuously monitoring the changes in the temperature measurement results of the temperature sensor in the reference temperature source, inversely calculating and regularly recording the resistance value through the temperature-resistance function relationship, subtracting the absolute deviation of the temperature measurement circuit, obtaining the drift amount of the temperature sensor in the reference temperature source, and obtaining the drift law of the same batch of sensors operating on orbit.

9. The in-situ composite calibration method according to claim 1, wherein: In step 5, the relative calibration step includes: correcting the resistance drift of the temperature sensor outside the on-board reference temperature source according to the on-orbit drift law of the temperature sensor in the reference temperature source, and calculating the actual resistance value of the on-board sensor when it is running on orbit.

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