Method and system for determining liquid level position in profound hypothermia test

Abstract

The invention discloses a method and a system for determining a liquid level position in a profound hypothermia test, and aims to solve the problems that the immersion depth of a sensor is inconsistent and the repeatability of a test result is poor due to the fact that the liquid level cannot be observed. The method comprises the following steps: controlling a test clamp bearing a to-be-tested sensor to move towards liquid nitrogen, and continuously receiving temperature data of the sensor and position data of a driving device during movement; when the real-time temperature is lower than a preset liquid phase temperature threshold value for the first time due to contact with the liquid nitrogen, the corresponding position data at the moment are captured in time and marked as accurate liquid level position coordinates. The coordinate can be used as a dynamic reference for calculating the immersion depth in a subsequent automatic impact test. According to the invention, the sensor itself is used as a probe, high-precision automatic positioning based on objective physical quantity is realized, blind operation is converted into quantifiable accurate control, and the consistency of test conditions and the reliability of test results are improved.

Description

Technical Field

[0001] This application relates to the field of cryogenic testing technology, and in particular to a method and system for determining the liquid level position in deep cryogenic testing. Background Technology

[0002] Cryogenic sensors are key components in cutting-edge technologies such as aerospace, quantum information, and liquid hydrogen energy. To ensure the performance stability and structural reliability of these sensors in extreme environments, rigorous environmental simulation tests must be conducted. Among these tests, liquid nitrogen temperature shock testing is a core reliability verification method. It evaluates the sensor's operational lifespan and performance consistency under drastic temperature changes by repeatedly and rapidly cycling the sensor between room temperature and liquid nitrogen (approximately -196°C).

[0003] Currently, the common method for conducting such tests in the industry mainly relies on manual operation. The specific procedure is as follows: the operator fixes the cryogenic sensor to be tested on a test bracket, then manually holds the bracket and lowers it vertically from the opening of the Dewar flask until the sensor is immersed in the liquid nitrogen inside, and holds it for a period of time to complete one cryogenic shock.

[0004] However, Dewar flasks used to store liquid nitrogen are vacuum-insulated containers with opaque walls and typically small openings, making it impossible for operators to directly observe the real-time liquid nitrogen level inside. Therefore, during the lowering of the sensor, operators can only rely on touch or experience to determine whether the sensor has touched the liquid surface and the depth of immersion, which is essentially a "blind operation."

[0005] This "blind operation" directly impacts the precise control of testing conditions. In cryogenic testing, the immersion depth of the sensor is a critical parameter. If the immersion is too shallow, the sensor may be located in the gas-liquid transition zone above the liquid surface. This region has a large and unstable temperature gradient, failing to provide a uniform 77K testing environment for the sensor, leading to inaccurate test data. On the other hand, if the immersion is too deep, the test support itself will have an excessively large surface area immersed in liquid nitrogen, increasing heat conduction from the outside to the cryogenic zone. This not only accelerates the ineffective evaporation of liquid nitrogen but also prolongs the warm-up time for each cycle.

[0006] Because this positioning method relies entirely on the operator's personal experience, it is difficult to ensure that the immersion depth remains consistent across all tests, or even between different cycles within the same test. This inconsistency directly leads to fluctuations in the testing environment, resulting in poor repeatability and high data dispersion in the test results, thereby reducing the efficiency and reliability of the entire sensor verification process. Summary of the Invention

[0007] This application provides a method and system for determining the liquid level position in cryogenic testing, which solves the problem of poor repeatability and high data dispersion caused by fluctuations in the testing environment due to operational inconsistencies.

[0008] In a first aspect, this application provides a method for determining the liquid surface position in a cryogenic test, applied to an intelligent positioning control system. The system includes a drive device electrically connected to a controller and a sensor under test fixed to a test fixture at the movable end of the drive device. The method includes: the controller sending a command to the drive device to control the test fixture carrying the sensor under test to move towards liquid nitrogen within a Dewar flask; continuously receiving position data from the drive device and temperature data from the sensor under test during the movement of the test fixture; continuously comparing the received real-time temperature data with a preset liquid phase temperature threshold; and marking the corresponding position data received at this moment in a memory as the initial position coordinates of the liquid surface when the real-time temperature data first falls below the liquid phase temperature threshold, and performing subsequent impact tests.

[0009] The above embodiment uses the sensor under test as a probe during the sensor's descent, linking its temperature data with the position data of the driving device in real time. When the temperature drops sharply for the first time due to contact with liquid nitrogen and falls below the liquid phase temperature threshold, the system can instantly capture the critical state of sensor contact with the liquid surface and automatically determine the precise liquid surface coordinates based on the position data at that moment. This method transforms the positioning reliance from a difficult-to-reproduce "feel" to a physical quantity (temperature) that the system can objectively record and determine. This avoids fluctuations in test conditions caused by inconsistent immersion depths, providing a reliable and reproducible positional reference for subsequent impact tests, and improving the consistency and reliability of test results.

[0010] In conjunction with some embodiments of the first aspect, in some embodiments, the step of the controller sending a command to the drive device to control the test fixture carrying the sensor under test to move towards liquid nitrogen inside the Dewar flask specifically includes: the controller sending a first movement command to the drive device to control the test fixture to descend from an initial position at a first preset speed; during the descent of the test fixture at the first preset speed, the controller continuously compares the received real-time temperature data with a preset predicted temperature threshold; when the real-time temperature data first falls below the predicted temperature threshold, the controller sends a second movement command to the drive device to control the test fixture to switch to a second preset speed to continue descending, the second preset speed being lower than the first preset speed.

[0011] The above embodiment establishes a predicted temperature threshold higher than the liquid phase temperature, allowing the system to move at a higher first preset speed for most of the sensor's travel away from the liquid surface. Only when the temperature signal indicates that it is about to contact the cryogenic region of liquid nitrogen does it switch to a lower second preset speed for precise detection. This strategy reduces the time spent moving in non-critical areas without affecting the final positioning accuracy; at the same time, compared to simply moving at high speed, it avoids overshooting and misjudgment of the liquid surface position that may be caused by motion inertia. This design achieves a technical balance between detection efficiency and positioning accuracy, improving the overall operational efficiency of the automatic liquid surface positioning process.

[0012] In conjunction with some embodiments of the first aspect, in some embodiments, the method further includes a periodic adaptive detection method, which specifically includes: the controller starts and maintains the operation of the periodic timer; the controller continuously compares the count value of the periodic timer with a preset re-detection period duration; when the controller determines that the count value has reached the re-detection period duration, it re-executes the step of determining the liquid surface position to obtain new liquid surface position coordinates; the controller updates the initial liquid surface position coordinates in the memory to the new liquid surface position coordinates, resets the periodic timer, and starts the timing of the next cycle.

[0013] The above embodiment automatically re-executes the liquid surface positioning process after each preset cycle duration via a timer to obtain and update the current real-time liquid surface position coordinates. This avoids subsequent impact tests always using the initial, potentially invalid, liquid surface data, ensuring that the immersion depth calculation for each impact cycle is based on the updated liquid surface position. This achieves adaptive tracking and compensation for dynamically changing test environments, further improving the long-term stability of test conditions throughout the entire testing process.

[0014] In conjunction with some embodiments of the first aspect, in some embodiments, the subsequent impact test specifically includes: the controller performing the following cyclic test until a preset number of cycles is completed: the controller sends a descent command to the drive device, controlling the test fixture to move from the room temperature environment to the impact position, the impact position being determined by the initial liquid surface coordinates in the memory and a preset immersion depth value; after the test fixture reaches the impact position, the controller starts a cryogenic timer and controls the test fixture to remain at the impact position; after the cryogenic timer's count value reaches a preset cryogenic immersion time, the controller sends an ascent command to the drive device, controlling the test fixture to move from the impact position to a preset room temperature zone position; after the test fixture reaches the room temperature zone position, the controller starts a high-temperature timer and controls the test fixture to remain at the room temperature zone position; when the high-temperature timer's count value reaches a preset high-temperature recovery time, the controller sends a descent command to the drive device.

[0015] The above embodiment uses the previously obtained liquid surface coordinates as a dynamic reference and combines them with a programmable "preset immersion depth value" to enable the controller to automatically calculate the precise impact position to be reached in each cycle. Simultaneously, low-temperature and high-temperature timers are introduced, transforming the duration of the immersion and rewarming phases into precisely quantifiable control parameters. This solution converts the core process parameters of the entire thermal shock cycle (immersion depth, immersion duration, and rewarming duration) into programmed instructions that are automatically executed by the system. This not only automates the entire testing process but also ensures that each impact cycle strictly adheres to the same quantifiable testing specifications, thereby reducing interference introduced by human error and improving the reliability of test results and batch-to-batch consistency.

[0016] In conjunction with some embodiments of the first aspect, in some embodiments, during the execution of the cyclic test, the method further includes: the controller continuously receiving real-time position data of the test fixture; the controller comparing the real-time position data with a preset upper limit safety position threshold and a preset lower limit safety position threshold; when the controller determines that the real-time position data is higher than the upper limit safety position threshold or lower than the lower limit safety position threshold, the controller sends an emergency braking command to the drive device to immediately stop all movement of the test fixture and issue a safety alarm signal.

[0017] The above embodiment introduces a parallel-operation safety monitoring mechanism, setting clear upper and lower safety position thresholds and continuously comparing the real-time position data of the test fixture with these thresholds. Once the real-time position is detected to exceed the preset safe operating area, the system bypasses the normal test procedure logic, directly sending a highest-priority emergency braking command to the drive device and triggering an alarm. This provides an independent safety protection layer based on position redundancy judgment. It can intervene promptly and forcibly stop the equipment movement in extreme situations where the test process becomes uncontrollable, thereby avoiding or mitigating serious consequences such as collisions and damage that may be caused by the equipment exceeding its travel limits, and improving the robustness and safety of the entire automated testing system.

[0018] In conjunction with some embodiments of the first aspect, in some embodiments, during the execution of the cyclic test, the method further includes: the controller continuously receiving and recording real-time resistance data of the sensor under test; when the test fixture is in the impact position, the controller compares the real-time resistance data with a preset cold resistance threshold range; when the test fixture is in the room temperature range, the controller compares the real-time resistance data with a preset hot resistance threshold range; when the real-time resistance data exceeds the cold resistance threshold range or the hot resistance threshold range, the controller marks the sensor under test as faulty and issues a sensor fault alarm signal.

[0019] The above embodiments achieve real-time detection of sensor failure events by dynamically comparing the collected real-time resistance data with targeted preset cold and hot resistance threshold ranges when the test fixture is stationary at the impact position and the room temperature range, respectively. This enables immediate alarm issuance when a sensor malfunctions, avoiding unnecessary testing resources on damaged samples and providing more accurate diagnostic basis for subsequent failure analysis by distinguishing whether the failure occurs during cold impact or the recovery phase.

[0020] In conjunction with some embodiments of the first aspect, in some embodiments, during the execution of the cyclic test, the method further includes: the controller comparing the initial position coordinates of the liquid surface with a preset minimum liquid level threshold; when the initial position coordinates of the liquid surface are lower than the preset minimum liquid level threshold, the controller issues a system status abnormality alarm signal and stops the cyclic test.

[0021] The above embodiment introduces a pre-verification of the liquid level before the cyclic test is executed. The acquired liquid level coordinates are compared with a threshold representing the lowest effective liquid level, and this is used as the basis for determining whether to continue the test. This method adds a crucial test condition verification logic, which can promptly terminate invalid tests when the cryogenic medium is insufficient, avoiding the continued waste of system resources under conditions that do not meet basic test conditions, and to a certain extent ensuring the validity of each set of test data obtained.

[0022] In a second aspect, embodiments of this application provide an automatic liquid level impact testing device, which includes: one or more processors and a memory; the memory is coupled to the one or more processors, and the memory is used to store computer program code, which includes computer instructions, and the one or more processors call the computer instructions to cause the automatic liquid level impact testing device to perform the method described in the first aspect and any possible implementation thereof.

[0023] Thirdly, embodiments of this application provide a computer program product containing instructions that, when the computer program product is run on an automatic liquid level impact testing device, cause the automatic liquid level impact testing device to perform the method described in the first aspect and any possible implementation thereof.

[0024] Fourthly, embodiments of this application provide a computer-readable storage medium including instructions that, when executed on an automatic liquid level impact testing device, cause the automatic liquid level impact testing device to perform the method described in the first aspect and any possible implementation thereof.

[0025] Understandably, the automatic liquid level impact testing equipment provided in the second aspect, the computer program product provided in the third aspect, and the computer storage medium provided in the fourth aspect are all used to execute the methods provided in the embodiments of this application. Therefore, the beneficial effects they can achieve can be referred to the beneficial effects in the corresponding methods, and will not be repeated here.

[0026] One or more technical solutions provided in the embodiments of this application have at least the following technical effects or advantages: 1. This application uses the sensor under test itself as a probe to correlate its temperature with the position data of the driving device in real time, and uses the physical phenomenon of the sudden drop in temperature when the sensor comes into contact with liquid nitrogen to automatically calibrate the liquid surface coordinates. This automated positioning method, which is based on the change of objective physical quantities and can be accurately quantified, improves the problem of test condition fluctuations caused by inconsistent immersion depths and provides a reliable position reference for testing.

[0027] 2. This application achieves fully automated control of the entire process from liquid surface detection to multi-cycle impact testing by using precisely calibrated liquid surface coordinates as a dynamic reference and combining them with preset core process parameters such as immersion depth, low-temperature immersion time, and high-temperature recovery time. This reduces random interference caused by individual differences in operators and operator fatigue, ensuring that the test specifications are strictly and consistently executed in each cycle, thereby improving the reliability of test results and batch-to-batch consistency.

[0028] 3. This application introduces a periodic liquid level re-detection mechanism to actively adapt to and compensate for the dynamic drop in liquid level caused by liquid nitrogen evaporation during the testing process. This ensures that the calculation of the impact position is always based on updated valid liquid level data during long-term, multi-cycle testing. This method can maintain the long-term stability of testing conditions, reduce the risk of subsequent test data becoming invalid due to liquid level changes, and thus guarantee the effectiveness of the entire testing process. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the intelligent positioning control system in an embodiment of this application; Figure 2 This is a flowchart illustrating the liquid level positioning method in an embodiment of this application; Figure 3 This is a flowchart illustrating a segmented speed control method in an embodiment of this application; Figure 4 This is a flowchart illustrating a cyclic impact testing method in an embodiment of this application; Figure 5 This is a schematic diagram of the physical structure of an automatic liquid level impact testing device in the embodiments of this application. Detailed Implementation

[0030] The terminology used in the following embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. As used in the specification of this application, the singular expressions “a,” “an,” “the,” “the,” and “this” are intended to include the plural expressions as well, unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used in this application refers to any or all possible combinations including one or more of the listed items.

[0031] Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as implying or suggesting relative importance or implicitly indicating the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature, and in the description of the embodiments of this application, unless otherwise stated, "multiple" means two or more.

[0032] To facilitate understanding, the application scenarios of the embodiments of this application are described below.

[0033] Cryogenic sensors are key components in cutting-edge technologies such as aerospace and quantum information, and their performance and reliability in extreme environments are crucial. Liquid nitrogen temperature shock testing, which involves repeatedly cycling the sensor between room temperature and liquid nitrogen (approximately -196°C), is a core testing method for evaluating their reliability. Some related technologies rely heavily on manual operation, where the operator fixes the sensor to be tested on a test bracket and manually lowers it into the liquid nitrogen inside a Dewar flask to complete a cryogenic shock. However, due to the opaque nature of the Dewar flask, the operator cannot directly observe the real-time liquid nitrogen level inside the flask and can only rely on feel or experience to judge the depth of immersion. This "blind operation" makes it difficult to accurately control and maintain a consistent immersion depth: too shallow an immersion results in an uneven cryogenic environment, leading to inaccurate test data; too deep an immersion accelerates liquid nitrogen evaporation and prolongs the test cycle. This inconsistency in test conditions caused by human factors seriously affects the repeatability and reliability of test results, reducing the efficiency of sensor verification.

[0034] This application provides a method and system for automatically locating the liquid nitrogen surface. Please refer to [link / reference]. Figure 1This is a schematic diagram of the intelligent positioning control system in an embodiment of this application. The system mainly consists of a controller (the computer shown in the figure), a drive device (such as a servo motor M), a test fixture (the thermometer transfer bracket shown in the figure), and a data acquisition device. Specifically, the controller, as the core of the system's computation and control, runs a preset test program. On one hand, it sends action commands to the servo motor, which acts as the drive device, to precisely control the vertical displacement and speed of the thermometer transfer bracket mechanically connected to the motor; on the other hand, it continuously receives and processes temperature signals from the thermometers being tested on the test fixture, as well as position data fed back by the servo motor itself (e.g., through an encoder), through the data acquisition device. The thermometer transfer bracket is used to carry the sensors under test. Its bottom view shows that multiple thermometers under test and one Zone standard thermometer can be installed on the bracket simultaneously, enabling batch testing. The entire system is tested inside a Dewar flask used to store liquid nitrogen.

[0035] To facilitate understanding, the method provided in this implementation will be described in detail below, using the above scenario as an example. Please refer to [link / reference]. Figure 2 This is a flowchart illustrating the liquid level positioning method in an embodiment of this application.

[0036] S201. The controller sends a command to the drive unit to control the test fixture carrying the sensor under test to move towards liquid nitrogen inside the Dewar jar.

[0037] The controller can be an industrial computer (IPC), a programmable logic controller (PLC), or an embedded microcontroller (MCU); the test fixture is usually made of glass fiber composite material with low thermal conductivity (such as G-10) or polyether ether ketone (PEEK) to reduce heat conduction to the low temperature region; the sensor under test refers to the object of this test, that is, the sensor element that needs to be verified for performance or reliability in a deep low temperature environment.

[0038] The above steps constitute the initial stage of the entire automated testing process. Specifically, based on its internal program logic, the controller first determines the target direction of movement as vertically downwards (i.e., towards the liquid nitrogen at the bottom of the Dewar flask). Subsequently, the controller sends a start-movement command to the servo motor driver via its communication interface (e.g., RS-485 bus, EtherCAT bus, or I / O port). This command includes key parameters such as initial speed, acceleration, and direction of movement. After parsing this command, the driver precisely controls the servo motor to cause the test fixture to descend vertically.

[0039] In this embodiment, for simplicity, the movement trajectory is assumed to be vertically downward (i.e., along the negative Z-axis). However, the scope of protection of this application is not limited to this. In some specific testing scenarios, such as when the structure of the device under test is special or the opening position of the Dewar flask is restricted, the movement trajectory can also be a preset inclined straight line path, or even a more complex curved path. The core of the method of this application lies in its ability to correlate the precise position coordinates (whether one-dimensional, two-dimensional, or three-dimensional) of the test fixture on the preset movement trajectory in real time when the sensor parameters change abruptly. Therefore, any controlled movement trajectory that enables the sensor to eventually contact the liquid surface falls within the scope of the protection concept of this application.

[0040] S202. During the movement of the test fixture, position data from the drive device and temperature data from the sensor under test are continuously received.

[0041] The above steps are executed throughout the entire movement process in S201, until the liquid level position is determined in S204 or other termination conditions occur. Specifically, the controller initiates two parallel, high-frequency data acquisition tasks. The first is position data acquisition: the controller periodically sends data requests to the servo motor driver via the communication bus, or configures the driver to actively report data in the form of a data stream. The driver reads the pulse count from the encoder at the tail of the servo motor in real time and, combined with the lead parameter of the ball screw, accurately converts it into the linear displacement of the fixture (e.g., in mm, with an accuracy down to the micrometer level). For example, every 10 milliseconds, the controller acquires the precise Z-axis coordinate value of the current fixture. The second is temperature data acquisition: in parallel, the controller reads the raw signal from the sensor under test through its analog input module (if the sensor output is a voltage / current signal) or digital communication interface (such as SPI, I2C, or if the sensor has its own digital output). After signal conditioning, amplification, and A / D conversion, the signal is then converted into a standard Celsius or Kelvin temperature value based on the sensor's characteristic curve (such as the Callendar-Van Dusen equation for Pt100). These two tasks are executed synchronously. The data processing unit inside the controller associates and binds each set of acquired [timestamp, location data, temperature data] to form a data triplet, which is then stored in a circular buffer or real-time database for judgment and analysis in the next step, S203.

[0042] In other embodiments of this application, alternative implementations exist. Besides temperature sensors, any sensor whose physical parameters undergo a measurable abrupt change upon contact with liquid nitrogen can serve as a probe for liquid level detection. Correspondingly, the physical parameter data received by the controller can also be the sensor's capacitance data (due to changes in dielectric constant), resistance data (due to the temperature characteristics of material resistivity), optical characteristic data (such as changes in refractive index in fiber optic sensors), or mechanical characteristic data (such as the vibration frequency data of piezoelectric ceramics), etc. Those skilled in the art will understand that as long as the sensor's output signal can produce a clear, identifiable abrupt change such as a step, steep slope, or characteristic peak upon contact with liquid nitrogen, this change can be used as a basis for judgment, correlated with the position data at that moment, to accurately calibrate the liquid level.

[0043] S203. Continuously compare the received real-time temperature data with the preset liquid phase temperature threshold.

[0044] The liquid phase temperature threshold serves as the criterion for distinguishing between gaseous nitrogen and liquid nitrogen within the Dewar flask. In some preferred embodiments, this threshold is set to 75K. Setting it to 75K is based on a deep understanding of physical phenomena: the standard boiling point of liquid nitrogen is approximately 77.36K. Setting the threshold at 75K, slightly below its boiling point, aims to ensure that the sensor not only momentarily comes into contact with the liquid surface, which may be slightly warmer due to boiling or surface disturbance, but must have been stably immersed in the liquid nitrogen and completed sufficient heat exchange before triggering subsequent actions.

[0045] S204. When the real-time temperature data is lower than the liquid phase temperature threshold for the first time, the corresponding position data received at this moment is marked in the memory as the initial position coordinates of the liquid surface, and subsequent impact tests are carried out.

[0046] Specifically, the controller's internal program logic continuously monitors the output status of S203. When a state transition from never falling below a threshold to falling below a threshold is detected, the program immediately executes the "data capture" command, locks the currently processed data triplet [position, temperature, time], and precisely extracts the position data value (e.g., -135.78mm fed back by a grating ruler or servo motor encoder). Subsequently, this position value is written to a predefined memory address or the variable liquidSurfaceZeroPosition, completing the marking. Afterward, the control program switches to impact test mode and calculates all subsequent motion target points using this coordinate as the base point (e.g., the target point for immersion of 10mm is -135.78mm - 10mm).

[0047] In some other embodiments of this application, the method further includes a periodic adaptive detection method, which specifically includes: the controller starts and maintains the operation of the periodic timer; the controller continuously compares the count value of the periodic timer with the preset re-detection period duration; when the controller determines that the count value has reached the re-detection period duration, it re-executes the step of determining the liquid surface position to obtain new liquid surface position coordinates; the controller updates the initial liquid surface position coordinates in the memory to the new liquid surface position coordinates, resets the periodic timer, and starts the timing of the next cycle.

[0048] Among them, the periodic adaptive detection method is a control strategy designed to periodically and automatically recalibrate the reference position of the liquid surface during long-term continuous thermal shock testing in order to cope with the problem of liquid surface drop caused by natural evaporation of liquid nitrogen. The re-detection cycle duration represents a time interval that can be estimated and set by the user based on the experimental environment (such as the size of the Dewar flask opening, ambient temperature and humidity) and the liquid nitrogen consumption rate, for example, set to 10 minutes. "Re-execute the steps to determine the liquid surface position" means that the controller completely calls and executes all the aforementioned processes S201 to S204 to find the true liquid surface position at the current moment. Specifically, this method is activated at the start of the entire test task. The controller runs a timer in parallel in the background. The main program is responsible for executing the thermal shock cycle test based on the current `liquidSurfaceZeroPosition`, while the background monitoring program is only responsible for one thing: comparing the current timer value with the re-detection cycle duration. For example, if the cycle is set to 600 seconds, when the timer reaches 600 seconds from 0, the monitoring program sends a recalibration interrupt signal to the main program. After completing the current shock cycle (e.g., returning from 10mm below the liquid surface to 5mm above), the main program responds to the interrupt, pauses the regular shock test, and jumps to the liquid surface search subroutine (i.e., S201-S204). Only after the new liquid surface coordinates are successfully captured and updated to the `liquidSurfaceZeroPosition` variable will the controller clear the interrupt flag, reset the timer to 0, and continue executing subsequent thermal shock cycle tests based on this new, lower reference coordinate.

[0049] Based on the positioning method of the above embodiments, in order to further improve the calibration efficiency, this application also discloses an optimization scheme based on dual-speed control, which aims to solve the problem of balancing detection efficiency and positioning accuracy with a single speed. By using a variable speed strategy of high-speed seeking and low-speed approximation, the time consumed in the liquid level calibration process is shortened while ensuring accuracy.

[0050] The following provides a more detailed description of the process of the method provided in this implementation. Please refer to [link / reference]. Figure 3 This is a flowchart illustrating a segmented speed control method in an embodiment of this application.

[0051] S301, The controller sends a first movement command to the drive device to control the test fixture to descend from the initial position at a first preset speed.

[0052] Specifically, after the test program starts, the controller first reads the parameter value of the first preset speed (e.g., V1 = 20 mm / s) from its configuration storage area. Then, the controller generates a motion control command and sends it to the servo driver via a bus (such as CANopen or EtherCAT). This command instructs the driver to drive the motor, controlling the test fixture connected to the motor to descend vertically at a constant speed of 20 mm / s. During this process, the controller continuously obtains position feedback from the motor encoder or external linear encoder to achieve closed-loop speed control, ensuring that the actual descent speed is accurately and stably maintained at 20 mm / s. This step shortens the time required to move from the high standby point to the area near the liquid surface, improving the overall execution efficiency of the test.

[0053] S302. During the process of the test fixture descending at a first preset speed, the controller continuously compares the received real-time temperature data with a preset predicted temperature threshold.

[0054] The predicted temperature threshold is typically set to 85K. This value is chosen because it is significantly lower than the temperature of the gas phase far from the liquid, while precisely slightly higher than the boiling point of liquid nitrogen (approximately 77K at standard atmospheric pressure). It does not represent a broad "cold zone," but rather the extremely thin saturated vapor boundary layer above the liquid nitrogen surface, formed by intense evaporation, where the temperature gradient is steepest.

[0055] Specifically, after the controller initiates S301, it enters a high-speed loop judgment logic. In this loop, the controller continuously reads the real-time value T_current of the temperature sensor through its data acquisition interface and compares it with the internally stored fixed threshold T_pre = 85K. When the test fixture descends in the gas phase space above the Dewar flask, T_current may gradually decrease from 290K to 100K, but it always satisfies T_current>85K, the comparison result is "false", the controller does not trigger any action, and only allows the rapid descent of S301 to continue. Only when the sensor probe is extremely close to the liquid surface and enters the saturated low-temperature vapor layer formed by the violent boiling of liquid nitrogen will the temperature drop sharply. In a certain control cycle, the reading of T_current will first suddenly drop from (for example) 86.1K to 84.5K. At this moment, the condition T_current<85K is met for the first time, the comparison result becomes "true", and the controller immediately uses this event as a trigger signal to execute the deceleration command of the next step S303.

[0056] S303. When the real-time temperature data is lower than the predicted temperature threshold for the first time, the controller sends a second movement command to the drive device to control the test fixture to switch to the second preset speed to continue to descend. The second preset speed is lower than the first preset speed.

[0057] The second preset speed is used for fine searching in the area very close to the liquid surface; "the second preset speed is lower than the first preset speed" clarifies the order of magnitude between the two speed parameters and is the core logic for realizing "speed change" control.

[0058] Specifically, once the comparator within the controller detects that T_current drops below 85K for the first time, it immediately interrupts the regular monitoring loop and executes step S303. The controller first reads the value of the second preset speed, V2 = 0.5 mm / s, from the configuration parameters. Then, it sends a speed update or mode switch command to the servo drive, such as a command containing the new speed parameter VELOCITY = 0.5. Upon receiving this command, the high-end servo drive utilizes its built-in acceleration / deceleration curve (such as an S-curve) algorithm to smoothly and seamlessly transition the motor speed from the high speed corresponding to V1 to the low speed corresponding to V2 within a very short time (typically milliseconds). The physical movement of the test fixture also changes from rapid descent to slow crawling. This step seamlessly switches the test system from a high-speed, efficiency-oriented operating mode to a low-speed, accuracy- and safety-oriented operating mode, preparing for the final liquid level determination and testing.

[0059] After obtaining accurate liquid level reference coordinates using the methods described in the above embodiments, this application also provides a method for performing automated and standardized thermal shock cycling tests using this dynamic reference. This testing process is a core application step in achieving the purpose of this invention, namely, to assess the reliability of the sensor.

[0060] The following provides a more detailed description of the process of the method provided in this implementation. Please refer to [link / reference]. Figure 4 This is a flowchart illustrating a cyclic impact testing method in an embodiment of this application.

[0061] S401. The controller performs the following cyclic test until the preset number of cycles is completed: The controller sends a descent command to the drive device to control the test fixture to move from the room temperature environment to the impact position. The impact position is determined by the initial position coordinates of the liquid surface in the memory and the preset immersion depth value.

[0062] The trigger condition for this step is the start of the entire cycle test or the end of the high-temperature warm-up phase (S405) of the previous cycle. Specifically, at the start of a new cycle, the controller first reads two core data from its internal memory: the calibrated liquid level P_level and the user-defined immersion depth P_depth. Then, the controller performs a core coordinate calculation: impact position P_target = P_level + P_depth. This calculation transforms the abstract "immersion depth" requirement into precise physical world coordinates that the servo system can understand and execute. Subsequently, the controller issues a point-to-point (PTP) motion command to the servo drive, which reads "move to the target position P_target at high speed V_fast". The drive then controls the motor to move the test fixture quickly and accurately from the room temperature zone (e.g., P_room) to the calculated impact position P_target. This step enables the sensor under test to be quickly, accurately, and repeatedly delivered to a precisely controllable depth below the liquid surface, creating standardized initial conditions for the subsequent low-temperature immersion test (S402).

[0063] S402. After the test fixture reaches the impact position, the controller starts the cryogenic timer and controls the test fixture to stay at the impact position.

[0064] This step is applied in the "cryogenic immersion" phase of a thermal shock cycle. Specifically, after the servo drive completes the point-to-point motion command from S401 and returns an in-position flag to the controller, the controller immediately performs two parallel actions: First, it starts the internal cryogenic timer and loads it with the user-preset cryogenic immersion duration (T_soak), for example, 180 seconds; second, it continuously sends position-holding commands to the servo drive, causing the motor to lock its current position with extremely high torque, preventing position drift caused by factors such as cable tension and vibration. During this period, the controller's main task is to monitor the cryogenic timer's count value, while the data acquisition module continuously records the temperature readings of the sensor under test and the standard temperature sensor during this immersion process for subsequent performance analysis.

[0065] S403. After the count value of the low temperature timer reaches the preset low temperature immersion time, the controller sends an upward command to the drive device to control the test fixture to move from the impact position to the preset room temperature zone position.

[0066] This step is applied in the liquid-to-temperature transition phase of a thermal shock cycle. Specifically, when the controller detects that the internal cryogenic timer reaches T_soak (e.g., 180 seconds), it reads the preset room temperature zone coordinates P_room from memory. Then, the controller sends an ascent command to the servo drive, such as "move to P_room at the rewarming speed V_return". Upon receiving the command, the servo drive controls the motor to rotate in the opposite direction, smoothly pulling the test fixture out of the liquid nitrogen, across the gas-liquid interface and the Dewar flask opening, and finally stopping precisely at the room temperature zone position. This step, after precise cryogenic immersion, quickly and reliably transfers the sensor under test to the rewarming environment, thus completing a full "V"-shaped temperature shock from room temperature to deep cryogenics and back to room temperature, and preparing for the subsequent S404 high-temperature residence phase.

[0067] S404. After the test fixture reaches the room temperature zone, the controller starts the high temperature timer and controls the test fixture to stay in the room temperature zone.

[0068] This step is applied in the "room temperature recovery phase" of a thermal shock cycle. Specifically, after the servo driver moves the test fixture to P_room and sends a positioning signal, the controller immediately starts the high-temperature timer and loads it with the user-preset high-temperature recovery time (T_recovery), such as 30 minutes. This time is set based on the sensor's thermal mass and packaging characteristics, ensuring that the sensor core can fully recover to ambient temperature. During the T_recovery timeout, the controller continuously locks the test fixture's position to prevent any accidental movement. Simultaneously, the data acquisition system continuously monitors the sensor's temperature recovery curve, which itself is crucial data for evaluating the sensor's recovery characteristics.

[0069] S405. When the high temperature timer reaches the preset high temperature recovery time, the controller sends a descent command to the drive device.

[0070] This step is used at the point where a complete temperature cycle ends and a new cycle begins. Specifically, when the controller detects that the high-temperature timer's count has reached the preset T_recovery value, the system checks whether the current number of cycles has reached the user-defined total number of cycles (N_cycles). If not, the controller will re-execute the logic of S401, that is, recalculate or call P_target based on the current (possibly updated) liquid level data, and then send a rapid descent command to the servo drive device that is exactly the same as that during the first impact, thereby initiating the second, third, ... and even the Nth thermal shock cycle.

[0071] In some preferred embodiments, during the execution of the cyclic test, the controller continuously receives the real-time position data of the test fixture; the controller compares the real-time position data with a preset upper safety position threshold and a preset lower safety position threshold; when the controller determines that the real-time position data is higher than the upper safety position threshold or lower than the lower safety position threshold, the controller sends an emergency braking instruction to the driving device to immediately stop all movements of the test fixture and issue a safety alarm signal.

[0072] Among them, the upper safety position threshold and the lower safety position threshold jointly define an absolutely safe software "Safe Zone" where the test fixture is allowed to move. The upper threshold (Z_max_safe) is usually set slightly below the physical limit position of the driving mechanism to prevent hitting the top, and the lower threshold (Z_min_safe) is set above the safe distance at the bottom of the Dewar flask to prevent hitting the bottom.

[0073] The application scenario of this mechanism is all-time safety protection, and its execution timing is at any moment after the system is powered on and running. As a high-priority watchdog program, it runs continuously. Specifically, an independent monitoring thread runs inside the controller, and this thread reads the real-time position value of the encoder from the driver at a very high frequency (such as every 5 milliseconds). In each monitoring cycle, the controller performs a comparison: if (current_position>Z_max_safe || current_position<Z_min_safe). Under normal circumstances, since both P_room and P_target are set within the safe zone, this condition is always false. But if due to any abnormal situation - such as a software logic error outputting an out-of-range target point, the servo motor running out of control and "racing", or the user wrongly setting a dangerous P_target - the real-time position crosses the safety boundary, this condition will immediately become true. The controller will immediately execute two actions in parallel: 1) send an emergency braking instruction to the servo driver; 2) activate the alarm I / O port to trigger an audible and visual alarm.

[0074] In some preferred embodiments, during the execution of the cyclic test, the controller continuously receives and records the real-time resistance data of the sensor to be tested; when the test fixture stays at the impact position, the controller compares the real-time resistance data with a preset cold-state resistance threshold range; when the test fixture stays at the room-temperature zone position, the controller compares the real-time resistance data with a preset hot-state resistance threshold range; when the real-time resistance data exceeds the cold-state resistance threshold range or the hot-state resistance threshold range, the controller marks the sensor to be tested as a fault state and issues a sensor fault alarm signal.

[0075] The cold resistance threshold range refers to the allowable resistance range that the sensor should have for normal operation after undergoing cryogenic shock and stabilizing at liquid nitrogen temperature (77K). It is defined by a lower limit (R_cold_min) and an upper limit (R_cold_max). The hot resistance threshold range refers to the allowable resistance range that the sensor should have for normal operation after fully recovering to room temperature. It is also defined by a lower limit (R_warm_min) and an upper limit (R_warm_max). These two threshold ranges are pre-set qualification standards based on the sensor's design specifications or preliminary experimental data.

[0076] Specifically, the controller's data processing module continuously receives resistance data streams, but activates the decision logic only under specific system states: When the system executes S402 and the cryogenic timer starts counting, the controller initiates the cold state determination logic. It compares the acquired real-time resistance value with [R_cold_min, R_cold_max].

[0077] When the system executes S404 and the high-temperature timer starts counting, the controller initiates the thermal state determination logic. It compares the acquired real-time resistance value with [R_warm_min, R_warm_max].

[0078] If the real-time resistance value exceeds the corresponding threshold range within any window period, the controller will immediately set the sensor to fault status and trigger an alarm.

[0079] In some preferred embodiments, during the execution of the cyclic test, the controller compares the initial position coordinates of the liquid surface with a preset minimum liquid level threshold; when the initial position coordinates of the liquid surface are lower than the preset minimum liquid level threshold, the controller issues a system status abnormality alarm signal and stops the cyclic test.

[0080] The minimum liquid level threshold, denoted as L_min_level, is the lowest liquid level required to ensure that the sensor under test can be fully and effectively immersed in the cryogenic liquid for sufficient heat exchange. It is a safety and quality control parameter set based on sensor size and experience. This threshold is usually set lower than "impact position P_target + sensor height" to allow sufficient margin. Specifically, after the operator starts the entire loop test task, the controller first calls the liquid level calibration subroutine to obtain the current P_liquid value. Immediately afterwards, the controller performs an access judgment: if (P_liquid < L_min_level). If this condition holds, it means that the liquid nitrogen inventory in the current Dewar is insufficient to support an effective thermal shock test. The controller will immediately abort all subsequent test steps, and at the same time display a clear prompt such as "Low liquid level, please replenish liquid nitrogen!" on the human-machine interface (HMI), and may trigger a buzzer. Only when this condition does not hold, the test process is allowed to continue to execute down to S401. This step reduces the possibility of performing invalid tests when the test resources (cryogenic liquid) are insufficient, ensuring the effectiveness of each test cycle.

[0081] The automatic liquid level shock test device in the embodiment of the present invention application will be described from the perspective of hardware processing. Please refer to Figure 3 , which is a schematic structural diagram of a physical device of the automatic liquid level shock test device in the embodiment of the present application.

[0082] It should be noted that Figure 3 The structure of the automatic liquid level shock test device shown is only an example and should not impose any limitations on the functions and usage scope of the embodiments of the present invention.

[0083] [[ID=…]] Figure 3 As shown, the automatic liquid level shock test device includes a central processing unit (Central Processing Unit, CPU) 301, which can perform various appropriate actions and processes according to the program stored in the read-only memory (Read-Only Memory, ROM) 302 or the program loaded from the storage part 308 into the random access memory (Random Access Memory, RAM) 303, such as executing the methods described in the above embodiments. In the RAM 303, various programs and data required for system operation are also stored. The CPU 301, ROM 302, and RAM 303 are connected to each other through a bus 304. The input / output (Input / Output, I / O) interface 305 is also connected to the bus 304.

[0084] ​The following components are connected to I / O interface 305: input section 306 including audio input devices, push-button switches, etc.; output section 307 including a liquid crystal display (LCD) and audio output devices, indicator lights, etc.; storage section 308 including a hard disk, etc.; and communication section 309 including a network interface card such as a LAN (Local Area Network) card, modem, etc. Communication section 309 performs communication processing via a network such as the Internet. Drive 310 is also connected to I / O interface 305 as needed. Removable media 311, such as a disk, optical disk, magneto-optical disk, semiconductor memory, etc., are installed on drive 310 as needed so that computer programs read from them can be installed into storage section 308 as needed.

[0085] In particular, according to embodiments of the present invention, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments of the present invention include a computer program product comprising a computer program carried on a computer-readable medium, the computer program containing computer programs for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via communication section 309, and / or installed from removable medium 311. When the computer program is executed by central processing unit (CPU) 301, it performs the various functions defined in the present invention.

[0086] It should be noted that specific examples of computer-readable storage media may include, but are not limited to: electrical connections having one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM), flash memory, optical fiber, portable compact disc read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof. In this invention, a computer-readable storage medium can be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device.

[0087] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present invention. Each block in a flowchart or block diagram may represent a module, program segment, or portion of code, which contains one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those shown in the drawings.

[0088] Specifically, the automatic liquid level impact testing device of this embodiment includes a processor and a memory. The memory stores a computer program. When the computer program is executed by the processor, it implements the method for determining the liquid level position in the deep cryogenic test provided in the above embodiment.

[0089] In another aspect, the present invention also provides a computer-readable storage medium, which may be included in the automatic liquid level impact testing device described in the above embodiments; or it may exist independently and not assembled into the automatic liquid level impact testing device. The storage medium carries one or more computer programs that, when executed by a processor of the automatic liquid level impact testing device, cause the automatic liquid level impact testing device to implement the method for determining the liquid level position in a deep cryogenic test provided in the above embodiments.

[0090] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit it. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

[0091] As used in the above embodiments, depending on the context, the term "when..." can be interpreted as meaning "if...", "after...", "in response to determining...", or "in response to detecting...". Similarly, depending on the context, the phrase "when determining..." or "if (the stated condition or event) is interpreted as meaning "if determining...", "in response to determining...", "when (the stated condition or event) is detected", or "in response to detecting (the stated condition or event)".

[0092] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. This program can be stored in a computer-readable storage medium, and when executed, it can include the processes described in the above method embodiments. The aforementioned storage medium includes various media capable of storing program code, such as ROM or random access memory (RAM), magnetic disks, or optical disks.

Claims

1. A method for determining the liquid surface position in a deep cryogenic test, characterized in that, An application in an intelligent positioning control system, the system comprising a drive device electrically connected to a controller and a sensor to be tested fixed to a test fixture at the movable end of the drive device, the method comprising: The controller sends a command to the drive device to control the test fixture carrying the sensor under test to move towards liquid nitrogen inside the Dewar flask; During the movement of the test fixture, position data from the drive device and temperature data from the sensor under test are continuously received; The received real-time temperature data is continuously compared with the preset liquid phase temperature threshold. When the real-time temperature data first falls below the liquid phase temperature threshold, the corresponding position data received at this moment is marked in the memory as the initial position coordinates of the liquid surface for subsequent impact testing.

2. The method according to claim 1, characterized in that, The step of the controller sending a command to the drive device to control the test fixture carrying the sensor under test to move towards liquid nitrogen inside the Dewar flask specifically includes: The controller sends a first movement command to the drive device, controlling the test fixture to descend from the initial position at a first preset speed; During the process of the test fixture descending at a first preset speed, the controller continuously compares the received real-time temperature data with a preset predicted temperature threshold. When the real-time temperature data first falls below the predicted temperature threshold, the controller sends a second movement command to the drive device to control the test fixture to switch to a second preset speed to continue descending. The second preset speed is lower than the first preset speed.

3. The method according to claim 1, characterized in that, The method further includes a periodic adaptive detection method, which specifically includes: The controller starts and maintains the periodic timer in operation; The controller continuously compares the count value of the periodic timer with the preset re-detection period duration; When the controller determines that the count value has reached the re-detection cycle duration, it re-executes the step of determining the liquid surface position to obtain new liquid surface position coordinates. The controller updates the initial liquid surface position coordinates in the memory to the new liquid surface position coordinates and resets the cycle timer to start the next cycle.

4. The method according to claim 1, characterized in that, The subsequent impact tests specifically include: The controller performs the following cyclic test until the preset number of cycles is completed: The controller sends a descent command to the drive device to control the test fixture to move from room temperature to the impact position, which is determined by the initial liquid surface coordinates and the preset immersion depth value stored in the memory. After the test fixture reaches the impact position, the controller starts a cryogenic timer and controls the test fixture to remain at the impact position; After the count value of the low temperature timer reaches the preset low temperature immersion time, the controller sends a rising command to the drive device to control the test fixture to move from the impact position to the preset room temperature zone position. After the test fixture reaches the room temperature zone, the controller starts the high temperature timer and controls the test fixture to stay at the room temperature zone. When the count value of the high temperature timer reaches the preset high temperature recovery time, the controller sends the descent command to the drive device.

5. The method according to claim 4, characterized in that, During the execution of the cyclic test, the method further includes: The controller continuously receives real-time position data of the test fixture; The controller compares the real-time location data with a preset upper limit safe location threshold and a preset lower limit safe location threshold; When the controller determines that the real-time position data is higher than the upper limit safe position threshold or lower than the lower limit safe position threshold, the controller sends an emergency braking command to the drive device to immediately stop all movement of the test fixture and issue a safety alarm signal.

6. The method according to claim 5, characterized in that, During the execution of the cyclic test, the method further includes: The controller continuously receives and records the real-time resistance data of the sensor under test; While the test fixture remains at the impact position, the controller compares the real-time resistance data with a preset cold resistance threshold range; While the test fixture remains in the room temperature zone, the controller compares the real-time resistance data with a preset hot resistance threshold range. When the real-time resistance data exceeds the cold resistance threshold range or the hot resistance threshold range, the controller marks the sensor under test as faulty and issues a sensor fault alarm signal.

7. The method according to claim 6, characterized in that, During the execution of the cyclic test, the method further includes: The controller compares the initial position coordinates of the liquid surface with a preset minimum liquid level threshold. When the initial position coordinates of the liquid surface are lower than the preset minimum liquid level threshold, the controller issues a system status abnormality alarm signal and stops the cyclic test.

8. An automatic liquid level impact testing device, characterized in that, The automatic liquid level impact testing device includes: one or more processors and a memory; the memory is coupled to the one or more processors, the memory is used to store computer program code, the computer program code includes computer instructions, and the one or more processors call the computer instructions to cause the automatic liquid level impact testing device to perform the method as described in any one of claims 1-7.

9. A computer-readable storage medium comprising instructions, characterized in that, When the instruction is executed on the automatic liquid level impact testing equipment, the automatic liquid level impact testing equipment performs the method as described in any one of claims 1-7.

10. A computer program product, characterized in that, When the computer program product is run on the automatic liquid level impact testing equipment, the automatic liquid level impact testing equipment performs the method as described in any one of claims 1-7.

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