A testing method and system for ultrasonic ranging sensors used in high-temperature operating conditions

Abstract

This invention belongs to the field of sensor testing technology, specifically a testing method and system for ultrasonic ranging sensors under high-temperature conditions. The method includes constructing test benchmark data, establishing a first-wave trigger stability criterion under low signal-to-noise ratio conditions, setting a dynamic threshold range that varies with temperature, and a high-temperature dynamic calibration standard. Multi-temperature gradient testing is performed, raw echo waveform data is collected and filtered for enhancement, the first-wave arrival time is extracted, and the validity of the first-wave trigger is determined by combining the dynamic threshold range to obtain calibrated ranging data. The calibrated ranging data is compared with the true standard distance value to calculate the measurement error and repeatability accuracy. If the first-wave trigger stability criterion fails to meet requirements or the measurement error exceeds the allowable range within multiple consecutive test cycles, the sensor under test is deemed unqualified under high-temperature conditions. This invention improves trigger reliability, significantly enhances test accuracy, efficiency, and reliability, and strengthens the adaptability of the testing method to different high-temperature conditions.

Description

Technical Field

[0001] This invention belongs to the field of sensor testing technology, specifically a testing method and system for ultrasonic ranging sensors used in high-temperature operating conditions. Background Technology

[0002] Ultrasonic ranging sensors are widely used in industrial inspection, intelligent equipment, aerospace, and other fields due to their advantages such as resistance to electromagnetic interference, low cost, and simple structure. However, in applications and testing under high-temperature conditions, existing technologies have significant shortcomings, which severely restrict the accurate evaluation of sensor performance and the effectiveness of practical applications.

[0003] Existing testing methods for ultrasonic ranging sensors generally neglect the impact of high-temperature conditions on echo signal attenuation. In high-temperature environments, the absorption of ultrasonic waves by the air medium increases significantly with rising temperature, leading to a substantial attenuation of echo signal energy and a sharp decrease in the signal-to-noise ratio. Simultaneously, high-temperature conditions easily generate thermal airflow disturbances and fluctuations in turbulence intensity, further exacerbating problems such as echo waveform jitter and time delay drift. This renders the fixed first-wave identification threshold and single criterion in traditional testing methods completely ineffective, easily resulting in missed or false first-wave triggering, and positional jumps. This makes it impossible to reliably identify valid first waves, severely impacting the accuracy of ranging data.

[0004] Furthermore, existing test standards are mostly based on normal temperature conditions, failing to consider the impact of temperature changes on ultrasonic propagation speed and absorption coefficient, and also failing to adapt to interference from varying intensities such as hot airflow and turbulence. Using fixed thresholds and static criteria for testing cannot adaptively adjust to changes in temperature, signal attenuation, and disturbance intensity, resulting in large test result deviations, poor repeatability, and an inability to objectively reflect the sensor's true performance under actual high-temperature conditions.

[0005] Therefore, there is an urgent need for a testing method and system for ultrasonic ranging sensors under high-temperature operating conditions, which can achieve stable initial identification and accurate ranging, in order to overcome the limitations of existing technologies and ensure the accuracy and effectiveness of ultrasonic ranging sensor testing under high-temperature operating conditions. Summary of the Invention

[0006] To overcome the shortcomings of existing technologies, this invention proposes a testing method and system for ultrasonic ranging sensors under high-temperature operating conditions. This invention primarily addresses the problems of sensor testing neglecting severe echo signal attenuation, low signal-to-noise ratio, and difficulty in stable identification and judgment of the first wave under high-temperature conditions, and the inability of testing criteria to adapt to different temperatures and disturbance intensities.

[0007] The technical solution adopted by this invention to solve its technical problem is: a testing method for an ultrasonic ranging sensor under high-temperature working conditions, comprising:

[0008] Collect the physical specifications of the sensor under test and the environmental parameters of the high-temperature operating conditions, identify the thermal airflow distribution characteristics in the high-temperature operating conditions, extract the air absorption coefficient and turbulence intensity from the environmental parameters, and combine them with the thermal airflow distribution characteristics to form test benchmark data.

[0009] Based on test benchmark data, a stability criterion for the first wave triggering under low signal-to-noise ratio is constructed, and a dynamic threshold range that varies with temperature and a high-temperature dynamic calibration standard are set.

[0010] Perform multi-temperature gradient testing, control the temperature of the test chamber to rise to the target high temperature point at a preset rate and keep it at that temperature, drive the sensor under test to emit ultrasonic pulses and receive echo signals to obtain the original echo waveform data.

[0011] The original echo waveform data is filtered and enhanced according to the high temperature dynamic calibration standard. The arrival time of the first wave is extracted, and the validity of the first wave triggering is judged by combining the dynamic threshold range to obtain the corrected ranging data.

[0012] By comparing the calibrated distance measurement data with the true value of the standard distance, the measurement error and repeatability accuracy are calculated. If the stability criterion of the first wave trigger does not meet the requirements or the measurement error exceeds the allowable range in multiple consecutive test cycles, the sensor under test is deemed to be unqualified under high temperature conditions.

[0013] The present invention provides a testing method for an ultrasonic ranging sensor used in high-temperature operating conditions, the steps of which include obtaining the distribution characteristics of hot airflow are as follows:

[0014] The rated operating parameters and structural parameters of the sensor under test are collected as physical specifications, and the temperature range, heating rate, holding time, temperature fluctuation range, medium parameters and sensor layout parameters corresponding to the high-temperature operating conditions under test are collected as environmental parameters.

[0015] A test environment was set up to simulate actual high-temperature working conditions. Temperature distribution was monitored in real time along the ultrasonic propagation path, and airflow velocity, direction, and pressure fluctuation data were collected as airflow data.

[0016] The intensity of natural convection, direction and stability of hot air velocity, and amplitude and frequency of airflow disturbance are extracted from airflow data as characteristics of hot airflow distribution.

[0017] The present invention provides a testing method for an ultrasonic ranging sensor used in high-temperature operating conditions, the steps of which include constructing test reference data are as follows:

[0018] Temperature data at multiple locations along the ultrasonic propagation path are extracted from environmental parameters. Gas composition, ambient atmospheric pressure, humidity, and dust concentration are extracted as medium environmental parameters. The ultrasonic center frequency and transmission power are extracted from physical specification parameters as sound wave related parameters.

[0019] Based on temperature data and sound wave parameters, the theoretical sound absorption coefficient is calculated according to the acoustic attenuation model.

[0020] The theoretical sound absorption coefficient is corrected based on the medium environment parameters to obtain the sound absorption coefficient corresponding to each temperature point, which is then used as the air sound absorption coefficient.

[0021] The average wind speed is calculated by continuously collecting wind speed sequences at preset time intervals. The root mean square of the wind speed fluctuation is calculated as the wind speed fluctuation amplitude, and the ratio of the wind speed fluctuation amplitude to the average wind speed is used as the single-point turbulence intensity.

[0022] The turbulence intensity at each of the multiple measuring points along the ultrasonic propagation path is calculated, and the average value is taken to obtain the turbulence intensity under the current operating condition.

[0023] Test baseline data are obtained by structurally integrating the characteristics of hot airflow distribution, air absorption coefficient and turbulence intensity according to temperature conditions.

[0024] The present invention provides a testing method for an ultrasonic ranging sensor used in high-temperature operating conditions, the steps of which include constructing a first-wave trigger stability criterion:

[0025] The total attenuation rate is calculated based on the air absorption coefficient and the test distance. The theoretical value of the echo amplitude is calculated by combining the sensor's transmitting power and receiving gain. The signal-to-noise ratio is calculated by comparing it with the circuit noise amplitude. The operating conditions are divided into multiple signal-to-noise levels by combining the turbulence intensity.

[0026] A multi-condition joint criterion is constructed based on amplitude condition, waveform rising edge condition, time window constraint condition, and continuity condition.

[0027] The stability index of multiple echoes within the statistical time window is collected, the stability of the first wave is calculated, the stability of the first wave is classified into levels according to the preset stability threshold, and the strictness of the multi-condition joint criterion is dynamically adjusted according to the distribution characteristics of the thermal airflow to obtain the stability criterion for the first wave trigger.

[0028] This invention provides a testing method for an ultrasonic ranging sensor used in high-temperature operating conditions, comprising the steps of setting a dynamic threshold range and a high-temperature dynamic calibration standard, including:

[0029] Noise baseline data, signal attenuation characteristics, and disturbance amplitude characteristics at different temperatures are extracted from the test baseline data. Based on the noise baseline data, the basic threshold for attenuation with temperature is calculated.

[0030] The basic threshold is corrected based on the signal attenuation characteristics and disturbance amplitude characteristics to determine the upper and lower limits of the threshold, thus obtaining the temperature threshold range.

[0031] Using the current temperature as the x-axis and the upper and lower limits of the threshold as the y-axis, two curves are generated using a piecewise linear interpolation method. Combined with the first wave stability feedback, the interval strictness is dynamically adjusted to obtain the dynamic threshold interval.

[0032] Using a fixed standard distance as the true benchmark, the original flight time is collected under multiple temperature gradients to establish a temperature sound speed correction coefficient model. Sound absorption attenuation and time delay drift are introduced to correct the first wave identification deviation, forming a high-temperature dynamic calibration calculation model.

[0033] The present invention provides a testing method for an ultrasonic ranging sensor used in high-temperature operating conditions, the steps of which include obtaining the raw echo waveform data are as follows:

[0034] Multiple test temperature zones are set from room temperature to the maximum operating temperature. Each temperature zone includes a heating section, a heat preservation and stabilization section, and a test section.

[0035] After confirming that the uniformity of the temperature field distribution inside the test chamber meets the preset requirements in the heat preservation and stabilization section, the test section begins.

[0036] During the test section, the sensor under test is triggered at high frequency to collect a preset number of raw echo waveform data, and the environmental parameters under this temperature range are recorded simultaneously.

[0037] The present invention provides a testing method for an ultrasonic ranging sensor used in high-temperature operating conditions, the steps of which include obtaining the arrival time of the first wave are as follows:

[0038] The calibration parameters corresponding to the current temperature are retrieved from the high-temperature dynamic calibration standard, and the original echo waveform is subjected to noise filtering to obtain a preliminary processed waveform.

[0039] The amplitude enhancement step size of the initial processed waveform is adjusted based on the air absorption attenuation characteristics at the current temperature. The waveform is then jitter-corrected based on the turbulence intensity and airflow drift characteristics. The first processed waveform is obtained by combining the convex rising edge characteristics of the time region where the first wave is located.

[0040] The arrival time of the first wave is calibrated by using sound absorption attenuation delay compensation, airflow drift compensation, and sound velocity correction to output the arrival time of the first wave.

[0041] The present invention provides a testing method for an ultrasonic ranging sensor used in high-temperature operating conditions, the steps of which to obtain calibrated ranging data include:

[0042] Based on the current temperature corresponding to the dynamic threshold range, check the signal amplitude at the first wave arrival time and the first wave position to determine whether it falls within the current dynamic threshold range. If so, the first wave trigger is considered valid.

[0043] The valid arrival time of the first wave will be determined and corrected according to the high-temperature dynamic calibration standard to obtain the calibrated flight time.

[0044] Using the calibrated time of flight and the ultrasonic velocity at the current temperature, the one-way distance from the sensor to the target reflecting surface is calculated.

[0045] By combining the one-way distance with the system error compensation value, and averaging multiple sets of valid data at the same temperature point, the corrected distance measurement data is obtained.

[0046] This invention provides a testing method for an ultrasonic ranging sensor used in high-temperature operating conditions. The steps of comparing and correcting the ranging data with the true value of the standard distance include:

[0047] The calibrated distance measurement data for each test cycle is compared with the true standard distance value, and the measurement error at each temperature point is calculated.

[0048] At the same temperature point, select all the calibration ranging data of the first wave trigger that are valid and calculate the average value. Calculate the deviation of each set of valid data from the average value and take the difference between the maximum and minimum deviation values ​​as the repeatability accuracy.

[0049] For each test cycle, the sensor under test is comprehensively judged based on measurement error, repeatability accuracy, and initial trigger stability criteria. If any one of the requirements is not met, the sensor is judged to be unqualified.

[0050] This invention provides a testing system for an ultrasonic ranging sensor used in high-temperature operating conditions, comprising:

[0051] The parameter benchmark construction module is used to collect the physical specifications of the sensor under test and the environmental parameters of the high-temperature operating conditions, identify the thermal airflow distribution characteristics in the high-temperature operating conditions, extract the air absorption coefficient and turbulence intensity from the environmental parameters, and combine them with the thermal airflow distribution characteristics to form test benchmark data.

[0052] The criterion setting module is used to construct the first-wave trigger stability criterion under low signal-to-noise ratio based on test benchmark data, and to set the dynamic threshold range and high-temperature dynamic calibration standard that vary with temperature.

[0053] The multi-temperature gradient test module is used to perform multi-temperature gradient tests, control the temperature of the test chamber to rise to the target high temperature point at a preset rate and maintain the temperature, drive the sensor under test to emit ultrasonic pulses and receive echo signals to obtain the original echo waveform data.

[0054] The echo processing and correction module is used to filter and enhance the original echo waveform data according to the high-temperature dynamic calibration standard, extract the arrival time of the first wave, and determine the validity of the first wave triggering by combining the dynamic threshold range to obtain the corrected ranging data.

[0055] The accuracy assessment module is used to compare the corrected distance measurement data with the true value of the standard distance, calculate the measurement error and repeatability accuracy. If the stability criterion of the first wave is not met or the measurement error exceeds the allowable range in multiple consecutive test cycles, the sensor under test is determined to be unqualified under high temperature conditions.

[0056] The beneficial effects of this invention are as follows:

[0057] 1. This invention constructs a multi-condition joint stability criterion and dynamic threshold range, which can adapt to changes in temperature, attenuation, and turbulence, significantly reducing false triggers and missed triggers, and improving the success rate and stability of first-wave recognition. A temperature-velocity of sound correction model is established, and sound absorption attenuation and time delay drift correction are introduced, greatly reducing the system ranging error under high-temperature conditions. Through noise filtering, amplitude enhancement, jitter correction, and rising edge prominence processing, weak echo characteristics are made more obvious, and the first-wave arrival time extraction is more accurate. Piecewise linear interpolation is used to generate a continuous temperature threshold curve, and the first-wave stability interval is tightened / widened in real time, ensuring optimal recognition performance under different temperatures and disturbance intensities. By comprehensively judging the performance based on measurement error, repeatability accuracy, and continuous periodic stability, the qualification evaluation is made more scientific, reproducible, and traceable, enhancing the adaptability of the testing method to different high-temperature conditions. Attached Figure Description

[0058] The invention will now be further described with reference to the accompanying drawings.

[0059] Figure 1 This is a flowchart illustrating a testing method for an ultrasonic ranging sensor under high-temperature conditions provided in an embodiment of the present invention.

[0060] Figure 2 This is a schematic diagram of the process for obtaining the arrival time of the first wave in a test method for an ultrasonic ranging sensor used in high-temperature working conditions, provided by an embodiment of the present invention.

[0061] Figure 3 This is a schematic diagram of a test system for an ultrasonic ranging sensor under high-temperature conditions provided in an embodiment of the present invention. Detailed Implementation

[0062] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0063] like Figures 1 to 3 As shown in the figure, an embodiment of the present invention provides a testing method for an ultrasonic ranging sensor used in high-temperature operating conditions, comprising:

[0064] Collect the physical specifications of the sensor under test and the environmental parameters of the high-temperature operating conditions, identify the thermal airflow distribution characteristics in the high-temperature operating conditions, extract the air absorption coefficient and turbulence intensity from the environmental parameters, and combine them with the thermal airflow distribution characteristics to form test benchmark data.

[0065] The steps to obtain the characteristics of thermal gas distribution include:

[0066] The rated operating parameters and structural parameters of the sensor under test are collected as physical specifications, and the temperature range, heating rate, holding time, temperature fluctuation range, medium parameters and sensor layout parameters corresponding to the high-temperature operating conditions under test are collected as environmental parameters.

[0067] Medium parameters include ambient gas type, such as air, flue gas, inert gas, etc., relative humidity, pressure, and dust concentration range.

[0068] The layout parameters for data acquisition include sensor installation location, target reflector location, spacing, installation angle, and dimensions of the surrounding hot wall structure.

[0069] A test environment was set up to simulate actual high-temperature working conditions. Temperature distribution was monitored in real time along the ultrasonic propagation path, and airflow velocity, direction, and pressure fluctuation data were collected as airflow data.

[0070] Airflow velocity and direction acquisition: Real-time acquisition of airflow velocity and direction at each monitoring point, recording instantaneous, average, and maximum values ​​of airflow velocity, and analyzing the stability of airflow direction. In high-temperature conditions, rising airflow from natural convection and lateral airflow from forced airflow can both cause deviations in the ultrasonic wave propagation path, affecting ranging accuracy.

[0071] Pressure fluctuation acquisition: Real-time acquisition of pressure fluctuation data within the test chamber, and analysis of the correlation between pressure fluctuations and airflow velocity and temperature. Pressure fluctuations can cause changes in sound velocity and may also induce airflow pulsations, generating periodic interference and affecting the stability of the echo signal.

[0072] The intensity of natural convection, direction and stability of hot air velocity, and amplitude and frequency of airflow disturbance are extracted from airflow data as characteristics of hot airflow distribution.

[0073] Natural convection intensity: to determine whether the hot airflow is mainly due to natural convection, without forced airflow, and the rising speed and range of influence of natural convection.

[0074] Hot air velocity direction and stability: Determine the main flow direction of the airflow, and determine whether there is any directional deviation or abrupt change, as well as the magnitude of the deviation.

[0075] Periodic airflow disturbance: Determine whether there are periodic airflow pulsations, such as those caused by fan rotation or furnace door opening and closing, as well as the frequency and amplitude of the pulsations.

[0076] The steps involved in constructing test baseline data include:

[0077] Temperature data at multiple locations along the ultrasonic propagation path are extracted from environmental parameters. Gas composition, ambient atmospheric pressure, humidity, and dust concentration are extracted as medium environmental parameters. The ultrasonic center frequency and transmission power are extracted from physical specification parameters as sound wave related parameters.

[0078] Based on temperature data and sound wave parameters, the theoretical sound absorption coefficient is calculated using the acoustic attenuation model, expressed by the following formula:

[0079]

[0080] In the formula, It is the theoretical sound absorption coefficient. It is the center frequency of the ultrasound. It is absolute temperature, it is Correction factors related to gas composition and pressure.

[0081] The theoretical sound absorption coefficient is corrected based on the medium environment parameters to obtain the sound absorption coefficient corresponding to each temperature point, which is then used as the air sound absorption coefficient.

[0082] Because of the presence of dust, water vapor, and fumes at the site, additional attenuation is added. Therefore, the additional attenuation is adjusted according to the dust concentration and humidity. Pressure correction is performed based on the degree of pressure deviation from standard atmospheric pressure to finally obtain the true and effective air absorption coefficient under this high-temperature operating condition.

[0083] The average wind speed is calculated by continuously collecting wind speed sequences at preset time intervals. The root mean square of the wind speed fluctuation is calculated as the wind speed fluctuation amplitude, and the ratio of the wind speed fluctuation amplitude to the average wind speed is used as the single-point turbulence intensity.

[0084] Wind speed sequence is expressed as The formula for calculating average wind speed is expressed as:

[0085]

[0086] In the formula, It is the average wind speed. This is the total number of wind speed data points. It is the first The wind speed observation value at each moment.

[0087] The formula for calculating the root mean square of wind speed fluctuations is expressed as:

[0088]

[0089] In the formula, It refers to the amplitude of wind speed fluctuations.

[0090] The turbulence intensity at each of the multiple measuring points along the ultrasonic propagation path is calculated, and the average value is taken to obtain the turbulence intensity under the current operating condition.

[0091] Test baseline data are obtained by structurally integrating the characteristics of hot airflow distribution, air absorption coefficient and turbulence intensity according to temperature conditions.

[0092] Each set of baseline data is labeled with information including: current target temperature, test step number, sensor installation location, and standard distance measurement true value.

[0093] Construct structured benchmark entries, with each benchmark data entry including: temperature conditions, air absorption coefficient, average wind speed, turbulence intensity, and description of thermal airflow distribution.

[0094] Based on test benchmark data, a stability criterion for the first wave triggering under low signal-to-noise ratio is constructed, and a dynamic threshold range that varies with temperature and a high-temperature dynamic calibration standard are set.

[0095] The steps to construct the first-wave trigger stability criterion include:

[0096] The total attenuation rate is calculated based on the air absorption coefficient and the test distance. The theoretical value of the echo amplitude is calculated by combining the sensor's transmitting power and receiving gain. The signal-to-noise ratio is calculated by comparing it with the circuit noise amplitude. The operating conditions are divided into multiple signal-to-noise levels by combining the turbulence intensity.

[0097] The operating conditions are divided into: normal signal-to-noise ratio (SNR), low signal-to-noise ratio (SNR), low signal-to-noise ratio (SNR), high turbulence intensity (TI), and extremely low signal-to-noise ratio (approaching loss of echo).

[0098] A multi-condition joint criterion is constructed based on amplitude condition, waveform rising edge condition, time window constraint condition, and continuity condition.

[0099] Amplitude condition: The peak value of the echo signal must be greater than: dynamic noise floor + sound absorption attenuation correction coefficient + turbulence disturbance margin. This is not a fixed threshold, but changes in real time with high temperature and airflow.

[0100] Waveform rising edge condition: The first wave should have a clear and steep rising edge: Calculate the rising edge slope. If the slope is lower than a certain value, it is judged as noise or clutter and will not be triggered. Turbulence will "smooth out" the rising edge. This step can filter out a lot of interference.

[0101] Time window constraint: Based on the sound speed and standard distance at the current temperature, calculate the theoretical arrival time of the first wave and set a time window: ttheoretical ± Δt is allowed. Only waveforms falling within this window are recognized as the first wave. Δt is appropriately widened as the turbulence intensity increases, but cannot be widened indefinitely.

[0102] Continuity condition: A system is considered stable only if multiple consecutive sampling points can capture the first wave at similar locations. If a wave is captured in a single sampling but not before or after it, it is considered unstable and triggered.

[0103] The stability index of multiple echoes within the statistical time window is collected, the stability of the first wave is calculated, the stability of the first wave is classified into levels according to the preset stability threshold, and the strictness of the multi-condition joint criterion is dynamically adjusted according to the distribution characteristics of the thermal airflow to obtain the stability criterion for the first wave trigger.

[0104] Stability metrics include: number of valid triggers, standard deviation of the first wave arrival time, amplitude fluctuation range, and number of lost triggers. The formula for calculating the stability of the first wave is as follows:

[0105]

[0106] In the formula, It is the stability of the first wave. This refers to the number of valid triggers. It is the total number of samples. This is the standard deviation of the arrival time of the first wave. It is the weighting coefficient.

[0107] Stability threshold: ≥0.9 → Triggering stability.

[0108] 0.7≤ <0.9 → Basically stable.

[0109] <0.7→Instability in the first wave of triggering.

[0110] The greater the turbulence intensity TI, the wider the allowable time window Δt can be.

[0111] There are periodic pulsations in the airflow → Add pulsation period matching judgment to filter periodic interference.

[0112] A large angle between the airflow direction and the ultrasound path → increases the amplitude threshold to avoid false triggering by oblique reflected waves.

[0113] If a vortex region exists, enable waveform similarity judgment and compare it with the reference waveform. If the difference is too large, it is deemed invalid.

[0114] The first wave trigger is considered stable when the following conditions are met: the echo amplitude is within the dynamic threshold range.

[0115] The first wave occurred within the theoretical time window.

[0116] The slope of the rising edge of the waveform meets the requirements.

[0117] The location consistency is high and the time drift is small when triggered multiple times in a row.

[0118] The trigger success rate is higher than the set threshold, and there are no frequent losses.

[0119] The steps for setting dynamic threshold ranges and high-temperature dynamic calibration standards include:

[0120] Noise baseline data, signal attenuation characteristics, and disturbance amplitude characteristics at different temperatures are extracted from the test baseline data. Based on the noise baseline data, the basic threshold for attenuation with temperature is calculated.

[0121] Noise baseline data: Extract the raw noise amplitude when the sensor is not emitting ultrasonic waves at different temperatures.

[0122] Signal attenuation characteristics: Extract the air absorption coefficient at different temperatures, the test distance, and the total signal attenuation calculated from both.

[0123] Disturbance amplitude characteristics: Extract the turbulence intensity and thermal airflow fluctuation range at different temperatures, and calculate the maximum fluctuation of the echo amplitude.

[0124] First, a fixed noise multiplier is determined to set the baseline threshold at a level significantly higher than the noise level. The initial baseline threshold is obtained by multiplying the noise floor amplitude at the current temperature by this multiplier. Then, the initial baseline threshold is adjusted to compensate for the attenuation of the ultrasonic signal at that temperature, ensuring the threshold adapts to the weakening signal at high temperatures, ultimately yielding a baseline threshold that varies with temperature.

[0125] The basic threshold is corrected based on the signal attenuation characteristics and disturbance amplitude characteristics to determine the upper and lower limits of the threshold, thus obtaining the temperature threshold range.

[0126] The baseline threshold, after temperature attenuation compensation, is used as the lower threshold to ensure that weak echoes can be captured normally. Based on the amplitude fluctuation range caused by hot airflow and turbulence, a fluctuation margin is added to the lower threshold as the upper threshold to prevent false triggering caused by clutter and large-amplitude noise. For each temperature point, a corresponding lower and upper threshold are obtained in this way, forming the threshold range at that temperature.

[0127] Using the current temperature as the x-axis and the upper and lower limits of the threshold as the y-axis, two curves are generated using a piecewise linear interpolation method. Combined with the first wave stability feedback, the interval strictness is dynamically adjusted to obtain the dynamic threshold interval.

[0128] The lower and upper threshold limits for all temperature points are treated as two sets of data. With temperature on the horizontal axis and threshold value on the vertical axis, piecewise linear interpolation is used to connect the discrete points, generating two continuous and smooth threshold curves. During actual testing, the initial trigger stability is calculated in real time.

[0129] If the stability of the first wave is high, it indicates that the identification is reliable. The threshold range should be narrowed appropriately to improve the anti-interference ability.

[0130] If the stability of the first wave is low, it indicates that the wave is easily lost. The threshold range should be appropriately widened to improve the echo capture rate.

[0131] After curve generation and adaptive stability adjustment, a dynamic threshold range that can change with temperature in real time is finally obtained.

[0132] Using a fixed standard distance as the true benchmark, the original flight time is collected under multiple temperature gradients to establish a temperature sound speed correction coefficient model. Sound absorption attenuation and time delay drift are introduced to correct the first wave identification deviation, forming a high-temperature dynamic calibration calculation model.

[0133] A standard reflective target surface that is fixed in position and not easily deformed by heat is installed inside a high-temperature test chamber.

[0134] A high-precision ranging device is used to accurately calibrate the distance from the sensor probe to the target surface, and this calibration value is used as the true standard distance that remains constant throughout the test. During the test, the sensor and target surface are kept in a fixed position to ensure that the reference distance does not shift.

[0135] The temperature is increased sequentially according to a preset temperature gradient. After maintaining the temperature at each point and achieving a uniform temperature field, data acquisition begins. The sensor is driven to emit ultrasonic waves, and the raw flight time from the emission of the signal to the receipt of the echo signal is recorded. Multiple acquisitions are performed at each temperature point, and the average value is taken to obtain the stable raw flight time at that temperature.

[0136] Based on the true value of the standard distance and the measured original flight time, the actual propagation speed of ultrasound at the current temperature is calculated. The corresponding theoretical sound speed is calculated based on the current temperature and gas composition. The actual propagation speed is compared with the theoretical sound speed to obtain the sound speed correction coefficient at the current temperature. The sound speed correction coefficients at each temperature point are mapped to the temperature, forming a temperature-sound speed correction coefficient model that can be queried based on temperature.

[0137] Based on the air absorption coefficient at different temperatures and the test distance, the time deviation caused by the signal attenuation leading to the delayed identification of the first wave is calculated, and this delay is subtracted from the original flight time to complete the sound absorption attenuation correction.

[0138] Based on the turbulence intensity and airflow conditions at different temperatures, the first wave arrival time drift caused by the hot airflow is estimated, and the flight time is further corrected to eliminate deviations caused by airflow disturbances. After two corrections, a calibrated flight time that more closely approximates the actual propagation conditions is obtained.

[0139] By combining the corrected speed of sound with the corrected time of flight, the final calibrated distance measurement result is obtained.

[0140] The complete calculation process of the calibration model should be clearly defined, including the order and value method of sound velocity correction, attenuation correction, and airflow drift correction.

[0141] Establish calibration validity judgment rules, including the allowable range of distance measurement error at each temperature point and the repeatability requirements for multiple measurements.

[0142] The entire calculation process, correction methods, and judgment conditions are integrated to form a complete high-temperature dynamic calibration standard applicable to high-temperature operating conditions.

[0143] Perform multi-temperature gradient testing, control the temperature of the test chamber to rise to the target high temperature point at a preset rate and keep it at that temperature, drive the sensor under test to emit ultrasonic pulses and receive echo signals to obtain the original echo waveform data.

[0144] The steps to obtain the raw echo waveform data include:

[0145] Multiple test temperature zones are set from room temperature to the maximum operating temperature. Each temperature zone includes a heating section, a heat preservation and stabilization section, and a test section.

[0146] After confirming that the uniformity of the temperature field distribution inside the test chamber meets the preset requirements in the heat preservation and stabilization section, the test section begins.

[0147] During the test section, the sensor under test is triggered at high frequency to collect a preset number of raw echo waveform data, and the environmental parameters under this temperature range are recorded simultaneously.

[0148] Based on the rated operating temperature range of the sensor under test, a set of gradient temperature points is set from room temperature, such as 25℃, to the maximum operating temperature, such as 600℃. For example: 25℃→150℃→300℃→450℃→600℃. Each adjacent temperature point constitutes a test temperature zone. A heating rate is set for each temperature zone and input into the control system of the high-temperature test chamber. Simultaneously, a target temperature value is set for each temperature zone. When the temperature reaches the target value of the target temperature zone and stabilization is achieved, sensor triggering and data acquisition are automatically initiated.

[0149] The heating system of the high-temperature test chamber is activated, and the control system raises the temperature from the current temperature to the target temperature zone at a preset rate. The temperature curve is observed in real time to confirm that the heating process is stable and without overshoot (temperature exceeding the target value). Once the temperature display inside the chamber reaches the target value of the target temperature zone, the system automatically enters the heat preservation mode. During this stage, the temperature control system continuously fine-tunes the heating power to maintain a constant temperature. Real-time data from multiple temperature measuring points located inside the test chamber are retrieved. When the temperature difference between all measuring points is ≤ the preset value (e.g., ±1℃), and this state is maintained continuously for ≥20 minutes, it can be determined that the temperature field distribution is uniform and thermal equilibrium is achieved.

[0150] The original echo waveform data is filtered and enhanced according to the high temperature dynamic calibration standard. The arrival time of the first wave is extracted, and the validity of the first wave triggering is judged by combining the dynamic threshold range to obtain the corrected ranging data.

[0151] The steps to obtain the arrival time of the first wave include:

[0152] The calibration parameters corresponding to the current temperature are retrieved from the high-temperature dynamic calibration standard, and the original echo waveform is subjected to noise filtering to obtain a preliminary processed waveform.

[0153] Calibration parameters include sound velocity correction coefficient, sound absorption attenuation compensation, airflow drift compensation, and dynamic threshold range. The steps for noise filtering include:

[0154] Based on the noise floor size at the current temperature, select an appropriate filtering method to filter out high-frequency random noise in the original waveform.

[0155] Preserve the rising edge and amplitude characteristics of the effective echo to avoid over-filtering that could lead to the loss of the first wave information.

[0156] By combining the dynamic threshold range to determine the noise range, signals below the lower threshold limit are identified as background noise and smoothed and suppressed.

[0157] The amplitude enhancement step size of the initial processed waveform is adjusted based on the air absorption attenuation characteristics at the current temperature. The waveform is then jitter-corrected based on the turbulence intensity and airflow drift characteristics. The first processed waveform is obtained by combining the convex rising edge characteristics of the time region where the first wave is located.

[0158] The first processed waveform is compared with the dynamic threshold range corresponding to the current temperature to filter valid signals. Within the valid range, the first signal position that meets the amplitude and rise time requirements is identified, and the arrival time of the first processed waveform is obtained. The enhanced waveform is then compared with the dynamic threshold range corresponding to the current temperature. All valid signal points with amplitudes between the lower and upper limits of the dynamic threshold are filtered out, excluding noise below the lower limit and abnormal clutter above the upper limit. Within the valid signal range, the first signal position with a clear rise time and amplitude entering the threshold range is found as the candidate first wave region.

[0159] Within the candidate first wave region, the rate of change of the rising edge of the signal is detected to determine the location of the steepest rising edge. The starting point of the rising edge or the set trigger point is used as the initial identification of the first wave arrival time. Combined with the theoretical propagation time range in the high-temperature dynamic calibration standard, it is determined whether the position of the processed first wave waveform is within a reasonable time window, thus eliminating false signals.

[0160] The arrival time of the first wave is calibrated by using sound absorption attenuation delay compensation, airflow drift compensation, and sound velocity correction to output the arrival time of the first wave.

[0161] Based on the sound absorption attenuation delay compensation in the high-temperature dynamic calibration standard, the time of the first wave processed waveform is corrected to deduct the recognition lag caused by signal attenuation.

[0162] Based on the drift compensation caused by turbulence and hot airflow, the time deviation is further corrected to eliminate the time delay caused by airflow.

[0163] By incorporating the sound speed correction factor, the time position is fine-tuned to make the time value closer to the actual propagation time.

[0164] The steps to obtain calibrated distance measurement data include:

[0165] Based on the current temperature corresponding to the dynamic threshold range, check the signal amplitude at the first wave arrival time and the first wave position to determine whether it falls within the current dynamic threshold range. If so, the first wave trigger is considered valid.

[0166] Effective triggering: If the amplitude of the first wave is greater than or equal to the lower threshold and less than or equal to the upper threshold, it means that the first wave is a real ultrasonic wave reflection echo. The amplitude is strong enough but not strong enough to exceed the normal range. It is determined that the first wave triggering is effective and the first wave data can proceed to the next step.

[0167] Invalid trigger: If the amplitude of the first wave is below the lower limit of the threshold, it means that the first wave signal is too weak, and it is likely to be background noise or an invalid signal with excessive attenuation, and is therefore determined to be invalid. If the amplitude is above the upper limit of the threshold, it means that the signal is too strong, and it is likely to be external noise, and is also determined to be invalid.

[0168] The valid arrival time of the first wave will be determined and corrected according to the high-temperature dynamic calibration standard to obtain the calibrated flight time.

[0169] At high temperatures, the higher the air temperature, the faster the ultrasonic waves travel, which can lead to a shorter arrival time of the first wave. It is necessary to fine-tune the arrival time of the first wave according to the sound speed correction coefficient based on the current temperature to eliminate the deviation caused by the change in sound speed.

[0170] At high temperatures, air absorbs ultrasonic energy, causing a decrease in the amplitude of the first wave and a delay in recognition. In other words, the actual arrival time of the first wave is earlier than the original recognition time. It is necessary to subtract the time delay compensation caused by sound absorption attenuation to restore the true arrival time of the first wave.

[0171] Hot airflow and turbulence can cause the ultrasonic wave propagation path to deviate and its velocity to fluctuate, which in turn causes the arrival time of the first wave to drift. The time needs to be finally corrected according to the drift compensation amount corresponding to the turbulence intensity to eliminate the influence of airflow disturbance.

[0172] Using the calibrated time of flight and the ultrasonic velocity at the current temperature, the one-way distance from the sensor to the target reflecting surface is calculated.

[0173] Multiply the actual speed of sound at the current temperature by the calibration flight time to obtain the total round-trip distance of the ultrasonic wave. Divide the total distance by 2 to obtain the one-way distance from the sensor to the target reflecting surface. Ensure that the units of time and speed of sound are consistent during the calculation.

[0174] By combining the one-way distance with the system error compensation value, and averaging multiple sets of valid data at the same temperature point, the corrected distance measurement data is obtained.

[0175] Retrieve the preset "system error compensation value," a fixed value obtained through prior room temperature calibration and equipment calibration. This value is used to eliminate fixed deviations caused by sensor installation misalignment, circuit errors, structural deformation, etc. Add or subtract this system error compensation value to the one-way distance to eliminate the fixed error.

[0176] At the same temperature point, we will continuously collect multiple sets of initial wave data. After judgment, we will obtain multiple sets of "triggered valid" data. Each set of valid data will calculate a one-way distance value after error compensation.

[0177] For all valid compensated distance values ​​at the same temperature point, an arithmetic mean is calculated, i.e., all valid distance values ​​are added together and then divided by the number of valid data sets. This eliminates random fluctuations in a single measurement and can truly and accurately reflect the distance from the sensor to the target reflective surface.

[0178] By comparing the calibrated distance measurement data with the true value of the standard distance, the measurement error and repeatability accuracy are calculated. If the stability criterion of the first wave trigger does not meet the requirements or the measurement error exceeds the allowable range in multiple consecutive test cycles, the sensor under test is deemed to be unqualified under high temperature conditions.

[0179] The steps for comparing and correcting distance measurement data with the true standard distance include:

[0180] The calibrated distance measurement data for each test cycle is compared with the true standard distance value, and the measurement error at each temperature point is calculated.

[0181] Compare the calibrated distance measurement data in each test cycle with the true standard distance value one-to-one to clarify the deviation of each set of data from the true value—focusing on the "direction of deviation" and "magnitude of deviation" to avoid looking only at the numerical value and ignoring the pattern of deviation.

[0182] For each set of comparative data, the measurement error for a single period is calculated. The "absolute error" is obtained by subtracting the true standard distance value from the calibrated distance measurement data for that period. The "relative error" is then obtained by dividing the absolute error by the true standard distance value. The two errors can be used together to more comprehensively reflect the accuracy of distance measurement.

[0183] At the same temperature point, select all the calibration ranging data of the first wave trigger that are valid and calculate the average value. Calculate the deviation of each set of valid data from the average value and take the difference between the maximum and minimum deviation values ​​as the repeatability accuracy.

[0184] Repeatability accuracy determination: Compare the calculated repeatability accuracy with the preset allowable range. If it exceeds the allowable range, it indicates that the distance measurement stability of the sensor at that temperature point is insufficient, and its performance in subsequent test cycles needs to be closely monitored.

[0185] For each test cycle, the sensor under test is comprehensively judged based on measurement error, repeatability accuracy, and initial trigger stability criteria. If any one of the requirements is not met, the sensor is judged to be unqualified.

[0186] For each test cycle, check whether the first trigger of that cycle meets the stability criteria. The specific checks include: whether the first trigger is effective, whether the amplitude is within the dynamic threshold range, and whether the rising edge is steep.

[0187] Whether the stability of the first wave in multiple consecutive cycles meets the standard (e.g., stability ≥ 0.9).

[0188] There were no consecutive invalid triggers or significant changes in the initial position.

[0189] If a certain cycle does not meet any of the above conditions, it is determined that the "stability of the first wave trigger does not meet the requirements" for that cycle.

[0190] Check measurement error cycle by cycle: Combine measurement error to check whether the absolute error and relative error of each test cycle are within the preset allowable range. If they exceed the range, the cycle is judged to be "unqualified in measurement error".

[0191] Continuous Period Judgment Rules: Focus on performance across multiple consecutive test periods to avoid misjudgments caused by single, accidental interference. Specific rules are as follows:

[0192] Preset the number of consecutive judgment cycles.

[0193] If, within the preset continuous period, the error occurs such as "the stability of the first wave trigger does not meet the requirements" or "the measurement error exceeds the allowable range", or both occur simultaneously, then proceed to the next step of non-compliance judgment.

[0194] If only a single cycle fails to meet the requirements, but subsequent cycles return to normal, it is not considered unqualified; instead, that cycle is marked as abnormal, and testing and observation continue.

[0195] Formal determination of non-compliance: Clearly state the determination result – “The sensor under test failed the test under high temperature conditions”, and indicate the temperature points where non-compliance occurred. If only one high temperature point fails, it must be clearly marked. If multiple temperature points fail, they must be listed one by one.

[0196] Record and archive all core reasons for non-compliance and specific data to ensure traceability, with a focus on the following:

[0197] Specific manifestations of non-compliance include: unstable initial triggering, measurement error exceeding the allowable range, or both. Corresponding test cycles, calibrated distance data, true standard distance values, measurement error values, and initial wave stability data are required. Environmental parameters such as test temperature, turbulence intensity, and air absorption coefficient at the time of non-compliance are also important for analyzing the cause of the non-compliance.

[0198] Based on the same general inventive concept, this invention also protects a testing system for an ultrasonic ranging sensor under high-temperature operating conditions, comprising:

[0199] The parameter benchmark construction module is used to collect the physical specifications of the sensor under test and the environmental parameters of the high-temperature operating conditions, identify the thermal airflow distribution characteristics in the high-temperature operating conditions, extract the air absorption coefficient and turbulence intensity from the environmental parameters, and combine them with the thermal airflow distribution characteristics to form test benchmark data.

[0200] The criterion setting module is used to construct the first-wave trigger stability criterion under low signal-to-noise ratio based on test benchmark data, and to set the dynamic threshold range and high-temperature dynamic calibration standard that vary with temperature.

[0201] The multi-temperature gradient test module is used to perform multi-temperature gradient tests, control the temperature of the test chamber to rise to the target high temperature point at a preset rate and maintain the temperature, drive the sensor under test to emit ultrasonic pulses and receive echo signals to obtain the original echo waveform data.

[0202] The echo processing and correction module is used to filter and enhance the original echo waveform data according to the high-temperature dynamic calibration standard, extract the arrival time of the first wave, and determine the validity of the first wave triggering by combining the dynamic threshold range to obtain the corrected ranging data.

[0203] The accuracy assessment module is used to compare the corrected distance measurement data with the true value of the standard distance, calculate the measurement error and repeatability accuracy. If the stability criterion of the first wave is not met or the measurement error exceeds the allowable range in multiple consecutive test cycles, the sensor under test is determined to be unqualified under high temperature conditions.

[0204] In summary, the ultrasonic ranging sensor testing method and system provided in this embodiment for high-temperature operating conditions effectively compensates for the attenuation and distortion of sound waves caused by the high-temperature medium by introducing corrections for air absorption coefficient and turbulence intensity. This makes the extracted first wave arrival time closer to the true value, significantly reducing ranging error. The introduction of dynamic threshold range and first wave trigger stability criterion enables the sensor to maintain stable triggering performance at different temperature points, solving the problem of "random jumps" or "no signal" caused by noise interference at high temperatures, and enhancing triggering reliability. Through multi-temperature gradient testing and comprehensive judgment logic, inferior sensors that perform well at room temperature but experience a sharp drop in performance at high temperatures are effectively eliminated, ensuring the environmental adaptability of the manufactured products.

[0205] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., including several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in various embodiments or some parts of the embodiments. Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention 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; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A testing method for an ultrasonic ranging sensor under high-temperature operating conditions, characterized in that, include: Collect the physical specifications of the sensor under test and the environmental parameters of the high-temperature operating condition under test, identify the thermal airflow distribution characteristics in the high-temperature operating condition under test, extract the air absorption coefficient and turbulence intensity from the environmental parameters, and combine the thermal airflow distribution characteristics to form test benchmark data; Based on the aforementioned test benchmark data, a first-wave trigger stability criterion under low signal-to-noise ratio is constructed, and a dynamic threshold range that varies with temperature and a high-temperature dynamic calibration standard are set. Perform multi-temperature gradient testing, control the temperature of the test chamber to rise to the target high temperature point at a preset rate and keep it at that temperature, drive the sensor under test to emit ultrasonic pulses and receive echo signals to obtain the original echo waveform data; The original echo waveform data is filtered and enhanced according to the high-temperature dynamic calibration standard, the arrival time of the first wave is extracted, and the validity of the first wave triggering is determined by combining the dynamic threshold range to obtain the corrected ranging data. By comparing the corrected distance measurement data with the true value of the standard distance, the measurement error and repeatability accuracy are calculated. If the first-wave trigger stability criterion does not meet the requirements or the measurement error exceeds the allowable range in multiple consecutive test cycles, the sensor under test is determined to be unqualified under high-temperature conditions.

2. The testing method for an ultrasonic ranging sensor under high-temperature operating conditions according to claim 1, characterized in that: The steps for obtaining the thermal gas distribution characteristics include: The rated operating parameters and structural parameters of the sensor under test are collected as the physical specifications parameters, and the temperature range, heating rate, holding time, temperature fluctuation range, medium parameters and sensor layout parameters corresponding to the high temperature condition under test are collected as the environmental parameters. A test environment was set up to simulate actual high-temperature working conditions. Temperature distribution was monitored in real time along the ultrasonic propagation path, and airflow velocity, direction and pressure fluctuation data were collected as airflow data. The natural convection intensity, hot wind speed direction and stability, and airflow disturbance amplitude and frequency are extracted from the airflow data as the hot airflow distribution characteristics.

3. The testing method for an ultrasonic ranging sensor under high-temperature operating conditions according to claim 2, characterized in that: The steps for constructing the test benchmark data include: Temperature data at multiple locations along the ultrasonic propagation path are extracted from the environmental parameters. Gas composition, ambient atmospheric pressure, humidity, and dust concentration are extracted as medium environmental parameters. The ultrasonic center frequency and transmission power are extracted from the physical specification parameters as sound wave related parameters. Based on the temperature data and the sound wave related parameters, the theoretical sound absorption coefficient is calculated according to the acoustic attenuation model. Based on the medium environment parameters, the theoretical sound absorption coefficient is corrected to obtain the sound absorption coefficient corresponding to each temperature point, which is then used as the air sound absorption coefficient. The average wind speed is calculated by continuously collecting wind speed sequences at preset time intervals. The root mean square of the wind speed fluctuation is calculated as the wind speed fluctuation amplitude. The ratio of the wind speed fluctuation amplitude to the average wind speed is used as the single-point turbulence intensity. The turbulence intensity at each of the multiple measuring points along the ultrasonic propagation path is calculated, and the average value is taken to obtain the turbulence intensity under the current working condition. The test baseline data is obtained by structurally integrating the hot airflow distribution characteristics, the air sound absorption coefficient, and the turbulence intensity according to the temperature conditions.

4. The testing method for an ultrasonic ranging sensor under high-temperature operating conditions according to claim 1, characterized in that: The steps for constructing the first-wave triggering stability criterion include: The total attenuation rate is calculated based on the air absorption coefficient and the test distance. The theoretical value of the echo amplitude is calculated by combining the sensor's transmitting power and receiving gain. The signal-to-noise ratio is calculated by comparing it with the circuit noise amplitude. The operating conditions are divided into multiple signal-to-noise levels based on the turbulence intensity. A multi-condition joint criterion is constructed based on amplitude condition, waveform rising edge condition, time window constraint condition, and continuity condition; The stability index of multiple echoes within the statistical time window is collected, the stability of the first wave is calculated, the stability of the first wave is classified into levels according to the preset stability threshold, and the strictness of the multi-condition joint criterion is dynamically adjusted according to the thermal airflow distribution characteristics to obtain the stability criterion for the first wave triggering.

5. The testing method for an ultrasonic ranging sensor under high-temperature operating conditions according to claim 4, characterized in that: The steps for setting the dynamic threshold range and the high-temperature dynamic calibration standard include: Noise baseline data, signal attenuation characteristics, and disturbance amplitude characteristics at different temperatures are extracted from the test baseline data, and a basic threshold for attenuation with temperature is calculated based on the noise baseline data. The base threshold is corrected based on the signal attenuation characteristics and the disturbance amplitude characteristics to determine the upper and lower limits of the threshold and obtain the temperature threshold range. Using the current temperature as the x-axis and the upper and lower limits of the threshold as the y-axis, two curves are generated using a piecewise linear interpolation method. Combined with the first wave stability feedback, the interval strictness is dynamically adjusted to obtain the dynamic threshold interval. Using a fixed standard distance as the true benchmark, the original flight time is collected under multiple temperature gradients to establish a temperature sound speed correction coefficient model. Sound absorption attenuation and time delay drift are introduced to correct the first wave identification deviation, forming a high-temperature dynamic calibration calculation model.

6. The testing method for an ultrasonic ranging sensor under high-temperature operating conditions according to claim 1, characterized in that: The steps for obtaining the original echo waveform data include: Multiple test temperature zones are set from room temperature to the maximum operating temperature. Each temperature zone includes a heating section, a heat preservation and stabilization section, and a test section. After confirming that the uniformity of the temperature field distribution inside the test chamber meets the preset requirements in the heat preservation and stabilization section, the test section is entered. In the test section, the sensor under test is triggered at high frequency to collect a preset number of raw echo waveform data, and the environmental parameters under this temperature range are recorded simultaneously.

7. The testing method for an ultrasonic ranging sensor under high-temperature operating conditions according to claim 1, characterized in that: The steps for obtaining the arrival time of the first wave include: The calibration parameters corresponding to the current temperature are retrieved from the high-temperature dynamic calibration standard, and the original echo waveform is subjected to noise filtering to obtain a preliminary processed waveform. The amplitude enhancement step size of the preliminary processed waveform is adjusted according to the air absorption attenuation characteristics at the current temperature, and the waveform is jittered according to the turbulence intensity and airflow drift characteristics. The first wave processed waveform is obtained by combining the convex rising edge characteristics of the time region where the first wave is located. The arrival time of the first wave processed waveform is calibrated by sound absorption attenuation delay compensation, airflow drift compensation, and sound speed correction, and the arrival time of the first wave is output.

8. The testing method for an ultrasonic ranging sensor under high-temperature operating conditions according to claim 1, characterized in that: The steps for obtaining the corrected ranging data include: Based on the dynamic threshold range corresponding to the current temperature, check the signal amplitude at the first wave location at the first wave arrival time, and determine whether it falls within the current dynamic threshold range. If it does, the first wave trigger is deemed valid. The valid arrival time of the first wave will be determined and corrected according to the high-temperature dynamic calibration standard to obtain the calibrated flight time. Using the calibrated flight time and the ultrasonic velocity at the current temperature, the one-way distance from the sensor to the target reflecting surface is calculated. The corrected distance measurement data is obtained by combining the single-trip distance with the system error compensation value and averaging multiple sets of valid data at the same temperature point.

9. The testing method for an ultrasonic ranging sensor under high-temperature conditions according to claim 8, characterized in that: The steps for comparing the corrected distance measurement data with the true standard distance include: The calibrated distance measurement data in each test cycle is compared with the true value of the standard distance, and the measurement error at each temperature point is calculated. At the same temperature point, the calibration ranging data of all cycles that are effective in the first wave of triggering are screened and the average value is calculated. The deviation of each group of effective data from the average value is calculated, and the difference between the maximum deviation value and the minimum deviation value is taken as the repeatability accuracy. For each test cycle, the sensor under test is comprehensively judged based on the measurement error, repeatability accuracy, and first-wave trigger stability criteria. If any one of the requirements is not met, the sensor is judged to be unqualified.

10. A testing system for an ultrasonic ranging sensor under high-temperature operating conditions, which is applied to the testing method for an ultrasonic ranging sensor under high-temperature operating conditions as described in any one of claims 1 to 9, characterized in that, The testing system includes: The parameter benchmark construction module is used to collect the physical specification parameters of the sensor under test and the environmental parameters of the high-temperature working condition under test, identify the thermal airflow distribution characteristics in the high-temperature working condition under test, extract the air sound absorption coefficient and turbulence intensity from the environmental parameters, and combine the thermal airflow distribution characteristics to form test benchmark data. The criterion setting module is used to construct the first-wave trigger stability criterion under low signal-to-noise ratio based on the test benchmark data, and to set the dynamic threshold range and high-temperature dynamic calibration standard that vary with temperature. The multi-temperature gradient test module is used to perform multi-temperature gradient tests, control the temperature of the test chamber to rise to the target high temperature point at a preset rate and keep it at that temperature, drive the sensor under test to emit ultrasonic pulses and receive echo signals to obtain the original echo waveform data. The echo processing and correction module is used to filter and enhance the original echo waveform data according to the high-temperature dynamic calibration standard, extract the arrival time of the first wave, and determine the validity of the first wave triggering in combination with the dynamic threshold range to obtain the corrected ranging data. The accuracy assessment and judgment module is used to compare the corrected distance measurement data with the true value of the standard distance, calculate the measurement error and repeatability accuracy. If the first wave trigger stability criterion does not meet the requirements or the measurement error exceeds the allowable range in multiple consecutive test cycles, the sensor under test is judged to be unqualified under high temperature conditions.

Images