A vehicle-mounted rainfall sensor anti-laser radar interference test system and test method

Abstract

This invention discloses a comprehensive testing system and method for resisting lidar interference in vehicle-mounted rain sensors, relating to the field of automotive sensor testing technology. The system includes a control system, an electromagnetic compatibility anechoic chamber, a vehicle body glass angle simulation device, a wiper loading mechanism, a rain simulation system, a lidar interference simulation device, a multi-degree-of-freedom vibration table, an ambient light simulation device, a temperature and humidity control device, and a multi-channel data acquisition system. This invention can simultaneously replicate complex environments such as vehicle installation posture, wiper operation, continuous adjustable rainfall, multi-source lidar interference, road vibration, and light, temperature, and humidity within a highly shielded anechoic chamber. It completes dry-state benchmark, single / dual interference source dynamic and static, rain coupling, vibration coupling, and multi-factor orthogonal combination tests. Through high-precision synchronous acquisition and data processing, it generates calibration maps and outputs interference thresholds, safety boundaries, and environmental compensation parameters, achieving a comprehensive, accurate, and automated evaluation of the lidar interference resistance performance of rain sensors. This solves the problems of traditional tests being unable to reproduce complex vehicle operating conditions and lacking sufficient quantitative assessment.

Description

Technical Field

[0001] This invention relates to the field of automotive sensor testing technology, specifically to a test system and method for testing the anti-LiDAR interference of an on-board rain sensor. Background Technology

[0002] The rain sensor in a car is mounted behind the windshield. Its function is to adjust the wiper action based on the amount of rain falling on the glass. It works by using a built-in light-emitting diode to emit far-infrared light. When the glass surface is dry, almost 100% of the light is reflected back. The more rain on the glass, the less light is reflected back, resulting in faster wiper action. LiDAR is a radar system that uses laser beams to detect the position, velocity, and other characteristics of a target. Its working principle involves emitting a detection signal (laser beam) towards the target, then comparing the received signal reflected back from the target (target echo) with the emitted signal. After appropriate processing, relevant information about the target can be obtained. Therefore, when two vehicles are facing each other, the laser emitted by the LiDAR can interfere with the signal of the rain sensor. If the rain sensor of the illuminated vehicle has weak electromagnetic interference immunity, an anomaly will occur.

[0003] Currently, rain sensors, wipers, controllers, and lidar in the industry are all tested for electromagnetic compatibility separately. The test conditions for each component are not clearly defined. Although the individual electromagnetic compatibility is qualified, without undergoing integration testing, electromagnetic interference incidents may occur after they are released to the market.

[0004] Therefore, it is essential to conduct radiation immunity tests on windshield wiper systems under lidar interference: to clarify the interaction test between the lidar interference signal strength and the acceptable electromagnetic redundancy of the rain sensor. Summary of the Invention

[0005] The purpose of this invention is to provide a test system and method for testing the anti-lidar interference of vehicle-mounted rain sensors, so as to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a rain gauge sensor anti-interference testing system, comprising: The test environment unit is configured to provide a controlled electromagnetic shielding environment; The sensor mounting and adjustment unit is configured to fix the rainfall sensor to be measured at an adjustable mounting angle. The windshield wiper simulation unit is configured to simulate the operating state of a vehicle's windshield wipers. The rainwater simulation unit is configured to provide steplessly adjustable rainfall simulation. The lidar interference simulation unit is configured to generate lidar interference signals with adjustable parameters and to operate at preset spatial positions, motion trajectories, and orientations. The vibration simulation unit is configured to provide multi-degree-of-freedom vibration simulation. The environmental simulation unit is configured to provide environmental simulation with adjustable spectrum, illuminance, temperature, and humidity. The central control unit is configured to control the emission parameters, spatial position, movement trajectory and orientation of the lidar interference simulation unit, and to control the rain simulation unit to achieve stepless rainfall adjustment; The data acquisition unit is configured to be electrically connected to the central control unit and at least one sensor, and is configured to synchronously acquire test data.

[0007] The aforementioned test environment unit includes a semi-anechoic chamber or a fully anechoic chamber, the chamber being equipped with absorbing materials, and the shielding effectiveness and background noise level of the chamber meeting the electromagnetic compatibility test requirements.

[0008] The aforementioned rainwater simulation unit includes an air source, a water storage tank, a flow meter, a deceleration valve, a water pump, and a nozzle array consisting of multiple independently controllable atomizing nozzles. The central control unit is configured to achieve stepless adjustment of the water flow rate by adjusting the water pump speed and the opening of the deceleration valve, and to automatically adjust the rainfall value to the user-set target value through closed-loop PID control based on a pre-generated calibration curve, supporting programming of the rainfall change rate.

[0009] As described above, the laser radar interference simulation unit is mounted on a motion mechanism, which includes a linear guide rail driven by a ball screw and a rotary table driven by a harmonic reducer; the central control unit is configured to programmatically control the linear motion speed, acceleration, position, rotational angular velocity, and angle of the laser radar interference simulation unit; the emission parameters supported by the laser radar interference simulation unit include selectable wavelength, adjustable pulse width, adjustable repetition frequency, adjustable peak power, and adjustable laser beam divergence angle.

[0010] The vibration simulation unit described above includes a six-degree-of-freedom vibration table, the frequency, acceleration and displacement of which are adjustable within a set range, and the vibration table has a built-in typical vibration power spectral density curve.

[0011] The data acquisition unit described above adopts a PXIe architecture and is equipped with a high-precision synchronization module. Its acquisition channels include a rain sensor output signal channel, a wiper motor current and position signal channel, a real-time position and angle channel of the interference simulator, a vibration table acceleration feedback channel, an ambient light intensity and temperature and humidity channel, and an actual water flow velocity channel; all channels are configured to be synchronized via a precision time protocol.

[0012] This invention also discloses a method for testing the anti-interference capabilities of a rain gauge, comprising the following steps: Benchmark test procedure: Under a rainless and interference-free setting environment, continuously monitor the output of the rain sensor to confirm that it is in a normal "rainless" state. Single interference source test steps: Fix the interference simulator at a set position and angle, and gradually change its emission parameters to record the interference parameters when the rain sensor first falsely triggers as the threshold; or control the interference simulator to move along a straight trajectory, continuously emit lasers during the movement, and synchronously record the output of the rain sensor and the real-time distance to extract the critical distance, relative speed and instantaneous incident angle at which false triggering or signal jitter occurs. Multi-interference source test procedure: Control multiple interference simulators to move towards each other and interleave, to record the response of the rain sensor throughout the process and evaluate the superposition effect; Rainy Condition Test Procedure: Under the continuously adjustable set rainfall value, repeat the above interference test items to plot the rainfall-interference threshold curve; and Multi-factor coupling and data analysis steps: conduct vibration and rainfall coupling tests, ambient light and temperature and humidity influence tests, combined working condition traversal tests, and preprocess the collected data, extract features, generate multi-dimensional relationship diagrams, and output calibration conclusions.

[0013] The aforementioned multi-factor coupling and data analysis steps include: rainfall scanning under a fixed vibration spectrum, comparing the results with data under no vibration conditions, and calculating the decrease in the interference threshold; and vibration frequency scanning to identify the frequency at which the output amplitude peaks.

[0014] The aforementioned multi-factor coupling and data analysis steps include: performing ambient light scanning to plot the illuminance-false trigger rate curve; performing infrared background light testing to observe the influence of infrared background on the sensor's interference sensitivity; and performing temperature characteristic testing to record the sensor's interference threshold drift at different temperatures.

[0015] The aforementioned multi-factor coupling and data analysis steps include: using orthogonal experimental design to select multiple factors and levels for combined testing; recording the number and type of abnormal wiper actions; performing analysis of variance to identify the main effects and interaction effects that have a significant impact on abnormal actions, and calibrating the working boundary of the system.

[0016] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention can reproduce multi-dimensional vehicle-mounted composite operating conditions on a single platform, realistically reproducing the actual vehicle usage environment, and providing comprehensive test coverage; laser interference, rainfall, illumination, and vibration are all adjustable in a closed loop, resulting in high simulation accuracy and good consistency; multi-channel synchronous acquisition and automated testing significantly improve efficiency; it can quantitatively identify interference thresholds, sensitive frequencies, and environmental influence patterns, directly supporting algorithm and structural optimization; it effectively solves the shortcomings of traditional testing methods, such as single operating conditions, uncontrollable interference, and unreliable data, significantly improving the anti-laser radar interference capability and operational reliability of vehicle-mounted rain sensors. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the system layout of the present invention; Figure 2 This is a schematic diagram of the testing steps of the present invention. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly, completely, and accurately described below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0019] The entire system will be installed in a semi-anechoic chamber (12) or a fully anechoic chamber conforming to GB / T 6113.104-2016. The shielding effectiveness of the chamber must be no less than 80 dB (10 kHz ~ 18 GHz), and the background noise level must be at least 6 dB below the limit. The chamber will be equipped with absorbing materials to eliminate the influence of multipath reflections on interference signal testing. The ambient temperature range within the chamber is -40℃ to 85℃, with a control accuracy of ±1℃; the humidity range is 20% to 95%RH, with a control accuracy of ±5%RH; and the illuminance range is 0 to 100 klx, using closed-loop feedback control. Before testing, the chamber environment will be set to standard operating conditions: temperature 25℃ ±2℃, humidity 50% ±10%RH, ambient light 1000 lx ± 100 lx (simulating daytime driving conditions). All unnecessary electromagnetic equipment (such as lighting fixtures, surveillance camera power supplies, etc.) will be turned off, leaving only the necessary power supply to the instruments for testing. The background noise in the anechoic chamber was scanned and confirmed using an electromagnetic interference receiver to ensure that no abnormal interference sources were present.

[0020] The rain sensor 4 to be tested is fixed on the windshield angle template 8 of the vehicle body according to the actual vehicle installation angle. The angle template is made of aluminum alloy and the surface is anodized to reduce reflection. The adjustable angle range of the template is 0°~90° with an accuracy of ±0.5°. It is driven by a stepper motor and can automatically change the angle during the test. Adjust the wiper arm gravity matching block 2 so that the pressure between the wiper blade and the glass surface is 15N~25N (adjustable, 1N step). Use a force gauge to perform three-point calibration in the middle of the wiper blade. The wiping angle range is set to 0°~120°, corresponding to the windshield curvature of different models (sedans, SUVs, MPVs, etc.). Connect the wiper motor 3 and the controller power supply, and send CAN / LIN commands through the control system (1) to confirm that the wiper can operate normally. The wiping frequency is adjustable from 30 to 80 times / minute, divided into three levels: low speed, medium speed, and high speed, as well as a custom continuous adjustment mode. After installation, run the wipers 10 times to check for any sticking, abnormal noises, or uneven wiping.

[0021] Pneumatic water circulation system calibration and stepless rainfall adjustment: Connect to air source 10. The air source output pressure adjustment range is 0.2~0.8MPa. It is recommended to use an oil-free air compressor equipped with a dryer filter to avoid oil in the water mist affecting optical testing. The built-in deceleration valve reduces the pressure to 0.1~0.3MPa, driving the deionized water (conductivity ≤5μS / cm, to prevent nozzle scaling) in the water storage tank 11 to be delivered to the rainwater simulation multi-nozzle circulation system 6 via flow meter 9. The nozzle array consists of 16 independently controllable atomizing nozzles, arranged in a rectangular distribution (coverage area 300mm×200mm). The flow rate of each nozzle can be calibrated individually to ensure rainfall distribution uniformity ≥90%.

[0022] Control system 1 achieves stepless adjustment of water flow rate, ranging from 0 to 200 L / min, with a control accuracy of ±2 L / min, by adjusting the water pump speed (0~3000 rpm) and the deceleration valve opening (0~100%). Calibration method: Place a standard rain gauge (accuracy ±1%, sampling area 100 cm²) at the rain sensor installation location. Starting from 0 L / min, gradually increase the flow rate to 200 L / min in 5 L / min increments. After stabilizing for 30 seconds at each point, record the deviation between the actual flow rate and the set value to generate a calibration curve (quadratic polynomial fitting, R²≥0.999). In subsequent tests, the user can directly input any target rainfall value (e.g., 0.5 L / min, 3.2 L / min, 15.8 L / min, 78.3 L / min, etc.), and the system will automatically adjust to the target value using a closed-loop PID controller, with an adjustment time ≤10 seconds and overshoot ≤5%. In addition, the system supports programming of rainfall change rate, such as linearly increasing from 0 to 150 L / min at a constant rate (0.5 L / min / s), or changing according to sine wave or square wave patterns to simulate showers or sudden rainfall events.

[0023] The laser radar signal interference simulator ①5 is mounted on a guide rail. The guide rail is driven by a high-precision ball screw with an effective stroke of 8m, an adjustable speed of 0~60km / h (corresponding to 16.7m / s), a maximum acceleration of 2m / s², a positioning accuracy of ±1mm, and a repeatability of ±0.1mm. A grating ruler is installed on the guide rail for position feedback. A rotary table (14) is located below the interference simulator, driven by a harmonic reducer, which can rotate continuously ±180° around the vertical axis, with an adjustable angular velocity of 0~90° / s, a maximum angular acceleration of 30° / s², and a positioning accuracy of ±0.1°. The interference simulator supports outputting pulsed lasers with wavelengths of 905nm or 1550nm, with an adjustable pulse width of 1~100ns (1ns step), an adjustable repetition frequency of 1~100kHz (1kHz step), and an adjustable peak power of 0~100W (0.1W step). The laser beam divergence angle is adjustable from 0.1 mrad to 10 mrad, achieved through a beam expander or beam reducer. A separate lidar signal interference simulator ②7 serves as a second interference source, capable of independent or synchronous movement. The position, orientation, trajectory, and emission parameters of both simulators can be programmed and controlled by the control system 1, supporting various modes such as relative motion, cooperative motion, and opposing motion. Before testing, a laser power meter is used to calibrate the actual received power density at the rain sensor installation location, and the free-space path loss is recorded for subsequent data analysis.

[0024] A six-degree-of-freedom vibration table is installed under the test bench. The vibration table uses electro-hydraulic servo or electromagnetic drive, with a frequency range of 1~200Hz, a maximum acceleration of ±1.5g in the Z-axis (no load), ±0.5g in the X / Y axes, and a peak-to-peak displacement of ±25mm (Z-axis) and ±10mm (X / Y-axis). The vibration table controller has built-in power spectral density (PSD) curves for typical vibrations such as urban roads, highways, idling, and cobblestone roads, and also supports user-defined PSDs. During installation, the mounting bases of the rain sensor 4 and the glass angle template 8 are connected to the vibration table surface via a rigid adapter plate and secured with at least four M10 high-strength bolts to ensure that the vibration transmission attenuation is ≤3dB (within 200Hz). Triaxial accelerometers are attached to the table surface and sensor mounting points for closed-loop control and monitoring of transmission characteristics. Before operating the vibration table, a no-load frequency sweep (1~200Hz, sine wave, 0.5g) must be performed to confirm the absence of resonance abnormalities. The frequency sweep should then be repeated after installing the load.

[0025] An adjustable spectrum LED array is arranged at the top and front of the darkroom. The LED array uses five color channels: RGB + cool white + warm white, with switchable color temperatures of 3000K, 4500K, and 6500K, and a color rendering index ≥90. The illuminance adjustment range is 0~120klx (at a distance of 1m from the sensor mounting surface), with a uniformity ≥80% (9-point measurement method). Two infrared supplementary lights (peak wavelength 940nm±10nm, half-width at half-maximum ≤30nm), with adjustable power from 0~50W, are also provided to simulate the infrared light source of oncoming vehicles. A power meter probe (response range 300~1100nm, dynamic range 60dB) is installed close to the rain sensor mounting location to provide real-time illuminance feedback to the control system, achieving closed-loop adjustment. All lights are DC powered and equipped with EMI filters to avoid introducing additional electromagnetic interference.

[0026] The temperature and humidity control unit is linked to the darkroom air conditioning system. An industrial-grade constant temperature and humidity unit is used, with top-supply and side-return airflow, and an air velocity ≤0.5m / s to avoid affecting the spray pattern. Temperature setting range: -40~85℃, fluctuation ±1℃; relative humidity setting range: 20~95%RH, fluctuation ±5%RH. Heating / cooling rate ≥1℃ / min, dehumidification capacity ≥2kg / h. A temperature and humidity recorder (accuracy ±0.3℃, ±2%RH) is installed at the sensor location to verify environmental conditions.

[0027] The data acquisition system adopts a PXIe architecture and is equipped with a high-precision synchronization module. Acquisition channels include: Rain sensor output signals: analog voltage (±10V, 16-bit, sampling rate ≥10kHz) or digital signal (CAN / LIN, message timestamp accuracy ≤0.1ms); wiper motor current (Hall current clamp, bandwidth DC~100kHz) and wiper position Hall signal (digital, sampling rate 1kHz); real-time position (grating ruler feedback, resolution 1μm), angle (encoder, resolution 0.01°), and transmit power (internal monitoring, sampling rate 1kHz) of the interference simulator; vibration table acceleration feedback (triaxial ICP accelerometer, sensitivity 100mV / g, sampling rate 2kHz); ambient light intensity (silicon photocell probe, sampling rate 100Hz), temperature and humidity (digital sensor, sampling rate 1Hz); actual water flow rate (electromagnetic flowmeter, 4~20mA output, sampling rate 100Hz); darkroom background noise (optional, recorded by spectrum analyzer).

[0028] All channels are synchronized via the IEEE 1588 Precision Time Protocol, with a time synchronization accuracy of ≤1ms. Data storage uses TDMS format, and the maximum recording duration for a single test is ≥24 hours.

[0029] The testing process is as follows: Rainless (dry) benchmark test: Turn off the water circulation system and wipe the glass surface with a clean non-woven cloth to ensure there are no water droplets or oil stains. Use a laser level to confirm that the glass angle template is level. Set the rain sensor angle to 45° (adjustable according to different vehicle models), wiper clamping force to 20N, and wiping frequency to 50 times / minute. Turn on the vibration table and apply a random vibration spectrum of urban roads (2~30Hz, PSD=0.01g² / Hz, total RMS=0.3g). Turn on ambient light at 1000lx±100lx. Preheat all equipment for 30 minutes until the temperature and humidity stabilize.

[0030] Interference-free benchmark: Turn off all interference simulators, continuously monitor the rain sensor output for 10 minutes, and record the mean, variance, maximum, and minimum values ​​of the output signal. Confirm that there are no abnormal triggers (the output corresponds to the "no rain" state, typically 2.5V DC or CAN message 0x00). If an abnormality occurs during the benchmark test, check the sensor installation and the anechoic chamber environment, troubleshoot the problem, and retest.

[0031] Single-source static test: Fix the interference simulator ① at a distance of 2.00m from the rain gauge sensor, with an incident angle of 0° (directly facing, i.e., the angle between the laser beam optical axis and the sensor optical axis). Set the laser parameters: wavelength 905nm, pulse width 50ns, repetition frequency 50kHz, peak power 50W. Gradually change the interference frequency: scan from 10kHz to 100kHz in 5kHz steps, holding each frequency point for 30 seconds, while recording the rain gauge sensor output. Observe the rain gauge sensor output signal. Record the interference frequency and power when the first false trigger occurs (output jumps from rainless state to rainy state and lasts for ≥100ms, or output signal jitter exceeds ±10% of the reference value). Repeat the test 3 times and take the average of the frequency thresholds.

[0032] Single-source dynamic motion test: The motion trajectory of the interference simulator ① was set: it approached from a distance of 5.00m at a constant speed of 20km / h (approximately 5.56m / s) to 0.50m, and then moved away at the same speed to 5.00m. Lasers were continuously emitted during the motion (parameters as above). The data acquisition system recorded the rain sensor output and real-time distance at a sampling rate of 1kHz. After the test, the time axis was converted to a distance axis, and the critical distance, relative velocity, and instantaneous incident angle (calculated based on geometric relationships) at which false triggering or signal jitter occurred were extracted. This was repeated 5 times, and statistical values ​​(mean ± standard deviation) were taken. Special attention was paid to whether there was asymmetry between the approaching and moving away phases.

[0033] Dual Interference Source Convergence Test: Interference simulators ① and ② were placed at opposite ends of the guide rail (8m apart) and set to move towards each other at a speed of 15km / h (relative speed 30km / h). The intersection point was located 1.00m directly in front of the rain sensor. The two interference sources had identical emission parameters (wavelength 905nm, pulse width 50ns, repetition frequency 50kHz, peak power 50W). The rain sensor's response was recorded throughout the process of the two interference sources simultaneously approaching, intersecting, and moving away. The output changes within ±0.5m before and after the intersection point were closely monitored to assess whether the dual-source superposition effect led to more severe interference.

[0034] Turning Simulation: While interfering with the simulator's motion, the turntable rotates at a constant angular velocity of 30° / s to simulate an oncoming vehicle cutting in from the left front side (azimuth -60°) to the right front side (+60°). The trajectory is as follows: starting from a distance of 3m and azimuth -60°, moving in a straight line to a distance of 0.5m and azimuth 0°, then moving away to 3m and azimuth +60°. The relationship between the rain sensor output and the relative azimuth is recorded. Special attention is paid to whether there are interference peaks within the azimuth ±30° range.

[0035] Rainy Condition Test (Infinite Rainfall Measurement) Users can set any rainfall value within the range of 0~200L / min according to their testing needs. The system will automatically adjust to the target flow rate and stabilize for 30 seconds before starting the test. The following typical rainfall points and continuous scanning methods are recommended.

[0036] Discrete rainfall point test: Rainfall values ​​were sequentially set to 0.2 L / min (drizzle), 1 L / min (light rain), 5 L / min (lower limit of moderate rain), 15 L / min (upper limit of moderate rain), 30 L / min (heavy rain), 80 L / min (torrential rain), and 150 L / min (extreme torrential rain). After each rainfall point stabilized, all interference test items in steps 2.1.2 to 2.1.5 were repeated. Before each rainfall point test, the water film on the glass surface needed to stabilize (usually 30 seconds), and the uniformity of water film coverage was confirmed using a high-speed camera (optional). The interference threshold power (i.e., the minimum peak power causing false triggering) at each rainfall point was recorded, and a rainfall-threshold curve was plotted.

[0037] Continuous Rainfall Scan Test: Rainfall was linearly increased from 0 L / min to 150 L / min at a rate of 5 L / min / s (total duration 30 seconds). A fixed interference mode was simultaneously activated (e.g., single interference source, distance 2m, incident angle 0°, fixed power 50W). The rain sensor output was continuously recorded (sampling rate 100Hz). After the test, the output values ​​were plotted against time / rainfall to create a "rainfall-interference-response" surface. This test revealed that the sensor is particularly sensitive to interference in certain rainfall ranges. For example, at moderate rainfall (10~20 L / min), a water film of a specific thickness (approximately 0.5mm) forms, causing a jump in infrared reflectivity and a sudden increase in interference coupling efficiency. The test was repeated three times to confirm the consistency of the sensitive range.

[0038] Rainfall step test: Under fixed disturbance (single source, 2m, 0°, 50W), the rainfall is instantaneously increased from 0 (≤0.5 seconds) to 10 L / min and maintained for 60 seconds. Observe the output response time of the rain gauge sensor (the time from the start of the step to 90% of the stable value) and whether there is overshoot or oscillation (output exceeding the stable value ±10% for more than 1 second). The same test is performed when the rainfall jumps back from 10 L / min to 0. Record the step response characteristics to assess the degree to which the sensor's dynamic performance is affected by disturbance.

[0039] Vibration and Rainfall Coupling Test Rainfall scanning under a fixed vibration spectrum: Maintain the vibration spectrum of urban roads (2~30Hz, 0.3g RMS) and repeat tests 2.2.1 and 2.2.2. Compare the results with the data under no-vibration conditions and calculate the decrease in the interference threshold (ΔP = P_no-vibration - P_with-vibration, in dB). Quantify the impact of vibration on interference sensitivity. For example, if the interference threshold power is 50W under no-vibration conditions and drops to 30W under vibration conditions, then ΔP = 10lg(50 / 30) ≈ 2.2dB.

[0040] Vibration frequency scanning: With a fixed rainfall value (e.g., 5 L / min) and fixed interference (single source, 2m, 0°, 50W), the vibration table outputs sinusoidal vibration, scanning the frequency from 1Hz to 50Hz (in 1Hz steps), holding each frequency point for 10 seconds, and maintaining an acceleration of 0.5g. Record the change in the output amplitude (peak-to-peak value) of the rain sensor as a function of the vibration frequency. Identify the frequency at which the output amplitude peaks; this is the resonance-sensitive frequency. If the output fluctuation at a certain frequency exceeds three times the reference value, that frequency is considered a dangerous frequency, and vehicle structure optimization or software notch filtering should be recommended.

[0041] Vibration-interference synchronization timing test: The vibration waveform was set to a 20Hz sine wave (simulating tire imbalance excitation) with an acceleration of 0.5g. The interference simulator emitted in 10Hz pulse mode (emitting once every 100ms, pulse width 10ms). Vibration displacement (via double integral of acceleration) and rain sensor output were synchronously recorded using a high sampling rate (10kHz). Through time-domain analysis, it was determined that interference pulses falling at the point of maximum vibration displacement (when the relative displacement between the sensor and the glass is at its maximum) are more likely to cause false triggering. The false triggering probability of falling in different vibration phase intervals among 100 pulses was statistically analyzed, and a phase-probability histogram was plotted.

[0042] Ambient light and temperature and humidity effect test Ambient light scanning: With a fixed rainfall of 5 L / min and fixed interference (single source, 2 m, 0°, 50 W), ambient light is gradually increased from 0 lx (complete darkness, using a blackout curtain) to 100 klx (midday sunlight), in steps of 5 klx (or logarithmically: 0, 0.1, 0.5, 1, 2, 5, 10, 20, 50, 100 klx). After each illuminance point stabilizes for 30 seconds, the rainfall sensor output is recorded (paying close attention to false triggers and changes in the output DC bias). An "illuminance-false trigger rate" curve is plotted. Generally, strong light saturates the photodetector, reducing its sensitivity to interference; while in low light, the detector gain is high, making it more prone to false triggers. A safe operating illuminance range needs to be determined.

[0043] Infrared background light test: Turn off the main illumination (ambient light < 1 lx), turn on the infrared supplementary light (940nm), and adjust the power to achieve an infrared illuminance of 10W / m² at the sensor installation location (measured using an infrared power meter). Simulate a scenario where an oncoming vehicle activates its infrared night vision system or infrared headlights. Repeat test 2.2.1 (discrete rain points) and observe whether the infrared background light reduces the sensor's sensitivity to laser interference (as the infrared background light may saturate the detector) or increases false triggering (if the laser wavelength is similar to the infrared background wavelength, beat frequency interference may occur). Record the differences.

[0044] Temperature Characteristic Test: The darkroom temperature was set to -20℃, 0℃, 25℃, 60℃, and 85℃ respectively. Each temperature was maintained for 1 hour (to ensure the sensor and glass reached thermal equilibrium), and then the test in section 2.2.2 (continuous rain scan) was repeated. The interference threshold drift of the sensor at different temperatures was recorded. For example, the responsivity of semiconductor devices may decrease at low temperatures, leading to an increase in the interference threshold; at high temperatures, the dark current increases, which may decrease the threshold. A three-dimensional graph of "temperature-rainfall-interference threshold" was output.

[0045] Humidity test: Humidity set at 95%RH (non-condensing), temperature 25℃. After maintaining this temperature for 1 hour, repeat test 2.2.2. Observe whether a uniform thin water film forms on the glass surface under high humidity conditions (different from the spray rain film), and whether the scattering / absorption characteristics of this water film change the interference coupling efficiency. Simultaneously monitor for signs of condensation inside the sensor (which can be observed through the transparent casing or checked after disassembly). If condensation occurs, the operating condition is determined to be a hazardous condition.

[0046] Combined operating conditions traversal (orthogonal experimental design) To evaluate the coupling effects of multiple factors within a finite timeframe, an orthogonal experimental design (L18 or L36 table) was employed. The following factors and levels were selected: Factor A: Rainfall (3 levels: 0, 5, 50 L / min); Factor B: Interference source configuration (3 levels: none, single, dual); Factor C: Vibration (2 levels: none, urban road spectrum); Factor D: Ambient light (2 levels: 100 lx, 10000 lx); Factor E: Temperature (2 levels: -20℃, 60℃); There are a total of 3×3×2×2×2=72 combinations. The test order is arranged according to an orthogonal array to balance the order effect. Each combination runs for 10 minutes, recording the number and type of abnormal wiper actions (false activation, false deactivation, abnormal wiping frequency, etc.). If a persistent abnormality occurs during the test, it can be terminated early and the time recorded. After the test, an analysis of variance (ANOVA) is performed to identify the main effects and interaction effects that significantly influence the abnormal actions, and to define the system's operating boundary (i.e., the probability of abnormality <1% when all factors are within the safe range).

[0047] Data post-processing and calibration result output: Raw data preprocessing: The acquired time-domain data is preprocessed as follows: Filtering: A zero-phase digital filter (such as a Butterworth low-pass filter with a cutoff frequency of 100Hz) is used to remove the 50Hz power frequency and its harmonics (using a notch filter).

[0048] Outlier removal: Using the 3σ criterion, points that exceed the mean ± 3 times the standard deviation are marked as outliers and replaced with linear interpolation.

[0049] Time axis alignment: unify the timestamps of all channels to the system reference clock and linearly interpolate to the same sampling grid (e.g., 1kHz).

[0050] Feature extraction: Extract the following features from the rain sensor output signal: Steady-state output value: Take the average value of the steady period (last 30 seconds) of each operating condition, corresponding to the rainfall sensing value (which needs to be converted by the pre-calibrated rainfall-output voltage curve).

[0051] Output fluctuation variance: Calculate the variance during the stable period to determine if it is affected by disturbances or jitter. If the variance exceeds twice the baseline (no disturbances, no vibrations), it is determined to be affected by disturbances.

[0052] Accidental triggering event: When the output changes from the "no rain" state (e.g., <0.5V) to the "rainy" state (e.g., >2V) for a duration of >100ms, it is counted as an accidental trigger.

[0053] Abnormal shutdown event: If the output remains "no rain" (<0.5V) for more than 10 seconds, even if the actual rainfall is >0 (confirmed by the flow meter), an abnormal shutdown is recorded.

[0054] Response delay: For step tests, calculate the time from the start of the rainfall step to the output reaching 90% of its stable value.

[0055] After calibrating the MAP diagram generation, draw the following multidimensional relationship diagram: Figure A: Rainfall setpoint (x-axis, logarithmic coordinate) vs. interference source power (y-axis, logarithmic coordinate) vs. false trigger probability (color mapping, 0~100%), with other conditions fixed (e.g., vibration = none, illumination = 1000 lx, temperature = 25℃). This figure represents the most basic interference threshold. Figure B: Interference simulator distance (x-axis) vs. relative velocity (y-axis) vs. rain sensor response delay (z-axis, contour lines). Reflects the impact of dynamic motion on response speed. Figure C: Vibration frequency (x-axis) vs. rainfall value (y-axis) vs. interference threshold decrease (color mapping, dB). Used to identify dangerous vibration frequency ranges. Figure D: Ambient illumination (x-axis) vs. temperature (y-axis) vs. interference power corresponding to the sensor saturation point (z-axis). Used to determine environmental compensation algorithm parameters. Figure E: Pareto plot of orthogonal experimental results, showing the effect sizes of each factor and their interactions.

[0056] All MAP plots are output in the form of digital tables (CSV) and 2D contour plots / 3D surface plots (PNG / PDF), and a comprehensive report (PDF) is generated, which includes test conditions, raw data summary, feature analysis, and conclusions and recommendations.

[0057] Based on the test data, the following conclusions are drawn regarding calibration: The absolute interference threshold (power, distance, angle) of the rain sensor under the current installation angle and clamping force. For example: under vibration-free conditions, 25℃, 1000lx, when a single interference source is directly facing 2m, the minimum peak power that will cause false triggering is XX W.

[0058] Safety boundaries under dynamic operating conditions: When the relative speed is >10km / h, the interference threshold increases by X dB (i.e., the interference risk decreases); when the relative speed is <5km / h, the risk increases significantly.

[0059] Vibration-sensitive frequency range: The interference threshold decreases the most under vibration of 20~25Hz. It is recommended to add a 20Hz notch filter to the sensor algorithm.

[0060] Ambient light compensation factor: When the ambient light is >50klx, the sensor gain is automatically reduced by 0.5dB; when the light is <1lx, the gain is increased by 1dB to maintain consistent interference immunity.

[0061] Temperature compensation coefficient: For every 10°C increase, the interference threshold decreases by approximately 0.3dB, requiring linear compensation in the software.

[0062] It is worth mentioning that in another preferred embodiment, the rain sensor installation angle was fixed at a typical value of 30° for a real vehicle, the lidar interference simulator used only a single-source 1550nm wavelength, the ambient light was fixed at nighttime conditions (<10lx), and the vibration spectrum used was the highway PSD curve. The test focused on evaluating the impact of rain film thickness on interference coupling efficiency at long wavelengths. The test showed that under moderate rain (15L / min) and a relative speed of 20km / h, the interference threshold power was increased by approximately 15% compared to Example 1, verifying the influence of different wavelengths and installation angles on interference sensitivity.

[0063] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A rain gauge sensor anti-interference testing system, characterized in that: include: The test environment unit is configured to provide a controlled electromagnetic shielding environment; The sensor mounting and adjustment unit is configured to fix the rainfall sensor to be measured at an adjustable mounting angle. The windshield wiper simulation unit is configured to simulate the operating state of a vehicle's windshield wipers. The rainwater simulation unit is configured to provide steplessly adjustable rainfall simulation. The lidar interference simulation unit is configured to generate lidar interference signals with adjustable parameters and to operate at preset spatial positions, motion trajectories, and orientations. The vibration simulation unit is configured to provide multi-degree-of-freedom vibration simulation. The environmental simulation unit is configured to provide environmental simulation with adjustable spectrum, illuminance, temperature, and humidity. The central control unit is configured to control the emission parameters, spatial position, movement trajectory and orientation of the lidar interference simulation unit, and to control the rain simulation unit to achieve stepless rainfall adjustment; The data acquisition unit is configured to be electrically connected to the central control unit and at least one sensor, and is configured to synchronously acquire test data.

2. The system according to claim 1, characterized in that: The test environment unit includes a semi-anechoic chamber or a fully anechoic chamber, the chamber is equipped with absorbing materials, and the shielding effectiveness and background noise level of the chamber meet the electromagnetic compatibility test requirements.

3. The system according to claim 1, characterized in that: The rainwater simulation unit includes an air source, a water storage tank, a flow meter, a deceleration valve, a water pump, and a nozzle array consisting of multiple independently controllable atomizing nozzles. The central control unit is configured to achieve stepless adjustment of the water flow rate by adjusting the water pump speed and the opening of the deceleration valve, and automatically adjust the rainfall value to the user-set target value through closed-loop PID control according to the pre-generated calibration curve, supporting the programming of rainfall change rate.

4. The system according to claim 1, characterized in that: The laser radar interference simulation unit is mounted on a motion mechanism, which includes a linear guide rail driven by a ball screw and a rotary table driven by a harmonic reducer. The central control unit is configured to programmatically control the linear motion speed, acceleration, position, rotational angular velocity, and angle of the lidar interference simulation unit; the emission parameters supported by the lidar interference simulation unit include selectable wavelength, adjustable pulse width, adjustable repetition frequency, adjustable peak power, and adjustable laser beam divergence angle.

5. The system according to claim 1, characterized in that: The vibration simulation unit includes a six-degree-of-freedom vibration table, the frequency, acceleration and displacement of which are adjustable within a set range, and the vibration table has a built-in typical vibration power spectral density curve.

6. The system according to claim 1, characterized in that: The data acquisition unit adopts a PXIe architecture and is equipped with a high-precision synchronization module. Its acquisition channels include a rain sensor output signal channel, a wiper motor current and position signal channel, a real-time position and angle channel of the interference simulator, a vibration table acceleration feedback channel, an ambient light intensity and temperature and humidity channel, and an actual water flow velocity channel; all channels are configured to be synchronized via a precision time protocol.

7. A method for testing the anti-interference capabilities of a rain gauge, characterized in that: Includes the following steps: Benchmark test procedure: Under a rainless and interference-free setting environment, continuously monitor the output of the rain sensor to confirm that it is in a normal "rainless" state. Single interference source test steps: Fix the interference simulator at a set position and angle, and gradually change its emission parameters to record the interference parameters when the rain sensor first falsely triggers as a threshold; or control the interference simulator to move along a straight trajectory, continuously emit lasers during the movement, and synchronously record the output of the rain sensor and the real-time distance to extract the critical distance, relative speed and instantaneous incident angle at which false triggering or signal jitter occurs. Multi-interference source test procedure: Control multiple interference simulators to move towards each other and interleave, to record the response of the rain sensor throughout the process and evaluate the superposition effect; Rainy condition test procedure: Under the continuously adjustable set rainfall value, repeat the above interference test items to plot the rainfall-interference threshold curve; as well as Multi-factor coupling and data analysis steps: Conduct vibration and rainfall coupling tests, ambient light and temperature and humidity influence tests, and combined working condition traversal tests. Then, preprocess the collected data, extract features, generate multi-dimensional relationship diagrams, and output calibration conclusions.

8. The method according to claim 7, characterized in that: The multi-factor coupling and data analysis steps include: rainfall scanning under a fixed vibration spectrum, comparing the results with data when there is no vibration, and calculating the decrease in the interference threshold; and vibration frequency scanning to find the frequency at which the output amplitude peaks.

9. The method according to claim 7, characterized in that: The multi-factor coupling and data analysis steps include: performing ambient light scanning to plot the illuminance-false trigger rate curve; performing infrared background light testing to observe the effect of infrared background on the sensor's interference sensitivity; and performing temperature characteristic testing to record the sensor's interference threshold drift at different temperatures.

10. The method according to claim 7, characterized in that: The multi-factor coupling and data analysis steps include: using orthogonal experimental design to select multiple factors and levels for combined testing; recording the number and type of abnormal wiper actions; performing analysis of variance to identify the main effects and interaction effects that have a significant impact on abnormal actions, and calibrating the system's working boundary.

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