Tilt angle sensor reliability evaluation method

Abstract

The invention relates to a reliability evaluation method of a tilt angle sensor. The method comprises the following steps: 1) constructing a reliability evaluation system of the tilt angle sensor; 2) configuring indexes in a reliability evaluation system according to the type of the tilt angle sensor; and 3) testing according to the configured indexes to obtain a reliability index score, and judging whether the reliability is qualified or not according to a reliability threshold value. Compared with the prior art, the method has the advantages of comprehensive consideration, quantitative evaluation, standardization, wide applicability and the like.

Description

Technical Field

[0001] The present invention relates to the field of production and manufacturing of inclination sensors, and particularly to a method for evaluating the reliability of inclination sensors. Background Art

[0002] An inclination sensor is a device used to measure the inclination angle of an object relative to the horizontal plane, and is widely used in fields such as industrial automation, construction engineering, aerospace, and automotive electronics. The core principle of an inclination sensor containing an accelerometer is to calculate the inclination angle by detecting the component of the gravitational acceleration on the sensitive axis of the sensor.

[0003] The reliability of an inclination sensor is an important basis for evaluating the quality of sensor products, and is the key to ensuring the stable and accurate operation of the inclination sensor in various environments. Through reliability evaluation, not only can accurate inclination data be provided under different conditions, avoiding potential safety hazards or economic losses caused by errors, but also potential problems can be identified and the design can be optimized, extending the service life of the sensor and reducing maintenance costs.

[0004] However, currently, there are many types of tests for the reliability of inclination sensors, the test steps are complicated, and the test parameters are numerous. There is no evaluation method to quantitatively evaluate the inclination sensor products in a systematic manner, so as to effectively monitor the quality of inclination sensor products intuitively and quantitatively. Summary of the Invention

[0005] To solve the technical problems in the background art, the present invention provides a method for evaluating the reliability of inclination sensors, including the following steps:

[0006] 1) Construct a reliability evaluation system for inclination sensors;

[0007] 2) Configure the indicators in the reliability evaluation system according to the type of inclination sensor;

[0008] 3) Perform tests according to the configured indicators to obtain the reliability index scores, and judge whether the reliability is qualified according to the reliability threshold.

[0009] Further, in the step 1), the reliability evaluation system of the inclination sensor is composed of three-level reliability indicators, indicator detection methods, and scoring criteria.

[0010] Further, among the three-level reliability indicators, the reliability indicators of the inclination sensor are used as the first-level indicators. The first-level indicators include nine second-level indicators, namely electrical indicators, mechanical indicators, environmental indicators, protection indicators, durability indicators, electromagnetic compatibility indicators, packaging material indicators, chemical coating indicators, and measurement performance indicators. Each second-level indicator includes multiple third-level indicators, and each third-level indicator corresponds to an indicator detection method and a scoring criterion respectively.

[0011] Further, the third-level indicators included in the electrical indicators are working voltage indicator, abnormal voltage resistance indicator, instantaneous supply voltage drop indicator, reverse voltage indicator, slow supply voltage change indicator, open circuit indicator, output short circuit indicator, signal line reverse connection prevention indicator, insulation resistance indicator, short-term power on / off indicator, and static operating current indicator; the third-level indicators included in the mechanical indicators are random vibration indicator, sine vibration test indicator, mechanical shock indicator, and three-in-one indicator; the third-level indicators included in the environmental indicators are low-temperature storage indicator, low-temperature operation indicator, high-temperature storage indicator, high-temperature operation indicator, low-pressure transportation indicator, low-pressure operation indicator, temperature shock indicator, power-on temperature cycle indicator, alternating damp heat indicator, condensation indicator, temperature gradient indicator, salt spray function and penetration indicator, salt spray surface corrosion indicator, and xenon lamp aging indicator.

[0012] Further, the third-level indicators included in the protection indicators are dust prevention indicator, waterproof indicator, and sealing performance indicator; the third-level indicators included in the durability indicators are thermal fatigue life indicator, power-on temperature cycle durability indicator, constant damp heat durability indicator, and high-temperature operation durability indicator; the third-level indicators included in the electromagnetic compatibility indicators are electrostatic discharge immunity indicator, electrical fast transient pulse group immunity indicator, and surge immunity indicator; the third-level indicators included in the packaging material indicators are free fall indicator and transportation vibration indicator; the third-level indicator included in the chemical coating indicators is surface coating indicator; the third-level indicators included in the performance indicators are measurement range indicator, resolution indicator, accuracy indicator, static redundancy error indicator, zero-point deviation indicator, repeatability indicator, precision indicator, non-linearity indicator, zero-point temperature drift indicator, full-scale temperature drift indicator, output frequency indicator, sensitivity indicator, sensitivity temperature drift indicator, response time / response frequency indicator, cross-axis sensitivity indicator, alarm function indicator, indicator light function indicator, delay indicator, hysteresis angle indicator, relative zero-point setting function indicator, communication protocol indicator, measurement direction indicator, wiring definition indicator, external dimension indicator, product identification / model indicator, parts list indicator, output power / output current indicator, and long-term stability indicator.

[0013] Further, the electrical indicators, mechanical indicators, environmental indicators, packaging material indicators, measurement direction indicators, and wiring definition indicators are all indicators that may have the risk of function loss.

[0014] Further, in step 3), the reliability index score of the inclination sensor is calculated by summing the scores of each secondary indicator, so there is:

[0015] A = A1 + A2 + A3 + A4 + A5 + A6 + A7 + A8 + A9

[0016] Among them, the reliability index A of the inclination sensor has a total score of 100 points, the electrical index A1 has a total score of 10 points, the mechanical index A2 has a total score of 10 points, the environmental index A3 has a total score of 10 points, the protection index A4 has a total score of 5 points, the durability index A5 has a total score of 5 points, the electromagnetic compatibility index A6 has a total score of 10 points, the packaging material index A7 has a total score of 5 points, the chemical coating index A8 has a total score of 5 points, and the performance index A9 has a total score of 40 points.

[0017] Further, when the reliability index score of the inclination sensor is equal to or less than 90 points, it is determined that the reliability of the inclination sensor is unqualified; when it is greater than 90 points and less than 100 points, it is determined that the reliability of the inclination sensor is qualified with risks; when it is equal to 100 points, it is determined that the reliability of the inclination sensor is qualified without risks.

[0018] Further, in the step 2), the types of inclination sensors include digital inclination sensors, analog inclination sensors, and inclination switches.

[0019] Further, the digital inclination sensor does not need to perform the three-level index tests of non-linearity and sensitivity. In the three-level index of measuring the performance index, the inclination switch only needs to perform the tests of measuring range index, alarm function index, delay index, hysteresis angle index, indicator light function index, relative zero setting function index, and output power / output current index.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] Since there is currently no reliability evaluation system and method for inclination sensor products, the present invention provides a reliability evaluation method for inclination sensors that is comprehensive in consideration and reasonable in evaluation, filling the technical gap in this field, and can be applied to the R & D and production stages, applicable to the quality inspection process of developed samples and mass-produced products, providing a quantifiable way for the evaluation of inclination sensor products. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a step flow chart of the reliability evaluation method for inclination sensors. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] The present invention will be described in detail below with reference to the drawings and specific embodiments. This embodiment is implemented on the premise of the technical solution of the present invention, and gives detailed implementation manners and specific operation processes, but the protection scope of the present invention is not limited to the following embodiments.

[0024] Embodiment

[0025] As Figure 1As shown in the figure, the present invention provides a method for evaluating the reliability of an inclination sensor, which is used to quantitatively evaluate the quality of the inclination sensor, ensure that the inclination sensor product can work normally under extreme temperature, humidity, vibration and other conditions, effectively reduce the risk of serious accidents caused by failures, and is crucial for ensuring accuracy, extending the service life, adapting to complex environments, enhancing competitiveness and reducing safety risks. The results of the evaluation can also optimize the design, improve the product performance, and meet the requirements of different applications. The invention includes the following steps:

[0026] Step S1: Construct a reliability evaluation system for the inclination sensor

[0027] As shown in Table 1, according to the performance requirements of the inclination sensor, the present invention designs a reliability evaluation system for the inclination sensor. This system consists of three-level reliability indicators, index detection methods, and scoring criteria. Among them, the three-level reliability indicators take the reliability indicators of the inclination sensor as the first-level indicators, and nine second-level indicators are respectively set under the first-level indicators, including electrical indicators, mechanical indicators, environmental indicators, protection indicators, durability indicators, electromagnetic compatibility indicators, packaging material indicators, chemical coating indicators, and measurement performance indicators. Each second-level indicator includes multiple third-level indicators, and each third-level indicator corresponds to its own test method. The scoring criteria include the scores of each second-level indicator set according to the importance of the influence of each second-level indicator on the reliability indicator and the deduction items corresponding to each third-level indicator.

[0028] Table 1 Inclination sensor reliability evaluation system table

[0029]

[0030]

[0031] The deduction items of each third-level indicator are deducted according to the corresponding judgment criteria, and the judgment criteria include the functional status class (FSC) and / or other criteria. Table 2 shows the definition of the functional status class FSC.

[0032] Table 2 Definition of the functional status class FSC

[0033]

[0034] The following will introduce each second-level indicator separately.

[0035] (1) Electrical indicators

[0036] Electrical indicators include 11 third-level indicators, namely working voltage indicator, abnormal voltage tolerance indicator, instantaneous supply voltage drop indicator, reverse voltage indicator, slow supply voltage change indicator, open circuit indicator, output short circuit indicator, signal line anti-reverse connection indicator, insulation resistance indicator, short-term power on / off indicator, and static operating current indicator. The following is an introduction to each third-level indicator.

[0037] 1.1 Working voltage indicator

[0038] This indicator is used to indicate whether the functional performance of the tilt sensor of the device under test (in this example, the tilt sensor product to be tested) is normal within the range of the lowest voltage and the highest voltage. The specific test method is to supply power to the effective input terminal of the tilt sensor product to be tested, and supply power to the tilt sensor product to be tested within the range of the lowest supply voltage Usmin, the nominal voltage Us, and the highest supply voltage Usmax.

[0039] Judgment criteria:

[0040] If the function is normal and the performance status level FSC reaches A, the judgment criteria are met.

[0041] 1.2 Abnormal voltage tolerance indicator

[0042] This indicator is used to indicate the tolerance ability of the tilt sensor product to be tested to long-term abnormal supply voltage. The specific test method is to supply power to the effective input terminal of the tilt sensor product to be tested at room temperature. For products with overvoltage protection, the supply voltage varies between Usmax * 150% ± 0.2V at a rate of 1V per minute; for products without overvoltage protection, the supply voltage is stabilized at Usmax * 150%.

[0043] Judgment criteria:

[0044] If the function is normal and the performance status level FSC reaches C (for safety-type tilt sensors, it is A), the judgment criteria are met.

[0045] 1.3 Instantaneous supply voltage drop indicator

[0046] This indicator is used to indicate the impact caused by a short-term drop in the supply voltage of the tilt sensor product to be tested. The specific test method is to apply the lowest supply voltage Usmin to the effective input terminal of the tilt sensor product to be tested, instantaneously reduce the supply voltage to 4.5V within no more than 10ms, the drop time is 0.1s, the rise and fall times ≤ 10ms, and then restore it to the lowest supply voltage Usmin.

[0047] Judgment criteria:

[0048] If the performance status level FSC reaches B, the judgment criteria are met.

[0049] 1.4 Reverse voltage index

[0050] This indicator is used to indicate the resistance of the inclination sensor product to reverse power connection. The specific test method is to apply a reverse voltage to the effective input terminal of the inclination sensor product to be tested. For products with a nominal voltage of 12V, the applied reverse voltage is 14±0.1V, and the reverse connection time is 60s; for products with a nominal voltage of 24V, the applied reverse voltage is 28±0.1V, and the reverse connection time is 60s.

[0051] Judging criteria:

[0052] If the performance status grade FSC reaches C, the judgment criteria are met.

[0053] 1.5 Supply voltage slow change indicator

[0054] This indicator is used to indicate the ability of the inclination sensor product to resist the change of supply voltage during the discharge and charging process of the battery. The specific test method is to gradually reduce the supply voltage of the inclination sensor product from the maximum supply voltage Usmax to 0V at a rate of 0.5V / min, and then increase it from 0V to the maximum supply voltage Usmax at the same rate, for a total of 1 cycle.

[0055] Judging criteria:

[0056] If the performance status grade FSC reaches A within the normal working range and reaches C in other ranges, the judgment criteria are met.

[0057] 1.6 Open circuit indicator

[0058] This indicator is used to indicate whether the inclination sensor product to be tested will not be damaged when subjected to an open circuit connection, and whether the function of the inclination sensor product to be tested will immediately return to normal after the connection is restored. The specific test method is to disconnect one circuit of the inclination sensor product to be tested, and then restore the connection, observe the situation of the inclination sensor product during and after the disconnection, and repeat the test for each circuit of the inclination sensor product to be tested, with a disconnection time of 10s and an open circuit impedance ≥ 10MΩ;

[0059] Judging criteria:

[0060] If the performance status grade FSC reaches C, the judgment criteria are met.

[0061] 1.7 Output short circuit indicator

[0062] This indicator is used to show that the inclination sensor product to be tested will not be damaged when suffering from short - circuit connection, and whether the function of the inclination sensor product to be tested can be immediately restored to normal after the connection is restored. The specific test method is to supply power to the inclination sensor product to be tested with the nominal voltage Us, short - circuit the output lines to each other or to the ground and apply power for 1 minute, then restore normal power supply, and observe the situation during and after the short - circuit of the inclination sensor product to be tested.

[0063] Judgment criteria:

[0064] If the performance status level FSC reaches C, the judgment criteria are met.

[0065] 1.8 Signal line reverse - connection prevention indicator

[0066] This indicator is used to show that the inclination sensor product to be tested will not be damaged when suffering from reverse connection of the signal line, and whether the function of the inclination sensor can be immediately restored to normal after the connection is restored. The specific test method is to supply power to the inclination sensor product to be tested with the nominal voltage Us, reverse - connect the signal line and apply power for 1 minute, then restore normal power supply, and observe the situation during and after the short - circuit of the inclination sensor.

[0067] Judgment criteria:

[0068] If the performance status level FSC reaches C, the judgment criteria are met.

[0069] 1.9 Insulation resistance indicator

[0070] This indicator is used to show the performance problems of the inclination sensor product to be tested caused by factors such as the reduction of the distance between circuit board traces or the degradation of insulator materials due to moisture ingress. The specific test method is to apply a 500V DC voltage between two connector terminals that are electrically insulated from each other, between a connector terminal and the metal housing of the component that are electrically insulated from each other, and between a connector terminal and the conductive material wrapped on the plastic housing of the component that are electrically insulated from each other, and maintain it for 60s, and judge whether the insulation resistance of the inclination sensor is greater than 10MΩ;

[0071] Judgment criteria:

[0072] If the insulation resistance of the inclination sensor is greater than 10MΩ, the judgment criteria are met.

[0073] 1.10 Short - time power - on and power - off indicator

[0074] This indicator is used to show the impact on the inclination sensor product to be tested caused by vehicle power - on and power - off during daily use. The specific test method is to supply power to the effective input terminal of the inclination sensor with the nominal voltage Us. Each 4s is used as a test cycle, including a 2s power - on and a 2s power - off, and a total of 500 cycles are carried out.

[0075] Judgment criterion:

[0076] If the performance status level FSC reaches B, the judgment criterion is met.

[0077] 1.11 Static operating current index

[0078] This index is used to indicate whether the current of the tilt sensor product to be tested meets the product design requirements during normal operation. The specific test method is to supply power to the effective input terminal of the tilt sensor with the nominal voltage Us, use a high-precision multimeter to switch to the current range, install the tilt sensor horizontally, connect the positive pole of the product to the positive pole of the DC power supply, the negative pole to the red test lead of the multimeter, the black test lead of the multimeter to the negative pole of the power supply, and keep other leads suspended, and read the reading of the high-precision multimeter (the product is at the 0° position);

[0079] Judgment criterion:

[0080] If the static operating current of the tilt sensor meets the product design index requirements, the judgment criterion is met.

[0081] (2) Mechanical indexes

[0082] The mechanical indexes include 4 third-level indexes, namely random vibration index, sine vibration index, mechanical shock index, and three-in-one index. Each third-level index will be introduced below.

[0083] 2.1 Random vibration index

[0084] This index is used to indicate the immunity performance of the tilt sensor product to be tested against vibrations on the vehicle. The vibration stress is the vehicle body vibration, which is the random vibration caused by the vehicle driving on a rough road. The specific test method is to place the tilt sensor product to be tested on a vibration table and simulate the vehicle body vibration. The vibration frequency is 10Hz - 1000Hz, the vibration direction is the three axes of X, Y, and Z, and the duration is 20h for each axis, and the total root mean square acceleration is 27.8m / s 2 .

[0085] Judgment criterion:

[0086] If the performance status level FSC reaches A, and the structure is intact and there are no cracks or damages on the appearance, the judgment criterion is met.

[0087] 2.2 Sine vibration index

[0088] This index is used to indicate the immunity performance of the tilt sensor product to be tested against vibrations generated on the vehicle. The specific test method is to place the tilt sensor product to be tested on a vibration table for sine vibration test, with a frequency sweep of 10 - 500Hz, an amplitude of 1.5mm, an acceleration of 20g, and each of the X, Y, and Z directions vibrates continuously for 2h.

[0089] Judgment criteria:

[0090] If the performance status level FSC reaches A, the structure is intact, and there are no cracks or damages on the appearance, then the judgment criteria are met.

[0091] 2.3 Mechanical shock index

[0092] This index is used to represent the resistance ability of the inclination sensor product to be tested against the impact acceleration generated when the vehicle quickly drives over road protrusions or pits or has an accident. The specific test method is to place the inclination sensor product to be tested on an impact testing machine, simulate the impact caused by the inclination sensor following the vehicle through the road shoulder, stones or deep roadside potholes. The impact acceleration is 25g, the waveform is half-sine, the duration is 10 ms, the application directions are six directions of ±X, ±Y, ±Z, and the number of times is 400 times for each direction, a total of 2400 times.

[0093] Judgment criteria:

[0094] If the performance status level FSC reaches A, the structure is intact, and there are no cracks or damages on the appearance, then the judgment criteria are met.

[0095] 2.4 Three-combination index

[0096] This index is used to represent the comprehensive immunity performance of the inclination sensor product to be tested against climate and vibration on the vehicle. The specific test method is as follows:

[0097] On the vehicle, the occurrence of vibration fatigue stress generally accompanies extreme low or high temperature environments. Therefore, during the entire test cycle, temperature stress and vibration stress need to be applied simultaneously, as follows:

[0098] Temperature stress: Cool down from 20°C to the minimum operating temperature TminOP in 60 min, maintain at the minimum operating temperature TminOP for 90 min, recover from the minimum operating temperature TminOP to 20°C in 60 min, then heat up from 20°C to the maximum operating temperature TmaxOP in 90 min, maintain at the minimum operating temperature TmaxOP for 120 min, and finally recover to 20°C for 60 min. Conduct a function check before powering on before the end of the low-temperature hold, power off after the check, and start powering on until the end of the hold at the maximum operating temperature TmaxOP during the stage of heating up from 20°C to the maximum operating temperature TmaxOP. A function check can be carried out during this stage, and observe whether the function changes until the power-on ends.

[0099] Vibration stress: The vibration of the vehicle body is random vibration caused by driving on a rough road surface. In the specific parameters, the vibration frequency is 10 Hz - 1000 Hz, and the total root mean square acceleration is 27.8 m / s 2, the vibration directions are the three axes of X, Y, and Z, and the test time is 8 hours for each axis.

[0100] Judgment criteria:

[0101] If the performance status level FSC reaches A, the structure is intact, and there are no cracks or damages on the appearance, then the judgment criteria are met.

[0102] (3) Environmental indicators

[0103] The environmental indicators include 14 third-level indicators, namely low-temperature storage indicator, low-temperature operation indicator, high-temperature storage indicator, high-temperature operation indicator, low-pressure transportation indicator, low-pressure operation indicator, temperature shock indicator, power-on temperature cycle indicator, alternate damp heat indicator, condensation indicator, temperature gradient indicator, salt spray function and penetration indicator, salt spray surface corrosion indicator, xenon lamp aging indicator. The following is an introduction to each third-level indicator.

[0104] 3.1 Low-temperature storage indicator

[0105] This indicator is used to represent the low-temperature resistance performance of the tilt sensor product to be tested. The specific test method is to place the tilt sensor product to be tested in a constant-temperature test chamber, set the temperature to the lowest storage temperature TminST, keep it for 24 hours, and after the test, the tilt sensor is restored under standard atmospheric conditions for 1 - 2 hours, and the temperature rise and fall rate is 1°C / min.

[0106] Judgment criteria:

[0107] If the performance status level FSC reaches A, the structure is intact, and there are no cracks or damages on the appearance, then the judgment criteria are met.

[0108] 3.2 Low-temperature operation indicator

[0109] This indicator is used to represent whether the tilt sensor product to be tested will have electrical failures when operating in a low-temperature environment. The specific test method is to place the tilt sensor product to be tested in a constant-temperature test chamber, set the temperature to the lowest operating temperature TminOP, keep it for 24 hours, and the temperature rise and fall rate is 1°C / min.

[0110] Judgment criteria:

[0111] If the performance status level FSC reaches A, the structure is intact, and there are no cracks or damages on the appearance, then the judgment criteria are met.

[0112] 3.3 High-temperature storage indicator

[0113] This indicator is used to represent the high-temperature resistance performance of the tilt sensor product to be tested. The specific test method is to place the tilt sensor product to be tested in a constant-temperature test chamber, set the temperature to the maximum storage temperature TmaxST, keep it for 24 hours, after the test, the tilt sensor is restored under standard atmospheric conditions for 1-2 hours, and the heating and cooling rate is 1°C / min;

[0114] Judgment criteria:

[0115] If the performance status level FSC reaches A, and the structure is intact and there are no cracks or damages on the appearance, then the judgment criteria are met.

[0116] 3.4 High-temperature operation indicator

[0117] This indicator is used to represent whether electrical faults will occur when the tilt sensor product to be tested operates in a high-temperature environment. The specific test method is to place the tilt sensor product to be tested in a constant-temperature test chamber, set the temperature to the maximum operating temperature TmaxOP, keep it for 24 hours, and the heating and cooling rate is 1°C / min.

[0118] Judgment criteria:

[0119] If the performance status level FSC reaches A, and the structure is intact and there are no cracks or damages on the appearance, then the judgment criteria are met.

[0120] 3.5 Low-pressure transportation indicator

[0121] This indicator is used to represent the low-pressure environment encountered by the tilt sensor product to be tested at an altitude of 15240m, and to verify the bearing capacity of the airtightness of the tilt sensor's housing to the internal and external air pressure difference. The specific test method is to place the tilt sensor product to be tested in a low-pressure test chamber, set the test pressure to 11 kPa (equivalent to an altitude of 15240m), the temperature is at normal temperature, and the test time is 8 hours.

[0122] Judgment criteria:

[0123] If the performance status level FSC reaches A, and the structure is intact and there are no cracks or damages on the appearance, then the judgment criteria are met.

[0124] 3.6 Low-pressure operation indicator

[0125] This indicator is used to represent the adaptability of the tilt sensor product to be tested to the high-altitude low-pressure environment. The specific test method is to place the tilt sensor product to be tested in a low-pressure test chamber, set the test pressure to 59 kPa, the temperature is at normal temperature, and the test time is 16 hours.

[0126] Judgment criteria:

[0127] If the performance status level FSC reaches A, and the structure is intact and there are no cracks or damages on the appearance, then the judgment criteria are met.

[0128] 3.7 Temperature shock index

[0129] This index is used to represent the adaptability of the tilt sensor product to be tested to rapidly changing ambient temperature. The specific test method is to place the tilt sensor product to be tested in a thermal shock cabinet or a rapid temperature change chamber to simulate temperature shock. The high temperature is set to the maximum storage temperature TmaxST, and the low temperature is set to the minimum storage temperature TminST. The temperature change time is less than or equal to 30 s; the holding time is specifically 30 min (less than 0.68 kg), 60 min (0.68 kg to 4.53 kg), 90 min or longer, and is selected according to the material characteristics, volume, heat capacity of the tilt sensor or other characteristics.

[0130] Judgment criteria:

[0131] The performance status level FSC reaches C, the structure is intact, and there are no cracks or damages on the appearance, then the judgment criteria are met.

[0132] 3.8 Powered temperature cycle index

[0133] This index is used to represent whether the tilt sensor product to be tested can work normally during the temperature change process. The specific test method is as follows:

[0134] 1. Place the tilt sensor product to be tested in a constant temperature test chamber, cool down from 20 °C to the minimum operating temperature TminOP, which takes 60 min, and hold for 90 min at the minimum operating temperature TminOP stage;

[0135] 2. Recover from the minimum operating temperature TminOP to 20 °C, which takes 60 min, and then continue to heat up from 20 °C to the maximum operating temperature TmaxOP, which takes 90 min;

[0136] 3. Hold for 120 min at the maximum operating temperature TmaxOP stage, and finally recover to 20 °C, which takes 60 min;

[0137] 4. Power on for function check before the end of the low temperature hold, power off after the check, and start power on from 20 °C to the maximum operating temperature TmaxOP stage until the end of the hold at the maximum operating temperature TmaxOP. Function check is also required during this stage, and observe whether the function changes until the power on ends. A total of 6 cycles are performed.

[0138] Judgment criteria:

[0139] The performance status level FSC reaches A, the structure is intact, and there are no cracks or damages on the appearance, then the judgment criteria are met.

[0140] 3.9 Damp heat, cyclic

[0141] This index is used to represent the tolerance ability of the tilt sensor product to be tested in an alternating humid and hot environment. The specific test method is as follows:

[0142] Place the tilt sensor product to be tested in a thermo-hygrostat chamber. Raise the temperature from room temperature to 65°C within 1 hour, and at the same time raise the humidity to 95%. Maintain this state for 4 hours. Cool the temperature from 65°C to room temperature within 2 hours, while keeping the humidity unchanged. Maintain this state for 1 hour. Raise the temperature to 65°C again within 1 hour, with the humidity remaining unchanged. Maintain this state for 4 hours. Adjust the temperature to room temperature within 2 hours, and keep the humidity unchanged. Maintain this state for 9 hours. Raise the temperature to 65°C again within 1 hour, with the humidity unchanged. Maintain this state for 4 hours. Adjust the temperature to room temperature within 2 hours, and keep the humidity unchanged. Maintain this state for 1 hour. Raise the temperature of the test chamber to 65°C again within 1 hour, with the humidity unchanged. Maintain this state for 4 hours. Adjust the temperature to room temperature within 2 hours, and keep the humidity unchanged. Maintain this state for 2 hours. Lower the temperature from room temperature to -10°C within 1 hour, and lower the humidity to 0. Maintain this state for 3 hours. Restore the temperature to room temperature within 1 hour, and maintain for 2 hours. The cumulative test duration above is 48 hours, which is 1 cycle, and a total of 5 cycles are carried out.

[0143] Judgment criteria:

[0144] If the performance status level FSC reaches A, and the structure is intact and there are no cracks or damages on the appearance, then the judgment criteria are met.

[0145] 3.10 Condensation index

[0146] This index is used to represent whether the functions and performance of the tilt sensor product to be tested meet the design index requirements in an extremely humid environment. The specific test method is as follows:

[0147] 1. Place the tilt sensor in a thermo-hygrostat chamber at an environment of 0 - 2°C for 2 hours, with no requirement for relative humidity;

[0148] 2. After the holding is completed, transfer the tilt sensor to a high-humidity test chamber within 3 minutes;

[0149] 3. In the high-humidity test chamber, the environmental temperature is 40°C ± 2°C, and the relative humidity is 98% - 100%, and it is stored in this environment for 22 hours;

[0150] 4. The above steps 1) - 3) are 1 cycle, and a total of 10 cycles are carried out;

[0151] Judgment criteria:

[0152] If the performance status level FSC reaches A, and the structure is intact and there are no cracks or damages on the appearance, then the judgment criteria are met.

[0153] 3.11 Temperature gradient index

[0154] This indicator is used to represent the performance of the mechanical and electrical devices of the tilt sensor product to be tested under temperature change environments, and to evaluate its adaptability and reliability among different temperature regions. The specific test method is to place the tilt sensor in a thermostatic test chamber, with the high temperature limit being the maximum operating temperature TmaxOP and the low temperature limit being the minimum operating temperature TminOP. Starting from room temperature, the temperature is decreased in steps of 5°C until the minimum operating temperature TminOP, and then increased from the minimum operating temperature TminOP to the maximum operating temperature TmaxOP. After the temperature reaches the set value at each step, power is applied for function detection, and after the detection is completed, the power is turned off and the gradient test continues; the holding time is the detection duration.

[0155] Judgment criteria:

[0156] If the performance status level FSC reaches A, the structure is intact, and there are no cracks or damages on the appearance, then the judgment criteria are met.

[0157] 3.12 Salt spray function and penetration index

[0158] This indicator is used to represent whether the functions and performance of the tilt sensor product to be tested will be affected in a corrosive environment. The specific test method is to place the tilt sensor in a salt spray test chamber, with the concentration of the salt solution being 5±1%; when the pH value is at 35±2°C, the value is between 6.5 and 7.2, the temperature of the chamber is set at 35°C, and the temperature of the pressure barrel is 47°C;

[0159] Pretreatment: For continuously used incubators, the solution collected during each test is detected. The collection amount per hour within 80 cm 2 should be between 1.0 mL and 2.0 mL. For non-continuously used test chambers, a 16 - 24 h trial operation should be carried out before the test. The working mode of the test chamber is 8 h of spraying + 16 h of static placement. The cumulative duration of 24 h is one cycle, and a total of 6 cycles are carried out. During the spraying stage of each cycle, a power-on operation check is carried out on the tilt sensor once, and the power-on time point is 4 h after spraying.

[0160] Judgment criteria:

[0161] If the performance status level FSC reaches A, and there are no bulges, white rust, oxides, powdering, peeling, etc. on the surface of the tilt sensor, and there is no salt water penetration inside after disassembling, then the judgment criteria are met.

[0162] 3.13 Salt spray surface corrosion index

[0163] This index is used to represent the surface corrosion resistance of the tilt sensor product to be tested. The specific test method is to place the tilt sensor in a salt spray test chamber. The concentration of the salt solution is 5±1%, and the pH value is between 6.5 and 7.2 at 35±2°C. The temperature of the chamber is set at 35°C, and the temperature of the pressure barrel is 47°C;

[0164] Pretreatment: For the continuously used incubator, the solution collected during the test is detected after each test. The hourly collection volume within the range of 80m 2 should be between 1.0 mL and 2.0 mL; for the intermittently used test chamber, a 16 - 24h trial run should be carried out before the test starts; the working mode of the test chamber is: continuous spraying for 96h;

[0165] Judgment criteria:

[0166] The performance status level FSC reaches A, and there are no bulges, white rust, oxides, powdering, peeling, etc. on the surface of the tilt sensor, and there is no penetration of salt water inside after disassembling, then the judgment criteria are met.

[0167] 3.14 Xenon lamp aging index

[0168] This index is used to represent the ability of the tilt sensor product to be tested to accelerate aging after being irradiated by sunlight through window glass. The specific test method is to place the tilt sensor in a xenon lamp aging chamber. The filter is a window glass filter, the wavelength is 420nm, and the irradiance is 1.20±0.02W / m 2 ;

[0169] 1. During the light exposure stage, the blackboard temperature is 89±3°C, the air temperature in the chamber is 62°C±2°C, the relative humidity is 50%±5%, and the running time is 228 minutes;

[0170] 2. During the dark stage, the blackboard temperature is 38°C±3°C, the air temperature in the chamber is 38°C±3°C, the relative humidity is 95%±5%, and the running time is 60 minutes; the above two steps are one cycle, and a total of 125 cycles are carried out;

[0171] Judgment criteria:

[0172] The performance status level FSC reaches A, and there are no bulges, cracks, peeling, etc. on the surface of the tilt sensor (slight surface discoloration is allowed), then the judgment criteria are met.

[0173] (4) Protection index

[0174] The protection index includes 3 third - level indexes, namely the dust - proof index, the waterproof index, and the sealing index. The following introduces each third - level index.

[0175] 4.1 Dust - proof index

[0176] This indicator is used to represent the protection level of the tilt sensor product to be tested, for protecting the equipment inside the enclosure from solid foreign objects entering. The specific test method is to place the tilt sensor in a dust-proof test chamber. For the IP6X level, the dust used is talcum powder, with 2 kg of talcum powder per cubic meter in the test chamber. A negative pressure is generated in the chamber by a vacuum pump to force the dust into the equipment, maintaining the negative pressure below 20 mbar and spraying continuously for 8 hours.

[0177] The test temperature is room temperature, and the product temperature is the ambient temperature.

[0178] The shielded parts need to be protected; after the test, wipe the surface of the tilt sensor with a brush or a clean cotton cloth.

[0179] Judgment criteria:

[0180] The performance status level FSC reaches A, and there is no dust entering the inside of the tilt sensor after the test, then the judgment criteria are met.

[0181] 4.2 Waterproof index

[0182] This indicator is used to represent the protection level of the tilt sensor product to be tested, for protecting the equipment inside the enclosure from the harmful effects of water entering. The specific test method is to place the tilt sensor in a waterproof test chamber. For the IP6X level, a 12.5-mm nozzle test equipment is used; the water flow rate is 100 L / min; the center part of the main water flow is a circle with a diameter of 120 mm at a distance of 2.5 m from the nozzle; the spraying time on the surface of the enclosure is about 1 min per square meter; the test time is at least 3 min; the distance from the nozzle to the surface of the enclosure is 2.5 m to 3 m.

[0183] For the IP7X level, a water storage bucket is used as the test equipment; for tilt sensors with a height less than 850 mm, the lowest point is 1000 mm below the water surface; for tilt sensors with a height equal to or greater than 850 mm, the highest point is 150 mm below the water surface; the test time is 30 min; the temperature difference between the water temperature and the specimen is not more than 5 degrees.

[0184] Judgment criteria:

[0185] The performance status level FSC reaches A, and there is no water entering the inside of the tilt sensor after the test, then the judgment criteria are met.

[0186] 4.3 Sealing index

[0187] This index is used to represent the shell sealing performance of the inclination sensor product to be tested. The specific test method is to place the inclination sensor in a test chamber at the maximum operating temperature TmaxOP for 0.5 h, then take out the inclination sensor from the test chamber and immediately immerse it in a liquid at 0 °C with an immersion depth of 76 ± 5 mm for 0.5 h. At this time, keep the inclination sensor powered on and check whether the function is normal. Repeat the above steps 4 times, for a total of 5 times;

[0188] Judgment criteria:

[0189] If the performance status level FSC reaches A and there is no water entering the inside of the inclination sensor after the test, the judgment criteria are met.

[0190] (5) Durability index

[0191] The durability index includes 4 third-level indexes, namely the thermal fatigue life index, the damp heat endurance index under constant conditions, the high-temperature operation durability index, and the low-temperature operation durability index. The following is an introduction to each third-level index.

[0192] 5.1 Thermal fatigue life index

[0193] This index is used to represent the reliability of the inclination sensor product to be tested against environmental temperature changes. The specific test method is to conduct temperature shock durability tests and powered-on temperature cycle durability tests respectively.

[0194] Temperature shock durability test:

[0195] Place the inclination sensor product to be tested in a thermal shock cabinet, set the high temperature to the maximum storage temperature TmaxST, and the low temperature to the minimum storage temperature TminST; the conversion time is less than or equal to 30 s, and the high and low temperature holding times are 10 min. After reaching the temperature, hold it. A thermocouple sensor can be used in conjunction with a data logger to detect and make the temperature arrival time more accurate; the number of cycles is determined according to the number of test samples, and the number of cycles is 632 cycles;

[0196] Powered-on temperature cycle durability test

[0197] Place the inclination sensor product to be tested in a constant temperature test chamber, set the high temperature to the maximum operating temperature TmaxOP, and the low temperature to the minimum operating temperature TminOP. The temperature change rate is (1 - 3) °C / min, and the high and low temperature holding times are 10 min; after reaching the temperature, hold it. A thermocouple sensor can be used in conjunction with a data logger to detect and make the temperature arrival time more accurate; the number of cycles is determined according to the number of test samples, and the number of cycles is 211 cycles;

[0198] Judgment criteria:

[0199] If the performance status level FSC reaches A, the judgment criteria are met.

[0200] 5.2 Damp Heat, Steady State Endurance Index

[0201] This index is used to indicate whether the tilt sensor product under test can meet the specified operating life requirements. The specific test method is to place the tilt sensor product under test in a thermo-hygrostat chamber with the temperature set at 85°C and the humidity set at 85%, for a duration of 1000 h.

[0202] Judgment Criteria:

[0203] If the Functional Status Class (FSC) reaches A, the judgment criteria are met.

[0204] 5.3 High Temperature Operating Endurance Index

[0205] This index is used to indicate the durability and reliability of the tilt sensor product under test during continuous operation in a high temperature environment. The specific test method is to place the tilt sensor product under test in a thermostat chamber with the temperature set at the maximum operating temperature TmaxOP, and the test duration is 96 h.

[0206] Judgment Criteria:

[0207] If the Functional Status Class (FSC) reaches A, the judgment criteria are met.

[0208] 5.4 Low Temperature Operating Endurance Index

[0209] This index is used to indicate the durability and reliability of the tilt sensor product under test during continuous operation in a low temperature environment. The specific test method is to place the tilt sensor product under test in a thermostat chamber with the temperature set at the minimum operating temperature TminOP, and the test duration is 48 h.

[0210] Judgment Criteria:

[0211] If the Functional Status Class (FSC) reaches A, the judgment criteria are met.

[0212] (6) Electromagnetic Compatibility Index

[0213] The electromagnetic compatibility index includes three third-level indexes, namely the electrostatic discharge immunity index, the electrical fast transient pulse group immunity index, and the surge (impact) immunity index. Each third-level index is introduced below.

[0214] 6.1 Electrostatic Discharge Immunity Index

[0215] This index is used to indicate the anti-interference ability of the tilt sensor product under test against electrostatic discharge. The specific test method is to conduct contact discharge and air discharge tests on the tilt sensor product under test respectively.

[0216] Judgment Criteria:

[0217] If the Functional Status Class (FSC) reaches B, the judgment criteria are met.

[0218] 6.2 Electrical fast transient burst immunity index

[0219] This index is used to indicate whether the performance of the tilt sensor product under test degrades when the power supply port, signal port, and ground port are subjected to repetitive fast transient interference under the action of the disturbance signal. The specific test method is as follows:

[0220] 1. Configure the test equipment;

[0221] 2. When the cable length between the tilt sensor product under test and the output end of the coupling network exceeds 0.5m ± 0.05m, the excess length shall be folded in a non-inductive manner and placed together with the device under test 0.1m above the ground reference plane;

[0222] 3. Each side of the ground reference plane shall extend at least 0.1m beyond the device under test;

[0223] 4. Conduct the test on the power supply port or other specified ports according to the specified test level requirements, and the test duration shall be at least 1 minute.

[0224] 5. Test twice, once with the product case grounded and the other without grounding, and both must be satisfied;

[0225] Judgment criterion:

[0226] If the performance status class FSC reaches B, the judgment criterion is satisfied.

[0227] 6.3 Surge (impact) immunity index

[0228] This index is used to indicate the immunity of the tilt sensor product under test to indirect lightning strikes under the action of the disturbance signal. The specific test method is as follows:

[0229] 1. The number of surge pulses applied to the DC power supply terminal of the tilt sensor product under test is 10 times for both positive and negative polarities;

[0230] 2. The time interval between consecutive pulses is 1 minute or shorter;

[0231] 3. When the cable length between the device under test and the output end of the coupling network exceeds 1m, the excess length shall be folded in a non-inductive manner;

[0232] Judgment criterion:

[0233] If the performance status class FSC reaches B, the judgment criterion is satisfied.

[0234] (7) Measuring performance indicators

[0235] The measurement performance of the inclinometer sensor product determines whether the product can meet the usage requirements of customers, and it is also the main goal to be achieved during the R & D and production process of the inclinometer sensor product. Therefore, the evaluation criteria and evaluation range for the measurement performance indicators are relatively important contents. This invention comprehensively considers the requirements in various aspects involved in the actual application of the inclinometer sensor product, and involves a total of 28 third-level indicators, specifically including measurement range, resolution, accuracy, static redundancy error, zero deviation, repeatability, precision, non-linearity, zero temperature drift, full-scale temperature drift, output frequency, sensitivity, sensitivity temperature drift, response time / response frequency, cross-axis sensitivity, alarm function, indicator light function, delay, hysteresis angle, relative zero setting function, communication protocol, measurement direction, wiring definition, form factor, product identification model, parts list, output power / output current, and long-term stability indicators.

[0236] The following introduces each third-level indicator.

[0237] 7.1 Measurement range indicator

[0238] The measurement range indicator is defined as the area determined by two values of the measured quantity within the allowable error limit. The highest and lowest values of the measured quantity respectively become the "upper limit value" and "lower limit value" of the measurement range. The specific test method is as follows:

[0239] Install the inclinometer sensor product with the theoretical output at the zero-degree position on a high-precision turntable. Select several points within the set measurement range and take one detection point every 1 degree outside the specified measurement range until the output limit. The area corresponding to the lowest and highest values of the input quantity within the allowable error limit of the test result is the actual measurement range of the test sample.

[0240] Judgment criterion:

[0241] If the measurement range meets the requirements specified in the product design (the specified measurement range should be less than the actual measurement range), then it meets the judgment criterion.

[0242] 7.2 Resolution indicator

[0243] The resolution indicator is defined as the minimum change in the measured quantity that the inclinometer sensor product can detect within the specified measurement range. The specific test method is as follows:

[0244] Install the inclinometer sensor product with the theoretical output at the zero-degree position on a high-precision turntable. Rotate the turntable within the measurement range of the inclinometer sensor to change the sensor indication value, record the reading of the turntable at this time, then continue to rotate the turntable to make the sensor indication value change by one resolution, and record the reading of the turntable again. The absolute value of the difference between the two readings is the resolution of the sensor. Repeat the above process 3 times and take the maximum value as the final result.

[0245] Judgment criterion:

[0246] If the resolution meets the requirements specified in the product design (the test result is less than or equal to the specified value), then the judgment criterion is met.

[0247] 7.3 Accuracy Index

[0248] The accuracy index is defined as the degree of agreement between the measurement result and the true value of the measured quantity. The specific test method is as follows:

[0249] Install the inclination sensor product with the theoretical output at the zero-degree position on a high-precision turntable. Adjust the turntable so that the output value of the inclination sensor is zero. At this time, clear the angle value displayed on the turntable. Within the measurement range of the inclination sensor, select at least five measurement points and record the readings of the inclination sensor at the test points respectively. Among all the test points, measure from the small angle (or negative angle) to the large angle (or positive angle) in sequence, which is the forward stroke, and vice versa is the reverse stroke. Each sensor measures one forward stroke or reverse stroke. Among all the test points, the one with the largest absolute value of the error is defined as the accuracy.

[0250] Judgment Criterion:

[0251] If the accuracy meets the requirements specified in the product design (the test result is less than or equal to the specified value), then the judgment criterion is met.

[0252] 7.4 Static Redundancy Error Index

[0253] The static redundancy error index is defined as the angular deviation of the redundant sensors in the inclination sensor product when static. The specific test method is as follows:

[0254] Place the inclination sensor product on a marble platform. When the product is horizontal or vertical to the marble plane, it is the zero point of the sensor. Record the two-channel output values of the sample at this time and calculate the difference between the two-channel output values.

[0255] Judgment Criterion:

[0256] If the static redundancy error meets the requirements specified in the product design (the test result is less than or equal to the specified value), then the judgment criterion is met.

[0257] 7.5 Zero-Point Deviation Index

[0258] The zero-point deviation index is defined as the output when the inclination sensor is placed on a marble plane. The specific test method is as follows:

[0259] Place the inclination sensor product on a marble platform. When the product is horizontal or vertical to the marble plane, it is the zero point of the sensor. Record the output value of the sample at this time;

[0260] Judgment Criterion:

[0261] If the zero deviation meets the requirements specified in the product design (the test result is less than or equal to the specified value), then the judgment criterion is met.

[0262] 7.6 Repeatability Index

[0263] The repeatability index is defined as the consistency between the results obtained from continuous multiple measurements of the same measured quantity under the same measurement conditions. The specific test method is as follows:

[0264] For full-scale repeatability:

[0265] Install the inclinometer sensor product with the theoretical output at the zero-degree position on a high-precision turntable. Adjust the turntable so that the output value of the inclinometer sensor is zero. At this time, clear the angle value displayed on the turntable. Select at least five measurement points within the measurement range of the inclinometer sensor, and record the readings of the inclinometer sensor at the test points respectively. Among all the test points, measure from the small angle (or negative angle) to the large angle (or positive angle) in sequence, which is the forward stroke, and vice versa for the reverse stroke. One cycle consists of the forward stroke plus the reverse stroke. Each sensor is measured for three cycles; calculate the experimental standard deviation of each calibration point, and take the maximum value as the repeatability. The calculation formula is as follows:

[0266]

[0267] In the formula, s is the full-scale repeatability, and x i is the result of the i-th measurement, is the arithmetic mean of the n measurement results;

[0268] For zero-point repeatability:

[0269] Install the inclinometer sensor product with the theoretical output at the zero-degree position on a high-precision turntable. Adjust the turntable so that the output value of the inclinometer sensor is zero. At this time, clear the angle value displayed on the turntable. Within the measurement range of the inclinometer sensor, rotate the turntable from the zero point to any point and then back to the zero point position. Repeat the above process 3 times, and take the maximum value among them as the zero-point repeatability;

[0270] Judgment Criterion:

[0271] If the repeatability meets the requirements specified in the product design (the test result is less than or equal to the specified value), then the judgment criterion is met.

[0272] 7.7 Accuracy Index

[0273] The accuracy index is defined as the degree of closeness between the measurement result and the true value. Specifically, it is to calculate the root mean square at multiple points within the measurement range. The specific test method is as follows:

[0274] Select several detection points within the measurement range, record the output values of each detection point, and calculate the root mean square error. Then there is:

[0275]

[0276] Where: σ x is the accuracy (i.e., root mean square error), x i is the output value of a certain detection point, x0 is the output value of the starting point, x is the angle value corresponding to the rotation of the turntable, and n is the total number of detection points;

[0277] Judgment criterion:

[0278] If the accuracy meets the requirements specified in the product design (the test result is less than or equal to the specified value), then the judgment criterion is met.

[0279] 7.8 Nonlinearity index

[0280] The nonlinearity index is defined as the degree of deviation between the calibration curve and the set straight line, that is, the degree of coincidence (deviation) between the actual input-output curve (calibration curve) of the tilt sensor and the fitted straight line. The fitted straight line is obtained by the least squares method. The specific test method is as follows:

[0281] Use the same method as the repeatability test to obtain the actual output values of each calibration point for 3 cycles, enter the output quantity and the corresponding input quantity of the calibration point into the data processing table, and calculate the nonlinearity. The calculation formula is as follows:

[0282]

[0283] Where: ⊿max is the maximum deviation between the actual input-output curve and the fitted straight line, and yFS is the full-scale output;

[0284] The setting principle of the calibration point is:

[0285] For products with a measurement range of -15° to 15°, the number of calibration points shall not be less than 5; for products with a measurement range of -45° to 45°, the number of calibration points shall not be less than 7; for products with a measurement range of -60° to 60°, the number of calibration points shall not be less than 9; for ranges greater than or equal to ±90°, the number of points shall not be less than 13.

[0286] Judgment criterion:

[0287] If the nonlinearity meets the requirements specified in the product design (the test result is less than or equal to the specified value), then the judgment criterion is met.

[0288] Note: Digital tilt sensor products do not need to be tested for nonlinearity.

[0289] 7.9 Zero temperature drift index

[0290] The zero temperature drift index is defined as the change amount of the zero point of the tilt sensor changing with temperature. The specific test method is as follows:

[0291] Install the inclination sensor product with its theoretical output at the zero-degree position inside the high and low temperature chamber. Set the test chamber temperature to 25°C, the lower limit value of the operating temperature range, and the upper limit value of the operating temperature range, three environmental temperatures. Stabilize for 2 hours at each environmental temperature, and record the output values A_middle, A_lower, and A_upper of the sample under the three environmental temperature conditions respectively. Calculate the zero-point temperature drift, then there is:

[0292] Zero-point temperature drift = MAX[ABS(A_lower - A_middle), ABS(A_upper - A_middle)]

[0293] Judgment criterion:

[0294] If the zero-point temperature drift meets the requirements specified in the product design (the test result is less than or equal to the specified value), then it meets the judgment criterion.

[0295] 7.10 Full-scale temperature drift index

[0296] The full-scale temperature drift index is defined as the change in the angle within the full scale of the sensor as the temperature changes. The specific test method is as follows:

[0297] Install the axis of the high-precision turntable inside the high and low temperature chamber, and install the inclination sensor product with its theoretical output at the zero-degree position on the high-precision turntable. Adjust the turntable to make the output value of the inclination sensor zero, and at this time, clear the angle value displayed on the turntable; set the test chamber temperature to 25°C, the lower limit value of the operating temperature range, and the upper limit value of the operating temperature range, three environmental temperatures. Stabilize for 2 hours at each environmental temperature. Within the measurement range, randomly rotate the turntable at least 7 points at each temperature, record the output value of the product, subtract it from the output value of the corresponding product at room temperature of 25°C, take the maximum value as the full-scale temperature drift value of this sample divided by the corresponding temperature difference, and take the maximum value as the full-scale temperature drift value of this sample;

[0298] Judgment criterion:

[0299] If the full-scale temperature drift meets the requirements specified in the product design (the test result is less than or equal to the specified value), then it meets the judgment criterion.

[0300] 7.11 Output frequency index

[0301] The output frequency index is defined as the number of times the inclination sensor outputs information per second. The specific test method is as follows:

[0302] Use a stopwatch to record the time and record the number of output data bytes within the timing time;

[0303] Output frequency = Total number of output bytes / Number of bytes in a group of data / Timing time (seconds);

[0304] Note: The test time cannot be less than 100 times the output period (the reciprocal of the output frequency);

[0305] Judgment criterion:

[0306] If the output frequency meets the requirements specified in the product design, the judgment criterion is met.

[0307] 7.12 Sensitivity index

[0308] The sensitivity index is defined as the ratio of the change value of the sensor output quantity to the change value of the corresponding measured quantity. The units used for this index are: voltage mV / °, V / °; current mA / °, A / °. The specific test method is as follows:

[0309] For the linear output sensitivity, the recorded value of the non-linearity is substituted into the performance calculation to automatically calculate the sensitivity. The sensitivity at any point (except the zero point) within the linear range is calculated according to the following formula:

[0310] Sensitivity = Output range / Corresponding input range or Actual output change of the product / Angle change of the turntable;

[0311] For the sensitivity of the non-linear output, at any point (except the zero point) within the full range, it can be calculated according to the following formula:

[0312] Sensitivity = (VX / IX - offset) / sinX

[0313] Where: Offset is the zero point output, and VX / IX is the output at any angle of the product;

[0314] Judgment criterion:

[0315] If the sensitivity meets the requirements specified in the product design, the judgment criterion is met.

[0316] Note: Digital inclinometer sensor products do not need to be tested for sensitivity.

[0317] 7.13 Sensitivity temperature drift index

[0318] The sensitivity temperature drift index is defined as the change in the sensitivity output within the change interval of a certain environmental quantity (time, temperature, etc.). The units used for this index are: % / °C, %. The specific test method is as follows:

[0319] Put the turntable axis into the high and low temperature chamber, install the sample on the high-precision turntable axis, rotate the turntable to make the product output zero, and then clear the angle value displayed on the measuring instrument at this time; Set the test chamber temperature to 25°C, the lower limit value of the working temperature range, and the upper limit value of the working temperature range at 3 environmental temperatures respectively. Stabilize for 2 hours at each environmental temperature, then rotate the turntable to 75% of the upper limit value and the lower limit value of the measuring range respectively, record the readings of the product output at this time, and calculate the sensitivity of each temperature range according to the following formula;

[0320] For digital output products:

[0321] Sensitivity = actual output change of the product / angle change of the turntable;

[0322] SIN curve: The sensitivity is {Vout(@) - Vout(-@)} / 2 * SIN(@) (the sensitivity temperature drift of the SIN curve is within the range of the measuring range, and 5 symmetric points are randomly selected for inspection);

[0323] Based on the calculated sensitivity, calculate the sensitivity temperature drift, then there is:

[0324] The positive half-axis sensitivity at the lower limit temperature value is A, the negative half-axis sensitivity is C, the positive half-axis sensitivity at 25°C is B1, and the negative half-axis sensitivity at 25°C is B2; then the positive half-axis sensitivity temperature drift at the lower limit temperature value = (A - B1) / B1, the negative half-axis = (C - B2) / B2, and the one with the largest absolute value is the sensitivity temperature drift at the lower limit temperature value. The method for calculating the sensitivity temperature drift at the upper limit temperature value is the same as that at the lower limit temperature value;

[0325] Judgment criterion:

[0326] If the sensitivity temperature drift meets the requirements specified in the product design, it meets the judgment criterion.

[0327] Note: Digital inclinometer sensor products do not need to be tested for sensitivity.

[0328] 7.14 Response time / response frequency index

[0329] The response time / response frequency index is defined as the time required for the sensor output to rise to its final specified percentage due to a step change in the measured quantity. The specific test method is as follows:

[0330] For analog output:

[0331] Place the test sample at the zero output position and then quickly rotate it by the set angle, and use an oscilloscope to record the time it takes for the output of the test sample to change from zero to 85% of the set angle;

[0332] For digital output:

[0333] Calculate by measuring the output frequency;

[0334] 1. The lower limit and upper limit of the measuring range are symmetric, and the set angle is the lower limit value or the upper limit value;

[0335] 2. The lower limit and upper limit of the measuring range are asymmetric, and the set angle is taken as the maximum value of the absolute value of the lower limit value and the upper limit value;

[0336] 3. Repeat the above process 3 times and take the maximum value as the final result; for a biaxial sensor, any axis can be tested;

[0337] 4. When the set angle 85% is greater than 90°, only the response time from 0 to 90° or 0 to -90° needs to be tested;

[0338] Judgment criteria:

[0339] If the response time meets the requirements specified in the product design, then the judgment criteria are met.

[0340] 7.15 Cross-axis sensitivity index

[0341] The cross-axis sensitivity index is defined as the percentage of the ratio of the change in the measurement axis to the change in the cross-axis that causes this change. The specific test method is as follows:

[0342] Measurement of the Y-axis cross-axis sensitivity: Adjust the X-axis output of the test sample to 0 degrees. Rotate the X-axis to the maximum value, zero degree, and minimum value within the measurement range respectively, and record the maximum, 0°, and minimum values of the X-axis output as A, B, and C respectively; at this time, record the corresponding Y-axis output values Y+, Y0, and Y-. Then there is:

[0343] Y-axis cross-axis sensitivity = ((Y+) - (Y0)) / (A - B) or ((Y-) - (Y0)) / (C - B), take the maximum value

[0344] The measurement of the X-axis cross-axis sensitivity is the same as that of the Y-axis;

[0345] Judgment criteria:

[0346] If the cross-axis sensitivity meets the requirements specified in the product design, then the judgment criteria are met.

[0347] Note: Digital inclinometer sensor products do not need to be tested for cross-axis sensitivity.

[0348] 7.16 Alarm function index

[0349] The alarm function index applies to tilt switch products. The specific test method is as follows:

[0350] Zero the product on the installation surface; for products without a zeroing switch, use relevant equipment to level the installation surface; rotate the turntable to confirm the output state of the product when the sample is tilted at angles less than and greater than the alarm angle respectively;

[0351] Judgment criteria:

[0352] If the alarm logic meets the requirements specified in the product design, then the judgment criteria are met.

[0353] 7.17 Indicator light function index

[0354] The indicator light function index applies to welding lamp products. The specific test method is to visually check whether the indicator light function of the test sample is consistent with the description in the instruction manual.

[0355] Judgment criteria:

[0356] If the indicator light function meets the requirements of the product design logic, the judgment criteria are met.

[0357] 7.18 Delay index

[0358] The delay index applies to tilt switch products. The specific test method is as follows:

[0359] Install the product on the turntable and zero the product. Step by step according to the accuracy / precision value until the sample changes from one state to another; calculate the time required for the state change; the delay includes alarm delay and recovery delay;

[0360] Judgment criteria:

[0361] If the indicator light function meets the requirements of the product design logic, the judgment criteria are met.

[0362] 7.19 Hysteresis angle index

[0363] The hysteresis angle index applies to tilt switch products. The specific test method is as follows:

[0364] Install the product on the turntable and zero the product. Rotate the turntable in the opposite direction with the hysteresis angle as the step point until the sample changes from one state to another; confirm the required angle;

[0365] Judgment criteria:

[0366] If the hysteresis angle meets the requirements specified in the product design, the judgment criteria are met.

[0367] 7.20 Relative zero setting function index

[0368] The relative zero setting function index applies to tilt switch products. The specific test method is as follows:

[0369] Within the measurement range, fix the sample at any angle and press the zero button. After the indicator light (working current of the product without a light) changes and the state remains unchanged, release the button and the zero setting is successful.

[0370] Judgment criteria:

[0371] If the zero setting function meets the requirements specified in the product design, the judgment criteria are met.

[0372] 7.21 Communication protocol index

[0373] The specific test method for this index is as follows:

[0374] Conduct the test according to the requirements of the relevant documents of the test sample. During the test, use cross-testing, that is, use other command words to detect whether the current command takes effect. The default settings should be restored after the test.

[0375] Judgment criteria:

[0376] If the communication protocol meets the requirements specified in the product design, the judgment criteria are met.

[0377] 7.22 Measurement direction index

[0378] The specific test method for this index is as follows:

[0379] Tilt the test sample according to the requirements of the test sample, and observe whether the output of the test sample is consistent with the description in the instruction manual.

[0380] Judgment criteria:

[0381] If the measurement direction meets the requirements specified in the product design, the judgment criteria are met.

[0382] 7.23 Wiring index

[0383] The specific test method for this index is to wire according to the requirements of the instruction manual and check whether the functions of the test sample are normal.

[0384] Judgment criteria:

[0385] If the wiring definition meets the requirements specified in the product design, the judgment criteria are met.

[0386] 7.24 Outer dimension index

[0387] The specific test method for this index is to measure the key dimensions of the product shell using an electronic digital caliper.

[0388] Judgment criteria:

[0389] If the outer dimensions meet the requirements specified in the product design, the judgment criteria are met.

[0390] 7.25 Product identification / model number index

[0391] The specific test method for this index is to check whether the contents and pasting positions of each label on the sample are correct.

[0392] Judgment criteria:

[0393] If the product identification and model number meet the requirements specified in the product design, the judgment criteria are met.

[0394] 7.26 Parts list index

[0395] The specific test method for this index is to visually check whether the parts and quantities of the test sample are correct according to the requirements of the list.

[0396] Judgment criteria:

[0397] If the contents of the parts list meet the requirements specified in the product design, the judgment criteria are met.

[0398] 7.27 Output power / output current index

[0399] This index is applicable to inclinometer switch products. The specific test method is as follows:

[0400] Determine the product load size and wiring method according to the test conditions specified in the relevant product documents. When the load current reaches the required value, check whether the function of the test sample is normal.

[0401] Judgment criteria:

[0402] If the output power meets the requirements specified in the product design, the judgment criteria are met.

[0403] 7.28 Long-term stability index

[0404] This index is defined as the ability of the sensor to maintain its characteristics constant over a long period of time. For an inclinometer sensor, its key characteristics include zero output and accuracy. The specific test method is as follows:

[0405] 1. Zero output stability test method:

[0406] Fix the sensor at the zero position, continuously power it on and measure the change of its output over time;

[0407] 2. Accuracy stability test method:

[0408] When measuring, turn on the power supply and measure the change of its accuracy over time;

[0409] Note: The test time is generally in months, such as: degree / month; according to different test requirements, it can also be in hours or years as the test time unit;

[0410] Judgment criteria:

[0411] For products with digital output, the angle change does not exceed the following regulations:

[0412] 1. When accuracy and precision > 0.5°, the angle change does not exceed 1 times of accuracy and precision;

[0413] 2. When 0.3° < accuracy and precision ≤ 0.5°, the angle change does not exceed 2 times of accuracy and precision;

[0414] 3. When 0.1° < accuracy and precision ≤ 0.3°, the angle change does not exceed 3 times of accuracy and precision;

[0415] 4. When 0.05° < accuracy and precision ≤ 0.1°, the angle change does not exceed 5 times of accuracy and precision;

[0416] 5. Accuracy and precision ≤ 0.05°, and the angle change does not exceed 6 times the accuracy and precision.

[0417] For products with analog output, the angle change does not exceed the following regulations:

[0418] 1. Nonlinearity ≤ ±0.2% FS, and the angle change does not exceed 0.5°.

[0419] 2. Nonlinearity > ±0.2% FS, and the angle change does not exceed 1°.

[0420] (8) Packaging material indicators

[0421] The packaging material indicators include 2 third-level indicators, namely the free fall indicator and the transportation vibration indicator. The following is an introduction to each third-level indicator.

[0422] 8.1 Free fall indicator

[0423] This indicator is used to represent the degree of influence on the appearance and function of the inclination sensor product to be tested after experiencing free fall during transportation. The specific test method is to simulate free fall. In the specific parameters, the number of drops for each sample is 10 times, the drop height is 1000 mm, the drop surface is required to be a concrete floor or a steel plate surface, the drop directions are 1 corner, 3 edges, and 6 faces. Additionally, when selecting the corner, the center of gravity of the entire packaging material is used as the reference point for consideration.

[0424] Judgment criteria:

[0425] When the performance status level FSC reaches A, and there are obvious damages on the appearance or damages detected through visual inspection, but the damaged state has no impact on the function, then the judgment criteria are met.

[0426] 8.2 Transportation vibration indicator

[0427] This indicator is used to represent the tolerance of the inclination sensor product to be tested to the vibration generated during transportation in the packaged state. The specific test method is to place the inclination sensor in the transportation packaging box, which also contains all the packing materials; the simulation state of the vibration table conforms to the actual situation, and it is necessary to avoid using the method of directly fixing with a pressing block or a pressing strip. The preferred fixing method is to install protective columns around the vibration table and do a good job of protection around it. Place the packaged inclination sensor directly in the middle and let it move freely, or use a binding band, and rigid fixing is not allowed.

[0428] In the detailed test parameters of transportation vibration, the vibration frequency is 10 Hz - 300 Hz, the vibration directions are the three axial directions of X, Y, and Z, and the test time is 24 h for each axial direction.

[0429] Judgment criteria:

[0430] The performance status level FSC reaches A, and the structure is intact without cracks or damage on the appearance, then the judgment criteria are met.

[0431] (9) Chemical coating index

[0432] The chemical coating index only includes 1 third-level index, which is the surface coating index. The following introduces this third-level index.

[0433] This index is used to represent the tolerance ability of the outer surface of the tilt sensor product to be measured for chemicals. The specific test method is to clean and dry the outer surface of the tilt sensor to be measured, apply a certain amount of chemicals (such as artificial sweat, ether, hydrochloric acid, diesel, gasoline, etc.), observe for a certain period of time (such as 24 hours), and check whether there are phenomena such as corrosion, discoloration, blistering, softening, etc. on the surface;

[0434] Judgment criteria:

[0435] If there are no phenomena such as corrosion, discoloration, blistering, softening, etc. on the appearance surface, then the judgment criteria are met.

[0436] Step S2: According to the type of the tilt sensor to be measured (including digital tilt sensor, analog tilt sensor, and tilt switch), configure the corresponding indicators in the reliability evaluation system constructed in step S1. For example, for a digital tilt sensor, there is no need to conduct relevant tests on non-linearity and sensitivity; for a tilt switch, in the measurement performance indicators, only the measurement range, alarm function, indicator light function, and relative zero setting function tests are required; while for an analog tilt sensor, all tests need to be conducted;

[0437] Step S3: Test the tilt sensor to be measured according to the corresponding test indicators respectively, obtain the finally quantified reliability index score, and determine whether the reliability of the current tilt sensor to be measured is qualified according to the reliability threshold.

[0438] As can be seen from Table 1, the tilt sensor reliability index A is calculated by summing the scores of each secondary index, so there is:

[0439] A = A1 + A2 + A3 + A4 + A5 + A6 + A7 + A8 + A9

[0440] Among them, the total score of the tilt sensor reliability index A is 100 points, the total score of the electrical index A1 is 10 points, the total score of the mechanical index A2 is 10 points, the total score of the environmental index A3 is 10 points, the total score of the protection index A4 is 5 points, the total score of the durability index A5 is 5 points, the total score of the electromagnetic compatibility index A6 is 10 points, the total score of the packaging material index A7 is 5 points, the total score of the chemical coating index A8 is 5 points, and the total score of the performance index A9 is 40 points.

[0441] In Table 1, the measurement direction indicators and wiring definition indicators under the electrical indicator A1, mechanical indicator A2, environmental indicator A3, packaging material indicator A7, and performance indicator A9 are all indicators that may pose a risk of function loss, and the remaining indicators are indicators that may experience performance degradation. Therefore, if the judgment criteria are not met during the test scoring, it can be directly determined that the reliability is unqualified.

[0442] Regarding the reliability indicator A of the tilt sensor, if the reliability indicator A score of a certain model of tilt sensor is greater than 90 points (in this example, it cannot be 90 points because the principle of the evaluation method of the present invention is to allow performance degradation of the tilt sensor to be measured, but function loss is never allowed), then it is determined that the reliability of this model of tilt sensor is qualified (scores in the range of (90, 100) are considered to pass with risk, and 100 points is considered to pass without risk). Otherwise, it is determined that the reliability of this model of tilt sensor is unqualified, and improvement design or component replacement is required.

[0443] In summary, since there is currently no reliability evaluation system and method for tilt sensor products, the present invention provides a reliability evaluation method for tilt sensors that is comprehensive in consideration and reasonable in evaluation, filling the technical gap in this field, and can be applied to the R & D and production stages, applicable to the quality inspection process of developed samples and mass-produced products, providing a quantifiable method for the evaluation of tilt sensor products.

[0444] The preferred specific embodiments of the present invention have been described in detail above. It should be understood that those of ordinary skill in the art can make many modifications and variations based on the concept of the present invention without creative work. Therefore, all technical solutions that can be obtained by those skilled in the art in the technical field of the present invention based on the concept of the present invention through logical analysis, reasoning, or limited experiments on the basis of the prior art should be within the protection scope determined by the claims.

Claims

1. A reliability evaluation method for an inclination sensor, characterized in that, It includes the following steps: 1) Construct a reliability evaluation system for the tilt sensor; 2) Configure the indicators in the reliability evaluation system according to the type of tilt sensor; 3) Conduct tests according to the configured indicators to obtain the reliability index scores, and judge whether the reliability is qualified according to the reliability threshold.

2. The reliability evaluation method of an inclination sensor according to claim 1, wherein In step 1), the reliability evaluation system of the tilt sensor consists of three-level reliability indicators, indicator detection methods, and scoring criteria.

3. The reliability evaluation method of an inclination sensor according to claim 2, characterized in that Among the three-level reliability indicators, the reliability indicators of the tilt sensor are used as the first-level indicators. The first-level indicators include nine second-level indicators, namely electrical indicators, mechanical indicators, environmental indicators, protection indicators, durability indicators, electromagnetic compatibility indicators, packaging material indicators, chemical coating indicators, and measurement performance indicators. Each second-level indicator includes multiple third-level indicators, and each third-level indicator corresponds to an indicator detection method and a scoring criterion respectively.

4. The reliability evaluation method of an inclination sensor according to claim 3, characterized in that, The third-level indicators included in the electrical indicators are working voltage indicator, abnormal voltage resistance indicator, instantaneous power supply voltage drop indicator, reverse voltage indicator, slow change of power supply voltage indicator, open circuit indicator, output short circuit indicator, signal line anti-reverse connection indicator, insulation resistance indicator, short-term power on / off indicator, and static working current indicator; the third-level indicators included in the mechanical indicators are random vibration indicator, sine vibration test indicator, mechanical shock indicator, and three-in-one indicator; the third-level indicators included in the environmental indicators are low-temperature storage indicator, low-temperature operation indicator, high-temperature storage indicator, high-temperature operation indicator, low-pressure transportation indicator, low-pressure operation indicator, temperature shock indicator, power-on temperature cycle indicator, alternating damp heat indicator, condensation indicator, temperature gradient indicator, salt spray function and penetration indicator, salt spray surface corrosion indicator, and xenon lamp aging indicator.

5. A method for evaluating the reliability of an inclination sensor according to claim 4, characterized in that, The third-level indicators included in the protection indicators are dust prevention indicator, waterproof indicator, and sealing performance indicator; the third-level indicators included in the durability indicators are thermal fatigue life indicator, power-on temperature cycle durability indicator, constant damp heat durability indicator, and high-temperature operation durability indicator; the third-level indicators included in the electromagnetic compatibility indicators are electrostatic discharge immunity indicator, electrical fast transient pulse group immunity indicator, and surge immunity indicator; the third-level indicators included in the packaging material indicators are free fall indicator and transportation vibration indicator; the third-level indicator included in the chemical coating indicator is surface coating indicator; the third-level indicators included in the performance indicators are measurement range indicator, resolution indicator, accuracy indicator, static redundancy error indicator, zero point deviation indicator, repeatability indicator, precision indicator, non-linearity indicator, zero point temperature drift indicator, full-scale temperature drift indicator, output frequency indicator, sensitivity indicator, sensitivity temperature drift indicator, response time / response frequency indicator, cross-axis sensitivity indicator, alarm function indicator, indicator light function indicator, delay indicator, hysteresis angle indicator, relative zero point setting function indicator, communication protocol indicator, measurement direction indicator, wiring definition indicator, external dimension indicator, product identification / model indicator, component list indicator, output power / output current indicator, and long-term stability indicator.

6. The reliability evaluation method of an inclination sensor according to claim 5, characterized in that, The electrical indicators, mechanical indicators, environmental indicators, packaging material indicators, measurement direction indicators, and wiring definition indicators are all indicators that may have the risk of function loss.

7. A reliability evaluation method for an inclination sensor according to claim 3, characterized in that, In step 3), the reliability index score of the inclination sensor is calculated by summing the scores of each secondary index, so we have: A = A1 + A2 + A3 + A4 + A5 + A6 + A7 + A8 + A9 Among them, the total score of the reliability index A of the inclination sensor is 100 points, the total score of the electrical index A1 is 10 points, the total score of the mechanical index A2 is 10 points, the total score of the environmental index A3 is 10 points, the total score of the protection index A4 is 5 points, the total score of the durability index A5 is 5 points, the total score of the electromagnetic compatibility index A6 is 10 points, the total score of the packaging material index A7 is 5 points, the total score of the chemical coating index A8 is 5 points, and the total score of the performance index A9 is 40 points.

8. A reliability evaluation method for an inclination sensor according to claim 7, characterized in that When the reliability index score of the inclination sensor is equal to or less than 90 points, it is judged that the reliability of the inclination sensor is unqualified; when it is greater than 90 points and less than 100 points, it is judged that the reliability of the inclination sensor is qualified with risks; when it is equal to 100 points, it is judged that the reliability of the inclination sensor is qualified without risks.

9. A reliability evaluation method for an inclination sensor according to claim 1, characterized in that In step 2), the types of inclination sensors include digital inclination sensors, analog inclination sensors, and inclination switches.

10. A reliability evaluation method for an inclination sensor according to claim 9, characterized in that, The digital inclination sensor does not need to be tested for the third-level indicators of non-linearity and sensitivity. Among the third-level indicators of measuring the performance index of the inclination switch, only the measuring range index, alarm function index, delay index, hysteresis angle index, indicator light function index, relative zero setting function index, and output power / output current index need to be tested.

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