1. Preparation before calibration
Determine the calibration cycle:Determine the calibration cycle based on the frequency of use and environmental conditions of the accelerometer.
It is usually recommended to calibrate once every six months or one year.
In critical tests or high-cost destructive tests, it is recommended to calibrate before each use.
Choose a calibration system:
Choose a suitable calibration system based on the number and type of accelerometers.
When there are a large number of accelerometers, it is recommended to use an automatic frequency sweep calibration system to improve efficiency.
Prepare calibration equipment:
Ensure the accuracy and reliability of the calibration equipment (such as vibration table, calibrator, etc.).
Check whether the calibration equipment is in good working condition.
2. Calibration steps
Static calibration:Place the accelerometer on a horizontal surface and record its output value.
Determine the zero drift and sensitivity of the accelerometer by comparing it with the known gravity acceleration value.
Dynamic calibration:
Fix the accelerometer on the vibration table and set the vibration frequency and acceleration of the vibration table.
Record the output value of the accelerometer and compare it with the expected acceleration value.
Determine the deviation of the accelerometer by calculating the difference.
Comparison calibration:
Comparing and calibrating the accelerometer with a reference accelerometer of known higher accuracy.
Place the two accelerometers on the same object and perform the same movement.
Record and compare the output values of the two accelerometers to determine the error of the accelerometer to be calibrated.
3. Calibration considerations
Sensor installation method:Different installation methods will significantly affect the resonant frequency and high-frequency response of the sensors.
Screw installation is preferred, followed by hot melt glue or instant glue, and then double-sided tape, etc.
Cable selection and fixing:
Choose cables with softer outer skins (such as silicone or PVC cables) to reduce the impact on the sensor and the vibration table moving core.
Fix the cable and sensor on the same structure to reduce the impact of the limited mounting surface.
Problem handling during calibration:
If the sensor has no output or the output curve is abnormal, check the cable connection, signal conditioner settings, and whether the vibration table is vibrating.
If the sensor's low frequency exceeds the specification, check whether the cable layout is appropriate and try to lift the cable before fixing it.
4. Post-calibration processing
Record calibration results:Record the data, steps, and results of the calibration process in detail.
Compare the calibration results with the previous calibration data to analyze the performance changes of the accelerometer.
Adjust the accelerometer:
Adjust or correct the accelerometer according to the calibration results.
If the accelerometer has serious errors or damage, replace or repair it on time.
Recalibration:
It is recommended to recalibrate after long-term use or major environmental changes.
Repeat the calibration regularly to ensure the accuracy and reliability of the accelerometer.
In summary, accelerometer calibration is a complex and important process that needs to be strictly followed in accordance with the calibration steps and precautions. Through the correct calibration method and usage skills, the measurement results of the accelerometer can be ensured to be accurate and reliable.