With the development of the industrial Internet of Things, the industry is paying more and more attention to reducing wiring and utilizing wireless, ultra-low power technology. This makes the MEMS accelerometer in size, weight, power consumption and other leading advantages, and it is possible to achieve integrated intelligent characteristics, state monitoring applications in industrial applications in the future will be more and more widely used. In fact, the excellent performance of the three-axis MEMS accelerometer shows that the application of accelerometer is not limited to the general industrial vibration environment testing, in a wider range of related fields, such as intelligent operating room, precision guidance manipulator, UAV detection applications, precious equipment position tracking and so on. MEMS accelerometers can be seen almost everywhere.
In industrial manufacturing, the failure of mechanical equipment not only causes the loss of production capacity, but also may cause chain reaction in the platform system in extreme cases, resulting in large-scale damage and then production shutdown, and even the industrial accident of machine destruction. In addition, many industries replace or overhaul machinery and equipment according to preventive maintenance schedules, especially in applications where unplanned downtime is not tolerated. As a result, many industries often spend too much money on rebuilding machinery with a long service life. If the accelerometer is embedded in the bearing or other rotating equipment, its working condition can be determined by detecting the vibration of the bearing or other rotating equipment, its service life can be prolonged, the maintenance cost of the unit can be reduced, and the utilization rate and safety factor can be improved.
Industrial vibration monitoring faces these challenges.
Accelerometer - can measure acceleration, tilt, impact and vibration, so it has a wide range of applications in wearable areas to industrial platform stabilization systems. The traditional piezoelectric sensor is the principle of the spring mass system. The mass of the sensing core produces a force proportional to the acceleration when it is subjected to the vibration acceleration. The piezoelectric material forms a charge signal proportional to the force along its surface. Piezoelectric accelerometer is widely used in vibration measurement because of its wide dynamic range, wide frequency range, durability, small external interference and no external power supply is needed for the self-generated charge signal of piezoelectric materials. The utility model has the advantages of simple structure, convenient material extraction and long service life. Now leads the accelerometer market.
Accelerometer grades and typical application areas
With the development of the industrial Internet of Things, the industry is paying more and more attention to reducing wiring and utilizing wireless, ultra-low power technology. This makes the MEMS accelerometer ahead of the piezoelectric accelerometer in size, weight, power consumption and other aspects, and it is possible to achieve integrated intelligent characteristics. Although the most commonly used sensors for industrial condition monitoring are piezoelectric accelerometers, they have good linearity, SNR, high temperature performance and wide bandwidth (typically between 3 Hz and 30 kHz, and in some cases up to hundreds of kHz). However, the performance of piezoelectric accelerometers in DC range is poor, so a large number of faults may occur in low frequency to DC range, especially in wind turbine and similar low RPM applications. The mechanical properties of piezoelectric sensors make it difficult to achieve mass production like MEMS, with higher cost and lower flexibility in interface and power supply.
But the piezoelectric accelerometer also has its limitations. When measuring low frequency vibration, especially small amplitude vibration, the acceleration value is small and the sensitivity of the sensor is limited, so the output signal will be very weak and the signal-to-noise ratio is very low. In addition, the leakage of charge, the drift of the integration circuit (used to measure the vibration speed and displacement), the noise of the device are not. Avoidable, so the actual low frequency terminal also has a "cut-off frequency" of about 0.1 ~ 1Hz. Because of the limitation of piezoelectric materials, it is easy to be disturbed by external factors, such as sound, temperature and so on.
It is a well-known and mature equipment maintenance method to determine the condition of bearings by using the vibration 3 "characteristics" of bearings, but in order to obtain accurate results, a wide measurement bandwidth is needed. MEMS accelerometers are considered ideal for this type of testing, but before ADI's ADXL001 accelerometers were introduced, the cost of accelerometers and related signal conditioning equipment was very high. Now, ADXL001 with a wide bandwidth (22 kHz) and internal signal conditioning capabilities has become an ideal choice for low-cost bearing maintenance applications.