What is the selection principle of vibration sensor?

Modern sensors vary widely in principle and structure. How to choose the sensor reasonably according to the specific measurement purpose, measurement object and measurement environment is the first problem to be solved when measuring a certain quantity. When the sensor is determined, the matching measuring method and measuring equipment can also be determined. The success or failure of the measurement results largely depends on whether the sensor selection is reasonable.

1. Determine the type of sensor according to the measurement object and measurement environment.

To carry out specific measurement, we should first consider what kind of sensor to use, which needs to be determined after analyzing many factors. Because, even when measuring the same physical quantity, there are many kinds of sensors to choose from. To choose which one is more suitable, we need to consider the following specific issues according to the measured characteristics and the use conditions of the sensor: the size of the measurement range; Requirements of the measured position on the sensor volume; Whether the measurement method is contact or non-contact; Signal extraction method, wired or non-contact measurement; The source of the sensor is domestic or imported, affordable or independently developed.

After considering the above problems, we can determine which type of sensor to choose, and then consider the specific performance indicators of the sensor.

2, the choice of sensitivity

Generally, within the linear range of the sensor, the higher the sensitivity of the sensor, the better. Because only when the sensitivity is high, the value of the output signal corresponding to the measured change is relatively large, which is beneficial to signal processing. However, it should be noted that the sensitivity of the sensor is high, and external noise unrelated to the measurement is easy to be mixed in, and it will also be amplified by the amplification system, which will affect the measurement accuracy. Therefore, the sensor itself is required to have a high signal-to-noise ratio and try to reduce the interference signals introduced by the outside world.

The sensitivity of the sensor is directional. When the measurement is unidirectional and requires high directivity, sensors with low sensitivity in other directions should be selected; If the measured vector is a multi-dimensional vector, the smaller the cross sensitivity of the sensor, the better.

3. Frequency response characteristics

The frequency response characteristics of the sensor determine the frequency range to be measured, so it is necessary to maintain the undistorted measurement conditions within the allowable frequency range. In fact, there is always a certain delay in the response of the sensor, and it is hoped that the shorter the delay time, the better.

The higher the frequency response of the sensor, the wider the frequency range of the measurable signal. However, due to the influence of structural characteristics, the inertia of mechanical system is large, and the frequency of measurable signal is low because of the low frequency of sensor.

In dynamic measurement, the response characteristics should be based on the characteristics of the signal (steady state, transient state, random, etc.). ) avoid the mistake of going too far.

4. Linear range

The linear range of the sensor refers to the range in which the output is proportional to the input. Theoretically, within this range, the sensitivity remains unchanged. The wider the linear range of the sensor is, the larger its range will be, and a certain measurement accuracy can be guaranteed. When selecting a sensor, after determining the type of the sensor, we should first look at whether its range meets the requirements.

But in fact, no sensor can guarantee absolute linearity, and its linearity is relative. When the required measurement accuracy is low, in a certain range, the sensor with small nonlinear error can be approximately regarded as linear, which will bring great convenience to the measurement.