The success or failure of the measuring device depends on whether the sensor is selected reasonably

Modern sensors vary widely in principle and structure. How to select sensors according to specific measurement purposes, measurement objects and measurement environment is the first problem to be solved when performing a certain amount of measurement.

When the sensor is determined, the matching measurement method and measuring device can be determined. The success or failure of the measurement results depends to a large extent on whether the sensor selection is reasonable.

To carry out a specific measurement work, we must first consider what kind of sensor should be used, which needs to be analyzed after analyzing various factors.

Because even if it is measuring the same physical quantity, there are many kinds of sensors available for selection. Which kind of sensor is more suitable, you need to consider the following specific problems according to the characteristics to be measured and the conditions of use of the sensor:

1 size of the range;

2 The position of the measured position on the sensor volume;

3 measurement method is contact or non-contact;

4 signal extraction method, wired or non-contact measurement;

5 The source of the sensor, domestic or imported, the price can withstand, or it is self-developed. After considering the above issues, you can determine which type of sensor to use and then consider the specific performance of the sensor.

Generally, in the linear range of the sensor, it is desirable that the sensitivity of the sensor be as high as possible. Because only 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 the external noise that is not related to the measurement is easily mixed in, and is amplified by the amplification system, which affects the measurement accuracy. Therefore, the sensor itself should be required to have a high signal-to-noise ratio and minimize interference signals introduced from the outside.

The sensitivity of the sensor is directional. When the measurement is a single vector and its directivity requirements are high, other sensors with small sensitivity should be selected; if the measurement is a multi-dimensional vector, the cross sensitivity of the sensor is required to be as small as possible.

The frequency response characteristics of the sensor determine the frequency range to be measured. The measurement conditions must be kept undistorted within the allowable frequency range. In fact, the response of the sensor always has a certain delay, and the shorter the delay time, the better.

The frequency response of the sensor is high, and the range of the measurable signal frequency is wide, and the inertia of the mechanical system is large due to the structural characteristics, so the frequency of the signal with low frequency can be measured.

In dynamic measurement, the response characteristics should be based on the characteristics of the signal (steady state, transient, random, etc.) to avoid excessive errors.

The linear range of the sensor is the range in which the output is proportional to the input. In theory, within this range, the sensitivity remains constant. The wider the linear range of the sensor, the larger the range and the guaranteed measurement accuracy. When selecting a sensor, when the type of sensor is determined, it is first necessary to see if its range meets the requirements.

But in reality, any sensor can't guarantee absolute linearity, and its linearity is relative. When the required measurement accuracy is relatively low, within a certain range, the sensor with less nonlinear error can be approximated as linear, which will bring great convenience to the measurement.

After the sensor has been used for a while. The ability to maintain its performance unchanged is called stability. Factors that affect the long-term stability of the sensor are in addition to the structure of the sensor itself. It is mainly the use environment of the sensor. Therefore, the sensor must have good stability and the sensor must have strong environmental adaptability.

Accuracy is an important performance indicator of the sensor, which is an important part of the measurement accuracy of the entire measurement system. The higher the accuracy of the sensor, the more expensive it is. Therefore, the accuracy of the transmitter can be as long as it satisfies the accuracy requirements of the entire measurement system, and it is not necessary to select too high. This makes it possible to select a cheaper and simpler sensor among the many sensors that meet the same measurement purpose.