How should we choose the type of sensor when we are choosing it in our daily work? The recommendations made by experts are based on the following six selection principles.
Determine the type according to the measuring object and the measuring environment
In order to carry out a specific measurement work, the first thing to consider is the principle of the sensor, which needs to analyze a variety of factors before determining. Because, even if the same physical quantity is measured, there are many kinds of sensors to choose. Which principle is more suitable for the sensor, we need to consider the following specific issues according to the characteristics of the measurement and the conditions of the use of the sensor: the size of the measurement range; the requirement of the measured position on the volume of the sensor; the measurement method is contact. Type or non-contact; signal extraction method, wired or non-contact measurement; sensor source, domestic or imported, affordable price, or self-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.
Selection based on sensitivity
Generally, in 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 larger, which is beneficial to signal processing. However, it should be noted that the sensor has high sensitivity, and the external noise unrelated to the measurement is easy to mix in. It will also be amplified by the amplification system, which will affect the measurement accuracy. Therefore, the sensor itself should have a high signal-to-noise ratio to minimize the interference signal introduced from the outside world.
Sensitivity of the sensor is directional. When the measured value is a single vector and the directivity of the sensor is high, the sensor with low sensitivity in other directions should be selected; if the measured value is a multi-dimensional vector, the smaller the cross sensitivity of the sensor is, the better.
Judging Frequency Response Characteristics
The frequency response characteristic of the sensor determines the measured frequency range, and must be kept undistorted in the allowable frequency range. In fact, the response of the sensor always has a definite delay, and the shorter the delay time, the better. The higher the frequency response of the sensor, the wider the frequency range of the measurable signal.
In dynamic measurement, the response characteristics of signals (steady state, transient, random, etc.) should be considered to avoid excessive errors.
According to the linear range of the sensor
The linear range of the sensor refers to 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 is, the larger the measurement range is and the measurement accuracy can be guaranteed. When choosing sensors, when the types of sensors are determined, the first thing is whether their range meets the requirements.
But in fact, no sensor can guarantee absolute linearity, and its linearity is relative. When the required measurement accuracy is relatively low, in a certain range, the sensor with small non-linear error can be approximated as linear, which will bring great convenience to the measurement.
According to the stability of the sensor
The ability of the sensor to keep its performance unchanged after a period of time is called stability. Besides the structure of the sensor itself, the main factor affecting the long-term stability of the sensor is the use environment of the sensor. Therefore, in order to make the sensor have good stability, the sensor must have strong environmental adaptability.
Before choosing sensors, we should investigate their use environment, and choose appropriate sensors according to the specific use environment, or take appropriate measures to reduce the impact of the environment.
Accuracy of sensors can not be neglected
Accuracy is an important performance index of sensor, and it is an important link related to the measurement accuracy of the whole measurement system. The higher the accuracy of the sensor, the more expensive it is. Therefore, the accuracy of the sensor can only meet the accuracy requirements of the whole measurement system, without having to choose too high. In this way, we can choose the cheaper and simpler sensor Atlas air compressor accessories among many sensors that meet the same measurement purpose.
If the purpose of measurement is qualitative analysis, the sensor with high repetition accuracy can be selected, but the absolute value with high accuracy should not be selected; if it is for quantitative analysis, the precise measurement value must be obtained, and the sensor whose accuracy level can meet the requirement needs to be selected.