Modern sensor principle and structure vary widely, depending on how the measurement object, the measurement object and measuring environment reasonable selection of sensors, is a measurement of the amount during the first problem to be solved. When the sensor is determined, with the support of measurement methods and equipment will be determined. Measurement results the success or failure depends largely on the sensor selection is reasonable.
ã€€ã€€1. according to the measured object determines the type of sensor and measurement environment
Can only be determined after a detailed survey work, we must first consider what kind of principle of the sensor, which requires analysis of many factors – to be. Because, even measure the same physical quantity, there are many principles of sensor types are available, what kind of principle of the sensor is more appropriate, we need to consider some of the following specific issues based on conditions measured characteristics and sensors: Range of size; the measured position of the sensor size requirements; measurement of contact or non-contact; signal extraction method, wired or non-contact measurement; source sensor, domestic or imported, the price can not stand, or developed.
After considering the above problems can determine what type of sensor selection, and then consider the specific performance of the sensor.
ã€€ã€€2. sensitivity selection
Typically, within the linear range of the sensor, we hope sensitivity of the sensor as high as possible. Because only when the high sensitivity, the value measured by the corresponding change in the output signal was relatively large, in favor of signal processing. But note that the high sensitivity of the sensor to be measured independent of external noise is also easy to mix, will be amplification system amplification, affect measurement accuracy. Therefore, the requirements of the sensor itself should have a high signal to noise ratio, to minimize interference from outside signals introduced.
Sensitivity of the sensor is directional. When measuring the amount of a one-way, and the higher its directivity requirements, you should choose the other direction sensitivity small sensor; if the measure is a multidimensional vector, requires cross-sensitivity of the sensor as small as possible.
ã€€ã€€3. the frequency response characteristic of
Frequency response characteristics of the sensor determines the frequency range to be measured, it must be maintained without distortion within the allowable frequency range. In fact there is always a response of the sensor – set delay, hoping to delay the shorter the better.
The frequency response of the sensor, the more wide frequency range of the signal can be measured.
In dynamic measurement, the response should be based on the characteristics (steady state, transient, random, etc.) signals, in order to avoid excessive errors.
ã€€ã€€4. the linear range
Linear range of the sensor means output proportional to the input range. In theory, within this range, the sensitivity is constant. Wider linear range of the sensor, then the greater the range, and can guarantee a certain accuracy. When selecting a sensor, when the sensor type is determined after the first look at its range meets the requirements.
But in fact, any sensor can not guarantee linear, its linearity is relative. When the required measurement accuracy is relatively low, within a certain range, the smaller sensor nonlinearity error approximated as linear, this measure will bring great convenience.
Sensors use for some time, and its ability to maintain the same performance called stability. Factors affecting the long-term stability of the sensor in addition to the structure of the sensor itself, the main sensor’s environment. Therefore, if the sensor has good stability, the sensor must have a strong environmental adaptability.
Before selecting a sensor, it should investigate the use of the environment, and select the appropriate sensor according to the specific use of the environment, or to take appropriate measures to reduce the environmental impact.
Stability of the sensor quantitative indicators over the use period, before use should be re-calibrated to determine the performance of the sensor is changed.
In some long-term use but requires that the sensor can not be easily replaced or calibration of the occasion, the choice of sensor stability requirements more stringent, to be able to withstand the test of time.
Accuracy is an important performance indicators of the sensor, it is related to the entire measurement system is an important part of precision. The higher the accuracy of the sensor, the more expensive the price, so the accuracy of the sensor as long as meet the accuracy requirements of the entire measurement system can be, do not choose too high. So you can choose relatively cheap and simple sensors Atlas air compressor accessories to meet many of the same measurement purpose sensor.
If the aim is to measure the qualitative analysis, the choice of high repeatability of the sensor can be, should not use the absolute value of high accuracy; if we are to quantitative analysis, must obtain accurate measurements, it is necessary to select the sensor accuracy level to meet the requirements.