Sensors on the principle and structure of differ in thousands ways, according to the specific purpose, object measurement, as well as the measurement environment reasonably choose sensor, is when making a certain amount of measurements to solve the problem in the first place. When the sensor was determined, and matching measuring method and measuring equipment also can be determined. Success or failure of the test results, to a large extent depends on the selection of sensors is reasonable.
1.according to the object and the measurement environment determine the type of sensor
Do you want to work - a specific measurement, the first thing to consider what principle of the sensor, the need to analyze various factors to determine. Because, even if it is to measure the same quantity, there are a variety of available for selection principle of the sensor, which one of the principle of sensors is more suitable, need according to the characteristics of the measured and sensor under consideration of the use conditions of some concrete problems: the size of the range; Measured the position of sensor volume requirements; For the contact and non-contact measurement mode; Signal method, the derivation of the cable or contact measurement; The source of the sensor, the domestic or imported, the price can afford, or developing itself.
After considering the above problems can determine what type of sensor, then consider the specific performance index of the transducer.
2.the sensitivity of choice
Usually, within the scope of the sensor is linear, hope that the sensitivity of the sensor, the higher the better. Because only high sensitivity, and the corresponding value of the output signal is measured change to bigger, is advantageous to the signal processing. But note that the sensor is of high sensitivity, has nothing to do with the measured outside noise also is easy to mix, will also be amplified system amplifier, affect measurement accuracy. For sensor itself, therefore, should have high signal-to-noise ratio, all member to reduce plant introduced from outside interference signal.
The sensitivity of the sensor is a direction. When the measurement is a single vector, and the direction the demand is higher, should choose other small sensor sensitivity; If the measurement is a multi-dimensional vector, cross sensitivity requires sensor as small as possible.
Sensor determines the frequency range of the measured frequency response characteristics, must be allowed to remain undistorted measurement frequency range condition, in fact, the response of the sensor there - always delay, hope delay time as short as possible.
High frequency response of the sensor, the measured signal frequency range is wide, but due to the influence of the structural characteristics, mechanical system of the large inertia, due to low frequency of the frequency of the sensor measured signal is low.
In dynamic measurement, should according to the characteristics of the signal (steady state and transient, stochastic, etc.) response characteristics, lest produce the error of the fire.
Linear range sensor refers to output is proportional to the input range. In theory, in this range, sensitivity to keep constant value. Sensor linear range is wide, the greater the range, and can guarantee the accuracy of measurement. When choosing sensor, when sensors to determine the kinds of the first to see whether the range meet the requirements.
But in fact, any sensor cannot guarantee absolute linear, its linearity is relative. When required by the measurement accuracy is low, in a certain range, smaller sensor nonlinear error can be approximately as a linear, it will bring great convenience measurements.
Sensors use after a period of time, the ability of keeping its performance change called stability. Factors affecting the stability of sensor for a long time in addition to the sensor itself structure, mainly is the sensor using the environment. Therefore, to make the sensor has good stability, sensor must have stronger ability to adapt the environment.
Before choosing sensor, deal with the use environment investigation, according to the use of specific environment to choose the appropriate sensor, or to take appropriate measures to reduce the influence of the environment.
The stability of the sensor with quantitative indicators, after more than life, before use should be to calibrate, to determine whether the performance of the sensor is changing.
In some sensors can use for a long time and cannot be easily replaced or calibration, chooses the sensor stability requirements more stringent, to be able to withstand the test of time.
Accuracy is an important performance index of the sensor, it is related to the whole measurement system measuring accuracy is an important link. The higher the precision of the sensor, the price is more expensive, therefore, the precision of the sensor as long as can meet the requirements of the precision of measuring system, don't choose too high. Could be satisfied in many of the same measurement purpose sensor selection is cheaper and simple sensor.
If measurement purpose is qualitative analysis, choose high repeat precision of sensors, unfavorable choose high precision absolute value; If it is for the sake of quantitative analysis, it is necessary to obtain accurate measurements, we have to choose precision grade can meet the requirements of the sensor.
For some special occasions, unable to choose the appropriate sensor, is to design and manufacture of sensors. The performance of homemade sensors should satisfy the use requirement.