Modern sensors principle and structure differ in thousands of ways, how to choose the appropriate sensor depending on the measurement purposes, the measurement object and measuring environment, is the first problem to be solved before measurement. When the sensor is determined, the support of measurement methods and equipment will also be determined. Measurements success or failure depends largely on the sensor selection is reasonable.
1. According to the measurement object and measurement environment to determines the type of sensor
Before a detailed survey work, it is the first thing to consider what kind of principle of the sensor. This requires analysis of many factors. Because even measuring the same physical, there are many principles of sensors are available. Which is more appropriate sensor principle, it need to consider the following specific issues to be measured according to the conditions of use features and sensors: measure range; the requirements of measured position for the sensor volume; contact or non-contact; signal extraction methods; source sensor, domestic or imported, the price.
After considering the above problems the type of sensor could be determined, and then consider the specific performance of the sensor.
2. Sensitivity selection
Typically, within the linear range of the sensor, we hope the sensor sensitivity as high as possible. Because when sensor sensitivity is high, it is conducive to signal processing. But we should notice that outside noise is also easy to mix when using the high sensitivity sensor, this would affect measurement accuracy. Therefore, the requirements of the sensor itself should have a high signal to noise ratio, to minimize the interference signal introduced from outside.
3. Frequency response characteristic
Frequency response characteristic of the sensor determines the frequency range to be measured, it must remain within the allowable frequency range distortion. In fact, the delay of response always exist, we just hope the delay would be shorter.
4. Linear range
Linear range of the sensor means output proportional to the input range. In theory, within this range, the sensitivity is constant. The wider linear range of the sensor, the greater its range, and it can guarantee a certain accuracy.
But in fact, any sensor can not guarantee linear, its linearity is relative. When the required measurement accuracy is relatively low, it can be non-linear error smaller sensor approximated as linear in a certain range, this will bring great convenience during measuring.
5. StabilitySensor’s ability to maintain the same performance called stability. The structure of the sensor and sensor using environment would affect the long-term stability of the sensor. Therefore, if the sensor has good stability, the sensor must have a strong environmental adaptability.
Before selecting a sensor, they should investigate the using environment, and select the appropriate sensor according to the specific use of the environment, or to take appropriate measures to reduce the environmental impact.
Precision is an important performance indicator of the sensor, it is an important part of precision related to the entire measurement system. The higher accuracy of the sensor, the more expensive price we should pay. So the accuracy of the sensor just should meet the accuracy requirements of the entire measurement system, not the most expensive one.
For some special occasions, you can not choose the right sensor, we need to design and manufacture sensors. Homemade sensor performance should meet the requirements.