The choice of sensors


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Modern sensors vary widely in principle and structure. How to select high accuracy temperature sensors reasonably according to the purpose of measurement, measurement object and measurement environment is the first problem to be solved when carrying out a certain amount. When the sensor is determined, with the matching measurement methods and measurement equipment can also be determined. The success or failure of a measurement depends to a large extent on the reasonableness of the sensor selection.

1.according to the measurement object and the measurement environment to determine the type of sensor: To carry out a specific measurement, we must first consider what principle of the sensor, which requires analysis of many factors before the determination. Because, even when measuring the same physical quantity, there are various principles of the temperature sensor are available, the principle of one kind of sensor that is more appropriate, the following specific issues need to be considered according to the conditions and the measured sensor characteristics: size range; measured The size of the sensor on the location requirements; measurement methods for contact or non-contact; signal extraction method, wired or non-contact measurement; sensor source is imported or domestic, the price can accept, or self-developed.

  1. The choice of sensitivity: Usually, in the linear range of the sensor, the sensor’s sensitivity is as high as possible, because only when the sensitivity is high, the output signal corresponding to the measured change is more conducive 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 also easy to be mixed in. It is also amplified by the amplification system to affect the measurement accuracy. Therefore, the sensor itself needs to have a high signal-to-noise ratio Plant worry signal. Sensitivity of the sensors is directional. When the measurement is a single vector, but also for its high direction of the direction, you should choose the other direction of the sensor sensitivity, if the measurement is multidimensional vector, the cross-sensitivity of the sensor requires the smaller the better.

3.The frequency response characteristic: the frequency response characteristic of the sensor determines the frequency range to be measured, undistorted measurement conditions must be maintained within an allowable frequency range, the overall response of the sensor in fact a certain delay, the desired delay as short as possible. The frequency response of the sensor is high, and the measurable frequency range of the signal is wide. Due to the structural characteristics, the inertia of the mechanical system is large, because the frequency of the signal with the low frequency is lower. In the dynamic measurement, response characteristics should be based on the characteristics of the signal (steady state, random, etc.) to avoid over-fire error.

  1. Linear range: The linear range of the sensor is the output and the input is proportional to the range. Theoretically, within this range, the sensitivity to maintain a fixed value, the wider the linear range of the sensor, the greater the range, and can guarantee a certain degree of measurement accuracy. In the choice of sensors, when the type of sensor to determine whether the first of its range to meet the requirements. But in fact, any air conditioning temperature sensor can not guarantee absolute linearity, and its linearity is relative. When the required measurement accuracy is low, the sensor with less nonlinear error can be approximated as linear within a certain range, which brings great convenience to the measurement.

5, Stability: After the sensor is used for a period of time, the ability of its performance to remain unchanged calls stability. Long-term stability of the sensor factors in addition to the structure of the sensor itself, the main sensor is the use of the environment. Therefore, to make the sensor have good stability, the sensor must have a strong ability to adapt to the environment. Before choosing a sensor, it should investigate its use environment and select the appropriate sensor according to the specific use environment, or take appropriate measures to reduce the environmental impact. In some applications require long-term use of the sensor can be easily replaced or calibrated occasions, the choice of the sensor stability requirements more stringent to be able to stand the test of time.

6, Accuracy: Accuracy is an important sensor performance indicators, it is related to the measurement accuracy of the entire measurement system which is an important part. The higher precision of the sensor, its price is more expensive, and therefore, the accuracy of the sensor as long as the overall accuracy of the measuring system can be, not necessarily selected too high, so that you can choose simpler and cheaper in many sensor measurements to meet in the same sensor. If the measurement object is qualitative analysis, selection of a sensor of high accuracy can be repeated, should not use a high-accuracy absolute magnitude; if for quantitative analysis, must obtain accurate measurements, it is necessary to select the sensor accuracy level can meet the requirements. For some special occasions, can not choose the right sensor, you have to design and manufacture of sensors, home-made sensor performance should meet the requirements.


#2

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