1. According to the measurement object and measurement environment
In order to carry out a detailed measurement operation, it is necessary to consider the principle of the sensor first, which needs to analyze many factors before confirmation. Because, even if the same physical quantity is measured, there are a variety of principles of sensors to choose from, which principle of the sensor is more suitable, it is necessary to consider the following detailed issues according to the characteristics of the measured and the application conditions of the sensor: the size of the range, the requirements of the measured position on the volume of the sensor, the measurement method is touch type or wrong touch type, the signal elicitation method, wired or wrong touch measurement, the source of the sensor, the domestic or imported, the price is acceptable, or self-developed; After considering the above questions, it is possible to determine the type of sensor to use, and then to consider the detailed functional objectives of the sensor.
2. Selection of sensitivity
In general, within the linear scale of the sensor, the higher the sensitivity of the sensor, the better. Because as long as the sensitivity is high, the value of the output signal corresponding to the measured change is relatively large, which is conducive to signal processing. However, it should be noted that the sensitivity of the sensor is high, and the external noise that has nothing to do with the measurement is also easy to mix, and it will also be expanded by the expansion 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.
The sensitivity of the sensor is directional. When the measured quantity is a one-vector quantity and has high requirements for its directionality, the sensor with low sensitivity in other directions should be selected. If the measured is a multi-dimensional vector, the sensitivity of the sensor is required to be as small as possible.
3. Frequency echo characteristics
The frequency response characteristics of the sensor determine the frequency scale to be measured, and it is necessary to insist on not distorting within the allowable frequency scale. In fact, there is always a certain delay in the response of the sensor, and the shorter the delay time, the better. The higher the frequency response of the sensor, the wider the frequency scale of the signal that can be measured. In dynamic measurement, the characteristics of the signal (steady-state, transient, random, etc.) should be echoed to avoid excessive errors.
4. Linear scale
The linear scale of a sensor refers to the size at which the output is proportional to the input. Theoretically, the sensitivity sticks to a fixed value at this scale. The wider the linear scale of the sensor, the greater its measuring range and the guaranteed measurement accuracy. When selecting a sensor, when the type of sensor is confirmed, the first thing to see is whether its range meets the requirements.
But in reality, no sensor can guarantee a certain linearity, and its linearity is also relative. When the required measurement accuracy is relatively low, within a certain scale, the sensor with small nonlinear error can be approximately regarded as linear, which will bring great convenience to the measurement.
5. Stability
The ability of a sensor to remain functional unchanged after a period of use is called stability. In addition to the structure of the sensor itself, the factors that affect the long-term stability of the sensor are mainly the operating environment of the sensor. Therefore, in order for the sensor to have good stability, it is necessary for the sensor to have strong environmental adaptability.
Before selecting a sensor, it is necessary to investigate the environment in which it will be used, and select the appropriate sensor based on the detailed application environment, or take appropriate measures to reduce the impact of the environment.
The stability of the sensor has a quantitative goal, and after the service life has passed, it should be calibrated from scratch before operation to confirm whether the function of the sensor has changed.
In some occasions where the sensor is required to be used for a long time and cannot be easily replaced or calibrated, the stability requirements of the selected sensor are more stringent, and it must be able to withstand the test for a long time.
6. Accuracy
Accuracy is an important functional goal of the sensor, and it is an important link related to the measurement accuracy of the entire measurement system. The higher the accuracy of the sensor, the more expensive its price, therefore, the accuracy of the sensor as long as it meets the accuracy requirements of the entire measurement system, and does not have to be too high. In this way, it is possible to choose the cheaper and simpler sensor Atlas air compressor accessories among the many sensors that are satisfied with the same measurement intention.
If the measurement intention is qualitative analysis, it is sufficient to choose a sensor with high repeatability, and it is not appropriate to choose a sensor with high accuracy of certain value; If it is necessary to obtain accurate measurement values for quantitative analysis, it is necessary to select a sensor with an accuracy level that satisfies the requirements.
For some special applications, if the appropriate sensor cannot be selected, the sensor needs to be designed and manufactured by itself. The function of the self-made sensor should be satisfactory to the application requirements.
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