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What issues need to be considered when choosing sensor?

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Be determined after a detailed survey work, we must first consider what kind of principle of the sensor, which requires analysis of many factors - should be. Because, even measuring the same physical quantity, there are a variety of sensors available for selection principle, the principle of the sensor which is more appropriate, you need to consider the following specific issues to be measured in accordance with the conditions of use features and sensors: range of sizes; the measured position of the sensor volume requirements; measurement of contact or non-contact; led approach signals, cable or non-contact measurement; sources sensors, domestic or imported, the price can not stand, or self-developed. 
1)After considering the above issues can determine what type of sensor selection, and then consider the specific performance of the sensor. 
2) the sensitivity of the selection 
Typically, within the linear range of the sensor, the higher the better hope sensitivity of the sensor. Because only when the high sensitivity, the value measured by the corresponding change in the output signal was relatively large, the signal processing in favor. But note that the high sensitivity of the sensor to be measured independent of the external noise is easily mixed, will also be amplified amplification system, affecting the measurement accuracy. Therefore, the requirements of the sensor itself should have a high signal to noise ratio, the best staff reduction plant introduced from outside interference signal. Sensitivity of the sensor is directional. When measuring the amount is one-way, and high directivity of its requirements, you should choose the other direction sensitivity of the small sensor; If the measure is multidimensional vector is required sensor cross-sensitivity as possible. 
3) Frequency response characteristic 
Frequency response characteristics of the sensor determines the frequency range to be measured, must be kept within the allowable frequency range undistorted measurement conditions, in fact, there is always the response of the sensor - fixed delay, hoping the shorter the delay time as possible. The high frequency response of the sensor can measure the signal frequency range is wide, due to the influence of the structural characteristics, the inertia of the mechanical system, due to the lower frequency of the low frequency signal, the sensor can be measured. In the dynamic measurement, response characteristics should be based on the characteristics (steady state, transient, random, etc.) signals, to avoid excesses of errors. 
4) The linear range 
Linear range of the sensor means that the range of input and output proportional. In theory, in this context, the sensitivity remains constant. The linear range of the sensor is wider, then the greater the range, and can guarantee a certain degree of accuracy. When selecting a sensor, the sensor determines the type When first look at its range meets the requirements. But in fact, any sensor can not guarantee absolute linearity, the linearity is relative. When the required measurement accuracy is relatively low, within a certain range, the nonlinear error smaller sensor approximated as linear, this measure will bring great convenience. 
5) Stability 
The sensor ages, its performance does not change the ability to maintain the stability referred to. The factors affecting the long term stability of the sensor in addition to the structure of the sensor itself, the main use of the environment sensor. Therefore, if the sensor has good stability, the sensor must have a strong environmental adaptability. Before selecting sensors respond to their environment to investigate 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 whether the performance of the sensor changes. In some require long-term use of the sensor and 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. 
6) Accuracy 
Accuracy is an important performance indicator of the sensor, which is related to the entire measurement system is an important part accuracy. The higher the accuracy of the sensor, the more expensive the price, so long as the accuracy of the sensor measurements to meet the accuracy requirements of the overall system can be, not necessarily selected to be too high. So that you can choose relatively cheap and simple sensors to meet the same measurement purposes many sensors. If the aim is to measure the qualitative analysis, the choice of high precision sensors to repeat, should not use the absolute value of high accuracy; If it is for the quantitative analysis, must obtain accurate measurements, you need to use precision levels to meet the requirements of the sensor. For some special occasions, you can not choose the appropriate sensor, you need to design and manufacture sensors. Homemade sensor performance should meet the requirements.

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