【 Weak current College 】 floor control system sensor selection

Sensor selection

Modern sensor in principle and structure can vary, depending on the measurement of objectives, measurement and measurement environment reasonably choose the sensor that is in progress when a measurement of first problem to be solved. When the sensor determines, in line with the measurement method and measurement devices can be determined. Success measurement results will depend to a large extent on the selection of the sensor are reasonable.

1) according to the measuring object and measurement environment determines the type of sensor
To carry out a specific survey, it is first necessary to consider the principle of the sensor, which requires analysis of the various factors to determine. Because, even on the same physical quantity measurement, there are a variety of sensor are available, which would be more appropriate for sensor, you need to be characteristic of the measurement and sensors use conditions to consider the following specific issues: the size of the range; the measured position on the sensor size requirements; measurement methods for the contact type or contactless; signal extraction method, wired or non-contact measurement;
The source of the sensor. In considering the above questions then you can determine what type of selection of the sensor, then consider the specific performance indicators of the sensor.

Select the sensitivity of 2)
Typically, in a linear range of the sensor, like the sensor's sensitivity the better. Because only high sensitivity, and measured change the corresponding value of output signals are relatively large, conducive to signal processing. However, the sensor's sensitivity is high, and is not related to the measurement of ambient noise can easily be mixed with amplification systems enlarge, affect measurement precision. Therefore, the requirements of the sensor itself should have a high signal to noise ratio, try ' reduce outside noise signal introduced plant.
The sensor's sensitivity is directional. When measurement is one-way, but also to its directional requirements are higher, you should choose a different orientation sensitivity small sensors; if you are measuring is multidimensional vector requires cross-sensitivity of the sensor as small as possible.

3) frequency response
The sensor determines the frequency response of the measured frequency range, must be allowed frequency range remain the distortion measurement conditions, sensor response always have — set delay, delay time as short as possible.
Sensor high frequency response, measurable signal frequency range is wide, but because of the structural characteristics of the mechanical system's inertia is large, because of the low frequency of the sensor can measure signals less frequently.
In dynamic measurement, should be based on the signal characteristics (steady-state, transient, random, etc) response to avoid overdoing errors

4) linear range
The linear range of the sensor is directly proportional to the output and input. In theory, in that context, the sensitivity remains constant. The linear range of the sensor and wider, the greater its range, and can guarantee a certain degree of measurement accuracy. In the select a sensor, the sensor type after it is first necessary to determine its range meets the requirements.
But in fact, any sensor can not guarantee absolute linear, linearity and relative. When the measurement accuracy is relatively low, within a certain scope, nonlinearity in a smaller sensor approximation as linear, it gives a great measure of convenience.

5) stability
The sensor uses a period of time, its performance remains the ability known as the stability of the change. Impact factor of long term stability of the sensor in addition to the sensor itself structure, mainly of the use of environmental sensors. Therefore, to make the sensor has a good stability, the sensor must have a strong environmental adaptability.r>In the choose the sensor that prior to its use of the environment, and depending on the usage environment, select the appropriate sensor, or take appropriate measures to reduce environmental impact.
Sensor stability have quantitative indicators, in more than use, before using the calibration should be conducted to determine whether the sensor performance changes.
In some of the requirements of the sensor can long term use and cannot be easily replaced or calibration, selected sensor stability requirements are more stringent, in order to be able to withstand the test of time.

6) accuracy
Precision is the sensor, an important performance indicator that it is related to the entire measurement system accuracy is an important aspect. The higher the accuracy of the sensor, the more expensive prices, therefore, the accuracy of the sensor meets the entire measurement system accuracy requirements can, having to choose too high. So that you can meet many of the same measurement purpose sensors in cheaper and simpler sensor.
If the measure is intended to repeat the selection of qualitative analysis, and high precision sensors, inappropriate choice of absolute precision higher value; if it is for the quantitative analysis, you must obtain a precise measuring values, you need to use precision grade to meet the requirements of the sensor.
For some special applications, there is no way to choose a suitable sensor, you need to design and manufacture sensors. Self-made sensor performance requirements should be met.