Analysis of seven characteristic indexes of sensor

Sensor is a device or device that can feel the specified measured signal and convert it into usable output signal according to a certain rule. In modern industrial production especially in the process of automatic production, to use a variety of sensors to monitor and control the various parameters in the production process, make the equipment work in the normal state or the best state, and make the product to achieve the best quality. Therefore, it can be said that without many good sensors, modern production will lose the foundation. There are many kinds of sensors, the author will give you the seven characteristics of the sensor summed up, in order to provide reference for your future application.

1. Sensitivity of sensor

Sensitivity refers to the ratio of the change in output △y to the change in input △x of the sensor under steady-state operation. It is the slope of the output - input characteristic curve. If there is a clear linear relationship between the output and input of the sensor, the sensitivity S is a constant. Otherwise, it will change with the amount of input. The dimension of sensitivity is the ratio of the dimensions of output to input. For example, for a displacement sensor, when the displacement changes by 1mm and the output voltage changes by 200mV, its sensitivity should be expressed as 200mV/mm. When the output and input dimensions of the sensor are the same, the sensitivity can be understood as the magnification.

2. Dynamic nature of sensor

Dynamic characteristic refers to the response characteristic of the sensor to the input quantity changing with time. Dynamic characteristic When the input signal changes, the output signal changes correspondingly with time, this process is called response. The dynamic characteristic of the sensor refers to the response characteristic of the sensor to the input quantity changing with time. Sensor with good dynamic characteristics, when the input signal is a dynamic signal changing with time, the sensor can timely and accurately track the input signal, and output the signal according to the change law of the input signal. When the sensor input signal changes slowly, it is easy to track, but as the change of the input signal accelerates, the timely tracking performance of the sensor will gradually decline. It is usually required that the sensor can not only accurately display the measured size, but also reproduce the change rule of the measured time, which is one of the important characteristics of the sensor.

3. Linearity of sensor

In general, the actual static characteristic output of the sensor is a curve rather than a straight line. In practice, in order to make the instrument have uniform scale reading, a fitting line is often used to approximate represent the actual characteristic curve, linearity (nonlinear error) is a performance index of this approximation degree. There are many ways to select the fitting line. For example, the theoretical line connecting zero input and full scale output points is taken as the fitting line; Or the theoretical line with the minimum sum of squares deviation from each point on the characteristic curve is taken as the fitting line, which is called the least square fitting line.

4. Repeatability of sensor

Repeatability refers to the degree to which the characteristic curve of the sensor is inconsistent when the input quantity is changed continuously in the same direction in the full range. The closer each characteristic curve is, the better the repeatability and the smaller the random error.

5. Stability of sensor

Stability represents the ability of a sensor to maintain its performance parameters over an extended period of time. Ideally, the characteristic parameters of the sensor do not change with time at any time. But in reality, the characteristics of most sensors change over time. This is because the characteristics of the sensitive device, or the components that make up the sensor, can change over time, thus affecting the stability of the sensor.

6, sensor resolution

Resolution refers to the ability of the sensor to perceive the smallest changes being measured. That is, if the input changes slowly from some non-zero value. When the input change value does not exceed a certain value, the output of the sensor will not change, that is, the sensor can not distinguish the change of the input. Only when the change in the input exceeds the resolution will the output change. Generally, the resolution of each point in the full scale range of the sensor is not the same, so the maximum change value of the input which can make the output step change in the full scale is used as the index to measure the resolution. The above index, if expressed as a percentage of the full scale, is called resolution.

7, the hysteresis of sensor

The hysteresis characteristic characterizes the degree to which the sensor's output-input characteristic curve is inconsistent between forward (increasing input) and reverse (decreasing input) strokes, usually expressed as the maximum difference between the two curves △MAX as a percentage of the full-scale output F·S. Hysteresis can be caused by the absorption of energy present in the components of the sensor.