Static and dynamic characteristics of the sensor

The static characteristic of the sensor refers to the correlation between the output and input of the sensor for the static input signal. Because the input and output are not related to time at this time, the relationship between them, that is, the static characteristics of the sensor can be an algebraic equation that does not contain time variables, or the input is used as the abscissa, and the corresponding output is taken as The static characteristics of the sensor drawn on the ordinate refers to the correlation between the output and the input of the sensor for the static input signal. Because the input and output are not related to time at this time, the relationship between them, that is, the static characteristics of the sensor can be an algebraic equation without time variables, or the input as the abscissa, and the corresponding output as the It is described by the characteristic curve drawn on the ordinate. The main parameters that characterize the static characteristics of the sensor are: linearity, sensitivity, hysteresis, repeated shift and so on. (1) Linearity: refers to the degree to which the actual relationship curve between sensor output and input deviates from the fitted straight line. It is defined as the ratio of the maximum deviation between the actual characteristic curve and the fitted straight line to the full-scale output value in the full-scale range.　　 (2) Sensitivity: Sensitivity is an important indicator of the static characteristics of the sensor. It is defined as the ratio of the increment of the output quantity to the corresponding increment of the input quantity that caused the increment. Let S denote sensitivity.　　 (3) Hysteresis: The phenomenon that the sensor's input and output characteristic curves do not coincide during the change of input quantity from small to large (positive stroke) and from large to small (reverse stroke) becomes hysteresis. For input signals of the same size, the positive and negative stroke output signals of the sensor are not equal, and this difference is called the hysteresis difference.　　 (4) Repeatability: Repeatability refers to the degree of inconsistency of the characteristic curve obtained when the sensor changes the full range several times in the same direction in the same direction.　　(5) Drift: The drift of the sensor refers to the change in the output of the sensor over time when the input is unchanged. This phenomenon is called drift. There are two reasons for drift: one is the structural parameters of the sensor itself; the other is the surrounding environment (such as temperature, humidity, etc.). The so-called dynamic characteristics refer to the characteristics of the output of the sensor when the input changes. In actual work, the dynamic characteristics of the sensor are often expressed by its response to certain standard input signals. This is because the sensor's response to the standard input signal is easy to obtain experimentally, and there is a certain relationship between its response to the standard input signal and its response to any input signal, and the latter can often be inferred by knowing the former. The most commonly used standard input signals are step signal and sinusoidal signal, so the dynamic characteristics of the sensor are also often expressed in step response and frequency response. There are many ways to select the sensor fitting line. For example, the theoretical straight line connecting the zero input and the full-scale output point is used as the fitting straight line; or the theoretical straight line with the smallest sum of square deviations from each point on the characteristic curve is used as the fitting straight line, this fitting straight line is called the least squares fitting line.合Straight line.