Cognition of linearity of displacement sensor
Release date: May 30, 2019
Linearity is an important index to describe the static characteristics of linear displacement sensor, which is based on the stable state of the measured input. Under specified conditions, the percentage of the maximum deviation (Δ ymax) between the sensor calibration curve and the fitting line and the full scale output (y) is called linearity (linearity is also known as "nonlinear error"), the smaller the value, the better the linearity. When it comes to the method of least square fitting, there is a straight line fitting method. Accuracy: it is determined by the basic error limit of the sensor and the change limit caused by the influence quantity (such as temperature change, humidity change, power supply fluctuation, frequency change, etc.).
The formula is as follows:
The concept of "fitting straight line" has been mentioned above. The fitting line is a straight line drawn by a certain method. The methods for finding the fitting line are: end base method, least square method, etc. The specific steps are not described here.
Some basic concepts about precision and linearity
Before talking about precision and linearity, let's talk about several concepts of error
1. Absolute error: the difference between the measured value and the ideal value;
2. Relative error: the ratio of absolute error of measured point to ideal value of measured point;
3. Quotation error: the ratio of absolute error of measured point to reference value (range);
(4) within the reference range of standard error;
5. Linear error: the deviation between the measured curve and the ideal straight line;
Accuracy: it is determined by the basic error limit of displacement sensor and the change limit caused by influence quantity (such as temperature change, humidity change, power supply fluctuation, frequency change, etc.).
Linearity: the concept of linearity: a measure of whether the output and input system of a test system can maintain the normal value proportional relationship (linear relationship) as the ideal system.
Linear range: the measurable range of the sensor in linear operation.