The invention relates to the technical field of valve testing, and discloses an online testing method for
friction force of a low-temperature pneumatic stop valve. According to the method, a plurality of test parameter data points of the low-temperature pneumatic stop valve are obtained firstly, and then
friction force testing is achieved through grouping
processing of the data points. And in any grouping
processing stage, determining a current activation group, selecting a preset number of previous reference grouping
processing stages, and dividing data points into corresponding data sets according to the distance between the test parameter data points and the group in each grouping stage. A
fuzzy group is obtained by analyzing the intersection of the current
data set of the activation group and the reference data sets of other groups, and after an adjustment factor is calculated, the
fuzzy group and the activation group are updated according to the adjustment factor. According to the method, multi-stage data can be integrated,
fuzzy data can be precisely processed, testing can be dynamically adjusted, the testing accuracy and reliability are improved, real-time testing can be conducted when the valve normally operates, production interference is reduced, and the method is suitable for performance testing of the low-temperature pneumatic stop valve.