On-line Detection of the Change of Friction in Control Valve

The function of stuffing box in pneumatic control valve is dynamic seal, but it also produces friction. The friction will affect the performance of position control. This article proposes a method based on the error integral indexes of control loop. On-line detection of the change of friction in control valve can use this method. Firstly, the researchers use TOPSIS method to choose the appropriate error integral index, and then using the appropriate index describes the change of friction. The results found that the relevance between the change of friction in control valve and the error integral of control loop is existing.