A Sigmoid Function based Method for Detection of Stiction in Control Valves

Abstract

Sticky control valve induced oscillations are the most common source of deteriorated control loop performance. Although there are many stiction detection algorithms, complexity remains as the top reason for their restricted applications. This work proposes a new method to detect malfunctioning control valves (due to stiction) in process control loops. The proposed method embroils in fitting a sigmoid function (or logistic function) to OP (controller output) and ΔPV (change in process variable (PV)). Effectiveness of the method is assessed by application to industrial control loops belonging to a wide variety of industries. Results demonstrate that the method can compete with the existing methods while being simple in applications.