PNEUMATIC CONTROL VALVE STICTION DETECTION AND QUANTIFICATION

Abstract

Pneumatic control valves are playing major role in the closed loop process control system. It is found in
literature there are 20-30% (chodhury et al 2005) of process industries having limit cycle oscillations due to control
valve nonlinearity which is the only mechanical device in closed loop process control system and deteriorate the end
products. In the control valve stiction is the major nonlinearity problem than the other nonlinearities like backlash,
hysteresis and saturation. This stiction nonlinearity causes the wastage of utility in the process industry. Recently there
are so many methods to understand, define, model and detect stiction. Here for identification of stiction the Adaptive
Neuro Fuzzy Inference Methodology have been used. For a vertical two tank level process with kano’s model of stiction
is considered to obtain necessary required data to formulate objective function. Here the ANFIS method simultaneously
detect and quantify stiction. The work is being carried out in the MATLAB/SIMULINK platform