Non linear PID and its application in process control

In the last four decades, the proportional, integral and derivative (PID) controller remains by far the most widely used in industry and continues to be an important method in control engineering, along with high control performance requirements, advanced control techniques are needed. Since 90 percent of applied control technique among industry is related to PID, any improvement of this technique may result a big impact on all related industrial processes [1]. Furthermore, it is well known that most of the industrial processes are nonlinear and inherit long time delay i.e. thermal, pressure, P.H and flow. Since the conventional PID is a linear controller it is efficient only for a limited operating range when applying in nonlinear processes. During the last two decades, a nonlinear PID forms has been developed. This paper reviews one of the nonlinear PID methods, suggests an optional tuning rules accompanied with simulation results and the implementation in Programmable Logic Controller (PLC).