Abstract:
The proportional-integral-derivative (PID) controller is tuned to find its parameters values. Generally most of the tuning methods depend mainly on the experimental approach of open-loop unit step response. The controller parameters can be found if the system truly can be approximated by First Order Plus-Dead Time (FOPDT). The problem with such type of controllers is that: the performance of most of them deteriorates as the ratio ( ) of approximated equivalent delay L to the overall time constant T changes. The optimum tuning always checks this ratio and considers it in its formulae. The performances of different PID tuning techniques are simulated for different systems and analyzed based on the transient responses. MATLAB simulation results are presented and compared for different higher order systems. For the same characterization procedure, optimally tuned PID controller shows better performances over Ziegler-Nicholas (Z-N) and Cohn-Coon tuned. Superiority of the optimal PID tuning techniques sustained for variety of higher order systems.
