Effect of Dead-time Approximation on Controller Performance/Robustness Designed for a First Order plus Dead-time Model
Arun R. Pathiran
industrial process control
PID controller is considered as the most generally used feedback controller design in process control industries with the longest history and most vital development. It is well-known that the performance of a PID controller is inadequate for processes with long dead-time. Smith Predictor is a kind of predictive control scheme that is effective for processes with long dead-time. PID controllers can be derived from predictive control schemes by approximating the dead-time for FOPDT process models. In this work, the predictive control scheme and dead-time approximated PID controller have been designed with various values of desirable closed loop time constants. A comparative study has been performed for closed loop performance/robustness for the actual and the dead time approximated controllers.
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