Application of fuzzy logic to reduce modelling errors in PIDSP for FOPDT process control

In this paper, a PID controller with a Smith Predictor (PIDSP) for a First Order Plus Dead Time (FOPDT) process is first presented. From simulation evaluation, it was found that there is a significant sensitivity to the process modelling errors (process gain, time constant and dead time). As a result, a Fuzzy Logic compensator has been developed to be used as an internal feedback to compensate for process model parameter variations. This proposed approach reduces considerably the effects of the process modelling errors in gain, time constant or dead time.