Genetic tuning scheme of PID parameters for first-order systems with largedead times

PID control schemes have been widely used in most of process control system s. Most of these processes are often treated as first-order systems with de ad times. And also, in many cases, PID parameters are usually tuned based o n the process parameters, i.e., the time constant, the dead time and the pr ocess gain. However, since these process parameters can not be obtained exa ctly, it is well known that it is difficult to find the suitable PID parame ters in practice. In this paper. we propose a genetic tuning scheme of PID parameters for first-order systems with large dead times. The authors have already proposed a tuning method of PID parameters using a genetic algorith m (GA), which was based on the relationship between PID control and general ized minimum variance control(GMVC) laws. In practice, for large dead time systems, first-order low pass pre-filters are often used. The proposed meth od is an extended version of the previously proposed method mentioned above to the system with a pre-filter due to the large dead time, i.e., a tuning method of both PID parameters and the pre-filter using a GA. The proposed control scheme is numerically evaluated on some simulation examples.