Even though lots of the modern control theories are developed, the PID control is the most widely used in real industrial field which is familiar to control engineer. It offers satisfactory control performance in most case of industrial applications.
However, traditional PID control has fixed gain for particular operating conditions, thus the conventional unique PID strategy would be unsatisfactory when the system parameters have changed due to the change of operating condition, aging, etc. of the controlled plants. The author, therefore, propose a fuzzy-PID controller which combines PID control and fuzzy technique to obtain the good performance of water level control system on the whole operating range.
To combine the PID controller with fuzzy logic, at first, the sub-PID controller is designed at each water level, whose parameters are adjusted using trial and error. Then fuzzy "If∼Then" rules combine the sub-PID controllers as a consequence part.
Finally, the effectiveness of the proposed fuzzy-PID controller is verified through computer simulation.