Hybrid Fuzzy Controller for Temperature Process

Abstract

Temperature control is a process in which change of temperature of a space is measured or otherwise detected, and the passage of heat energy into or out of the space is adjusted to achieve a desired average temperature. Control of such a temperature process is achieved by means of a closed loop circuit in contrast to an open loop in the case of measurement only. To accurately control process temperature without extensive operator involvement, a temperature control system relies upon a controller, which accepts a temperature sensor such as a thermocouple or Resistance Temperature Detectors (RTD) as input. It compares the actual temperature to the desired control temperature, or setpoint, and provides an output to a control element. The controller is one part of the entire control system, and the whole system should be analyzed in selecting the proper controller. Ultimately, the control of temperature is done by regulating the power to the heater. The whole process was tested with a PID controller and the results were compared with a Fuzzy PID controller. The process considered is a non-linear dynamic process, hence the entire region is split into three linear regions and piece-wise modelling has been done. Design of controllers for each region is a hectic and challenging task. Conventional PID controllers has to be tuned for different operating regions but design of Fuzzy PID controller will adapt to the dynamic process and vary the controller gain with the knowledge based rules. Also the conventional PI controllers, offers overshoot, and slow settling time. The proposed Fuzzy PID controller provides overshoot but is efficient in terms of faster settling time and reduced oscillations.

Keywords: Fuzzy PI, PI controller, peak overshoot, settling time, oscillations