comparison between Fuzzy and Conventional Control

In order to design a conventional controller for controlling a physical system, the mathematical model of the system is needed. A common form of the system model is differential equations for continuous-time systems or difference equations for discrete-time systems. Unless physical insight and the laws of physics can be applied, establishing an accurate nonlinear model using measurement data and system identification methods is difficult in practice. Even if a relatively accurate model of a dynamic system can be developed, it is often too complex to ISSN: 0975-5462 4511G.Sakthivel et. al. / International Journal of Engineering Science and Technology Vol. 2(9), 2010, 4511-4519 use in controller development, especially for many conventional control design procedures that require restrictive assumptions for the plant [12], [13].As an alternative, fuzzy control provides a formal methodology for representing, and implementing a human’s heuristic knowledge about how to control a system, which may provide a new paradigm for nonlinear systems. Fuzzy controller is unique in its ability to utilize both qualitative and quantitative information. Qualitative information is gathered not only from the expert operator strategy, but also from the common knowledge [12], [13]. Fuzzy control should not be employed if the system to be controlled is linear, regardless of the availability of its model. PID control and various other types of linear controllers can effectively solve the control problem with significantly less effort, time, and cost. The benefits of fuzzy controllers could be summarized as follows:
1. Fuzzy controllers are more robust than PID controllers because they can cover a much wider range of
operating conditions than PID can, and can operate with noise and disturbances of different nature.
2. Developing a fuzzy controller is cheaper than developing a model-based or other controller to do the same thing.
3. It is easy to learn how fuzzy controllers operate and how to design and apply them to a concrete application