Defining Fuzzy Sets

Fuzzy Operations

Fuzzy Decisions

Fuzzy Engineering


History and Objections


Fuzzy Logic Applications

    Almost any control system can be replaced with a fuzzy logic based control system. This may be overkill in many places however it simplifies the design of many more complicated cases. So fuzzy logic is not the answer to everything, it must be used when appropriate to provide better control. If a simple closed loop or PID controller works fine then there is no need for a fuzzy controller. There are many cases when tuning a PID controller or designing a control system for a complicated system is overwhelming, this is where fuzzy logic gets its chance to shine.

    One of the most famous applications of fuzzy logic is that of the Sendai Subway system in Sendai, Japan. This control of the Nanboku line, developed by Hitachi, used a fuzzy controller to run the train all day long. This made the line one of the smoothest running subway systems in the world and increased efficiency as well as stopping time. This is also an example of the earlier acceptance of fuzzy logic in the east since the subway went into operation in 1988. For more information on this see: http://sipi.usc.edu/~kosko/Scientific%20American.pdf(pdf) or http://www.smart.sunderland.ac.uk/f_succ.htm

    The most tangible applications of fuzzy logic control have appeared commercial appliances. Specifically, but not limited to heating ventillation and air conditioning (HVAC) systems. These systems use fuzzy logic thermostats to control the heating and cooling, this saves energy by making the system more efficient. It also keeps the temperature more steady than a traditional thermostat. For more information on this application see: http://www.fuzzytech.com/e/e_a_esa.html

    Another signifigant area of application of fuzzy control is in industrial automation. Fuzzy logic based PLCs have been developed by companies like Moeller. These PLCs, as well as other implementations of fuzzy logic, can be used to control any number of industrial processes. For some examples see: http://www.fuzzytech.com/e/e_a_plc.html

    Fuzzy logic also finds applications in many other systems. For example, the MASSIVE 3D animation system for generating crowds uses fuzzy logic for artificial intelligence. This program was used extensivly in the making of the Lord of the Rings trilogy as well as The Lion, The Witch and the Wardrobe films.

    As a final example of fuzzy logic, it can be used in areas other than simply control. Fuzzy logic can be used in any decision making process such as signal processing or data analysis. An example of this is a fuzzy logic system that analyzes a power system and diagnoses any harmonic disturbance issues. The system analyzes the fundamental voltage, as well as third, fifth and seventh harmonics as well as the temperature to determine if there is cause for concern in the operation of the system. A complete explanation of this project can be found in this paper: Harmonic Distortion Diagnostic using Fuzzy Logic(pdf)


Fuzzy Logic