Intelligent Systems II · M2 · read
Fuzzy theory: definitions, architecture, advantages and applications
2. Fuzzy logic, from meaning to full solutions
Definitions → membership graphs → operations → rules → defuzzification → complete controller.
Explain fuzzy logic with one application. [2 marks · Practice]
Answer
Fuzzy logic represents gradual truth or category membership using values between 0 and 1. A temperature controller can use Low, Medium and High temperature sets. It evaluates rules such as IF temperature is High THEN fan speed is High, combines the rule outputs and defuzzifies them into a numerical fan speed. This permits gradual control around category boundaries.
Give the advantages and limitations of a Mamdani fuzzy controller. [3 marks · Practice]
Answer
| Advantages | Limitations |
|---|---|
| Human-readable rules express expert knowledge | Membership functions and rules require careful design |
| Can model gradual boundaries without an exact analytic plant model | Rule count can grow rapidly with more inputs and categories |
| Handles overlapping linguistic descriptions | A poorly chosen rule base can produce poor or uncovered outputs |
| Suitable for many control applications | Does not automatically learn or guarantee optimal control |
Describe the design of a fuzzy fan controller. [3 marks · Practice]
Answer
Choose temperature and occupancy as inputs and fan speed as output. Define their ranges and Low/Medium/High membership functions. Construct a rule table linking input labels to output labels. Fuzzify measured inputs, use min to obtain AND-rule strengths, clip the consequent sets and max-aggregate them. Apply the specified defuzzification method to obtain a fan speed. Test the design at normal inputs and range boundaries.
Other applications you can explain
| Application | Inputs | Example rule | Output |
|---|---|---|---|
| Washing machine | Dirtiness, load | IF dirt High AND load High THEN wash time Long | Wash duration |
| Loan decision support | Income, credit score | IF income High AND credit Good THEN approval suitability High | Suitability score (not an automatic legal lending decision) |
| Fire warning | Temperature, smoke | IF temperature High OR smoke High THEN risk High | Alarm-risk score |
| Vehicle control | Distance, relative speed | IF distance Small AND closing speed High THEN braking Strong | Braking command |
Yaad rakho: Theory answer mein definition → blocks/steps → ek concrete example. Sirf headings se marks nahi milte.