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DRAGON SCIENCE: Driven to the Wall

In its transformation to a hi-tech nation, China is using fuzzy logic to manufacture smart cars and consumer goods. Scientist and entrepreneur Wei Xu accompanies FRONTIERS host Alan Alda on a harrowing test ride into the heart of Beijing to find out if a fuzzy braking system can stop a car. In another application, an experiment with a train uses fuzzy logic to check power lines that keep trains running. With many specialists working in this field, China is well on its way to a fuzzy 21st century.

Curriculum Links
Activity 1: Graphing Fuzzy Logic



fuzzy logic,
neural network,


fuzzy engineering,
traffic control systems


binary processing,
fuzzy sets

Beijing, China


Fuzzy logic is a revolutionary approach to computer programming that mimics the way the human brain thinks and solves problems. Prior to fuzzy logic, computers and electronic devices processed data using binary logic, which is based upon only two alternatives (0 or 1, either/or). Fuzzy systems use a series of simple rules, based upon experience, much as the human brain does.

A binary system processes data in black and white; a microprocessor switch must be in either the on or off position. In contrast, fuzzy logic deals with "grayness." Fuzzy systems adjust to a continuum of choices ("the coffee is warm," "this ice cream is sweet"). Everything is a matter of degree in fuzzy logic; a switch can be 20 percent on and 80 percent off (think of a lamp with a dimmer switch). Fuzzy systems are also cheaper to produce.

Fuzzy logic pioneer Lotfi Zadeh first labeled the concept in the 1960s, when he worked with fuzzy sets at the University of California at Berkeley. Japan embraced the concept of fuzzy logic and used the system to invent a myriad of smart machines. China soon followed and today has more fuzzy specialists than any other nation.

Objective: Use this activity to further understand fuzzy logic by interpreting data on a graph.


The graph above illustrates the variable condition of a lamp controlled by a fuzzy logic circuit. The horizontal line represents the time in minutes; the vertical line represents the degree of on/offness. At time zero, the lamp is 0 percent on and correspondingly, 100 percent off. As we move along the bottom line, the lamp begins to increase in its on state, while decreasing in its off state. Eventually, it attains a full on position. Then, the lamp begins its decline to off. Study the graph shown here, then answer the following questions.

  1. At what time(s) is the lamp half on?

  2. If a lamp is 70 percent off, then how much is it on? Explain.

  3. What condition does the plateau on the dotted line represent?

  4. What can you infer from the slope angles?

  5. How would this graph be different if the process were controlled by binary logic?
< Answers:
  1. 5.5 and 13 minutes.

  2. 30 percent; it must add up to a full condition of 100 percent.

  3. The lamp is 100 percent on or 100 percent off.

  4. The speed at which the switch is changed.

  5. The slopes would be parallel to the y-axis, representing instantaneous change.
  • Explain how the fuzzy logic systems on Frontiers are different from binary processing.

  • A washing machine that uses a fuzzy logic system can vary its speed and water levels, depending on the size of the load and how dirty the clothes are; put food in a fuzzy microwave and it senses how long and how hot to cook it; a fuzzy camcorder adjusts for shakiness. Apply fuzzy logic to these devices: a camera, a vacuum cleaner, an exercise machine, a coffeemaker, a TV.

  • Brainstorm and design a product or appliance that utilizes fuzzy logic.


Scientific American Frontiers
Fall 1990 to Spring 2000
Sponsored by GTE Corporation,
now a part of Verizon Communications Inc.