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Line FollowingWith One Light Sensor

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Attach a light sensor

To attach a light sensor to the EduBot, refer to pages 32-33 of the NXT Building Guide (that

comes with the Education Kit).

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Click

twice to

Then keep clicking untilNow select the port the light sensor is in, probably Port 3.

Reading the value of your light sensor

Select

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Light readings for lots of things

Midair ____________Colored surface (Color ________ ) ____________Colored surface (Color ________ ) ____________Colored surface (Color ________ ) ____________ Darkest reading ____________Brightest reading ____________Black line on line follow board ____________White area on line follow board ____________

Try getting light sensor readings for the following:

Note: The light sensor does not read color. It reads how much light is reflected – which is different for different colors.

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Edge following or line following?

The easiest way to follow a line is to follow

the edge, moving on and off the black.

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When on white it needs to go to black.

When on black it needs to go to white.

?

?

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. . . And back to black again.

While doing this, it edges up the line.

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ForwardB

Stops

Basic Line Follow

Switch

Left

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Basic Line Follow

The trigger point value determines when the sensor is seeing black or white. It is the average between the black % and white %.

The Switch blockand its configuration panel

(Black% + White%) ÷ 2

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Basic Line FollowA partially completed line-follow program should look like this . . .

Set Move block duration to “Unlimited.”

IMPORTANT

Don’t download yet…

What still needs to be added

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Add a Loop block. (The EduBot needs to line follow forever.)

1 2

3

Then Download.

Then drag the Switch into the Loop.

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Have some fun following the line . . .

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And for the teacher . . .

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Finished Line (Edge) Follow Program

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