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[on:]

Hello,

Had a question about the line following robot, the type that is able to follow a black or white line. I am using an 8 LED strip. I'm going to be on blacktop and my tape (path) is going to be white.

Does the 8 LED strip need to be entirely over the strip? Or shoudld I have the two outside LEDs over blacktop. THanks
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[Reply #1 on:]

What does the LED strip do?

[Reply #2 on:]

Is your "LED Strip", an array of phototransister(or LDR)-LED pairs similar to this?

http://www.pololu.com/catalog/product/961

If so, you want to mount the array so that the line intersecting all the LEDs is perpendicular to the line you are trying to follow. Your path only needs to be wide enough to make at least one of the sensors out of the 8 register a change in reflected light.

The reason the array is so wide is so your robot can know not only if it is on the line or not, but also how far off of center it is. You can build a line-follower that has only a single sensor instead of the eight used in an array like this but it won't be able to go very fast. By increasing the number of sensors you increase the resolution at which you can determine how much you need to correct to get back over the line which leads to smoother turns which leads to higher speeds.

The higher speeds is the fun part.

So most like this I guess:

Code:

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[Reply #3 on:]

7th graders can do this with a Lego controller and just a single light sensor, mounted close to the center of rotation. They get a numerical # back and use that to follow the edge of the line.

[Reply #4 on:]

7th graders can do this with a Lego controller and just a single light sensor, mounted close to the center of rotation. They get a numerical # back and use that to follow the edge of the line.

A 7th grader with a Lego controller could also connect it to multiple light sensors and get it to go much faster than would be possible with a single sensor. Using a more advanced algorithm, such as PID control, also becomes possible once you have greater than single bit resolution on line position.