Line Tracking Robot

Question

Me and my friends are building a line tracking robot based on my previous question about how to track white line on a black surface. We settled on using photo resistors and a arduino board. Now all the reflectance sensors I've found are should be placed very close to the line 1 - 2 cm above the line. Now one of my team mates had a heated argument with the professor that there are reflectance sensors that can track 10cm or more but we could not find any.

Are there any type of sensor that would allow us to track the line farther away?

Answer 1

Using an arduino, you are most likely going to use the pololu library for reflectance sensors. Even using an array of sensors of this type, you are looking at a maximum sensing distance of just UNDER a cm (9.5 mm.) I think your teammate was out by a factor of ten, you can score this one to the professor!

The lego light sensor is a good example of this type of sensor. If you can get your hands on an NXT kit, it is an alternative to the arduino. And who doesn't enjoy playing with lego!!

Kindness,

Dan

Answer 2

You need a laser sensor if you want a range more than a few centimeters and don't want to bother with doing it yourself. Google for "laser contrast sensor" if you really need it.

One way to increase sensitivity is, lighting the white band with an array of LEDs perpendicular to it and sequentially turning one on and off, tracking the reading of the photoresistor in software. Of course you probably want to optically focus the LEDs some and use modulation to minimize interference if you use simple photoelements. It will be interesting to see the actual distribution of resistance values along the LED array on the white line.