Jan 21, 2010

NXT 1.0 Line Following and Light Sensor Calibration

I have updated the original NXT 1.0 Line Follower project at nxtprograms.com to improve the original programs a bit and include a new "proportional" line following program. I also included some separate light sensor calibration utility programs and some discussion of light sensor calibration, as calibration can be a somewhat confusing concept in practice (although it can simplify your programs and/or make your robot more flexible once you understand how to use it).

Comparing this to my new NXT 2.0 Line Follower, with essentially the same program, I notice that it doesn't perform as well. I think this is for two reasons: NXT 2.0 programs execute faster than 1.x, and my older 1.x robot design is inferior. In particular, I think the light sensor is too far ahead of the wheels. Making the wheel track (left-to-right) wider would probably also help. Give a try at making it better!

3 comments:

Ron said...

Dave,

One of the big reasons 2.0 programs run faster is the V1.28 firmware. I'd be interested to see if your 1.0 programs run differently/better when using the V1.28 firmware.

Also, how about using the same exact 2.0 robot but with a light sensor in place of the color sensor for a side-by-side comparison?

Ron.

Armagon said...

Keep up the great work! People are always wondering how a line follower works, and I can not point them to nxtprograms.com.

Thanks!

Dave Parker said...

OK, I tried a couple of quick experiments. First, the 2.0 program and newer/better robot using a light sensor instead of the color sensor performed the same (as expected), so the color sensor in light sensor mode is similar to the light sensor (using calibrated/scaled values, not raw).

The newer/better robot design using a 1.0 brick and the 1.0 program (NXT-G 1.1 compile to 1.01 firmware) is pretty good (much better than the older/worse robot) but noticeably less smooth. So the better speed of the 1.28 firmware definitely makes a noticeable difference, but most of the problem was with the robot.

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