August 13, 2006

Mindstorm NXT

Mindstorm NXT

Introduction

The purpose of this article is to compare the original Lego Mindstorm system with the new Mindstorm NXT. My primary interest was how well could the NXT be used for building robots to compete in events like the annual PAReX competition.

What's New

The NXT comes with over 500 pieces, including 3 motors, a light sensor, a touch sensor, ultrasonic range sensor, and a sound sensor. The motors are continuous rotation servos, with rotation encoders. The sound and ultrasonic sensors are new with NXT, offering more complex operations with your robot. The RCX or brick has been upgraded to a 32-bit processor, graphic display, 4 sensor inputs (1 more then the older RCX), and a USB interface replaces the IR tower of the original. Blue tooth is also available for wireless connectivity.

Old vs. New

The new RCX or "Brick" is slightly larger then the original.
Starting from left to right, we have the original touch sensor and light sensor. Then there's the new light sensor and touch sensor.
And finally there's the original motor and the hugh NXT motor.

Mini-Sumo

Building a mini-sumo with NXT would be a difficult feat. The RCX is bigger and the motors are hugh, compared to the original. The robot would need to be constructed with both the motors and RCX mounted vertical to fit within the 10cm starting square, which would make the robot top-heavy. The RCX with batteries, plus two motors, and light sensor weigh in at 510 grams, exceeding the limit for mini-sumo.

Maze Runner

The NXT lends itself well to create a maze robot. The ultrasonic range sensor could be used to follow walls. The built-in rotation sensor would keep the robot moving in a straight line. Two touch sensors would work better for a two- sided bumper system, so you'd have to buy another sensor for this ability. I'll have to put together a robot to see how well it drives straight and get an idea as to how small it can be built. I like to keep the maze runner size around 6"x6" so it can move through the maze corridors easily, but you could go as big as 8" and still be able to turn without hitting walls. You need to be perfectly centered in order to do this though.

Line Follower

I think we have the most potential here for the NXT. There's no size restrictions to get in the way. The shortage of sensors becomes a problem though, since a good line follower needs at least two line sensors, but the NXT only comes with one. Again, further experimenting is needed to see exactly what we can do with the new system.

Conclusion

The NXT is a great looking new product. Since it uses technic style parts, it's much faster to get a project built up, then past designs that were all brick. I wouldn't get it for doing mini-sumo, but it might be a worthwhile investment for other projects or events.

Posted by Kelly Small at August 13, 2006 06:34 PM