LEGO Mindstorms Robogator Build

Logo Mindstorms NXT 2.0

By Ryan Winters
Product Marketing Manager

Skill Level: Beginner
Assembly Time: 1 to 2 hours

Lego Logo Parts List:
LEGO Mindstorms NXT
(6) AA Batteries

I've built several projects with the LEGO Mindstorms NXT 2.0. My first build was the humanoid-looking Alpha Rex robot for display at the RoboGames event earlier this year. Then I reluctantly dismantled my desktop bot to build the Color Sorting Machine. I looked at the box to see what other builds were included, and that's when I remembered the gator.

I originally passed it up because it was one of the easiest on the difficulty scale, and I also wanted to see the full capabilities of the NXT. But look at those teeth; so menacing! Let's see if he's really got bite.

Robogator The alligator utilizes all three motors, two touch sensors and ultrasonic distance sensors. Two of the motors are used for the rear legs, while the other motor is used to actuate its jaw. That's right, I said motorized jaw. The two touch sensors are used in conjunction with the rear leg motors to determine when a leg has made a rotation. The ultrasonic distance sensor is used, for distance, but it also has the added visual effect as eyes on the alligator's head.

If you aren't familiar with LEGO Mindstorms, it uses similar building blocks to the Technic line of LEGOs, but it adds sensors and a microprocessor that is almost as advanced as some satellites in space. They save a couple trees by having all of the build instructions accessible through the included software. The instructions are typical wordless pictographs that show a handful of pieces that are to be used in the step, and you look at the picture to see what goes where. They do a great job of showing you which pieces to use first and how to combine them with the remaining pieces to complete each step. After all, Emperor Napoleon said, "Un bon croquis vaut mieux qu'un long discours," or "a good sketch is better than a long speech". Pardon my French.

Mr. Alli Gator is no exception. The steps are clear and easy to follow. The reptile is built as separate modules and then the three or four modules are brought together around the microprocessor brick for final assembly. When you've finished building the robogator, you can open the sample program and download it into your NXT.


The included program makes the robogator protect his territory by lying patiently with his jaws wide open, and when something passes close enough, he'll lunge forward while biting and then crawl back. It may be a little startling, but no kid I've shown this gator to (or adult for that matter) can resist putting their hand or other objects into his mouth. It was definitely a fun project and should only take about one to two hours to build. There's extra fun because you can create your own program for the gator using the drag-and-drop style block programming. There are also hundreds of other fun builds available from friendly folks online. The LEGO Mindstorms NXT 2.0 is really a gift that keeps on giving. Pick one up for the holidays while they're available because this kit offers a lifetime of value.

Ryan Winters is a Product Manager at Jameco Electronics and a Bay Area, California native. He is mostly self-taught and his hobbies include working on cars and computers, fiddling with electronic gadgets and experimenting with robotics.