Multi-Robot Communication with LEGO Mindstorms[1]

So, you have a LEGO Robotics Invention System, and now your friend has one too. (Or maybe you're lucky enough to have two of your own!) Perhaps now you're thinking to yourself, "is there any way to make two robots play with each other?" The answer is, of course, yes! The next question, then, is: how?

There are several ways you can try to make two RCX bricks "talk" to each other. For example, you might imagine constructing some form of sound sensor, and making the RCXs beep at each other. Alternately, you could make each robot capable of turning on or off a light, and use the light sensors included in the RIS kits to detect that. Also, if you just want to have two RCX bricks work together but don't mind if they're physically connected, you could connect the output from one to the input of the other. The method addressed in these web pages, though, is infrared communication -- using the built-in IR port on the RCX (the thing you point toward the IR tower in order to program your robot).

This site assumes that you already know the basic functionality of the RCX. If you don't, I recommend going through missions that LEGO includes with the RIS, or just experimenting on your own for a while. Also, if you have used the control software that LEGO provides, you've probably discovered by now just how difficult it can be to use. Instead of struggling with that, I choose to use an alternative programming language called Not Quite C (NQC). NQC is fairly similar to standard C programming, so if you have used either C, C++, or Java, you will have no trouble at all picking up NQC. If you've never used a programming language before, you'll have a little more trouble, but NQC is really pretty easy to learn, and I would highly recommend putting the time into doing so. You'll have a lot more flexibility with your Mindstorms if you do.

Before you start programming multiple RCX units at once, please read a word of caution.

[1] LEGO, LEGO Mindstorms, Robotics Invention System, and RCX are registered trademarks of the LEGO Group, Inc.

This project is funded by Carnegie Mellon's Undergraduate Research Initiative. These results represent the views of the author and not those of Carnegie Mellon University.