Lego Mindstorms as a Prototyping Tool

Lego_pathfinderAlmost five years ago, just after I moved to Japan, I ran across the Lego Mindstorms website and was just blown away by the television commercial video on the site. I absolutely had to have a Mindstorms set....

But, as usual, life tends to lead us down other paths. I managed to buy a Mindstorms RIS 1.5 set, but because of the PC I had at the time time and the operating system, I wasn't able to get the RIS software setup and communicating with the IR tower. Everything went back in the box, and started collecting dust in my closet. From time to time I would run across the set while searching for something else that I had misplaced, but nothing inspired me to take it out of the box and try to get it working. Even when my interest in robotics was rekindled last year, I didn't think about pulling the RIS out. In fact, I couldn't even remember exactly what the problem was that kept me from getting it to work in the first place.

Then in the middle of December I was able to visit the San Francisco Bay area, and managed to squeeze in a trip by BART down to the Hobby Engineering store in Milbrae. I'll write more about my experience there in another post since there is a lot to tell. One of the 'goodies' that I picked up at the store was an accelerometer module. I really want to try putting together a self-balancing robot - something along the lines of the Legway. I know that other experimenters have been negative about using an accelerometer as the primary sensor in a balancing feedback loop, but I wanted to try it myself anyway. It should be a good learning experience, and if it turns out not to be practical, I'm sure I can find other uses for the module.

Back in Japan after the holidays, I started to think about how to prototype the robot. It would probably be a good idea to get the accelerometer up and running and talking to my microcontroller... But how to test that without actually going to all the trouble of building the robot? I really didn't want to put all the time and effort into a robot that had a major design flaw from the git-go. What I needed was a test fixture. Something I could mount the accelerometer on, then rotate it through different angles at different speeds. It would also be great if I could control the rotation with a microcontroller - especially if it was separate from the circuit under test.

In mulling over the alternatives, I remembered seeing a Mindstorms hobbyist that built a panoramic base for his camera using the RIS... What if I did the same thing, only tilted the rotating base vertically?

Bingo!

That was enough to inspire me to dig the Mindstorms set out of the closet and get back to work on it. Over the years I had purchased a new PC, this time running Windows XP, and thankfully the RIS software loaded and ran the first time I tried it. Within a couple of hours I had the Pathfinder robot running around on the floor frightening our dogs. The only slight disappointment was the pedantic nature of the tutorial software. I kept wanting to run while it kept holding me back. Still, I understand why it was designed that way.

The next step is to design a Mindstorms based test fixture and testing strategy.I doubt that I will invest a lot of time in building complex robots using the RIS, but as a quick and dirty fixturing tool to try out different concepts, I think it will turn out to be a tremendous asset.

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One comment

  1. Hi,
    most ppl don’t reccomend the accelerometer as the primary sensor as often it is not sensitive enough to be able to detect whether the robot is falling. It is often used as a secondary device to correct gyro drift.
    Thats as far as i gathered anyway.

    Daniel.

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