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More amateur robotics for you…

One of the things that I’ve been comparing between my old Lego Mindstorms RCX and my new Lego Mindstorms NXT is the ease of building things with each platform. While the NXT is naturally more capable than the RCX was, and the software is a lot more stable so it’s easier to program the platform, it’s a lot harder to physically build robots using the components in the box.

For example, on the RCX, it was relatively easy to build a basic four wheeled platform so that you could get the base upon which to construct more complicated things. When I built my first robot that didn’t fall off surfaces, it took about ten minutes to experiment and come up with the wheeled base, and the remaining few days I dedicated to the project to figuring out how best to place the sensors to detect collisions.

For almost two weeks on and off, I’ve been trying to build such a platform for the new NXT. Today, I actually pulled out the bricks and tried to assemble the platform. No joy. I’ve tried several configurations, but I’ve yet to be able to use either one or two motors to build this four wheeled base from which I can build something more advanced. Sure, there are plenty of platforms available online that I can customize to fit my needs, but it’s not the same as coming up with a basic platform on my own.

I have a few theories or reasons why this is so.

First, there are a lot fewer attach points on all the major components. Pretty much both top and bottom of the RCX are standard Lego attach points. There are also a couple of side Technic attach points, but not a whole heck of a lot. Still, many points overall. The NXT, by contrast, has about a dozen Technic attach points on each side and at the bottom, but none on the top; that’s a lot more on the sides, but it’s no longer possible to really attach a giant LEGO base frame and construct upon that. I’m not sure what the precise reasoning for that change was; to be sure, the old RCX really did need extra attach points, but I’m not sure why there are precisely no Lego attach points on the NXT. Which brings us to…

Second, the philosophy behind who should be using these kits has changed from absolute beginners to advanced and professional robot builders. The RCX and its associated kit was mainly Lego, with a few Technic pieces thrown in to connect things together and make everything work smoothly. There were also just a lot more parts in the original RCX kit. Maybe because the cost has gone up in the intervening years, or maybe because Technic parts are just more expensive, period, there are a lot fewer parts like beams and flats which can carry weight, and a lot more connectors, leading to a net reduction, for me, of useful parts. Also, a number of wheels and wheel types were eliminated with NXT kit, making it difficult to mobilize the bot.

Finally, the sizes have changed. I’m not sure what precisely was wrong with the size of the RCX motors, but the NXT has these really long, rather awkwardly shaped motors. In fact, almost all the electrically active bits seem to be just larger for no reason – the NXT brick itself, the sensors, the motors. Given the larger motors with a bulge, it makes it harder to fit it in neatly, whereas the mostly cuboid RCX motors fit in beautifully. Similarly, an individual and quite often awkward mounting needs to be made for each sensor, instead of it just being attached generally to a nearby beam that’s handy.

Given all of this, however, it’s still amazing how much one can build with either kit. One thing I wish I could do is use the two bricks, the NXT and the RCX simultaneously. The NXT is overkill for simple to-and-fro movement, while the RCX doesn’t have enough sensor ports. I know there are ways to use IR sensors to transmit back and forth, but I would love to have some sort of cable so I wasn’t forced to point the two together.

Have any of you got a robotics kit? Any thoughts?