ROBOTMAK3RS Blog

MCP Dave Astolfo has published a new NXT robot of his: the DualGrip . As the author states: "The idea was to have a treaded robot that could navigate varying terrain, turn quickly and of course, climb.  Based on my experience with my other robots using the same tracks (eg UNV and DynaTrax ), I found that they were not very good when it came to inclines.  I figured that the LEGO rubber wheels have great traction on most surfaces, so why not slap a set of them along with the treads." The point with the DualGrip is that it switches from tread drive to wheel drive when it encounters an incline - pretty good idea, isn't it? Have a look at the three web pages associated to the robot - there's a lot of information on the DualGrip to be found, including two more movies.

A friend of mine, John Brost, recently asked me if I had noticed that there were two types of the new tread links out there. Surprise surprise, it seems LEGO has modified the mold slightly. The new tread links will work fine with the old ones - there's no difference in the parts that connect link to link. However, some small new "bumps" on the new treads do change a few things for robot builders. First, they tend to make the side-to-side stability a little better (a good thing). Second, it means that using them "backwards" to form large wheels now works only with still larger diameters. Mixing them in an alternating fashion makes small "old style" (?) tread link wheels work... but you'd have to pay very careful attention to make sure multiple "new style" links aren't adjacent, or you might end up with flat places in your wheels. As to the why for this, it might have bee n to increase the side-to-side stability, or it might have been t...

Philo , MCP and relentless Wizard of LDraw parts, has published LDraw files for the treads contained in the NXT Education supplemental kit (other configurations of the treads can be found here and here ). Hence you can model your NXT robots that run on these treads now in LDraw. Thanks, Philo!

In preparation for the FTC competition, I've been getting familiar with RobotC, the language we're planning to use. In order to test my programs, I built a small rover that uses treads. Since the new plastic treads don't have good traction, I used the black rubber treads. Now, I don't think I've ever gotten a really good design with these treads! They're so small that it's hard to really secure them to the outside of a robot well. When I'd make a rover with these treads sticking out on both sides, I had trouble with the treads bending out and the chassis "sagging". So this time, I tried spreading the weight out more evenly, by positioning the motors directly above the treads. The result was really nice... a very strong and compact design that had no trouble with wheel camber. I even found a snug little place for the Ultrasonic sensor. :-) Notice that the treads are connected to the robot from both sides, increasing the strength of the chassis....

Earlier I was absently toying with the treads I posted about earlier while doing some studying, and I happened to find an interesting thing you can do with them. If you curve the treads backwards, you can make a circle out of them, where the insides of the links are facing outward: So I was wondering if maybe this construction could be used for something like a giant wheel or gear (turntable?), since sprockets can mesh with the outer rim of the circle to rotate it. And since the links have peg holes in them, you can put supports inside the circle: You can also use the peg holes to put an axle hole or something similar at the center of the circle, so it can attach to a robot (i.e. actually be useful :-) ). Any ideas for how to use/improve something like this? -Jonathan

This is just a design I came up with while working on another project, which I'll post about if successful. Ultimately, this robot was a failure because it's not powerful and can't steer (the treads are too close together), but it looked interesting. Also, since the treads go all around the robot, it can still drive when it's upside down or on either end, so that was pretty neat too. Anyway, how useful/practical have you found these treads? I like their size and the fact that you can make them as long as you want, but then I don't like their slipperiness (although people have fixed that with stuff like liquid rubber), and they don't seem to "fit" very well on robots (lots of times they're either too long or too short). -Jonathan