Half-Track?

[Rommel]

I guess this would be the correct board, so, has anyone had any experience with using a half-track design for their robot? 498 is currently kicking the idea around for either this year or possibly next year.


We were thinking of using escalator belts for the tread, and omni-wheels for the front.

If anyone has tried this, any comments would be appreciated.

[Tristan Lall]

Rommel contemplating a half-track? That's impressive.

As for the half-track robot, I don't recall seeing any. Are you thinking of using driven front wheels? If you don't, consider that you will be at a bit of a climbing and pushing disadvantage, compared to robots that can use their entire normal force to push on things (by powering all wheels); the track will mitigate this somewhat, but depending on the weight distribution, this might not be sufficient.

[Rommel]

Right now it's just in the preliminary planning stage but the reason this was brought up was that we were having problems turning smoothly because we had to drag out outside wheels around (we have a 6 wheeled robot with the middle 2 as the drive wheels). the idea of having a tread design is one that I personally like, but no one else is really behind it.

We were thinking that if we have a half-track with either casters or omni-wheels in the front then there would be less drag on the non-powered wheels, and thus, smoother turning..... as well as a cooler looking robot.

[Jeff K.]

We did something just like that for VEX.
I'll try to get some more pictures of it on the VEX bot though, I designed it around November for the VEX, so our team realized we hadn't seen anything like it really in FRC, so they named it the "Kane-O Drivesystem", We did it so we would have traction, but still be highly maneuverable, and also because it was pretty unique. We had the front omnis powered also to make the turning radius closer to the center rather than being in the middle of the tracks, which was closer to the rear of the robot.

Sorry for it being somewhat low quality, it was a quickie camera-phone picture.
It worked pretty well, surprisingly, it actually won in a pushing match against another full track design and an articulated track design, (think Scorpion from Halo).

But interesting choice for FRC, I'm interested in seeing how you would modify it for FRC and what advantages it would have over a fulltrack system in real life, compared to VEX scale...or it might just be the same...
Ya never know. lol

[Kevin Kolodziej]

1064 ended up with a half track in the end after several redesigns back in 2003. I'll have to see if I can find any pictures of it at that point, but it was something that just kind of happened in the pit as things were hacked and . The original design was 4 treads that could articulate up to four inner points (tip-toe if you will). MANY MANY things went wrong so we dropped to a half track and had mild success. We had the treads in the front half powered by CIMS and standard wheels in the back powered by the drill motors. Worked nicely, but still had some turning issues. The bigger issues were not the design, but the fabrication and implementation (no end bearings, no crowned wheels or guides for the track part, etc.). If you do go this route, be sure to take your time and design it propery...and don't use 3" tread like we did =)

Good luck!

Kev

[Leo 1529]

the only problem we could come up with for not doing a half track was that only half of the robot would drive... we couldnt see putting casters on our robot again this year...a half track would be a good idea but i see that there is a downside

[Ken Patton]

We did something similar to a half-track in 2002. We used a chain with metal cleats as the track (metal is now not allowed of course due to carpet damage potential), and in the front just one slippery wheel right in the center of the front end.

We reduced the track length just for the reasons you stated - to improve turning. It definitely helped. The track was roughly 1/2 the length of the robot. I hate to think of the side-scrub forces and the current load on a full length track when you are turning.

Tracks are a lot more effort than wheels imho - I wouldn't suggest it unless there was a really good reason (like crossing dunes in North Africa, General).

hth,
Ken