"Halftrack" robot drivetrain
 

OK, this probably sounds stupid, but it's just an idea I had. I'm not a drivetrain expert but maybe this isn't such a crazy idea. What if you built a robot that had some wheels connected with tank treads, and others that were not? Perhaps even a tank tread + omniwheel system? It gives you a combination of higher traction and not-so-bad maneuverability. For this game it might be beneficial to have treads on the front and wheels in the back, to navigate the barriers while still retaining maneuverability.

I'm not saying I think it will work, just throwing the idea out there for your consideration. It's not a new concept.

Attachment 11314

Does anyone think this might work?

Re: "Halftrack" robot drivetrain
 

Yes! My team is going to try out this design. We really liked the grip and stability of the tank treads but read too many horror stories to try them without first testing in off season. We decided a half and half system could prove to be just as- or more helpful in this game (and less costly!). Even if we cannot satisfactorily complete our partial tank drive, we are still thinking of having two different types of wheels- like maybe pneumatic in the front and omni in the back.

Re: "Halftrack" robot drivetrain
 

I wouldn't do this without omni wheels to back them up.

If not you might as well just go straight tread/tank drive. The mobility loss is the same both ways, and straight up tread/tank will give you more power.

Re: "Halftrack" robot drivetrain
 

What about a dropped-center half-track? Normal wheels at the ends, tread in the middle? Then, even if that fails to do anything, you can convert it to eight-wheel and pretend nothing ever happened.

Re: "Halftrack" robot drivetrain
 

How will tank tread give you more power?

Re: "Halftrack" robot drivetrain
 

the benifit of tank treads is also its downfall in this game. tank treads give you more Traction than wheels, but in order to turn they must slip and slide accross the floor in a circle, which would be very hard on carpet (most likely your tracks would come off your wheels if you tried to turn. tanks used treads to keep their supper heavy bodies from sinking into soft ground and getting stuck, and half-tracks, being lighter, used a hybrid desighn to increase manuverability and controll at higher speeds. seeing as how no robot is in danger of sinking into the floor with the current weight restrictions imposed by FIRST, i do not know how efective tank tracks would be

Re: "Halftrack" robot drivetrain
 

Our team has done tank treads for the past 6 years, so we have done quite a bit of research in the topic. If you are going to use treads, consider them just like wheels: Use 6 rollers on the bottom and drop the middle one (3 on each side). We used an inverted fan belt as our tread; you have the sproket from the gearbox pushing down on the top and driving it. If my explanation wasn't very good, the full CAD of our latest robot is on FRCDesigns . Team 639.

Re: "Halftrack" robot drivetrain
 

IIRC, didn't the Aim High triplets (1114/1503/1680) have a half-track with extra wheel configuration?

Re: "Halftrack" robot drivetrain
 

Pardon, I meant more pushing power, due to extra traction.

Re: "Halftrack" robot drivetrain
 

Our team was thinking that too, it seems like a good idea!

Re: "Halftrack" robot drivetrain
 

You don't need to qualify your ideas like that, this community is built on sharing ideas that might not work. I've posted plenty of ideas to see if they'll stick.


When I joined my first FIRST team, I used the previous year's robot to learn how to program (in PBASIC!). It was a hybrid half track, with casters in front and tracks in back. When combined with the weight distribution, the center of turning was extremely far to the back. This made it a bit twitchy and hard to control. I don't think this is true for all half tracks, but be sure to check for it.

Long story short: I'd hesitate to idle the wheels, check for twitchy turning.

Re: "Halftrack" robot drivetrain
 

Full tank treads in '06. I recall hearing that they had a ton of trouble with treads coming off or jamming that year.

Re: "Halftrack" robot drivetrain
 

They had an issue where if you pushed them sideways in a particular set of circumstances, it would tear a track.

Re: "Halftrack" robot drivetrain
 

Even a between-the-wheels tank tread would be useful (4wd) to scoot you along the barrier.

Re: "Halftrack" robot drivetrain
 

We too were looking at using the half track set up to maneuver the bump, but our lack of experience with tracks has us a little weary of the idea. If the track had some sort of simple suspension, the track would definitely be the way to go. All this said, we are a rookie team and have never worked on anything even remotely this complex before, although I do like the idea of the half track tread system.

Re: "Halftrack" robot drivetrain
 

I think that it's the suspension design that's the best feature of a tracked robot. if you can figure out a way to power each wheel yet still have each wheel move independently on its own suspension, you would be able to go over the bumps and ramps while avoiding the weak points of the track system, particularly involving turning and being de-tracked