Treads Vs. Wheels

[dprovin662]

Which do you think will be more beificial tracks or wheels?

[Rickertsen2]

Originally Posted by dprovin662

Which do you think will be more beificial tracks or wheels?

In this year's game it seems to me that menuverability is very key. Treads are good for tasks which require lots of pushing power. Also, as we saw today, wheels go up the stairs fine.

[KenWittlief]

In general, treads are only usefull if you are moving over soft ground - like mud or sand

you dont get any extra traction by using treads unless you have several wheels along the length, pushing it into the carpet - look at a photo of a tank or bulldozer, they have several wheels on each side applying downward force on the length of the whole tread.

because the friction of the tread is a function of the downward force on it - so if you have two wheels, with a tread running between them, you wont get anymore friction that if you simply wrapped the tread material around the wheels separately (like a tire)

but another issue this year is climbing the stairs - if you are going to do that, then treads might be the way to go

[kevin.li.rit]

Treads would be seem to have an easier time getting your robot up the step. But I would stick with wheels I think you can still get up the stairs fairly easiy with wheels+ you get more maneuverability. Less scrubbing I believe?

[Damian Manda]

I would stick with the wheels, as treads have a habit og getting loose and falling of the robot if they are not perfect. Then there is no way to really drive at all. Also, with the size of the wheels in the kit (12.6in) I'm sure there will be no problem getting up the stairs, seeing as they are only 1.5in tall. Now if you want to get up the 6 inch sides of the platform, you might need something better, although the large wheels might work.

[robo-gordo]

Originally Posted by KenWittlief

because the friction of the tread is a function of the downward force on it - so if you have two wheels, with a tread running between them, you wont get anymore friction that if you simply wrapped the tread material around the wheels separately (like a tire)

Just a clarification of friction in terms of physics:
In an ideal situation with constant coefficient of fricions, and simple, constant surfaces, the surface area of the wheel (or tread) does not matter. Though a tread has more surface area, the weight is distributed over that wider area, and it cancels out.

However...
When a wheel (or tread) has grooves, knobs, etc. it is quite different. The ability of a wheel to dig into the carpet, greatly improves it's traction.

The soft, tready rubber wheels they gave us are really good a)because those rubber skyway wheels have good traction both on the carpet and on the HDPE, and they are large enought to easily go over the small steps. (I suppose that with a large enough wheel (>12in) you could go directly over the 6in step.)

Treads will only help if they can get you over the steps easier, because they provide traction over the whole length of the robot. We saw how wheeled robots can get hung up on the edge of the steps. Caveat Builders!

[Cory]

You guys are all thinking "Oh, its so easy to get up the stairs" Yes, it is, but once you get up, you have very very little space to manuever in. the distance from the edge of the PVC to the side of the platform is 34". The stairs dont even go to the edge of the platform, so youre left with a very weird angle and a very tight space to negotiate. For some drivers, this is going to prove to be very tough, if not impossible

Cory

[Aignam]

Originally Posted by Cory

You guys are all thinking "Oh, its so easy to get up the stairs" Yes, it is, but once you get up, you have very very little space to manuever in. the distance from the edge of the PVC to the side of the platform is 34". The stairs dont even go to the edge of the platform, so youre left with a very weird angle and a very tight space to negotiate. For some drivers, this is going to prove to be very tough, if not impossible

Cory

That small space between the edge of the platform and the stationary goal is definitely going to prove challenging to maneuver around for teams looking to suspend themselves from the bar.

[Enslaved]

Wheels here...
The balls are light, so you really do not need a lot of traction or torque!

Well, and everyone will be busy gathering balls, I do not think any team will try strategizing to stop other robots from gathering balls, though hanging on the bar is another story!

[Damian Manda]

Originally Posted by Aignam

That small space between the edge of the platform and the stationary goal is definitely going to prove challenging to maneuver around for teams looking to suspend themselves from the bar.

If you are going to grab the bar, you have to first climb the 6 inch step onto the platform below it. If you can climb that step, then it will not be very hard to climb up the side of the large platform, as this is only six inches high as well. In this way there is less manuvering than trying to go around the stationairy goal. Thus, if you are going for the bar, I dont think it will be too much of a problem to get there in the first place.

--Damian Manda

[abeD]

The key to hanging is going to be who gets to that top piece first. Once you are on there it shouldn't be too hard to fend off opponents trying to get up since you are a step up above them.


Unless your opponents can grab the bar from the first tier and not have to be on the top platform...

[KenWittlief]

why climb up there at all? if you are going to reach up, reach up from the carpet and draaaaaaag yourself up!

[Aignam]

Originally Posted by KenWittlief

why climb up there at all? if you are going to reach up, reach up from the carpet and draaaaaaag yourself up!

Can you say torque?

[Anthony Kesich]

TREADS!

We used them last year (the only team to use them at Sacto and SVR) and never had much of a problem. No turning radius, never bottomed out, kept a low profile and could climb up 6-8 inch barriers with ease. If we increase our clearance this year, we will have no problem. The item i have with wheels is that if the driver goes up at an akward angle on the stairs (which i reccomend against) and screws up, I would not be surprised to see them bottom out and be stuck there and useless. But thats just me....

-Kesich

[kevin.li.rit]

We also had a zero turn radius with wheels, Haven't tried using it to climb stairs yet. But I still think it can be done just as well with wheels.