Hey has anyone ever tried using wheels and treads on the same base similar to a snowmobile? If so, how efficient was it? Also for the actual competition what are your opinions on treads versus wheels?
for competition, wheels-> i just know from others experience ->ask user ‘sunny’
Yeah, use wheels for competition. During the cuts program at my school one team used treads, they would have had a half decent robot by the standards used for these cuts (you are only allowed to use 3 motors) they might have stood a chance if it didn’t take them 5 minutes to move across the board.
Definately wheels. From FTC experience and from experimenting on my own. Treads look cool, but if directly driven are quite slow and don’t offer much grip.
We used treads last year very effectively. At Worlds we were ranked 5th. So we can’t be doing that much wrong. However for both at the same time, I dunno, I’ll let you know;)
I’ve never heard of a wheels+treads configuration on a bot, but there are certainly historical precedents for vehicles such as the half-track.
My concern is that you might end up with a “worst of both worlds” result if you were just trying to design a general purpose mobility base using both. Is there a particular goal you are trying to achieve, or just curious?
Treds in the back, two omni wheels in front… sounds like a fun experement!
How about tank tread drive and be able to turn the front wheels, not reverse the tank tread.
What? Are you suggesting making steering like a car, or driving the wheels and leaving the tread unpowered, or what?
Rack & Pinion (I think thats how it’s spelled) in front and tank trad in back… That actually sounds like it would work. (and Quazar’s Wiki article seems to somwhut conferm that)
Steering like a car with unpowered wheels in front, powered tank tread in the back.
I would go with the wheels, tank treads are to slow and when you gear them up you need a lot of motors to keep the tread going.
I use a 3 to 1 gear ratio on my robots with wheels and it works great, the treads on the other hand go slower and have less traction.
Rubber wheels grip a lot better than plastic tank treads that slide.
I am saying that if someone rammed your robot on a smooth surface your robot would be more prone to sliding sideways than you would with wheels.
This is what i think if you disagree feel free to post.
But then, you can use the grips from the upgrade kit, can’t you?
space them accordingly and you won’t lose too much manuverability and have more traction than wheels, since wheels, regardless of the size, will only have 1 point touching the ground (maybe a little more if it’s thicker)
And since the field will be foam tiles, treads may sink in a little and have a better grip than on other surfaces (i.e. wood)
Also, treads will theoretically allow a faster gearing without overloading the motors, so I think it’s a misconception that treads = slow
You just have to adjust the gears accordingly, since the driving gears are smaller than the wheels (Treads also allow a wider range of motor placement)
And according to the Law of Conservation of Energy, they should have more torque than speed if the gearing is the same as the wheels (Unless it is lost by being converted into Thermal Enrgy, which I highly doubt they all convert to thermal)
I may need to do more research, so don’t completely trust what i have said
Unless you have a better reason to go with treads, it would be better to go with wheels. They help with the stability factor of the robot, and in a game such as ftc this year, stability is HUGE. We used treads and although we were able to move around the field, i regret using treads, the stability was horrible and the robot was very shaky due to the “links” in the treads. Then, our treads actually came undone. That’ll never happen to wheels.
Treads are great for manipulators and etc. but as for drive train, treads aren’t the best thing in the world.
I disagree sunny, we used treads last year. We had no stability problems, no shaking problems, and we ended up ranked 5th at Worlds. If your treads came undone then you didn’t have them on correctly, they are hard enough to get apart in the first place. As for shaking, we only experienced this this year when we tried to put some traction links in. Also as far as stability goes the treads are great, I did more wheelies with wheels than treads.
What are the benefits for treads? I’ve seen a lot of reasons to use wheels, but none to use treads.
The ability to get up on objects would probably be one of them.
Well, the problem with PRHS’s tread drive was tht it didn’t have a lot of contact with the floor, and it had a large bump near the middle of the drive system tht caused the robot to lean forward or backward depending on the location of its arm
The traction link ratio also needed some adjustments
Too much traction links will cause the robot to be harder to maneuver, and will require you to align them properly before the match (so u don’t go left, right, left, right, … due to the traction links on each side hitting the ground at different times)
With the stability issue, u should have the base more solid, with the treads being at the exact mirrored location of the other and make sure that all links are attached properly to each consecutive link
the problem may have been because the arm was too heavy as well
Think about the center of gravity, as mentioned in the “Structure” section of the Vex Manual
It must’ve been the traction links. But, I really don’t see any benefit of treads. Our traction links were spaced properly to allow for great turning, that was the first thing we needed to test before we even went with treads.
If you didn’t notice, but our wheel base was larger than simply the treads, ;). And, yes, the robot was EXTREMELY heavy. It would’ve been heavier if I hadn’t convinced one of the guys to take out a counterweight in the back.
Maybe taking out the counter weight was the problem
You guys put it on to balance it out in the first place, right?
Also, I do not think that “heavy” is always a negative thing, unless it’s really an extreme