Treads, Tracks, Tank system Talk/Help

[IKE]

I have no robot experience with tank treads, but most tractors used a single powersource into a differential with turning brakes. This is common on wheeled tractors too (they are often called plow brakes). Using the differential and side brakes essentially allows for torque vectoring and keeping from a stall condition. A couple of teams did this style of drive system this year to help with Car-style steering robots. This probably won't help with the side traction hopping, but it may help keep the current loads lower.

[JesseK]

Originally Posted by IKE

I have no robot experience with tank treads, but most tractors used a single powersource into a differential with turning brakes. This is common on wheeled tractors too (they are often called plow brakes). Using the differential and side brakes essentially allows for torque vectoring and keeping from a stall condition. A couple of teams did this style of drive system this year to help with Car-style steering robots. This probably won't help with the side traction hopping, but it may help keep the current loads lower.

I watched a couple of shows on Discovery (one was JYW where their task was to build a tank) and I believe actual tanks used to be built the same way.

An idea I played around in CAD a few months ago took the 6WD rocking-style drive train and converted the front four wheels into tank treads. The design put most of the weight in the back so the 'bot never really rocked forward onto the treads, however the tank treads would greatly improve the ability to climb ramps. Maybe it's worth exploring, maybe not...I didn't have time to fully CAD it out and consider the possibilities.

[AndyB]

You can greatly increase the mobility of the tread system if you decrease the surface contact.

Take team 522 for example. Year after year they produce a successful tread system.

http://www.chiefdelphi.com/media/photos/17294

Their surface contact basically creates a square profile on the ground and allows the robot to turn with more ease.

[Gdeaver]

Thinking about tank treads and other drive configurations is probably a good idea. The past few years many teams have gone to 6 small wheel designs. For the most part the games have been played on flat surfaces. This has not always been true. What would your team do for a drive system if this years game required going up stairs or getting up on a platform?

[Cory]

Originally Posted by Gdeaver

Thinking about tank treads and other drive configurations is probably a good idea. The past few years many teams have gone to 6 small wheel designs. For the most part the games have been played on flat surfaces. This has not always been true. What would your team do for a drive system if this years game required going up stairs or getting up on a platform?

Pull yourself up to it from the floor

[Alan Anderson]

Originally Posted by Gdeaver

What would your team do for a drive system if this years game required going up stairs or getting up on a platform?

I'd suggest triwheels.

But I'm just a programmer, so when it comes to mechanical design I don't get too vocal about my preferences.

[Dick Linn]

Originally Posted by Gdeaver

... What would your team do for a drive system if this years game required going up stairs or getting up on a platform?

We did that once with a 2-wheel-drive setup. It all depends on the specifics.

[=Martin=Taylor=]

Originally Posted by Gdeaver

Thinking about tank treads and other drive configurations is probably a good idea. The past few years many teams have gone to 6 small wheel designs. For the most part the games have been played on flat surfaces. This has not always been true. What would your team do for a drive system if this years game required going up stairs or getting up on a platform?

Has there been a game yet that REQUIRED teams to climb obstacles? Seems a lot of the successful teams from 1999 and 2004 found clever ways to avoid climbing things.

[AndyB]

Originally Posted by Hachiban VIII

Has there been a game yet that REQUIRED teams to climb obstacles? Seems a lot of the successful teams from 1999 and 2004 found clever ways to avoid climbing things.

There have been games with obstacles that needed to be climbed. But I understand what your saying.

But treads, WHEN DONE RIGHT, are a great option for maneuvering up and over obstacles such as steps, ramps, etc...

There is a reason why tanks use treads.

[Andrew Schreiber]

Originally Posted by AndyB

There is a reason why tanks use treads.

Yes, the reason is that they are better at spreading the weight of an 80 ton battle tank when crossing mud.

I won't advise you how to do tank treads because I don't know how, but I will advise you to look to the military and their move away from treads. (run a search on Stryker) Tank treads are great for uneven and shifting terrains but for speed and maneuverability they are not the most effective.

Now, would it be cool to do a tank tread system that could climb a 70 degree incline as a demo? Oh you bet it would be. My best suggestion would be to look at the military tanks and how they work. An interesting thing to do might be to have a way of letting your treads lose friction as they are moving sideways (similar to omni wheels) Might be interesting to make work, dont know how useful it would be though.

Just my (programmer's) $.02

[UndergroundVoid]

I started this thread to help myself and other to improve and create ideas about track systems. Though it seems most here are rather happy to bury them in the ground and call it a night. I admit that a track system may not be the best drive system or easiest to build but that doesn't mean that they wouldn't be as effective to a game as any other drive system. It truly depends on how you build you machines and how you operate it.

To step back to the main part of my project folder which i didn't want to do . Here is the true purpose:
To create a universal framework that can be use for the most of the FIRST drive trains and to be suitable to the challenge.

So in my work I'm at the final part of this which is adapting it to a tank type since the wheeled versions are completed. Though since for track systems i only know a few minor things about I figured I might ask around to team who have tried them to get a better idea. I really don't want to talk about my projects since i filled in the gaps to this point and wanted to keep the thread focused on what i didn't know and what could be done for track systems. The funny thing is i didn't expect it to get unfocused and try to push me away from a track system.

[Mr.Rush]

Image from back in the day

I'm not sure if I can be much help to the cause but our team ran tank track back in the day, though now we are know by those who visit our pit for drum wheels.

Recently two of us attempted to resurrect this robot and learned a little about how the treads worked. It was tensioned with a worm gear, and before the old gear boxes gave way seemed to maneuver fairly well with the tension on the looser side of tight. It wreaked havoc on the breakers though you could year them popping clear across the shop when the tension was too great and it tried to draw more current.

[Alan Anderson]

Originally Posted by UndergroundVoid

Though since for track systems i only know a few minor things about I figured I might ask around to team who have tried them to get a better idea...The funny thing is i didn't expect it to get unfocused and try to push me away from a track system.

You've gotten a pretty consistent answer: the best way to do tank treads is not to do them. It seems that most teams who have tried tracks don't do them anymore. There's probably a good reason for that.

[UndergroundVoid]

Do people fail to see i will not take that answer, i will not quit if i fail the first time, I'll try again until i get it right. I feel that since i put help into the title i would get only help and some talk about track systems. So in my mind i feel that if you going to post anything about going to wheels or saying flat out that tracks should not be used i will close this tread and only communicate to those that have given interesting ideas and help. So help me if enough people do this I'll close the tread and not support the post count that it has generated for you just to try to kill a plausible idea.
People seem to think i know nothing about wheels here or any other type of drive systems, That i may lack the understanding of advantages and disadvantages, that i may not know strategies or something...............................I'm sorry just please for the love of something just help me with my questions and not put some tiny little post saying not to do this. Personally i never said it was for competition, i never said it was for cool factor, i didn't say it was for a lot of thing but people here seem to assume. I don't know what to do anymore i think i have enough to live by that i don't need some people here being bias and persecuting a idea. Man i feel like i might as well be in the past trying to challenge the church or something for wheels.

[Al Skierkiewicz]

Lynx,
You have to remember that the answers you receive here are tempered by our involvement in FIRST robotics competitions. The advice you receive is aimed at those competitions only. The comps are played on carpet which can be an unforgiving surface for tracked vehicles unless a particular game (and strategy) warrants their use. The picture above and the caption explains it pretty well, "It wreaked havoc on the breakers though you could year them popping clear across the shop". In addition, the type of treads used in this picture would not be allowed under 2008 robot rules as no metal can come in contact with the carpet. The only advantage in this picture is the curved ends of the tread cleats. In a turn, these tend to slide across the carpet while giving increased traction in the forward and reverse modes. I will say it again, treads in a turn or six wheels/no steering, create significant electrical loads that can comprimise the control system electrical power source. As such any good strategy would be to avoid, at all costs, mechanical designs that draw excessive currents. There have been (and likely will in the future be) games and strategies that use treads to a advantage. These games will likely involve climbing with little or no turning required.