[FTC]: Tank Treads [Archive]

Gearheads1

18-09-2015, 21:25

We are new to FTC and think that there may be a place for tank treads in this game. Have any FTC teams used tank treads from Tetrix, or do they tear up the field? Thanks in advance for your help.

dcribbs

19-09-2015, 11:49

Some of our teams have used tank treads in the past for various reasons. They do not tear up the field. The robot in the video (https://youtu.be/cjDtaQja2DA) (6635) would shudder a bit when turning due to the tank treads high grip.

The most challenging part is putting the rubber treads in the individual links.

RRLedford

19-09-2015, 18:23

In six years of FTC we have never done a treaded tank drive design before.
We have done 4-wheel omni, 3-wheel omni with triple-wheeled axles (Kiwi), and mecanum wheels twice, so we are not afraid to experiment with different drive types that best match up with the game.

We are this year still considering a customized treaded tank drive with cleats added on to snag the bars. The issue is with ;atera; swing friction. when turning

As far as the TETRIX plastic tread, goes I would not trust it under high loads, especially lateral loads.

My current thinking is to Have a very light bot and consider using a narrow ~1" timing belt driving a pair of close axle spacing inboard wheels on each side, and have omni wheels sandwiched on either side of the belts at front and rear, to reduce the turning drag,
With just the right amount of center drop on the central wheels, this could improve turning while allowing bot to roll along mostly up on the tops of the bars.

-Dick Ledford

cadandcookies

19-09-2015, 19:02

As far as the TETRIX plastic tread, goes I would not trust it under high loads, especially lateral loads.

Generally treaded drives have to be protected from lateral loads-- Tetrix treads are the same way, with the added restriction that they're pretty light duty.

If you're still interested in a treaded robot but don't want the difficulties of a fully treaded robot, you could try making a half-treaded robot-- ie, an 8-inch contact patch in the back of your robot and some omni wheels in the front.

I would also recommend looking at FTC 5975's Treadpods (http://5975cybots.weebly.com/treadpods.html) from last year. I was judging at North Super Regional last season and these were easily the coolest things I saw there.

Munchskull

20-09-2015, 22:17

Could you use a double sided timing belt for tank treads?

cadandcookies

20-09-2015, 22:56

Could you use a double sided timing belt for tank treads?

Or just single sided. In 2012 FRC 1816 did this with their robot, Zephyr. You could almost certainly get away with something similar on an FTC robot.

Greg Needel

21-09-2015, 01:44

Could you use a double sided timing belt for tank treads?

This is one of the things that we we are playing with also.

Gearheads1

21-09-2015, 09:18

Thanks for the great discussion! It's nice to have options! Best wishes for a great season!

Munchskull

21-09-2015, 14:37

Where can you buy doubles sided time belts for cheap?
Also what would be the recommendation for the with?

cadandcookies

21-09-2015, 14:45

Where can you buy doubles sided time belts for cheap?
Also what would be the recommendation for the with?

SDP-SI sells double sided timing belts in metric and imperial sizes (http://www.sdp-si.com/eStore/Catalog#). I would recommend metric, as you'll have more choices. You're looking under Timing Belts.

I'm looking at maybe doubling up 9mm belts, but you could also try 15mm or something thinner. You're looking at $20-$100 per tread depending on width and length of the belt.

Gdeaver

22-09-2015, 08:36

Monday night we took our summer practice bot and put some Tetrix tank treads on it. It was an ugly violent climb up the mountain but it did work. Need to make several geometry changes. Robot drives terrible on the floor. Good night in proof of concept but, a long way to go.
http://wiki.team1640.com/index.php?title=File:FTC7314_150921a.jpg

DavisDad

22-09-2015, 12:07

Monday night we took our summer practice bot and put some Tetrix tank treads on it...
http://wiki.team1640.com/index.php?title=File:FTC7314_150921a.jpg

Thanks for sharing your work, and the photo!

Sasha

22-09-2015, 18:02

We also put some tetrix tread on the robot. It climbed the inclined surface OK; didn't have time for test driving on the floor yet. Will test more next time. Meanwhile, here is the photo:
https://www.facebook.com/islandbots/photos/a.676200265735724.1073741829.676056399083444/967147859974295/?type=1&theater

Munchskull

23-09-2015, 00:45

Coach Seb

07-10-2015, 09:45

So any update on using the Tetrix tank treads ? We got our first prototype last night and because we did not have the rubber insert, we could not climb the ramp... just placed the order today and hopefully it will help !

https://www.facebook.com/groups/1433498156943429/1503782546581656/?notif_t=group_activity

Coach Seb
FTC 9819 RoboRats

DavisDad

07-10-2015, 11:00

SDP-SI sells double sided timing belts in metric and imperial sizes (http://www.sdp-si.com/eStore/Catalog#). I would recommend metric, as you'll have more choices. You're looking under Timing Belts.

I'm looking at maybe doubling up 9mm belts, but you could also try 15mm or something thinner. You're looking at $20-$100 per tread depending on width and length of the belt.

Here's a nice tool for sizing belts and pulleys: B&B Manufacturing Belt Calculator (http://www.bbman.com/catalog/belt-length-calculator.html)

cadandcookies

07-10-2015, 13:32

Here's a nice tool for sizing belts and pulleys: B&B Manufacturing Belt Calculator (http://www.bbman.com/catalog/belt-length-calculator.html)

That's a nice one. My favorite is the SDP-SI one (http://sdp-si.com/estore/centerdistancedesigner). Just another option.

polytechnique

12-10-2015, 17:29

My team has had poor experience with tank treads in the past. We've had issues with the treads coming apart or slipping off the wheels and pulleys due to contact from the side, resulting in a torquing motion.

Just to serve as word of caution, speaking from experience. They tend to be a hassle and result in a lot of pinched fingers.

DavisDad

14-10-2015, 05:58

I found some interesting videos for various climbing robots with treads and wheel designs:

Search YouTube: "asme robot competition" (https://www.youtube.com/results?search_query=ASME+Robot+Competition)