01-02-2008 11:16 PM

robostangs548

Re: pic: More CAD insanity

nothing eigh...... we will just have to see We have a little brainstorming cooking up a pretty nice idea, but we will have to see what the game is before we can even start thinking about that

01-02-2008 11:18 PM

robostangs548

Re: pic: More CAD insanity

Oh btw i forgot that is a sweet cad dude, nice job, you have "Chops" lol

01-03-2008 01:50 AM

popo308

Re: pic: More CAD insanity

Add a big sim (assuming its in the KOP) to that gear box so you have 2 small cims, 1 FP, and 1 large cim then i'm positive you will not be pushed around..

01-03-2008 09:41 AM

Peter Matteson

Re: pic: More CAD insanity

This doesn't make sense. You are already overpowered with the 2 small cims and FPs. Once you can slip your wheels adding power won't do anything. I can name a few teams who've learned this the hard way.

01-03-2008 09:47 AM

Richard McClellan

Re: pic: More CAD insanity

Wow, I have to say, that's a sweet design, as is almost everything that you post here. But I'm curious, is there any reason why you don't include the Dewalt gearboxes in any of your designs? It just seems like the weight trade off is too great to pass up.

01-03-2008 11:15 AM

Cory

Re: pic: More CAD insanity

It'd help you in high gear, but that's an awful lot of work and weight for a very very small benefit.

01-03-2008 01:59 PM

alex1699

Re: pic: More CAD insanity

that is SEXY!

01-03-2008 02:37 PM

CraigHickman

Re: pic: More CAD insanity

How about I accept the level of insanity that this design is already? Honestly, I'm of the position that 3 drive motors per gearbox is insane overkill, and is really quite pointless. The two designs that I've posted came from a discussion with a team member. We'll only build something remotely like this if we plan on defensive play.

Most of the time for a drivetrain, my reduction numbers needed for the desired speeds require a custom setup. If it were possible to get a more reasonable ratio out of the deWalt's, I might use them. Plus, I've had good experience with things I've made, and bad with pre made parts (banebots).

01-03-2008 02:52 PM

EricH

Re: pic: More CAD insanity

The ONLY gearbox I know of that had more than 3 motors was 118 last year. That was 6 motors (all the CIMs) for a 2-speed swerve. Most teams count 3 as the max or overkill. (I know 330 has never had more than 2 motors in a gearbox, and for many years only had one.)

And it's not how many motors you have, it's the traction and torque conversion that matters. I know of a case where a 2-motor drive pulled a 4-motor one around (pulling unintentional, the team would have preferred to push).

01-03-2008 03:07 PM

M. Mellott

Re: pic: More CAD insanity

Using the tread modules, it's a simple-yet-solid design...getting into a pushing match against this beast would be ugly! Very nice CAD work to boot!

Could you give us an estimated total weight, as well a mimimal breakdown on the overall weight, meaning 1. Outback tread modules, 2. Gearboxes w/motors, and 3. All other frame members?

01-03-2008 03:09 PM

CraigHickman

Re: pic: More CAD insanity

Previous iterations of the Outback tracks weren't fun to defend against, so I imagine this would be even better.

The track modules are 9 pounds per, including belts, standoffs, and all that. Inner Chassis: Somewhere around 3ish pounds? I forget... The gearboxes are close to 10 with motors.

01-03-2008 10:46 PM

pakratt1991

Re: pic: More CAD insanity

Wow, these are sexy!

I'll say it again that thes tracks never slipped on the carpet and this would only increase the performance.

01-03-2008 11:45 PM

Richard McClellan

Re: pic: More CAD insanity

118 actually called their crazy 6 motor gearbox 'fish and chips' because it had 2 fisher price motors, and 4 small CIMs, all going into one dewalt gearbox (those dewalts can definitely take a beating). They actually still got pushed around with their 4 wheel crab drive system.

I think there's something that makes a 6 wheel drive better than a 4 wheel drive when you look at dynamic events, because assuming you lower the center wheel, 6 wheel kind of seems to "stays on the ground" more frequently, thus the maximum normal force is always applied fairly evenly to each wheel.

01-04-2008 12:08 PM

lukevanoort

Re: pic: More CAD insanity

I think you may be overestimating the traction here; if the tracks don't ever slip then you can''t turn, and even if you could turn (by the frame flexing or something like that), you would draw massive amounts of current. A cim has a stall current of 133 amps and the FP stalls at, IIRC, 63 amps. The largest breaker you can use is 40A and the FP will smoke if run near 40A draw regularly. Now, breakers don't pop instantly, but that is still a bad situation to be in.

Brecoflex themselves actually say that red Linatex has a mu of 1.6, and it is in their interest to report a high number*. 1.6 is very, very high, but many robots can put out enough power (at least for a short time) to make it slip. Roughtop incline conveyor belting has been reported to possess a mu of 1.3, thus, you are getting about 23% more traction than a robot running common materials on a traction wheel. So, the traction is quite high, but definitely not 'unslippable.'


*I am not implying that they Brecoflex is falsifying data, I am merely saying that they wouldn't report a mu lower than it actually is, due to their financial interest in the matter.

01-04-2008 01:42 PM

CraigHickman

Re: pic: More CAD insanity

He was talking about slipping when pushing in a straight line. Of course it's going to slip side to side when turning, the treads have a chamfer cut into them, as well as having massively less resistence when trying to skid steer, due to contact patch shape.

01-04-2008 06:59 PM

pakratt1991

Re: pic: More CAD insanity

That is what I was trying to say, let me elaborate, even when we were pushed backwards, it was not due to the tracks slipping.

One drawback to the track system is they drain A LOT of batteries at a rapid rate.

01-04-2008 08:10 PM

Cory

Re: pic: More CAD insanity

if you got pushed backwards, didn't your tracks have to slip?