967 Off Season Project

Team 967 has been working very hard on a prototype and will be posting teasers of our new drivetrain over the next few weeks. The sheet metal frame is all CNC laser cut by a local manufacturing company, DAD Manufacturing, with parts donated by Master Tool Mfg. We hope to be able to take this drive along with an improved gatherer and shooter to off season events this year. And for all wondering, this is not just an ordinary 8 wheel. Any guesses are welcome.
#1:

I imagine that there is more than meets the eye with this chassis besides it being an 8 wheel, 4 center IFI w/ Blue Nitrile and 4 outer omnis? I don’t see much for shifting, though I don’t have much experience with custom shifters. (Only have experience with AM Supers)
I see a rectangular hole in the back that I’m going to say is for a battery. And given there are no openings in your chassis, I’d say that you’re designing an over the bumper collection system.

Anyways, that CNC laser job looks amazing! Competing against the Iron Lions is always a pleasure, and I look forward to next year! Perhaps we can help you scout again? (Well, more you helping us! :D)

Looks more like AM Performance wheels w/ Blue Nitrile.

Ah. My bad.

It has drop down casters/omnis in the back. Though with that setup, it would seem as though the robot would be lifted onto the casters/omnis in the back and the front omni wheels. Which would mean you could very easily be pushed.

The cutout in the belly pan could be for a balancing mechanism like a stinger.

No, it is too big. Actually you can see a drop down caster/omni assembly on the wildstang iteration thread.

http://www.chiefdelphi.com/forums/showthread.php?threadid=105969

This is some really solid sheetmetal work. Looks beautiful.

What is the drop on the center set of wheels? What reduction are you running in that gearbox and the overall reduction?

Looks great! I think you could simplify the frame rails and bit for easier assembly but other than that this is great.

Awesome drivetrain. What software are you using? What is the best way to model the cutout pattern and have it stop at a specified edge on the bellypan?

I’m not sure what they do, but it works pretty well to make an oversize diamond pattern and then just use an extrusion to make the border of the sheet. The same applies to the cutout or any electronics mounting you might add.

whistles

That is a really nice chassis! Can’t wait to see the final!

Thanks! The gearbox is 50:12, and the chains are 32:16. The axles are all level, but the omni wheel radius is around 0.10" smaller than the performance wheels with nitrile tread.

Assembly wasn’t too bad, but next time we’ll give ourselves some breathing room in certain places to make it easier (reducing time spent grinding…). What would you simplify on the side rails?

This is done in Inventor. Making the diamond pattern basically involves doing the math to figure out exactly how big the diamond needs to be in each direction, depending on the number of diamonds you want and the desired thickness of the material between the holes. I don’t know exactly what our student did in this one, but I’ve just made a couple of diamonds in a sketch, patterned them all the way out in two directions, then cut them all at once. Gray Adams’ suggestion sounds good, because it would save you from having to cut the diamonds on the edges in half.

While I disagree with a few of the detailed decisions in this, I can’t question the quality or the work ethic that brought this to existence. It’s this kind of detailed and quality work in the offseason that will bring your team to the top level.

I love the bellypan, in the future I would try to add material to the bellypan specifically for electronics; it forces a clean layout and lets you mount electronics with the minimal amount of weight.

I think switching to a 2-stage gearbox, then directly driving one of those wheels would clean up the assembly and increase reliability substantially.

The webb of the diamond pattern could be decreased for maximum weight efficiency, but probably isn’t too heavy now.

What is the weight of the two outer “rails”? Seems like a lot of material in there that could be pocketed out, especially with the reinforcement bumpers provide.

Why Omni on the outside, you could easily do traction without sacrificing turning speed or ability.

Overall I like it though, it definitely looks robust and quality. Don’t take my questions negatively, I just hold drive trains to a ridiculous standard.

What do you mean by this? Specific mounting holes for mounting jaguars, the pdb, etc.?

Thanks for the great reply.

I believe the outer rails are 2.25-2.5 lbs each, based on a pretty similar model that I have on my home PC. Agreed, some pocketing on those would be a good next step.

2 stage + direct drive would be smart, no doubt. We liked one stage because it is so light and simple, it puts the CIM motors a little lower, and it puts the weight right in the middle of the robot. We aren’t locked into a particular gearbox, though. Two speed is also an option that we will consider. We’ll try to drive this thing hard and see if we can break chains with it, and that might influence the direction we go.

There is a good reason for the omni wheels, but let me wait until the students put out their other teaser. You will probably see what we did from looking at that. We stole that wheel arrangment idea from Team Titanium, by the way. Their 2011 bot has a 2 speed 4WD with four unpowered omnis on the corners. It’s a cool drive.

A wild guess:
A wheel may be dropped through the hole on the frame, tilting the robot on the omni wheels. The dropped wheel is powered and lets the robot strafe.

I didn’t think someone would guess the drive correctly this fast. Good guess! Here is a link to a video of an earlier version of this drivetrain. http://www.youtube.com/watch?v=X5rNaMhytZQ
We’ll get our CAD model, pictures, and a video of the finished drive posted sometime early next week.

Very cool. Why not 3 traction wheels per side though, and the omnis at the other end from the drop down wheel?

Seriously this is cool. It would be such a pan trying to T-bone you.

i know you guys are still working on it, but how much does it weigh?