Wildstang 2012: After The Game

[Starke]

Thanks to Wildstang for posting these videos! It is great to see teams accepting the challenges put on by JVN and others. The FIRST community will only benefit from learning about how you came up with your designs, what worked, did not work, and would be changed for the future. I will definitely share these videos with my team. Thanks for sharing these wonderful resources!

- Matt

[HD]

Excellent job with the editing Steve! First time I've actually seen most of these since filming.

Originally Posted by sentientfungus

I just have a small question about those drive modules-- how do you assemble everything within them? Like, do you put all the chains and stuff together and then put it into the frame and the stick the axles through (excuse my rough description)? Or is there some other method that you use?

We had to assemble each bearing block around the main extrusion. When all of the mounting hardware is removed, the bearings are actually the only thing holding the carriages onto the extrusions. Then we put in everything else (axles/sprockets, gearbox output shaft), and then put the chain on. Gearbox was last. This is probably not the most efficient way to do it. These were inspired by our 2011 modules, but those were much easier to assemble because those bearing slots in the extrusion were cut out all the way to the ends so we could pre-assemble each bearing block. We changed that on the 2012 iteration to give the frame a bit more of a solid mounting point as the modules were part of the frame this year.

Originally Posted by JVN

Who is the gentleman doing most of the talking in these clips? I don't think I've met him before.

That would be me.

[SteveGarward]

Thanks everyone for the feedback.

Let me try address all the questions/comments in the posts...

Originally Posted by AllenGregoryIV

So many times it seems like the power house teams just know how to do it right because we don't see all the iterations that happen in the background.

As with anything, there is a lot to be said for experience in knowing where to start, but there is also a lot (possibly more) to be said for the experience in being able to iterate quickly, identify problems, and be confident with change.

Originally Posted by IKE

I really love in the chassis section the slow motion turning hop. This is a great way to document the pros/cons of descisions made during the season.

The high-speed (from a point & shoot) helped out a number of times through the season. Even though the design was done at that point, it allowed us to react to the issues we were seeing ahead of time, rather than see what happened on the field if we left it as it.

Originally Posted by apalrd

I really liked how you talked a lot about the failures of the initial designs, and your solutions to all of them. It really shows that you have to continually redesign and fix the weak points of any robot to stay on top in FRC.

We took continuous improvement to the extreme this year

Originally Posted by Samwaldo

This really taught me that you shouldn't be afraid to completely change a design in the robot, at any moment.

Continuing from the last point.. No, don't be afraid, but make sure it is a very carefully considered change, and one within your means/abilities. If you've spent 6 weeks designing and building your robot, make sure that change is the right change to make!

Originally Posted by ZipTie3182

As a few said before, it really is incredible to see how drastically your design changed - especially before champs! Wow!

Champs alone would be a whole extra video ...

Originally Posted by JVN

It is great that you guys decided to put them together, and even better than you decided to share with the community.

Originally Posted by Starke

It is great to see teams accepting the challenges put on by JVN and others. The FIRST community will only benefit from learning about how you came up with your designs, what worked, did not work, and would be changed for the future.

While I wasn't thinking of the challenge when doing this, I would love to see more teams do this in the future. Any team! Apart from thinking back on the season, these aren't much more than what you'd get if you talked to us in the pits. But, it's now available to everyone. I didn't really get to see anyone in the pits this year, and would love to see in detail what some other teams did.

[Rob Stehlik]

Thank you for spending the time to put together these videos. I love seeing the details in the design of successful robots.
I thought the lexan mounts on your first intake roller were brilliant. Allowing it to flex on impact makes a lot more sense than trying to make it strong enough not to break.
The drive modules are pretty cool too. The wrap around bearing mounts look like a good way to accomplish adjustable center distance chain tensioning. Were they made out of C channel or a piece of rectangular extrusion? What are the advantages of enclosing the chains? We built a belt drive in the off season with belts inside a square tube, and it made things pretty challenging to assemble and repair.
The drop down landing gear seemed like a great way to get over the barrier. Between the landing gear and the wedge you built for championships, which one do you think was more effective?

[Ether]

Hi Steve,

Thanks for posting these. I took a look at the #6 video (shooter), and several questions came to mind, if you'd be willing to share some more detail:

- with the 7:1 speed reduction and the 550's free speed of 19300 rpm, the top speed of your wheel would be somewhere around 2700 rpm (neglecting gear losses). What was your operating speed for shooting?

- what kind of speed control algorithm did you use? e.g. PID, bang-bang, voltage compensated open-loop, etc

- how long was your spin-up time from 0 rpm to operating speed?

- did you keep your wheel spinning continuously during the entire match, or did you spin it up when ready to shoot?

- what were your two launch angles?

- did you measure your actual launch speed?

[SteveGarward]

Let me try answer some of these..

Originally Posted by Ether

with the 7:1 speed reduction and the 550's free speed of 19300 rpm, the top speed of your wheel would be somewhere around 2700 rpm (neglecting gear losses). What was your operating speed for shooting?

Let me check if we did an accurate measurement or not.

Originally Posted by Ether

what kind of speed control algorithm did you use? e.g. PID, bang-bang, voltage compensated open-loop, etc

If I remember right, for the first shooter it was a manual adjustment through a potentiometer on the OI to adjust speed/voltage directly. In testing we found our happy place for values and would adjust to those. This also let us vary it slightly if we needed to. For the new flywheel we used bang-bang.

Originally Posted by Ether

how long was your spin-up time from 0 rpm to operating speed?

Spin-up time was roughly 2 seconds.

Originally Posted by Ether

did you keep your wheel spinning continuously during the entire match, or did you spin it up when ready to shoot?

Let me check on that with our operator tonight. From memory we would spin it up as we were approaching the goals. But, let me double check.

Originally Posted by Ether

what were your two launch angles?

We did not measure them, but I would put them at around 60 and 75-80 degrees. I can do a rough check of this tonight when I am at the workshop.

Originally Posted by Ether

did you measure your actual launch speed?

No.

[BrendanB]

Thank you for making and sharing these videos they are excellent!

[Phyrxes]

Just posted this link in my team's Facebook group, thank you for making them.

[Ether]

Originally Posted by SteveGarward

Let me check on that...

Hi Steve,

Not to bug you but if you found any more info I'm still interested. Thanks.

[ajlapp]

Awesome.

Wildstang is still my favorite team...even after the curtain has been pulled back to reveal that they are not super-human, infallible engineers.

Just really close to it.

[IKE]

What camera did you use for the high speed footage of both the chassis and the shooter? We have been looking for an affordable camera that shoots around 1000 FPS, and your shooter section 3:18 of video 6 seems to be at about that rate.

[Tom Line]

Beautiful videos.

Your unique roller powered by the shooter wheels made me kick myself.

We struggled all year with the differences between new and old balls, because the new ones had much higher friction and would grab our shooter wheels, transferring more momentum and flying much further.

Some teams (bees) structured their tower to have more ball 'wrap'. Low-robots had more wrap by definition: 67 had nearly 180 degrees. We had..... 50 degrees.

Your bottom roller addressed that beautifully (and perhaps without even realizing it?) by giving the ball additional distance to speed up to the shooter's speed.

I learn more in FIRST that I do my day job.

[SteveGarward]

Originally Posted by IKE

What camera did you use for the high speed footage of both the chassis and the shooter? We have been looking for an affordable camera that shoots around 1000 FPS, and your shooter section 3:18 of video 6 seems to be at about that rate.

We used a Canon point-and-shoot that does 240 FPS. I believe is was one of the ELPH HS series.

[Wildcats1378]

Hey great video series guys. It was really informative and well done

I do have one design question though. We struggled last year with a somewhat similar roller system, but we used rubber bands. They would constantly move left and right and get all messed up. What is poly cord and how do you keep them from floating all over the place?

Thanks

[MichaelBick]

Originally Posted by Wildcats1378

Hey great video series guys. It was really informative and well done

I do have one design question though. We struggled last year with a somewhat similar roller system, but we used rubber bands. They would constantly move left and right and get all messed up. What is poly cord and how do you keep them from floating all over the place?

Thanks

Poly cord is sold on mcmaster by the name urethane belt. Some teams use the round belt and some use the flat belt. Basically, you buy the polycord and install by cutting the belting to length(a little short so that you get tension on your belts) and weld the two sides together with heat(we have a polycord welding set, but it's really not needed. I've heard of a flame or a soldering iron working well). Our team used the round belt for 2012. We machined pulleys out of ABS to make sure that the belt wouldn't move. Many other teams have similar or the same way of keeping it in place. I've also heard good things about flat belt from teams like 341. Apparently if you wrap your shafts in electrical tape where you want your belts to stay the belts will actually walk back to their places if they get moved.