Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

wow, now this will make Arkansas regional even more interesting! Can't wait to watch yall drive circles around us and most of the other robots again!:p It really looks great, yall did a really good job this season. How did I know that yall would do a catapult? Gut feeling I guess?

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

This Bomb Squad machine looks to be one of your most competitive yet. Thanks again for the inspiration on the intake, FRC558 is running a polycarbonate armed, motor in roller, intake as well this year.

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

Nice to see another cam based catapult! We came up with a different solution to back driving that you may be interested in: The final 30 degrees of our cam profile is circular, so there is no reaction torque from the catapult springs. Once the cam follower gets to the circular part of the cam, there is no chance of back driving.



As a side note, we built a small cam driven catapult last year for a non FRC project, and experimented with a notch in the cam to prevent back driving. It worked, but we found there to be a large current spike when the motor was trying to get the follower out of the notch.

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

The reliability and repeatability of the cam driven catapult was the deciding factor for us.

We had a similar profile you describe, just not as long on the flat. Hitting that small window right before the roll over was tough. We also like the idea of being mechanically locked in there.

We do get a pretty significant current spike coming out of the notch. I watched our practice bit spike over 60A the other night. It took us several rounds to get the slope flat enough come back out to reliably fire.

Btw, y'all's robot looks very nice again this year. Good luck out there.

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

Please do. Nothing I like more than to geek out over swerve drive for a while.
:D

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

JT was mentioning you guys had some issues with Command Based robot stuff last year, care to elaborate?

And, I'll absolutely come over and geek out. :)

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

We also have Polycarb arms and inserted the motors inside the acquisition tube. I was wondering if anyone else would do this. See ya at QCR!

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

I wouldn't say we had issues, but we definitely didn't use commands this year. They overcomplicated the small tasks and made the more complicated tasks very difficult. Especially where we needed more time resolution than whatever cycle the commands were on. The compile time for that many objects was hard to stomach also.

Our 2013 code is up here if you want to see how we inplemented commands:
https://github.com/FRCTeam16/TMW2013

I guess we are using commands one place this year, dashboard buttons. We have two or three things we need to do infrequently enough that don't need to be accidentally pressed on the joystick. Commands make that very easy.

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

Yeah, the Lexan arms may look floppy and less "industrial" than rigid ones, but there's good reason we've had essentially this in 2008, 2010, 2012, and 2014. I'm beginning to see a pattern...

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

Interestingly, I felt similarly when I tried to use CPP for commands last year. Since switching to Java I found Command base was fairly simple and it meant a good chunk of our code was much cleaner than comparable other methods. I know it has allowed us to iterate our code far faster. I'll have to dig into this code and take a look at your new code at CMP this year.

Of course, my day job is primarily ruby/javascript code so that could explain why CPP felt less intuitive.

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

Could you provide some details about your swerve drive design? Such as wheel size, steering gearing, drive gearing, slip rings, or coaxial.
Our team did independent swerve drive for the first time this year.
Thanks in advance.

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

Just make sure the catapult is disabled before you stick your head in...that thing really scares me!

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

I'll avoid standing on it while it's loaded too. ;)

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

I have pictures. JT better stay clear of safety judges.

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

Our swerve drive uses slip rings mounted at the top and we use 6" AndyMark performance wheels. I have some CAD models of our 2013 drive train if you'd like to see. Our output gear ratio is about 9.5:1 on the drive and for steering we use AM 9015s geared down using Versaplanetaries from VexPro (I'll have to figure out the gearing of that when I go to the shop later today). Here are some pictures of the model for a more visual approach. If you have any other questions, please don't hesitate to ask. Just send me a PM asking for the gear ratios for the steering and I'll try to get them to you as quickly as possible.



-John Taylor Novak