pic: Team 846 Presents: Funk Cannon

[the.miler]

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[Stephen.Yanczura]

Nice machine! You'll do well.

I like how the intake keeps the ball in control until just before you fire the shooter; a small detail that will save you headaches during bouts of defense on the field.

What has your experience been with those 'W' tread wheels? How long do they last you?

[cmrnpizzo14]

Another fabulous intake system from you guys. Do you have active control of the ball at all times when its in the robot? That's how it appears to me but I'm not quite sure.

Good luck this season, I hope you can get that regional win this year!

[Tom Bottiglieri]

Sky restraining order.

Nice.

[Chinmay]

Great robot this year! Best of luck this coming week. I know that as soon as the competition bot is updated with the changes on the practice robot you guys will be a force to be reckoned with.

On a side note, I think this is one of the few years that I agree with the voice to use omni wheels. I'd love to see a defender try and pin you guys without you just spinning out of it

What's the final weight? Also, can you describe the mechanism that pulls back the shooter? I would love to know more about it

[nuclearnerd]

Assuming your video isn't just showing us the good shots, and your shooter is consistent, it looks like you've got a nearly perfect bot there! Can you share how you choke the power & angle to get your short shot?

[xSAWxBLADEx]

All I can think about when I see this video is "wow, I wish michigan had that weather right now..." On a side note, beautiful weath...I mean robot!

[xXhunter47Xx]

Tell me more about that drivetrain, looks like you have the outer wheels as omnis for less turning scrub but the center wheel for traction to avoid being pushed around. Very cool bot.

Amazing machine from 846. Can't wait to see y'all compete.

On a side note, am I correct when I see no Jaguars on your robot this year? Have you moved on from CAN and have joined the PWM world?

[Chinmay]

Alright, So while the team is flying to Ohio, I'll do my best to answer some questions. They can fill in the gaps later

What has your experience been with those 'W' tread wheels? How long do they last you?

no clue, but they can easily be changed out and they cost next to nothing

Do you have active control of the ball at all times when its in the robot?

Do you see the little pancake cylinders in the video? those have control of the ball once its inside the robot.

Can you share how you choke the power & angle to get your short shot?

There is a two-position latch, one for long and the other for short shots. Die springs absorb residual energy. I'm sure someone can post a closer picture later

Tell me more about that drivetrain, looks like you have the outer wheels as omnis for less turning scrub but the center wheel for traction to avoid being pushed around.

6-wheel drive (no center drop for stability) “Funky Drive” has a few advantages for this robot over a six wheel drop center. Early in the season, the decision was made to not have a dropped center wheel so that when the robot shoots, there isn't a rocking. To also make it easy to turn, there are 4 omni-wheels on the corners. This also has a convenient benefit of making it easy to get out of pins.

To answer a few of my own questions (now that I know some more)
Final weight is 99 pounds. I dont understand the details of the mechanism for retracting the springs well enough to describe it, but it is cool...

[Jean Tenca]

Man I love the detail work on this robot. Functionally, it's very similar to my team's robot (4488) but I like some of the different approaches you had to the same problem. I have to mention that your choo choo design and 2 level shooting mechanism are beautiful. It made me smile and forward this to my team to admire (and learn from). Best of luck to you guys!

[RKIyer]

Originally Posted by Stephen.Yanczura

What has your experience been with those 'W' tread wheels? How long do they last you?

The "W" Tread wheels have worked well on our practice bot so far. We have seen some gradual wear of the outer "spikes" however, through the course of driving for about 4 weeks.

[raphaelchang]

All right, sorry for the late replies; we started traveling this morning and are at last happily situated in our hotel right now. Thanks for all your kind words, we love Funk Cannon and are excited to put her to the test on the field tomorrow. To add on to what Chinmay's said already:

Originally Posted by Stephen.Yanczura

What has your experience been with those 'W' tread wheels? How long do they last you?

The 'W' pattern Versawheels wear quickly, but at a $5 per unit price we are very satisfied with them. With our drivetrain setup, it's a quick swap to get fresh ones on. I anticipate going through a set of center wheels once per event.

Originally Posted by cmrnpizzo14

Another fabulous intake system from you guys. Do you have active control of the ball at all times when its in the robot? That's how it appears to me but I'm not quite sure.

Good luck this season, I hope you can get that regional win this year!

Thank you. The mecanums were something we prototyped early in the season, and it was very satisfying to see them work so effectively on Funk Cannon. The collector does not have active control of the ball once it is in the shooter cradle, but we can easily dump the ball out the other side by reversing the reload motors, satisfying our design requirement that we must always be able to get the ball out of the robot for assists and the 1 pt. goal.

Originally Posted by Tom Bottiglieri

Sky restraining order.

Nice.

We love Skystalker, it's a great bot.

Originally Posted by nuclearnerd

Can you share how you choke the power & angle to get your short shot?

In the detailed design phase, we started by finding a torque profile on our spring/shooter arm geometry that would allow us to have a lower energy, higher angle shot as well as a higher energy, lower angle shot. This necessitated the usage of compression springs rather than constant force springs, torsion springs, etc. Then, we went about figuring out how to stop the arms early so we could get the required lower energy.

At the 17 second mark of our video (http://youtu.be/92IbHU0Z76I?t=17s), you can see the little latches that fall into place next to a slotted tube. A little aluminum piece, with two pegs that stick out of the slots, is attached to a threaded rod that the shooter arms drag back and forth when reloading and shooting as shown at the 24 second mark (http://youtu.be/92IbHU0Z76I?t=24s).

When we fire the short shot, the pegs hit our deployed latches, limiting the travel of the arms and increasing the angle of the shot. This also limits the change in spring compression, resulting in a lower energy imparted on the ball.

When we fire the long shot, the latches are retracted, and the pegs instead hit the end of the slots in the tube. More energy is released and the ball leaves at a lower angle for the longer range shot.

In both cases, when the pegs are stopped, the threaded rod will want to keep pulling through, compressing die springs that absorb the remaining energy, allowing us to safely perform our shots as well as dry fire.

After Buckeye I can post some close up pictures of the mechanism, if anyone is interested. Just let me know.

Originally Posted by xXhunter47Xx

Tell me more about that drivetrain, looks like you have the outer wheels as omnis for less turning scrub but the center wheel for traction to avoid being pushed around.

In order to ensure repeatability of our shot, especially on the fly, we did not desire to have rock in our drivetrain. This led to the decision to put at least a pair of omniwheels on our robot. Additionally, we required that our robot's driving characteristics remain the same going forwards and backwards, as we drive in both directions often. This almost resulted in a 4 omniwheel drive, but we wanted something a bit easier to handle, hence the center wheel.

I won't say we avoid getting pushed around. It doesn't matter as long as we're in range to make the shot. More important to us is that we're slippery; as Chinmay mentioned before, I think it'll be hard to pin us down, as we'll just spin out of it and continue on our way. Of course, that's only what I know from the robots we've practiced against. Maybe Buckeye will prove me wrong; we'll see.

[the.miler]

Also the reloading mechanism is a crank, JVN style, with some optimization. We also added a slot so that when the shooter arms have been stopped early for the short shot, we can still continue cranking until we pull the shooter arms out from under the short shot hooks so we can disengage them and choose which shot we want to do next.

In order to get a large reduction conveniently, since our required torque is fairly large, we use a worm gear setup. This has the added benefit of no backdriving and allowing us to go in either direction without worries.

Originally Posted by Andrew Lawrence

On a side note, am I correct when I see no Jaguars on your robot this year? Have you moved on from CAN and have joined the PWM world?

We did join the PWM world and are thus far happy with it, even though we can't get current readings and the benefits of cleaner wiring as easily. If a better solution appears, we will be happy to continue exploring CAN and Jaguars.

[the.miler]

We generally played well at Buckeye, ending the qualification rounds as the 4th seed. We were selected to play in the #1 alliance by 910, and managed to pick up 639 to create the awesome Buckeye Regional winning alliance. #redfunkyfreeze

Here's a highlight video: http://youtu.be/-FytjA6-5Bc

Best moment is at 2:12 with an awesome bank shot that made it into the goal. Sweet spot shots are good.

We've made a few adjustments to our robot since Buckeye to shoot balls of different inflations more consistently, as well as improve human loading. Hope to see it pan out well at SVR.

Also, we never replaced the Versawheels. They wore quite a bit, but our driver liked drifting a little bit. As long as the drift remains controllable, we'll keep it. VEXPro Omniwheels also held up well.