Are any teams planning on shooting the ball?

[Guy Davidson]

Originally Posted by Qbranch

FYI I used a little calculus to figure out a way to calculate trajectories. If you know how far down range and how far up you want the apex of the ball will be, my equations will tell you how fast and at what angle you have to shoot the ball. If you all are interested, I'll post a scan of my piece of notebook paper.

-q

I'd be interested in seeing those equations. Math is always fun, especially when it's useful.

[Tytus Gerrish]

Originally Posted by cgredalertcc

We are capturing the ball using a vacuum lifting the ball so that our arm is slightly below the rack and firing the ball over using two back to back 3/4 inch bore by 10 inch stroke cylinders we've had success with shorter stroke but we want to be sure we get it over so we opted for the longest ones. The funny thing is the 3/4's extend way faster than the 1&1/2's and the ball really doesn't require that kind of force so we get a pretty good shot out of it.

Please elaborate on your vacuum.
Are you pulling a vacuum inside the air cylinder by extending it, then plugging the compressed end, and then cocking the piston my some mechanical means?

[cgredalertcc]

we are generating a vacuum by the same means a shop vac would. We have been able to generate a vacuum of 26 inches of water using a multistage fan with the Fischer Price minus the gearbox. The conversion factor for vacuum is about 24 inches to 1 psi and based on the area of the cup we are using thats over 100 lbs of force on the ball. The rules specifically state that vacuums of this nature are permitted. I guess I wasn't clear in my explanation the cylinders are only for shooting the ball not pulling a vacuum. As of last night we decided to use three of the 3/4' bore cylinders to fire the ball.

[Furrah!!]

our team has decided to go with a "flinging plank" powered by surgical tubing. Our test have it flinging the ball around 8-10 feet in the air. We plan on using the momentum of the robot moving forward to create out trajectory. This launcher can also place the ball for end game consistently.

[Asiatique296]

Oui. L'équipe 296 de Montreal est entrain de fabriquer une catapulte pour lancer la balle par dessus la barre. On a deja lancé 9 pieds dans l'air plusieurs fois.
Les photos seront disponibles plus tard, car notre catapulte est top secret.




(Sorry about the french but i had to prove my Quebecness to my teammates. I know, its a horrible excuse, but it all makes sense to me.)

[Qbranch]

Originally Posted by sumadin

I'd be interested in seeing those equations. Math is always fun, especially when it's useful.

Ok, here's the (now well worn) piece of notebook paper that I did it on it Economics. Let's face it, the opportunity costs of doing it were very friendly since everyone can use a review of their calculus.

I'm sorry it's kind of hard to read in places, as i mentioned before it's not in the best shape anymore (has a few holes in it from folding/unfolding while we were designing our shooter). But, these equations have been empirically validated as accurate, so here you are. I know it got cut off but the top says "g should be put in negative" but you can see that in the test case down below anyhow.

Thankfully, the two really really important equations are clear and pretty easy to read Lymax is the Y location at which the trajectory peaks. Lx@ymax is the X location (how far down range) at which this Y peak (maximum height) occurs. The "test case" in the bottom 1/3 of the page shows an example using these equations.

If you have questions, please post. I realize it's hard to read, but it's also thankfully pretty high resolution, so just zoom in.

Click here to see the page (768k, png)

-q

[EZE115]

We Are and it works MUHAHAHA

[Captain Sugar]

Our launcher is spring-loaded and can fire the ball upwards about 8 feet. This is after 3 other failed designs ("Wow! We got nearly a foot that run!").

[Kevin.Core]

our primary focus is to make it around the field rather quickly while reserving the capability of lifting, and hurdling. A quick picture is posted in our showcase thread here. Should be a great game this year!

good luck!!

[Chaos in a Can]

We have a motor powered launcher.
It's basically one of the ever popular chain-driven elevated arms, but on steriods. And those steroid... they're on steroids too.

Due to what I'm assuming was a lack of decent squishy objects, our catapult's positive stop is currently cushioned with pink pencil erasers and duct tape.

During testing today, we could consistenly put the ball ~2 feet over the overpass.

[TheNotoriousKid]

I see every team at the "finish lines" crankin up a catapult to launch a 7.3lbs ball, and it actually scares me.

[ChrisMcK2186]

Our ball recently got rabies, so I have to take it out back and shoot it


He don't actually plan to hurdle it, but our "manipulator type thingy" will make the ball pop up at some point in the game.

Chris McKenzie
2186

[martin417]

We are also using a vacuum manipulator to control the ball, and Bimba cylinders to shoot. We have found several important things:

Leave the vacuum on to shoot, you get better distance (if your cylinders can overcome the vacuum)

Ball inflation makes a huge difference in ball travel! Soft balls don't shoot very well!

[feliks_rosenber]

To all the teams which plan on shooting the ball:

Team 2669 KY Bots from Kiryat Yam, Israel has prepared a simple presentation with suggestions from FIRST on how to insure safety when building a launching mechanism.

It is called "Safe Shooter"

You can download the presentation from here:

http://www.chiefdelphi.com/media/papers/2082

And remember, safety FIRST!

[AHepperla]

our initial design went bust so we are now lifting it and then launching it (our initial design would've flipped the robot...)