View Full Version : Are any teams planning on shooting the ball?
And by shooting I mean launching/ catapulting/ flinging/ popping/ flipping etc...
please share!!! I'm sure this has come across every FIRSTers mind at least once when brainstorming!
I hope someone is, that would be really cool to see.
Brandon Holley
16-01-2008, 18:37
yup.
We've been developing a primitive gas-spring powered catapult, and so far....it's smashed into the floor and broken, catapulting the ball about 4-feet vertically and 12 feet horizontally. The main issue is the momentum a catapult generates. It's enough to flip the robot forward unless you have some sort of wheelie bar.
The second issue is loading. We're thinking of a crude gripper to load the main launcher, and then a complicated lever system will amplify the force of a 250 ft-lbs. gas spring to launch the thing.
ScottieDo555
16-01-2008, 19:04
We've been developing a primitive gas-spring powered catapult, and so far....it's smashed into the floor and broken, catapulting the ball about 4-feet vertically and 12 feet horizontally. The main issue is the momentum a catapult generates. It's enough to flip the robot forward unless you have some sort of wheelie bar.
The second issue is loading. We're thinking of a crude gripper to load the main launcher, and then a complicated lever system will amplify the force of a 250 ft-lbs. gas spring to launch the thing.
good luck to you!
I have sufficient doubts that a team will find a safe, reliable way to hurdle the ball, but if a team does, they will probably be a strong contender.
Paul Copioli
16-01-2008, 19:29
I have sufficient doubts that a team will find a safe, reliable way to hurdle the ball,
I'll take that bet ....
BTW, the amount of torque that is needed for a 1 meter arm to catapult the ball over the overpass with sufficient margin is 330 Newton-meters ... incase you were wondering.
Padre_Vez
16-01-2008, 19:43
Can you put that in simple terms for we the stupid people?
can we get a video of this thing?
:D
i don't want to say too much, but pnumaticly speaking, it is possible to launch the ball, i am not sayingmy team is using a device like that, but i put in some sceintific formulas and found out that it is possible to do this challenge
We're going to hurdle, but we're not launching.
impossiblePossible. Maybe not practical, but impossible and impractical are two different things.
Oh, and the classic means of getting something "impossible" to work is now in effect. You say, impossible. The engineers say, how do we make it possible. Then they go put that plan into action. You eventually wind up agreeing that is totally possible--because they did it.:D
That said, my team is not attempting a launch. We are attempting a hurdle.
Tim Arnold
16-01-2008, 21:30
Yessir, I'll take that bet.
We are, as some of you remember from our 2006 (http://www.chiefdelphi.com/media/photos/22906), the catapult team.
P.S. Its really, really ridiculously fast.
=Martin=Taylor=
16-01-2008, 21:51
If by shooting you mean with a gun... than yes! We will have a small revolver mounted somewhere on the robot to pop the other alliances track-balls! :D
:D Hellooooo from the the North East
We at Team 88 TJ2 WILL try a hurdle (or are working on it ) ??????
Seeee Yaaaaaa Soooooon
MOE:yikes:
Tim,
Gambling already?:confused:
This is only week 2. I need a ham sandwich.:)
:yikes: HELLOOOooo from the North East
We at TJ2 only have 2 weeks left this will give us time to drive the wheels off TJ2. ( FAST baby FAST) SEEEEEE You Soooooooon !
oh yeah? OH YEAH !!!!!!!
MOE and TJ2:D
grantman54
16-01-2008, 23:04
we have some very impressive results for our launcher. :yikes: look forward to some videos in coming weeks
65_Xero_Huskie
16-01-2008, 23:28
I'll take that bet ....
BTW, the amount of torque that is needed for a 1 meter arm to catapult the ball over the overpass with sufficient margin is 330 Newton-meters ... incase you were wondering.
Hehe, Copioli is my hero (Next to Ken ofcourse)
Im sure team will start posting videos and pictures of their robots in a few wwek, everyone should be patient and wait to see the balls fly..or thrown or pushed..etc. :yikes:
Lions for First
17-01-2008, 00:20
330 Newton-meters :eek: thats 243.39551793777 foot-LBS how is it possible to do that with FIRST parts :ahh:
MrForbes
17-01-2008, 00:31
what are these newton meters that you speak of?
how about 200 ft lbs on a 2 foot arm?
Lions for First
17-01-2008, 00:38
thats a good idea thanks
P.S. squirrel, we saw your team at the FTC (congrats on makeing it to the finals) and that was an very good robot, and every time my team sees your team we bring it up (in fear)
Daniel Bathgate
17-01-2008, 00:50
For a while we were designing a robot that would use a massive spring to throw the ball over... but decided that we like our team members as they are, with limbs. We decided it was simply far too dangerous to continue.
some team will launch it i guarantee you that!
Maggie27
17-01-2008, 09:19
For a while we were designing a robot that would use a massive spring to throw the ball over... but decided that we like our team members as they are, with limbs. We decided it was simply far too dangerous to continue.
That's EXACTLY what we decided. Hahaha
wait I thought that <r23423a> prevented us from picking up the ball?
CodyJ543
17-01-2008, 10:55
At this point we are planning on using a sort of forklift catapult combo. But from our tests it takes a quite a bit of timing and power to launch those huge trackballs...
Andrew Schreiber
17-01-2008, 11:15
I garuntee you that some people's first thought was to shoot this thing. When you get thousands of imaginative kids together with the best engineers around I really doubt anything is impossible.
The only issue with shooting this thing is safety. The most important part in my opinion if you are using springs is not to try to slam them into a hard stop. Slow them down gradually or you will start breaking something. To hurdle requires minimally 22ft/s at the moment of launch.
If a team plans on doing this make sure you tell your members about how dangerous it is. And under no circumstances should you let people near it when it is live. These are 120lb machines, they ARE dangerous. Respect that.
team 1242 is hurdling as well, not launching.......i would like to say that any team that plans on launching should be extremely careful, those balls are heavy coming down and will destroy other robots and you might have 2 disable your device. we dropped the ball from 6.5 feet as if it were coming down from the overpass, i hope for the sake of alliance robots that nobody is under while the balls are knocked down....even worse if it it catapulted up!
Team 135
17-01-2008, 12:47
Team 135 has been working on making a spring loaded launch system. We are just starting the testing stage and will repost if we have any new developments.
Winterwolf
17-01-2008, 13:00
I think that witht he right springs and system, that a launcher could easily get a ball over that hurdle. However, when that ball comes down, it's going to be really dangerous.
We considered a pendulum-soccer-kick mechanism that was centered torwards the front of the bot. 25-lb. pendulum that was simply raised and dropped on a n-foot long arm with guide rails on the sides to keep it straight and a x-degree wedge on the end to pop it up like a golf club does. Low profile, easy to do while pushing the weight limits.
The team had doubts of long-term reliability & quality, so we went with a different design.
xcarmichael65x
17-01-2008, 13:25
all i can say....
its going to be A PAIN IN THE BUT
FOR THE FIELD SETING TEAM
:D
David Brinza
17-01-2008, 13:43
team 1242 is hurdling as well, not launching.......i would like to say that any team that plans on launching should be extremely careful, those balls are heavy coming down and will destroy other robots and you might have 2 disable your device. we dropped the ball from 6.5 feet as if it were coming down from the overpass, i hope for the sake of alliance robots that nobody is under while the balls are knocked down....even worse if it it catapulted up!The game animation explicitly stated that robots need to be able to survive being struck by falling trackballs. There's no way that the team that releases the ball will be disabled because their falling trackball damages another robot. Regardless, the ball release mechanism (launcher or otherwise) still must be deemed safe to be allowed in competition.
AdamHeard
17-01-2008, 14:01
I have a hard time believing a team can do all of these reliable and quickly;
secure the ball
safely store energy
launch the ball high/far enough
Actually, I think 71 might be up to the challenge....
MrForbes
17-01-2008, 14:29
It's a great challenge, isn't it Adam?
GaryVoshol
17-01-2008, 14:41
would like to say that any team that plans on launching should be extremely careful, those balls are heavy coming down and will destroy other robots and you might have 2 disable your device.Is the ball any lighter if it is just dropped over the bar, as opposed to tossed over? Those that shoot the balls will not be shooting them miles into the air - it will take just about everything they can do to get the ball above the 6.5 foot height, let alone tossing them 10, 15, 20 ... feet into the air.
I think that witht he right springs and system, that a launcher could easily get a ball over that hurdle. However, when that ball comes down, it's going to be really dangerous.The dangerous part will be the mechanism that sends the ball upward. Make sure nothing but the ball is in the way when firing!
I have a hard time believing a team can do all of these reliable and quickly;
secure the ball
safely store energy
launch the ball high/far enough
Actually, I think 71 might be up to the challenge....I suspect about 71 teams being able to shoot this ball is about right. (OK, OK, I knew what you meant. No need for everyone to explain Beatty to me.)
all i can say....
its going to be A PAIN IN THE BUT
FOR THE FIELD SETING TEAM
:DHuh? This will be one of the easiest games in memory to reset. You want scrambling around by resetters, try one of the VEX games.
1351 will attempt to catapult using a stored energy device (not springs!)
It will be amazing to see all these balls flying through the air during matches!
Sam
Team 16 is currently looking into some sort of catapult-ing. We know it can work. We just have to figure out how we'll make it work without somebody pulling strings. =D I'm not sure how far we're into it, though. They're at the cage, I'm at the computer.
How do we measure energy....in ft-lbs, ft-lbs...
http://www.acme.com/jef/singing_science/measure_energy-160.mp3
Ian Curtis
17-01-2008, 22:56
If a team can reliably launch a trackball, they will be an A list robot. Launching the trackball will save time, and will be safer for the robot (no chance of getting hung up on the overpass). It's something to consider as we move farther into the "Huh, we should probably figure out how we're gonna do this" stage of build season. (However, as this stage typically lasts until around February 20th, there's still plenty of thinking time left.) :rolleyes:
Also, has 217 considered naming their trackball scoring machine the Chicken Chucker? (http://www.mcphee.com/items/11305.html) :D
We have successfully launched it over the over pass i will put a video up soon of it!
And we were thinking of having are robot the "fluffy bunny" (monty python and the holy grail)
(killer bunny!)
Its pretty cool how it shoots it i will post a link in a bit for you guys to see it.
:D
s_forbes
17-01-2008, 23:02
However, when that ball comes down, it's going to be really dangerous.
Remember, the ball will hit the ground at about the same speed as a ball that was simply dropped over the overpass. The real danger is what the robot can do to someones hand/arm if the catapult fires without a ball loaded.
gurellia53
17-01-2008, 23:19
We ended up deciding to go with a catapult design. I was against it at first, but now I think it could work well. We did some testing and prototyping and it works very well. Hopefully we can pull it off =]. I may post a video sometime.
http://www.youtube.com/watch?v=Ak2ZgBLHALo
Here is are launcher teaser!
Enjoy
Wayne Doenges
18-01-2008, 07:10
Team 1501 had a great idea but we had to throw it out.
You have a ramp with a supply of automobile airbags. One airbag per launched trackball. Put airbag in place behind trackball and BANG, trackball is launched over rack and beyond :ahh:
What do you think?
GaryVoshol
18-01-2008, 08:08
Put airbag in place behind trackball and BANG, trackball is launched over rack and beyond :ahh:
What do you think?I think the GDC has already heard of this and nixed it: http://forums.usfirst.org/showthread.php?t=8246&highlight=airbag
http://www.youtube.com/watch?v=Ak2ZgBLHALo
Here is are launcher teaser!
Enjoy
Well, I think it's cool. :D
Brandon Holley
18-01-2008, 13:30
Well, I think it's cool. :D
sweet video
Mark Holschuh
18-01-2008, 13:35
So Winnovation and Robot Casserole are thinking of launching the ball. I'm really looking forward to the Wisconsin Regional now.
Too bad the Detroit Regional is the same weekend. I'd like to see what the Thunder Chickens are thinking of as well.
65_Xero_Huskie
18-01-2008, 13:40
Well, I think it's cool. :D
It would be cool if i didnt think it was someone throwing it over :\
Hehe, Atleast put some sound in it!
It would be cool if i didnt think it was someone throwing it over :\
Hehe, Atleast put some sound in it!
Allow me to put your mind at ease--the only thing that touched the ball was the shooting mechanism. In fact, we had to shoot the ball about 4 times before we got a video that didn't show the mechanism
Kevin Sevcik
18-01-2008, 14:42
Allow me to put your mind at ease--the only thing that touched the ball was the shooting mechanism. In fact, we had to shoot the ball about 4 times before we got a video that didn't show the mechanismAnyone who's lived through Joe Ross canceling The Championships automatically defaults to suspicion of just about any extreme claim. That said, I, personally, do not doubt that there will be launching teams out there. There are multiple mechanisms that would be capable of this and some of them aren't even outrageously complicated.
I'm still curious how launching teams are planning on corralling these trackballs after the hurdle. Unless you're launching nearly vertical, those trackballs are going to have a pretty decent horizontal velocity and are going to bounce around a rather lot. That's assuming you don't have a human on the other end to politely catch the ball for you. So I think launching the ball will be easier in some respects, but I think you'll end up losing time recapturing the ball afterwards. Plus you don't get the bonus points for ending with the ball on the overpass unless you're really, really talented.
MrForbes
18-01-2008, 14:43
We played with backspin when tossing the ball over by hand....it's not too hard to get it to bounce straight up
billbo911
18-01-2008, 14:45
Team 1501 had a great idea but we had to throw it out.
You have a ramp with a supply of automobile airbags. One airbag per launched trackball. Put airbag in place behind trackball and BANG, trackball is launched over rack and beyond :ahh:
What do you think?
One of our students actually suggested this as well. We all got a good chuckle out of it. Of course, we had to explain that using explosives to launch the ball would not be legal in competition. We also encouraged the kids to keep thinking outside the box like this. Then, see if the ideas they came up with fit within the rules, or as we use them, "Design Criteria".
Anyone who's lived through Joe Ross canceling The Championships automatically defaults to suspicion of just about any extreme claim. That said, I, personally, do not doubt that there will be launching teams out there. There are multiple mechanisms that would be capable of this and some of them aren't even outrageously complicated.
I'm still curious how launching teams are planning on corralling these trackballs after the hurdle. Unless you're launching nearly vertical, those trackballs are going to have a pretty decent horizontal velocity and are going to bounce around a rather lot. That's assuming you don't have a human on the other end to politely catch the ball for you. So I think launching the ball will be easier in some respects, but I think you'll end up losing time recapturing the ball afterwards. Plus you don't get the bonus points for ending with the ball on the overpass unless you're really, really talented.
Although you may think it will be difficult to recapture the ball and take extra time, a non-shooting mechanism will most likely need to lower after hurdling the ball to fit under the overpass. Also, if the ball does travel far, it will eventually hit the wall, where it will come back to you, or hit the corner and go into the next quadrant of the field. Grabbing the ball after launch won't take anymore time than if you weren't shooting the ball and still hurdling. Another thing is that at the end of a match, hurdling is not worth that much less than if you place the ball on the overpass. The best case would be to hurdle the ball and have an alliance member 'bump' or pass the ball back to you so you could place, getting the most points possible.
benhulett
18-01-2008, 18:31
So if your score 8 pts for getting the ball over the overpass, it would take an equivalent of 4 laps (am i correct) without pushing the ball, and 2 laps while pushing the ball? that's what was said on our team, and we want to go for launching as long as we can secure and launch a ball in that amount of time... or even better, less than that amount. it's 3rd on the list, but it's still on the list of things to do.
Kevin Sevcik
18-01-2008, 19:07
Although you may think it will be difficult to recapture the ball and take extra time, a non-shooting mechanism will most likely need to lower after hurdling the ball to fit under the overpass. Also, if the ball does travel far, it will eventually hit the wall, where it will come back to you, or hit the corner and go into the next quadrant of the field. Grabbing the ball after launch won't take anymore time than if you weren't shooting the ball and still hurdling. Another thing is that at the end of a match, hurdling is not worth that much less than if you place the ball on the overpass. The best case would be to hurdle the ball and have an alliance member 'bump' or pass the ball back to you so you could place, getting the most points possible.
First, just as I won't assume that all shooters are going to hurl the balls at ludicrous speeds, don't assume that non-shooting mechanisms are going to be painfully slow or something. While they might need to go up slowly, there's no real reason they need to lower slowly as well. I'm not really certain what the benefit of a bouncing trackball coming back at you would be, but still. As far as scoring the trackball at the end, I think the lift gives you more options. A shooter could make a last second hurdle, a lifter could make a last second hurdle and score the ball. Even if you don't have someone to roll it back to you, I'd give decent odds of having enough time to score it on the opponent's overpass.
LordKronus
18-01-2008, 20:18
Team 104 here, we are planning on hurdling but unsure if we will use a shooter or not. Personally I want to do a shooter, but hey team effort and all, not all my decision. Still I'm trying to prove it will work and, I'm almost done.:D
We are shooting it over. We think it is easier then most think. It is like kicking a field goal from the endzone. You really don't have to aim it and it will go over. :D
You can also make a robot with a very low center of gravity that will make your robot handle much better for the high speed cornering part.
robot2226
18-01-2008, 22:19
were hoping... and yes it is possible not "impossible"
LordKronus
18-01-2008, 22:43
We are shooting it over. We think it is easier then most think. It is like kicking a field goal from the endzone. You really don't have to aim it and it will go over. :D
You can also make a robot with a very low center of gravity that will make your robot handle much better for the high speed cornering part.
I am overeager to build a shooter as well but it may be a little harder than you may think. The math is killer. It takes a lot of force to get the ball in the air, and even more if your using stuff like punching pneumatics.
MrForbes
18-01-2008, 23:06
You can also make a robot with a very low center of gravity that will make your robot handle much better for the high speed cornering part.
heh....you too?
gurellia53
18-01-2008, 23:11
here's one of our first tests with catapulting a ball.:]
http://youtube.com/watch?v=l7Nl_QUvldc
MrForbes
18-01-2008, 23:13
that's great! just imagine how far it will go when you fill up the ball with air all the way :)
We are definitely throwing it over...
I gaurentee that nobody was punching it or anything!
We built a device that did that and it is fully functional we shot it over 10 times successfully from about the end of the lane divider clearly making it every time...
We would post the entire video but the team has decided to keep it secret for now.... We will post a video later in the season though when we have this thing mounted to are real frame not our prototype and we have it driving around... :D
....I know what your thinking. Did he shoot five trackballs or six. Listen punk, this is a frc robot and it will take your head clear off. so, do you feel lucky punk:cool:
AHepperla
19-01-2008, 09:56
Team #2202 (Brookfield, WI) has a design that will shoot the ball also, we're in prototype mode now and looks promising... now the wisconsin regional could get very interesting!
:D Team 1425 (Error Code Xero)
is planning to launch the ball over the rack. We have a prototype now that is more than up to the task.
zacattack
20-01-2008, 23:24
My team is just going to bump it off and herd it as fast as we can, hurdling is to much of an effort. Especially, for the robot to do it and my team to build it.
Aelta Eda 585
21-01-2008, 11:37
one of my team's mock-ups we were actually able to put the ball over the rack with a flywheel.
Video (http://youtube.com/watch?v=wXIndwxrIcs)
At the end is what you saw after we added the 10 pound weight. Not fun.
Jaybee1405
21-01-2008, 15:26
thats awesome 585
We seriously are serious about launching the trackball. We've got our prototype working wonderfully, and we've designed how it's going to work out. All we need to do is fabricate it (of course we'd need to do the robot first) and attatch. Of course, then we still have to hope it works out the same. We're confident.
teammember_342
21-01-2008, 20:09
Why what kind of ball is it?
Chaos in a Can
24-01-2008, 16:52
We discovered that one of the large CIMs is more than capable of launching a trackball.
We also discovered that it's more than capable of lifting a small filing cabinet filled with barbell weights into the air...
We discovered that one of the large CIMs is more than capable of launching a trackball.
We also discovered that it's more than capable of lifting a small filing cabinet filled with barbell weights into the air...
You mean the minibike motors from last year? The ones that had the odd-shaped front plate and the belting tensioner and the impossible-to-remove pulley?
If so, you should also discover that they are not legal this year, as they are not in the kit.
If you mean the ones from the kit this year (no odd front plate), then you are fine.
Chaos in a Can
24-01-2008, 17:08
Its one of the ones from this year's kit.
Its one of the ones from this year's kit.
OK, whew. I thought (by the reference to "large CIM") that you had used an illegal motor. Typically, the ones this year are just "CIMs" or "small CIMs". "Large CIM" refers to the biggest motor in the kit last year and the year before, which is no longer in the KOP.
SteveGPage
26-01-2008, 12:28
FRC836 Robobees ... shoots and scores! :)
We seriously are serious about launching the trackball. We've got our prototype working wonderfully, and we've designed how it's going to work out. All we need to do is fabricate it (of course we'd need to do the robot first) and attatch. Of course, then we still have to hope it works out the same. We're confident.
It would be wrong for the "bomb" squad not to launch a ball.
s_forbes
26-01-2008, 13:46
I just got word from the NERDS in the fab shop, and it sounds like they have achieved success as well! I think they'll be posting a video soon...
cgredalertcc
27-01-2008, 00:00
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.
MrForbes
27-01-2008, 00:08
The funny thing is the 3/4's extend way faster than the 1&1/2's
Not surprising at all, the 3/4" bore cylinders hold a lot less volume of air, so they fill much more quickly
7-11number1
27-01-2008, 16:35
Team 1711 will be hurdling the ball but instead of hurdling it from off the ground we will be grabing the ball and use an arm to lift it about 6 feet high then throw. That way we can continue driving under the over pass without waiting to lower the arm. Pics and video of our robot will soon be posted
FRC836 Robobees ... shoots and scores! :)
Holy cats!! :yikes:
Nice job! :D
1024 is perfecting the design for our linear pneumatic launcher. So far, our launcher (which currently resides on a 2x4 wooden frame) can put the ball, repeatably, on the overpass, but not launch it over. So, after when tune the launcher up some more and put it on it's mount (which is about 3' off the ground higher than it is now) it should work fine. It's flight path apexes three feet ahead of the robot.
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
cgredalertcc
28-01-2008, 10:46
Not surprising at all, the 3/4" bore cylinders hold a lot less volume of air, so they fill much more quickly
What I meant to say was that the result of using the 3/4" cylinders is a faster velocity on the ball after firing. We did some testing using a complete vertical shot on the ball and two 3/4" cylinders made the ball travel higher than two 1&1/2" of the same stroke. Any ideas on increasing the output of the shot. We already made a huge difference by placing storage after the regulator, but before the solenoid. Any advice would be appreciated. We have recognized some friction issues with our linear guide and we are considering switching to one of the micro series linear guides from NSK, because of the benefits of the bearings over the low friction plastic sliders with what we use now. Also we are stiffening the track that the guides ride on, because at current they are only fixed at one position. Adding a second attachment point should reduce some of the binding we see with the single attachment point. Right now we are unreliably shooting over the rack if we aren't lined up perfectly on the rails that are spaced wider. At the 14" points the ball bounces cleanly over.
Thanks, Charlie
We're lifting instead of launching. I feel like we'll be the odd bot out because of this thread, but whatever. The key to our bot is the ability to capture and irradically bouncing ball while being knocked around and then lift and/or place it over/on the overpass.
I will laugh at the match where there are 6 launcher/racer bots on the field and no one has a way to knock a ball off. It will be tragic, but you know it'll happen and it'll be ironic when it does. :yikes:
MrForbes
28-01-2008, 11:03
I will laugh at the match where there are 6 launcher/racer bots on the field and no one has a way to knock a ball off. It will be tragic, but you know it'll happen and it'll be ironic when it does. :yikes:
We're planning on using our ball knocker-offer (which was our first design concept) to hold the ball down on our catapult before launching.....yup, you definitely need a way to get the ball down if you're planning on shooting it!
JonathanLKS
28-01-2008, 11:13
We're also planning on shooting the ball. I'd post a video but they are all trapped inside our cell phones right now.
Guy Davidson
28-01-2008, 13:04
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
30-01-2008, 12:00
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
31-01-2008, 12:03
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!!
31-01-2008, 14:39
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
31-01-2008, 16:24
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.)
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) (http://www.ecu-engine-controls.com/OtherServedFiles/ProgTeam/QuickScan0001.png)
-q
We Are and it works MUHAHAHA
:yikes:
Captain Sugar
02-02-2008, 23:27
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
02-02-2008, 23:56
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 (http://www.chiefdelphi.com/forums/showthread.php?t=63109). Should be a great game this year!
good luck!!
Chaos in a Can
03-02-2008, 00:01
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
06-02-2008, 19:14
I see every team at the "finish lines" crankin up a catapult to launch a 7.3lbs ball, and it actually scares me.
ChrisMcK2186
06-02-2008, 20:04
Our ball recently got rabies, so I have to take it out back and shoot it:eek:
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
07-02-2008, 07:09
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
08-02-2008, 13:17
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
14-02-2008, 12:01
our initial design went bust so we are now lifting it and then launching it (our initial design would've flipped the robot...)
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