How do we launch this thing? 2014

[AhAhPatel]

Something I have been trying to solve is whether a linear system of shooting or a parabolic system of shooting will be best. By this I mean the flight path of the ball if shot at the 10 point goal

[Coin3]

Originally Posted by AhAhPatel

Something I have been trying to solve is whether a linear system of shooting or a parabolic system of shooting will be best. By this I mean the flight path of the ball if shot at the 10 point goal

Any shot you take than launches the ball into the air will take a parabolic path. For linear I guess you could... push/kick the ball into the front or side of the low goal?

[MrForbes]

We're looking at our 2008 robot design (there's not much left of the robot to look at, unfortunately). It worked....and this year's game piece is light and small, relatively speaking.

[AhAhPatel]

Originally Posted by Coin3

Any shot you take than launches the ball into the air will take a parabolic path. For linear I guess you could... push/kick the ball into the front or side of the low goal?

What I meant more was like the path it took in the shooter. Like a circular shooter we saw in rebound rumble or a linear one we saw in ultimate ascent. But thinking about it, a circular shooter would be massive. Probably not feasible either

[Mugurussa675]

Originally Posted by Maniac_Mechanic

Ah, that glorious engineering question- how do we get this thing in the air?

I understand the ball is 24 inches wide and ~2.5 lbs. If anyone has more detailed numbers or tolerances, please add them.

Pyrotechnics are right out. They would totally set fire to the fabric. I'm sure the first thoughts everyone has are catapult arms. I was thinking about this and one of my sketches caused another problem appear. If arms are used to launch the ball, their own unladen weight will slow down acceleration of the ball or require a huge force to move.

I'm thinking broadly now. What if you used some much smaller arm that hits the ball and the impulse sends it flying? What can we come up with here?

Other things worth consideration:

The springs offered as part of the voucher http://info.vulcanspring.com/first-robotics-competition
They are constant force flat coil springs, not helical coil springs as you might picture.

How quickly will it be necessary to retract/ prime whatever launcher you have?

Try using surgical tubing and making a slingshot

[cadandcookies]

Originally Posted by Mugurussa675

Try using surgical tubing and making a slingshot

When I talked to my electronics team: "Why would we use pneumatics when we can have a crossbow!"

In all seriousness, linear punches sound really good this year. But prototyping will determine where we ultimately go.

[thinker&planner]

One way to make a piston into a possibly better shooting using a "simple machine" would be to attach a piece of chain to a piston and wrap the chain around a curved piece of aluminum which is then attached to a kicker.
I know this is a bad description, but basically, when the piston retracts, it pulls the kicker around a pivot point, creating a "knee" joint and a mechanical leg kicker.

[TucoSalamanc]

Not an FRC-er, but a teacher that is shadowing the team at her future place of employment

From what I have seen so far, a flywheel is a perfectly viable solution. We used a flywheel on both sides of the ball each powered by a DEWALT 20-Volt Li-Ion Cordless Brushless Compact Drill. We had each going at about 2,500 RPM, which we believe is possible in the competition, spaced apart the recorded diameter will little luck. However, when we brought each in 1/5 inch the ball squeezed right through flying at the wall (10-25 feet away) and hitting with decent speed.

We took the rig outside (in heavy winds) and got recorded distances of 75ft lateral and what we believe to be 24 upwards (again, heavy winds). However, the ball popped after four throws. If you are confident in not completing more then four cycles, and have a blatant disregard for the sanctity of field elements, go for it. Too bad full-field tosses are illegal, because this thing is beastly.

Until then, we will be refining our shooter (Arial Accelerator, as the kids dubbed it) and work on getting videos up.

[DampRobot]

Originally Posted by TucoSalamanc

Not an FRC-er, but a teacher that is shadowing the team at her future place of employment

From what I have seen so far, a flywheel is a perfectly viable solution. We used a flywheel on both sides of the ball each powered by a DEWALT 20-Volt Li-Ion Cordless Brushless Compact Drill. We had each going at about 2,500 RPM, which we believe is possible in the competition, spaced apart the recorded diameter will little luck. However, when we brought each in 1/5 inch the ball squeezed right through flying at the wall (10-25 feet away) and hitting with decent speed.

We took the rig outside (in heavy winds) and got recorded distances of 75ft lateral and what we believe to be 24 upwards (again, heavy winds). However, the ball popped after four throws. If you are confident in not completing more then four cycles, and have a blatant disregard for the sanctity of field elements, go for it. Too bad full-field tosses are illegal, because this thing is beastly.

Until then, we will be refining our shooter (Arial Accelerator, as the kids dubbed it) and work on getting videos up.

Could you (or anyone else who's trying this method) upload a video? I'd be interested in seeing your results.

[TucoSalamanc]

Originally Posted by DampRobot

Could you (or anyone else who's trying this method) upload a video? I'd be interested in seeing your results.

We can upload one once we get our new ball. It is pretty easy to test yourself if you have a couple of worn out grinding wheels for your drills. We sanded the grinding wheels of spurs, then a filler primer, and then we took them to the lab. If you lock your elbows, tape the trigger down, and hold it upwards you can achieve the same result without a brace. If the ball evens come close it is going to go flying, so be as safe as you can be in this.

[bEdhEd]

Team 701 plans to use a spring loaded linear slider system that gets pulled back by a winch to reset, and when a pass or toss is necessary, we disengage the winch pneumatically, and the energy stored in the spring tosses the ball. We proved this concept today with a slingshot type prototype that uses surgical tubing instead of a spring to store energy. We used an old custom winch and our 2013 robot to power it, and the ball was lifted more than five feet in our trials. Our next prototype will involve an actual spring, and we plan our springs to be tough enough that they can launch the ball a good height and distance, with only needing to compress the springs a mere few inches, and probably no more than six inches. We hope that this should save space and weight on our robot

[dtengineering]

Jim has posted some really good suggestions here... this is, largely, a solved problem. Many teams found a way to launch balls in 2008 that were similar to these ones, but larger and heavier.

Dig back in the forums and videos and team websites if you weren't around FRC in '08.

And watch the BuildBlitz and Robot In Three Days (and a snowstorm) for ideas.

It isn't a question of how, so much as how to do it most efficiently!

Jason

Google: FRC 2008 launcher or maybe FRC Overdrive Launcher and check out the old videos and websites.

[Johnson.2937]

Originally Posted by TucoSalamanc

Too bad full-field tosses are illegal, because this thing is beastly.

Can you reference a rule that says this?

[Steven Donow]

Originally Posted by Johnson.2937

Can you reference a rule that says this?

Per the scoring section of the manual:

A BALL is considered SCORED in an ALLIANCE’S GOAL if

• a ROBOT causes one (1) of their ALLIANCE’S BALLS to cross completely through the opening(s) of one (1) of their ALLIANCE’S GOALS without intervening human contact,
• the ALLIANCE ROBOT last in contact with the BALL was entirely between the TRUSS and their ALLIANCE’S HIGH GOALS, and
• the BALL is not in contact with any ROBOT from that ALLIANCE.

Emphasis mine

[Jibri Wright]

There may be a way to get pistons to work. You guys have only thought about if pistons applied force directly. What if the pistons pulled the ball instead of pushed it? Just a thought