Re: ball cannon???
 

I think you might get a penalty if you are purposely throwing them off the field. As for <S01>, depending on how fast those balls are going and how often I don't think it posses a safety hazard.

Re: ball cannon???
 

Quote a rule.

As for whether or not they are a safety hazard, one or two by accident probably won't be. Several dozen by "accident" would be.

Re: ball cannon???
 

I could not find a quote to back my statement up. Yet if you're not purposely throwing them off the field they would not pose a safety hazard.

Re: ball cannon???
 

That remains to be seen, and must be judged individually.

Re: ball cannon???
 

Our team decided to build a shooter robot and were looking to use the ball pitcher/flywheel method to shoot the balls only to find that after repeated shooting the balls would break. We now have a prototype shooter that shoots quickly and fairly accurately with a range near 15 feet.

My question is if anyone else has encountered a problem with their balls breaking under the pressure of a ball pitcher? Could a ball pitcher be built to be both powerful and accurate without putting to great a stress on the Orbit balls?

As far as the problems with trying to load a turreted shooter, we are currently brainstorming about how to build a hopper that will effectively hold a number of balls and still have our shooter as high as possible on our robot. Since our shooter needs to be top loaded, we're working on a way to fit the shooter between 40'' and 50'' on our robot and it becoming obvious that it can be done with a little creative designing.

Re: ball cannon???
 

Was anyone penalized last year for shooting a Trackball off the field? (I know, obligatory reference to Dave, "This year's rules are not the same as last year's rules." But they are - there is no reference in 2008 or 2009 to a penalty for shooting a ball off the field.)

And back on topic, how many posts did we see last year predicting the inability of flinging (by whatever method) a Trackball over the Overpass?

Re: ball cannon???
 

seams very possible to me, DIFFICULT, but all to possible. Somebody will pull it off and my team should work our butts off to.

My current design, would fire balls around 85 feet at 420 balls per minute (7 balls per second), showed it to my coach and he said that were trying to score, not kill the other alliance. The only difficulty I'm having is working on a leading algorithm, why can't calculus be easy.

Re: ball cannon???
 

My team prototyped a design using a similar flywheel mechanism to Aim High's design and the wheels caused so much friction it just ripped the cover off the balls while only shooting the ball about 2 ft. I don't think we'll see many this year along those lines. For this reason we're moving to more of a catapult type launcher that can get about 5-8 shots off in autonomous.

Re: ball cannon???
 

Depending on how your shooter works, you could do it with just one-dimensional motion equations and some trig. Ignoring air-resistance, of course.

As for your 420 balls per minute, you better have a way to get a lot of balls fast.

Re: ball cannon???
 

How far are you planning to throw the balls? We have been playing with a flywheel type design, and can get 8-10 feet in a decent arc without any damage to the moon rocks.

I'm dubious that any *long range* shooting would be particularly accurate anyway, what with the aerodynamics of the Orbit Balls being rather, um, unpredictable.

Patrick

Re: ball cannon???
 

FWIW, the 85 feet XXShadowXX claims he can do is a bit overkill - the field is only 54 feet long!

With the field being 27 feet wide at any given point, you really only need 14 feet on a shooter to be able to control half the field. The closer your robot is to your target, the more accurate you'll be - that much is almost a certainty. While 85 feet is definitely cool - and could come in handy with off season events and pep rallies - it not needed here at all.

Re: ball cannon???
 

We made a turreted shooter for Aim High in 2006. There is a lot of design detail in the Behind the Design Book. I highly suggest reading that entry. A couple of things you will not find in the book directly:

Ball sorting is extremely difficult! in 2006 most Hopper style designs jammed when trying to serialize a bin of balls.

We went for a single wheel to a double wheel system, because while the single wheel was accurate, the spin on the ball descored about 50% of the shots we made. Also Spin energy was significant portion of the launch energy equation, and that was with a "solid" ball. Since the moon rock is a bit more of a "hollow sphere", this will become an even larger portion of the equation.

Turret to conveyor interface is super critical. You need a feed mechanism that consistantly delivers balls to the cannon at the same speed and position in order to be accurate.

With over 1500 teams, someone will have an amazing cannon this year.

As for range: Shaddowxx please recheck your numbers. To deliver that many balls at that rate of speed will require a ton of power. Not saying it can't be done, but that will require a lot of the power motors, or a lot of stored energy.

Re: ball cannon???
 

Spray and pray? :confused:

Re: ball cannon???
 

Has your team considered actively dumping? (Dumping but with something propelling the balls out of the dumper)

Re: ball cannon???
 

Awesome, I was going to say this.

Machine guns are great and all, but a sniper puts you in constant fear. I think being consistant will be crucial.

Slow and steady wins the race, right?