Best Way to Shoot the Balls??

Hey everyone! I would like to wish everyone luck in the upcoming competition! I think it will prove to be an exciting and fun new challenge.
My question envolves the method of getting the ball to the tall goal. After they showed the softball thrower during the kickoff, that was my best idea! Any other ideas out there that you want to share? its seems to me that anything pneumatic or spring loaded would take way too long to shoot, considering the number of balls on the field. Thanks a bunch and good luck in the upcoming competition!

Team 281 - ex student

im thinking of a hot wheels sort of thing where u pick the balls up they go down into a basket or some sort of holding device and then shoot up between 2 wheels kinda the same thing but w/e

softball type thing is way to go… i mean you can keep feedin’ um in and you can shoot a bunch at once. pneumatic and spring would take too long… i’d only do it that way if thats you secondary “weapon” or if your attempting to shoot from a distance ACCURATELY. i think only a handfull for teams are gonna go for that center goal too and theres gonna be a lot of defence and “battlebots” type action, except in a controled manner.

I find that really interesting you don’t think many will go for the center goal. i was honestly really usure about that myself. I mean, you only have to get 1 out of 3 to make it worth your while, but it will prove to be very challenging, no doubt there. thanks for the input

I think that it would be easy to do a pneumatic system that would be fast. You just use a double solenoid and a hopper (like a paint ball gun) and the ball falls down into chamber and than is shoved out by a plate on the end of a pnumatic system, than automatically the cylinder pulls back and another falls in and repeats, and if this isnt fast enough for you, these aren’t complex shooting machines which means you could build two of them fairly easily.
you can have alternating firing mechanisms, so that one fires while the other reloads. Also you could use a pulley system to shorten the time of retraction for your springs. If you’ve got any corrections plz feel free

the laws of physics say that any way you use to transfer energy to your shooter is going to take some time to get the necessary energy transferred to it for the first shot, and then to spool-up again for the repeated shots

something to keep in mind. Its easy to see with something like pneumatics, where the pressure has to be resupplied, and less obvious with something like a baseball (wheel based) launcher. It will slow down after a ball is fired, and will take a specific amount of time to get back up to launch-speed.

a trebuchet would totally win the cool award
Im trying to think of an effective way to rifle the ball in a mechanism similar to the softball laucher.
there are also many hybrid ideas to the softball laucher, including tubes with belts in them, multi-ball lauchers, “gatling guns” etc etc etc

I was thinking about rifling also. The main problem with putting groves in the barrel is that it would either cut up the ball or simply slow it down too much. I was thinking about adding a set of rotational wheels. If there’s a set of wheels mounted perpendicular to the “launching” wheels, it could spin the ball. You’d probably have to use a set of omniwheels though. You’d also have to make sure that the barrel is relatively low-friction.

For a little bit today, we were considering a gatling gun style device. Had it not been discounted for impracticality, it would have been pretty cool.

Pneumatics won’t fire at fast enough speeds. On paintball gunns the piston pulls back the bolt and pressurized gas shoots the ball.

I can’t wait to see people practicing in the pits. LOL

I’m not sure that you need to introduce that kind of axial spin to achieve greater accuracy. I would imagine it would be best, but very difficult. Air Soft guns use a system called Hop Up, where spin is put onto the pellet to increase accuracy and range. I do not believe that it gives spin in the direction rifling would, but rather, in a axis perpendicular to the direction of travel.

Ben good thread. My team after yestersday has a pretty good idea of what where going to be doing as far as the robot, however the shooting mechanism is something that was really up in the air yesterday as far as our ideas well a few arised but this one I think was the one I liked best. This idea uses the softball machine analogy, basically we were talking about using the four kit wheels with two motors and some how feeding them through the two sets of kit wheels. There are a few problems off the top of my head that I can think of with this, but just thowing an idea out there. I love the game it rocks, Shooting and shooting accurately is going to be a process to figure out.

Good luck to all the teams,

mm…no matter what the design i think the ball will need to have spin on it. if not, the ball may vibrate to a stall in a barrel. its a lot easier to get a metal bullet to slide through a gun, than a rubber ball. spin should keep the ball more stable and flying straighter.

Just a random thought about this whole barrel getting the ball to spin discussion. Is a barrel really necessary? If you look at a pitching machine, once the ball goes through the one or two wheels that propel it foreward, it doesn’t go through anything else. I understand that a barrel would perhaps put a corkscrew spin on the ball, thus making it more accurate, but when the wheel(s) make contact with the ball, wouldn’t it negate any spin that was there before? And if you are left with just the spin that the wheel(s) produce on the ball, isn’t that a constant spin that you can factor in when you aim you shooter? That’s just my two cents.

Michael C.

That might be true shooting heavy small objects, but we are launching large light objects. With the spin the ball expeiriences being launched, and with the lightness of the ball, those balls will be going every which way immediately after they go through the launcher. The game will come down to who can shoot their balls with the highest accuracy percentage.

well they give us those super cims(thats wat our team are calling them) anyone actually know the names of those motors. Those things could probley power a scooter. But a double belt system working on one of the motors or a one belt up inside a large barrel it would be fast accurate and easy to feed, with very little fear of jamming.

If you do a two-wheeled shooter (or two belt or whatnot), you could run the wheels at different speeds to put a backspin on the ball. Not all spin has to be like a spiraled football.

Making sure you get your wheels back up to speed before putting another ball it will be huge. High RPM and low torque wheels will slow down.

Who’s taking a field trip to a batting cage?

Thats only assuming you can make one of three in the same amount of time it takes another robot to get three one point goals. Speed scoring and defense will be a factor as well as accuracy.

Simple: Use two wheels (not just one like the softball launcher), but put them at a slight angle to the direction of travel - for example, the top one is canted 15 degrees to the left (CCW) and the bottom one 15 to the right (also CCW). This is how football launchers work.

I disagree, and I see no need for a ‘barrel’. In a protoype I built today (see photo), the balls went very very repeatably to the same spot. The biggest variable will be the supply voltage (= motor speed), but the astute student will figure out how to compensate for that :wink:

Umm, using what energy source? A tennis ball launcher uses what is essentially a vacuum cleaner, blowing instead of pulling, and shoots the ball out of a ‘barrel’. Longer barrels shoot further and flatter, and a screw-thingie on one side imparts spin. But, a 7 ball needs a LOT of air volume. Do the math with a 2’ long barrel - what is the volume of the barrel in cubic feet, and how many cubic feet per minute at (60?) PSI can that KOP compressor supply? That gives you your best firing rate, BUT there is no place to store that volume of air at 60 PSI on a legal robot.

The way I see it, the only viable options are wheel-based and spring-based launchers. (A trebuchet is spring-based [EDIT: No, it is powered by a falling mass[/EDIT], and I agree, it would be soooo cool).

In the photo, that is an 8" wheel. At about 1300 RPM it launches a 7" soccer ball about 10 feet (from a table 40" from the floor), and in ten tries they all landed within an inch of each other.

The biggest issues are balance of the wheel - it wobbles a lot at 1300 RPM, it’s not made for that - and the huge black marks the rubber leaves on the ball.




Am I the only person thinking about ball availability? If you’re on offense, and the opposing team is on defense, they have no reason to put balls in play where you can get them after you score them. So if you have 40 balls and score them all as one pointers, you get 40 points and have to wait until they give you your balls back. If you make 3’s, you get 3 points. the ones you miss are still available to you if you have a ball scoop, so if you start with 40 balls you could get a max of 120 points before you’ve run out of balls.