Re: Kicking System Design Considerations
 

Well, what if you have one in your possesion and you're about to kick it. And out of nowhere a ball gets close enough to be affected by one of your kickers and you end up kicking two at once. Is that a penalty?

Re: Kicking System Design Considerations
 

Agreed, 397 did this PART of the year in 2008 to throw the Trackball and it worked pretty good. We eventually switched to using just 4 1/5" diameter 12" stroke cylinders to lob the ball the length of the field (Kettering Kickoff and WMRI) If you are curious about the arrangement of these I can find it and send you a picture. We were able to shoot it over the overpass from ~12 feet at 30psi. (In competition we ran at 60psi)

You may also want to consider the kinetic energy of a moving object is 1/2 * m * v^2. In a perfect world (which this is not) in a collision the energy from the kicker would be transferred to the object being kicked. Therefore you will get a lot more omph if you increase your speed. Consider using a lever to increase your speed.

Re: Kicking System Design Considerations
 

Its really an 8 " stroke, it was a type on the video

Re: Kicking System Design Considerations
 

To my knowledge there is no rule against kicking multiple balls, only possessing more than one.

Re: Kicking System Design Considerations
 

Thank you for the information on the pistons and on the kicking rules.

Re: Kicking System Design Considerations
 

BTW, does anyone know if the ball is allowed to come off of the ground for a split-seconde before a kick so that we can get the ball over the bump? You see, with our design, we managed to get the ball over the bump, but it needs to be a little bit off of the ground to make it. So, can anyone help with this problem?

Re: Kicking System Design Considerations
 

Without seeing more of your design, it's hard to say....but there is a rule that says you can't CARRY the ball.

Sounds like fun!

Re: Kicking System Design Considerations
 

Try hitting the ball in an upward motion from low. Look at 842's kicker video for an example of this. A version I saw was hitting them ~40 feet accurately. The only problem is fine tuning it to get the right amount of loft and not just blasting away at it.

Re: Kicking System Design Considerations
 

Just to clear this up, it was deemed legal to kick multiple balls at once on the FIRST Q&A: http://forums.usfirst.org/showthread.php?t=13900

Re: Kicking System Design Considerations
 

It is better, when possible, to use cylinders-pistons in TENSION than in COMPRESSION, but if this requires cables, then it becomes nore complicated
Tension loading tends to keep the forces aligned along axis of rod, which is where cylinder has most strength. Compression force tends to initiate torque and bending forces at an angle to the piston as objects try to "roll" around and past each other.

Since a hinged kicker rotates and moves away from cylinder, angle of force on kicker changes. Max acceleration happens, with a hinged kicker, with cylinder's force applied at 90 degrees to a line out from kicker pivot point to where cylinder is attached during the arc of the kick. As kicker moves away, this change the 90 degrees force angle, and applied force drops off. So, the cylinder should be oriented such that the force applied stays close to 90 degrees during critical acceleratiom range of the kick arc. This is easier to achieve when the piston's attach point stays closer to the pivot point -- but. this also reduces the leverage of the cylinder for accelerating kicker, so a larger bore is needed to gain more force.

There is also the issue of rate of pressure build up inside cylinder. Since the energy delivered to the kicker (then to ball) is the force times the distance over which it gets applied, reaching maximum force early in the stroke is important, since there are only so many inches of travel in which to apply it.
Having piston connect nearer to pivot point (low leverage) means force builds up faster in the cylinder. So having a stronger cylinder that pushes a shorter stroke on a spot nearer the pivot point can deliver more energy early in the stroke than a weaker cylinder attached further away from pivot having better leverage, but also building up force more slowly.
Finding the sweet spot between these two extremes is the key to a good kicker design.

-RRLedford


stance traveled during by point that piston connects to kicker is short.

Re: Kicking System Design Considerations
 

my team is working on our kicker design, we are using a 5" stroke-9/16" bore(I think) piston, mounted to the bottom of our hinged plate(which is hinged at the top, so we get the most leverage) we get about 20" hight and about 5ft of distance in the air. this is enough to kick the ball over the bump from about 4ft away, but we need it to go further and higher, we could use a bigger piston but we dont really have the space. how could we make it kick farther?(I've thought about surgical tubing and springs already, but i was wondering if there was any other way?)

Re: Kicking System Design Considerations
 

I didn't say carry. I was wondering if, when the robot is stationary, the ball can be lifted so that it can get more air when kicked.

Re: Kicking System Design Considerations
 

It doesn't matter if the robot is stationary or moving. Look at the definitions quoted above. If you lift the ball, it's not in contact with the field. If you are possessing the ball - controling its position - you can't lift it off the ground or you are carrying it.

Re: Kicking System Design Considerations
 

Double your bore and connect at 1/2 way up the swing arc (not at bottom).
Four times more force plus faster pressure build up will reach higher much higher velocity before kicker contacts ball.
-RRLedford

Re: Kicking System Design Considerations
 

To clarify my original quote...It would be clearer if I had said "Only one [b]if it's[b]in your possession", sorry if I mislead.