Shooting from opposite side of the field

[Djur]

CIMs have a torque of 45 ounce-inches (0.234375 foot-pounds) at peak efficiency according to the manufacturer. The simplest solution is to just put a wheel on the end of a CIM to increase torque and increase linear momentum conveyed to the ball.

[Sparks333]

The fun thing about gearing though - it does come with a built-in cost. You can most certainly get a ball to go virtually any speed with a properly-geared CIM and wheel (within reason), but the higher the speed, the longer it will take the for motor to get the shooting wheel back up to launch speeds - don't expect to fire of a quick volley from that range with only one motor/wheel combo - expect a slower firing rate due to the energy required to fire the ball at that speed and the power available via the motor.

[pfreivald]

Originally Posted by Justin Montois

By "do it" do you mean just shooting from the far side of the field or actually scoring...

I think you will see some teams consistently (or nearly consistently) score from just past half-court.

[staplemonx]

If you can hit 1 of 5 or 1 of 6 from the far side of the court you are accomplishing 3 things.

1. you are scoring
2. You are feeding your team balls and elliminating the need for them to make a trip
3. You are defending by moving balls out of the opponents side

You still need to be accurate and we believe that you will also need to be 1 out 3 or 1 out of two in your zone to be truly an effective team mate.

Here is some info on targeting we have whipped up http://www.atomicrobotics.com/2012/0...ot-larry-bird/

[Brandon_L]

Originally Posted by Gray Adams

I haven't really done any math, but putting a wheel directly on a CIM spins terrifyingly fast, and has a sound to match.

but we are limited to 4 CIMs this year, and about 99% of teams are going to use them for drive.

http://www.andymark.com/product-p/am-0932.htm

http://banebots.com/p/S24K-C1-7

So the question becomes, FP or banebots.

And also, if banebots, one gearbox or two hooked up to a single wheel shooter? (Limit 2 FP, 4 Banebots [R65], and correct me if I am wrong but each box takes two motors)

[Chris is me]

Originally Posted by Gray Adams

I haven't really done any math, but putting a wheel directly on a CIM spins terrifyingly fast, and has a sound to match.

Yet it worked in 2006 and 2009!

[martin417]

Everyone seems to be focused on whether or not a team can achieve the distance on a given shot. I believe that will be fairly easy to do. The real problem with distance is accuracy. remember that no design can be 100% consistent, and higher velocity could increase the error. The error in the landing point is given by:

err=tan(angle error) X distance

(assume two dimensional, looking down on the bot, the problem is compounded in three dimensions)

If the angle error is small, the tangent of that angle is small also, but if the distance is large, even that small error can make a big difference in landing point.

Example:assume you launch and have a 1° error in your launch direction. If you are 10 feet from the goal, you will have an error of ~2.1 inches. Assuming your aim was perfect, the ball will land ~2.1" from the center of the hoop and score.

Now move to 50 feet away (for round numbers) and keep the error the same. Your positional error is now 10.5 inches. if your aim was perfect. you will hit the rim and very likely not score. The center of the ball will be 1" outside the rim.

If you now add vertical angle error into the equation, it becomes much worse because your distance has the same relationship. Hitting a long field shot will probably happen, As I have seen full court shots hit in basketball, but I doubt many games will be won due to super long shots.

[Bob Steele]

I agree with the above comment...
From my experience... when you lose contact with an object... all sorts of things happen to it that you can no longer correct for. The longer it is in the air the more things can happen...

Remember... at these big velocities you can no longer use the simple physics formulas that most of us learned in high school physics... air resistance is NO longer negligible .. and you may approach terminal velocity...

but even if you don't, you will have a constantly changing velocity due to air resistance...

Has anyone determined the terminal velocity of these basketballs?

I am very encouraged to see so many teams putting their effort into scoring from long range... I applaud their efforts... it is great physics/math and great engineering...

Now is it the best thing to win the field game with> ??? not so sure...
I do know that if I am watching an NBA game and a guard is getting ready to shoot from beyond the 3 point line ..that if he spies a team mate wide open with no defensive player on them closer to the basket ... that he will make the pass... and if he doesn't... the coach will pull him out...

That being said... who really is the winner in FIRST?
Doing the math/science to put in a shot from half court... that is also winning.... and maybe in a more important way....

Good luck to all of you

We will see you on the field!!

[FrankJ]

Do remember that after the first week the balls are going to be deformed from use which will affect the accuracy of long shots. Just to get them to the other side of the field will not take as much energy.

[rick.oliver]

We did some imperical testing using our Aim High robot. It appears to be feasible to shoot this year's game piece from about 30 feet with some consistency.

[Alan Anderson]

Originally Posted by FrankJ

Do remember that after the first week the balls are going to be deformed from use which will affect the accuracy of long shots.

FRC Regional competitions typically do not reuse game pieces from previous weeks.

[kaszeta]

Originally Posted by rick.oliver

We did some imperical testing using our Aim High robot. It appears to be feasible to shoot this year's game piece from about 30 feet with some consistency.

Based upon our experiences with FP-driven pinch rollers, yeah, I'd say 30-35 feet with consistency is reasonable.

Here's team 95's 2006 Aim High robot, Lilly (whose accuracy is better than it looks, since it had three parallel firing channels):

[Djur]

How accurate was it at 30' though? Aim High had a 30" goal and Rebound rumble has an 18" hoop, so you'd need to be accurate within a much smaller area.

EDIT: Check out this post. It doesn't say how accurate the shooter was, but a 60' shot is pretty good. (19:14 EST)

[davidthefat]

Have you guys considered the fact that only 4 CIMs are allowed this year? Are you willing to sacrifice 2 CIMs to use for a shooter instead of on the drive? Just from past experience, only using one per gear box (6 wheel here, not mech or omni) will trip the amp breaker. We had to gear it lower to actually move and the max FPS we got was about 8-9 FPS. Is that worth it this year? What motors are a good alternate for the shooter? Fisher Price ones?

[Ryan_Davis]

Originally Posted by pfreivald

I think you will see some teams consistently (or nearly consistently) score from just past half-court.

That's frightening.