Varying conditions of the balls

[Grim Tuesday]

So, in our shooter testing and calibration, we discovered that each ball has a different amount of squishyness. Somewhat hard to describe, but to say the effects, the ball we were using for testing went into the basket, and the brand new virgin one hit the ceiling. About 5 feet off. Our conclusion was that balls, throughout the competition will degrade in firmness, but each may degrade in a different way. This makes calibrating a shooter much more difficult. This could and very likely will be a major issue at competitions, when teams tear up balls and new ones are thrown onto the field.

How are you guys, besides the catapult/dumper teams, planning on dealing with this issue? We were prototyping a mechanism that would squish the balls against the side of the robot and detect force, but it was never finished. Has anyone had any luck detecting this decidedly qualitative factor?

[Shaun Coon]

no but we have figured out that with our shooter having 7ish inches between the 8in wheel and our pvc pipe arond 80 20 works wonderfully

[one4robots]

Originally Posted by Grim Tuesday

So, in our shooter testing and calibration, we discovered that each ball has a different amount of squishyness. Somewhat hard to describe, but to say the effects, the ball we were using for testing went into the basket, and the brand new virgin one hit the ceiling. About 5 feet off. Our conclusion was that balls, throughout the competition will degrade in firmness, but each may degrade in a different way. This makes calibrating a shooter much more difficult. This could and very likely will be a major issue at competitions, when teams tear up balls and new ones are thrown onto the field.

How are you guys, besides the catapult/dumper teams, planning on dealing with this issue? We were prototyping a mechanism that would squish the balls against the side of the robot and detect force, but it was never finished. Has anyone had any luck detecting this decidedly qualitative factor?

Team 2530 has also recognized this issue, and we may have dtermined one reason for the variance. The new balls have their coating intact. We believe this makes the ball less squishy because it takes more force to remove the air from inside the ball.

Unfortunately, we have no solutions for how to deal with it. At this point, we are accepting it as a variable outside of our control.

[bfk]

We noticed this too. Older balls have little breaks (or in one case a 2 inch tear) in the outer skin which allows air to escape, thus decreasing squishiness. Not sure what we can do about it. We thought of shining a light on the balls in our ball lifter and using shininess as an approximation of squishiness, but haven't done anything yet.
It was pointed out by others that the balls in the competition are unlikely to be new every round, more likely that the most beat up ones will be replaced as needed. This will probably lead to most of the balls being a bit chewed up, with a few new and a few on their last legs in each round.

[BrendanB]

Simon we have the exact same problem. Older balls will be a swish shot while the new ones go flying over the backboard. We numbered each ball and sent shot each ball several times and got the same results for each ball.

This can get extremely interesting seeing that by the end of build season our balls will be well worn whereas at competition they will be brand new!

[Ben Martin]

Originally Posted by BrendanB

Simon we have the exact same problem. Older balls will be a swish shot while the new ones go flying over the backboard. We numbered each ball and sent shot each ball several times and got the same results for each ball.

This can get extremely interesting seeing that by the end of build season our balls will be well worn whereas at competition they will be brand new!

We also numbered the balls in our lab. Each ball has a different level of "squish" when tested with a 12-pound weight and a different diameter. Each ball generally shoots consistently itself, though when compared against other balls the shots are significantly less consistent.

We did manage to get our shooter up to 85%-ish shooting layups off the backboard using a one-wheel shooter from close range.

[Grim Tuesday]

So now that we have confirmed the problem, lets start brainstorming solutions. My first thought was some sort of lead screw pushing into the ball until a pressure sensor read a certain force, and recording the number of inches of squish. Of course, this is really slow and inconvenient. Anyone else have any ideas? Could we pre-mash up a ball and get it ready to shoot and be consistent?

The other questions to ask are: What curve is there in the squish? Is there a point where balls move from 'hard' to 'squishy'? Or is it some sort of curve, or linear progression?

[Garrett.d.w]

Has anyone tried putting their intake rollers (if that is your chosen method), on springs and measuring deflection as the balls get sucked in?