Shooters: What have you learned?

[Grim Tuesday]

I doubt that next year will be a shooter game, but I can guarantee that some years down the road, there will be another year where a shooter is the de facto method of scoring. I hope this thread will be useful to teams when that year does roll around!

So what less than (or more than) obvious facts have you learned about shooter design this year? What problems did you run into that you weren't expecting, and how did you fix them?

I'll start off: Make a single axle shooter if you want backspin. And if you make one with two axles, make an easy way to adjust the squish and make it easy to take apart. Because you'll be doing a lot of that.

[jblay]

Backspin is nice, try to have it.

Don't put used wheels on your shooter, it's a dumb move.

Prototype your idea thoroughly, don't just assume it will work because you see that every team has built a shooter prototype that works.

[jspatz1]

Originally Posted by jblay

Don't put used wheels on your shooter, it's a dumb move.

Ummmmm......maybe not so dumb.

[Lil' Lavery]

Originally Posted by Grim Tuesday

I'll start off: Make a single axle shooter if you want backspin. And if you make one with two axles, make an easy way to adjust the squish and make it easy to take apart. Because you'll be doing a lot of that.

1712 had no issue getting backspin using a dual-axle shooter. We had each axle controlled independently so we adjust the backspin, but you could also find the ideal ratio and gear them to it. We never really adjust our backspin, so that capability is not the most useful in the world.

[Rizner]

One thing to keep in mind when prototyping is the amount balls squish change the distance they go (at least for this year/this type of ball), so to build a prototype which can quickly go from one distance to another can help see what you want to do. For us we had a top shield and bottom shield, with a space between the bottom shield and the shooter wheel to make contact with the ball and different amounts of spacers between the top and bottom shield to adjust the amount of space between the bottom shield and the wheel.

Not sure if that makes sense but hopefully it does.

[waialua359]

Originally Posted by jspatz1

Ummmmm......maybe not so dumb.

Darn, I guess we'll scrap ours as well.

[efoote868]

The theory I learned in Feedback System Analysis and Design actually works.

[jwfoss]

Consistent feed and positioning of the ball as it enters the shooter is absolutely critical. Our initial design allowed the ball to move left and right in the lift ~1/2" each way, after adding guides (and inducing a slight amount of lateral compression in the ball) we noticed a large increase in our accuracy.

For reference our shooter is a hooded shooter, 2 6"x1.5" colson wheels ~1.5" apart, and between 1"-1.5" in compression.

[thefro526]

Originally Posted by jblay

Don't put used wheels on your shooter, it's a dumb move.

This depends on the wheel, I guess.

Many teams using 2008/2010 KOP wheels on their shooters found it necessary to remove the crowns left on the wheels from the molding process, essentially breaking in the wheel before use.

Though, I know of a team using 2006 KOP Skyway wheels that ran into Issues with them wearing over the course of the season and losing grip.

[smistthegreat]

We're using this year's kit wheels, right out of the box, with no problems with wear after 2 events. I guess it all depends on your set up. Prototype, prototype, prototype!

[CalTran]

Consistent feed and positioning of the ball as it enters the shooter is absolutely critical. Our initial design allowed the ball to move left and right in the lift ~1/2" each way, after adding guides (and inducing a slight amount of lateral compression in the ball) we noticed a large increase in our accuracy.

^Truest statement I've ever heard.

Some balls lose their squish...and other balls just don't like to be squished all that much.

If the game requires precision distance shooting, do us all a favor and get the design done so you can tune said design. Just ramping up the power does NOT equate to making a shot.

Oh, and if you're using heavy, custom fab wheels, make sure the motors you pick have enough power to make them go...

[Hawiian Cadder]

Consistency can be gained through LOTS of compression. We ran our competition robot with 4-5 inches of it in order to ensure precision.

[Bongle]

Don't solid-mount your gyro to your turret or other vibrating chassis components. Use a soft material that will damp vibrations. Note: we only learned this yesterday, when we took the time to do proper analysis on our gyro's heading over time. Makes it hard to auto-aim straight if your gyro starts drifting about 1deg/sec when the shooter turns on.

[LeelandS]

Since I'm looking to mentor new teams next season, these are the things I'll be bringing if a shooter game comes back up:

• Lighter wheels - With lighter wheels, the wheel will be back up to speed faster. This is especially necessary if you're using a motor with less torque and power to run the shooter wheel.
• More time on programming - Shooters are almost definitely the best way to score this year, but a lot of shooters aren't used to their full potential because the programming wasn't up to par. Spending more time on the target tracking algorithm can allow a shooter to be very succesful.
• Watch the weight distribution - Our robot this year is a bit top heavy. That's being worked on and resolved for champs, but it hurt us at FLR. When designing a shooter in the future, I'd like to make sure the shooter doesn't have an uneven weight distribution. This prevents disadvantages in game situations such as the bridge, and prevents the robot from rocking and potentially tipping as it moves.
• Responsive, consistent turret - Part of the key to succesful shooting is having a quick, responsive turret to shoot at the proper angle to meet your target. With a turret that has the proper hardware and coding, shooting can be made greatly effective.
• Make sure the ball enters the shooter quickly and consistently. We have a nasty habit of coming up with some unnecessarily complex storage-to-shooter designs. With some thought, I think there could be a quicker, more consistent way of getting the balls into the shooter.
• Don't let the balls enter the shooter at an angle - Without making sure of this, balls may enter (and come out) at an angle, or not get into the shooter at all.

These things aren't NEEDED for a good/great shooting robot, but they are things I'm going to greatly consider next time there is a shooting game.

[pfreivald]

Originally Posted by Leeland1126

[*]Lighter wheels - With lighter wheels, the wheel will be back up to speed faster. This is especially necessary if you're using a motor with less torque and power to run the shooter wheel.

Interesting... If our shop wasn't getting knocked down next week (and rebuilt hopefully by September) we were going to add a bunch of weight flywheel-style to our shooter to see if that increases accuracy!

Also, this is just an anecdotal observation, but single-axle hood shooters seem to be much more reliable than double-axle shooters.