FRC 1058, the PVC Pirates Shooter

[Brandon Zalinsky]

the 1 wheel shooter than has been prototyped and is now consistently scoring... here ya go!

http://www.youtube.com/watch?v=MwVhQSd1TXw

[Daniel_LaFleur]

Originally Posted by Flak-Bait

the 1 wheel shooter than has been prototyped and is now consistently scoring... here ya go!

http://www.youtube.com/watch?v=MwVhQSd1TXw

Looks great guys.

can't wait to see y'all at GSR

[RB73]

Im curious, our team is doing something similar, but we are having some trouble finding a release point for the ball to make it go high enough. Could you provide some dimensions?

[pfreivald]

I hate to be a party pooper, but I have some questions. (These are aimed at making y'all think about these things if you haven't, as well as satisfying my own curiosity).

How are you aiming it? Can you achieve that kind of accuracy with human or robot control?
How are you determining range?
Have you tried it with more than one ball at a time? More than two? Three?
Why the heck aren't you wearing safety glasses?

And all that said -- GREAT JOB! That's awesome consistency from your upper mechanical team!

[ToddF]

Very nice. It's good to see something a little different.

[Brandon Zalinsky]

Originally Posted by pfreivald

How are you aiming it? Can you achieve that kind of accuracy with human or robot control?

It will be on a 240 degree turret. It is possible, the turning of the turret will be geared down heavily to give us errors of less than half a degree (I believe). The only problem will be that the turret will be dreadfully slow traversing, but that's a sacrifice we're willing to make. We'll be tracking the vision targets for distance and angle. We have a great system for tracking the vision targets, but I can't tell you all our secrets!

Originally Posted by pfreivald

How are you determining range?

We'll take measurements of the size of the vision target and work off that. I don't do code, so I'd have to speak to someone else on the team.

Originally Posted by pfreivald

Have you tried it with more than one ball at a time? More than two? Three?

Only one ball at a time. It takes about 3 seconds to spin up after firing. This is a fixable problem that we can work on.

Originally Posted by pfreivald

Why the heck aren't you wearing safety glasses?

I always do (Bruins shirt, white hat in the second half/longer range part of the video). Most of our members use the ones that the school's metal shop has, however, that day, the shop teacher decided to lock them all in a cabinet. Most of the members have their own now, this video was taken a week ago.

Thanks for the input!

[Ty Tremblay]

Originally Posted by Flak-Bait

Only one ball at a time. It takes about 3 seconds to spin up after firing. This is a fixable problem that we can work on.

Have you considered giving your wheel more inertia? You could put two flywheels (one on each side of the shooter wheel). This will help keep your wheel up to speed when shooting, reducing spin-up time as a result.

NOTE: This would be between-ball spin-up time. Initial spin up time from 0rpm would be increased, but you just have to find a balance between the two.

[Brandon Zalinsky]

Originally Posted by Ty Tremblay

Have you considered giving your wheel more inertia? You could put two flywheels (one on each side of the shooter wheel). This will help keep your wheel up to speed when shooting, reducing spin-up time as a result.

We were talking about this last night, as a matter of fact. The only reservation we have is that we don't know if it's worth it to put another CIM on the shooter. Would the time we save be worth the extra energy it sucks up?

[Aur0r4]

The tradeoff with a flywheel is that you have to invest more energy to start it (longer initial spinup) and to keep it going (marginally increased drag through the bearings). The benefit, like you said, Ty, is that you can fire off multiple balls faster.

The advantage of a lighter wheel with more motors is that you have the whole apparatus on for less time, and recovery can be just as fast because the moment of inertia is less. Of course, you're dragging around more weight and have to be a bit clever with allowing the motors to share the load consistently.

Our decision may depend on how the guidance system responds or what our game strategy is. If we take a while to lock on, we might want to be able to fire multiple balls quickly to take advantage of the target window. If our vision system and turret swing is quick, we may go with two motors and a quick spinup for a more drive-by approach.

We'll see! There's always multiple solutions...

[DavidGitz]

Originally Posted by Flak-Bait

We were talking about this last night, as a matter of fact. The only reservation we have is that we don't know if it's worth it to put another CIM on the shooter. Would the time we save be worth the extra energy it sucks up?

I think what he was suggesting was to put another wheel on your shooter, not another motor.

[Aur0r4]

We already chose the 1whl design over a 2whl design. Last night we were discussing options to reduce spin-up between shots, and one of the options was adding another CIM to have two CIM's running the single wheel.

The two sides essentially boil down to making more power available, or storing energy in a flywheel. Having built both before, we are familiar with the issues of each. Flywheels are great, but must be balanced. Extra motors add oomph, but must not fight each other which can add inconsistency. Neither are major issues, but simply part of the design considerations.

[Ty Tremblay]

Originally Posted by Flak-Bait

We were talking about this last night, as a matter of fact. The only reservation we have is that we don't know if it's worth it to put another CIM on the shooter. Would the time we save be worth the extra energy it sucks up?

That's another approach. You can either prevent (reduce) the single shooter wheel from slowing down during a shot with added inertia, or let it slow down but give it the power of an additional motor so that it can get back to speed faster.

If I were to go with the second option, I don't think I'd use two CIMs (not unless you want to shoot from the pits). Two FPs are more powerful than one CIM, but mounting these would require a complete rework of the shooter you have that already works. You guys are on the right track and always seem to produce awesome capable robots. You'll figure it out.

Originally Posted by Aur0r4

The tradeoff with a flywheel is that you have to invest more energy to start it (longer initial spinup) and to keep it going (marginally increased drag through the bearings). The benefit, like you said, Ty, is that you can fire off multiple balls faster.

The advantage of a lighter wheel with more motors is that you have the whole apparatus on for less time, and recovery can be just as fast because the moment of inertia is less. Of course, you're dragging around more weight and have to be a bit clever with allowing the motors to share the load consistently.

Our decision may depend on how the guidance system responds or what our game strategy is. If we take a while to lock on, we might want to be able to fire multiple balls quickly to take advantage of the target window. If our vision system and turret swing is quick, we may go with two motors and a quick spinup for a more drive-by approach.

We'll see! There's always multiple solutions...

My sentiments exactly.

(An aside: 1058's ball catching robot in 2004 was my favorite robot at BAE that year. Is that were you got the team name?)

[Brandon Zalinsky]

Originally Posted by Ty Tremblay

(An aside: 1058's ball catching robot in 2004 was my favorite robot at BAE that year. Is that were you got the team name?)

Yep, good memory! This year's robot is shaping up to live up to our name again, though!

[adf0221]

How high off the ground is the shooter? Is it within the height restrictions when its behind the bump?

[Brandon Zalinsky]

Originally Posted by adf0221

How high off the ground is the shooter? Is it within the height restrictions when its behind the bump?

It's just on top of our toolbox, so that won't be the final height, but yes.