Re: Shooters vs Arms
 

I can't say for an actual competition scrimmage, but at the scrimmage our team attended (which was really just an endless practice session on a full sized field) the 2 shooter bots totaled well over 20 hurdles, while the 5 or 6 arm bots totaled 1 or 2 hurdles. This might be slightly deceiving though as the shooters are extremely successful veteran teams (39 & 842) while most of the arms were fairly new teams and not yet finished with construction.

The one humongous disadvantage I see against shooter bots is that they don't get the courtesy of protection during hurdling really, as there is no way to judge when they are attempting to hurdle. Standard defensive maneuvers of parking in front of them won't work, but instead it's very easy to push them from behind and not give them a chance to slow down to a speed they want to shoot at, and simply push them past the line so they must go around the field again to hurdle. I also see stealing a ball that has been launched as easier to do than stealing a ball that is just dropped over the overpass.

Honestly I think shooters are a bit easier to defend than arms, so although they may be able to score faster in theory, I think more intense defensive strategies against them will balance out their success.

Re: Shooters vs Arms
 

Please read the thread before posting, this has been posted many times.

Re: Shooters vs Arms
 

He has a point. If the shooter stops and isn't raising the trackball, it can be hit. It won't be protected until the ball starts moving. Whereas, an arm/lift robot has protection until it releases above the overpass (it would be either raising or moving, or both). Just something to think about.

By the way, we are almost to the point where one side or the other will outperform the other. On the whole, they seem pretty even. There are exceptional arm robots and mediocre ones. The same for shooters. We will see what happens with exceptional arm vs. exceptional shooter, mediocre arm vs. mediocre shooter, and one mediocre and one exceptional (both ways).

Prediction: Those robots whose hurdling mechanism is... ummm...shall we say... less than mediocre will quickly find themselves running a lot of laps.

Re: Shooters vs Arms
 

Yes you could. But NON-theoretically speaking you probably would have to sacrifce some pick-up speed for some hurdling speed. :)

Trade-offs trade-offs!

Re: Shooters vs Arms
 

That isn't a flaw against arms at all...

973 has an arm, and at only 2/3 power it easily lifted a 130 pound freshmen.

Re: Shooters vs Arms
 

I would agree that it might be easier to park in front of a shooter...unless it can easily shoot over you. Or into you, if it has no reservations about knocking you over. Also, who says the shooter has to stop or even slow down significantly? And, with an increase of shooting range, it will become increasingly difficult to defend a shooter as you'd have to try to stay within the defensive restrictions for most of the home stretch. Some shooters will not have specific "sweet spots" they must shoot at, or speeds at which they must shoot to be successful, or large restrictions about what kind of space in front of them when they're shooting.

Also...pushing from behind won't work as well on a robot that can get out from in front of you before you touch them. :)

As a general warning, I would ask that teams with large arms or shields who intend on using them to block a shooter take the time to watch that team hurdle a few times before deciding to risk their robot. You could be submitting your arm to quite a large amount of force. I would personally hate to be responsible for breaking, tipping, or otherwise damaging an unwitting opponent, but my team will not hesitate to shoot through a block.

Re: Shooters vs Arms
 

I was referring more to herding only robots (or lap only bots, but not tiny ones with no pushing power) playing the defense, and I assume that most of the herder only bots will be able to outrun their heavier shooter/lifter counterparts. If a herder isn't built for speed I'm not sure what the point of making it was.

I definitely won't advocate trying to block a ball shot from a shooter though. I know I don't want the top of my robot snapped off or lying on the ground.

Re: Shooters vs Arms
 

I agree with this 100%. It doesn't matter how quickly you can hurdle if you have to chase the trackball all over the field. Until you have the ball in your posession, you can't do anything with it.

Re: Shooters vs Arms
 

I belive that the shooter is more efective it the teams that have it have incorperated a system that can also knock the balls off of the overpass because you can always derack a ball and it takes more time to place than hurdle.:cool:

Re: Shooters vs Arms
 

That was Team 980's conclusion - though some of us (including me) liked the idea of "extreme launching" of the balls.

The robot needs to be both agile and powerful to get in position to grab a Trackball. Once in position, a strong and reliable gripper is needed to secure the ball. Once the trackball is in possession it can be fed to a good launcher or just pushed over the overpass. Possession is the key...

Re: Shooters vs Arms
 

The problem with some arms I have seen is their ball graber. They have to line up just right to pick up the ball. Most launchers (including ours) have forks that pivoit back to hold the ball until launch. From testing, we have been able to pick up the ball without stoping (but we did slow down just a little:cool: ).

Re: Shooters vs Arms
 

You make a good point. Our pick-up mechanism can suck in the ball from angles varying up to about 40 degrees to the the side, although a straight shot is always best. If we have a straight-ish shot, we don't need to slow down at all.

I completely agree with everything you just said.

Re: Shooters vs Arms
 

Your not a moderator... if it is your opinion it is a redundant post then please tell the moderators, there job here is to, yes, moderate...


from the scrimmage in suffield I made a couple of conclusions of both shooters and arms.

Arms:
Very open to damage by the overpass
Tended to be slower
Tended to be more tippy

Shooters:
Far fewer shooters overall
Tended to be faster (when they worked)
Tended to be less tippy

Overall though (with the exception of the gaelhawks) I have to say they seemed to be working about the same.

What won and lost was the ability to grab the ball on the move with little effort lining it up.

Re: Shooters vs Arms
 

Summary so far:

Arms:

open to damage near overpass
tend to be slower
tend to be tippy
more of an entanglement risk with other robots
ball alignment during pickup can be too critical and slow
can play a "deny the ball" strategy by herding opponents track ball
harder to block before act of hurtling
can block from behind overpass
can easily place the ball on the overpass
can easily remove trackball from overpass
can be in possession of track ball at end of hybrid



Shooters:

can score faster and on the run
usually faster on the track due to lower CG
seem to be fewer shooters than arms
tend to be less tippy
greater track ball pick up range and speed
many not good at herding for defensive purposes [opponents ball]
can not possess track ball immediately after hybrid period
many less effective at removing trackball from overpass
less effective at placing track ball on overpass


but again then, who says an arm can't shoot!!! ;)

http://youtube.com/watch?v=N1BZAsH-RYA

Re: Shooters vs Arms
 

Our team uses an arm to get the ball up and uses a pneumatic 'poker' to actually hurdle the ball.

Our main problem is not getting the arm caught on the overpass, which isn't really a problem in driver-controlled mode, but is a problem for autonomous. We've also had some minor issues with tipping over (only under extreme circumstances), but since our robot only weighs 88 lbs, we are planning on adding at least 20 lbs of ballast.