Re: Upside down Frisbees; can your team get them out?
 

I was going to start a thread about upside-down discs, but remembered to search. Then I found this one. And decided to revive it.

Other than the teams mentioned, can you shoot discs upside down? Do you have a mechanism to flip them around/eject them?

My team can't shoot them upside down and doesn't have a way to get them out. We can try flipping the robot to get them out, but it hasn't worked if my memory serves me correctly. (happens within the first minute of teleop)

Also, could you describe why it doesn't shoot correctly? Ours has something to do with the mechanism that pushes our discs into our wheel, it can't catch the edge of it properly.

Re: Upside down Frisbees; can your team get them out?
 

Upside-down discs jam our shooter-loader piston and we have no way to eject them. Our floor pickup, however, will not pick them up.

Re: Upside down Frisbees; can your team get them out?
 

Our shooter is incompatible with upside-down discs. Our feeding mechanism, a shark fin shape actuated by a pneumatic cylinder, is designed to stay low and catch the bottom edge of discs that it feeds forward while also being able to slide backward when the next discs falls into place without snagging them. Unfortunately, its low profile means that it doesn't catch the rounded edge of upside-down discs and instead slides right under them.

After spending a season watching our offensive capabilities end during matches because of upside-down discs in our hopper we finally decided to add a flipper during IRI. We finished adding a 2 inch stroke pneumatic cylinder beneath our shooter with 2 matches to go. We inadvertently mounted the cylinder at a slight enough angle that it doesn't just push the discs up but, instead, flips them over.

We never used it during a match.

Re: Upside down Frisbees; can your team get them out?
 

At one point in time, our floor pickup could pick up upside down disks. Since then its been changed and somewhere along the lines it started rejecting them. However, once they are in, we have no problems jamming (because we don't stack frisbees, we store them in a line) and can shoot them exactly the same way as normal frisbees. We also mechanically have the ability to differentiate between right side up and upside down, but we never put it to use in code. All of this is possible because of a flange sticking out of the middle of our frisbee path which forces regular disks to be flat on the floor and upside down ones to be pushed up against the ceiling.

Re: Upside down Frisbees; can your team get them out?
 

Since we use an air cylinder shaft to catch the lip of the disc to send it on its way we, at first, could not eject an inverted disc.
After BMR I came up with the L.I.F.E. wedge.
Little
Inverted
Frisbee
Ejector

It pushes the inverted disc into the shooting wheel and ejects it. The disc doesn't fly far but it comes out screaming. At CRR we ejected an inverted disc at out opponents plexiglas and scared the #@*% out of them :D

Re: Upside down Frisbees; can your team get them out?
 

Could you post some pictures of the L.I.F.E wedge, and maybe video of matches where it can be seen being used?

Re: Upside down Frisbees; can your team get them out?
 

We human load, so we really didn't care to test it or anything. If an upside down disc ends up in the shooter, someone seriously messed up.

I imagine it could probably clear since we just push the disc from behind. Probably wouldn't fly well though.

Re: Upside down Frisbees; can your team get them out?
 

1310 had this issue all the way up until after the first match at champs. That was the only qual we lost, as we jammed at about the 1:40 mark, and ended up loosing by 2 points. Had it not been for that jam, we would have had #1 seed on curie, and things on that field would have been totally different.
http://www.youtube.com/watch?v=rfqeoMx0GeI
4814 pushes us into an upside down disk, then the wall. we normally cant pick up upside down ones, but with the walls help it went in at 1:36. it has difficulty going through the pickup, but makes it out the top from 1:36-1:39. we fire the 2 disks we picked up before that, then we jam for the rest of the match. If you cant tell, i have watched this match in detail multiple times to see exactly how it happened.

First a little background.

Our hammer (the part that pushed the Frisbee into the wheel) engages the outer edge of the Frisbee, and is powered by a spring out, air in piston. our hammer is a bent piece of 1.5" wide, 1/16th aluminium. The bend on the top was just enough to lift an upside down Frisbee, as it impacts right at the curve. this would cause our robot to be a glorified "dishwasher" as our students called it. We came up with the solution before champs, but reluctant to change things, we didn't implement it, as it had only happened once or twice all season. It was such a simple fix, and i bet it would work for any team with this issue and an external hammer.

The solution? A self tapping screw at the right height through our hammer. It is sharp enough to catch the rounded edge of the Frisbee, and eject it. the first time we tried it, it was magic. consistent ejection of upside down Frisbee's at a minimal weight gain. The screw needs to be for wood, as the tip is sharper.

Re: Upside down Frisbees; can your team get them out?
 

We have had minimal issues shooting upside-down discs. Once, an upside-down disc melted a piece of thin lexan that prevents misfires. Another time, it just ejected and fell out of the shooter right in front of the robot. The third time(at IRI) It went just like any other disc. Take a look at 1592's bot- they actually shot them upside down intentionally. They were the only team I saw all year who tried to do that.

Re: Upside down Frisbees; can your team get them out?
 

The bot preferred to pick them up upside down because the loader would flip them over before it shot but picking them up upside down or right side up didn't matter because it could gather and shoot both ways.

Re: Upside down Frisbees; can your team get them out?
 

During build season, I was designing a flipping mechanism in the conveyor system and it worked flawlessly. However due to size constraints in our chassis we had to scrap that design. :/ For our shooter on the other hand if there is an upside down frisbee in there we are doomed for the rest of the match and are forced to play defense.

Re: Upside down Frisbees; can your team get them out?
 

Our hopper is incompatible with inverted disks. They don't seem to settle right in the bottom. The shooter will shoot them, its just a matter of moving the disk the .5 inch from the hopper to the shooting wheel. We can sometimes accomplish this by running into the wall at a high rate of speed (how we cleared most jams actually) XD

This, fortunately, didn't happen too many times. We only human fed. The single time it did happen was during a practice match when we wanted to see what happened.

Edit: Obligatory 300th post edit :)

Re: Upside down Frisbees; can your team get them out?
 

We actually can't eject discs....and I really wish we could...once we get an upside down one we're done...time to go hang on 10pts. :/ Thankfully that's only happened three times during matches!

Re: Upside down Frisbees; can your team get them out?
 

[quote=Garrett.d.w;1287607]The shooter will shoot them, its just a matter of moving the disk the .5 inch from the hopper to the shooting wheel. We can sometimes accomplish this by running into the wall at a high rate of speed (how we cleared most jams actually) XD
/QUOTE]

Running into the wall is an interesting way to do that!...noted

Re: Upside down Frisbees; can your team get them out?
 

We eject them out of the side using our normal shooting mechanism. We've never had to do it since we human load, but we included it just in case our human player screwed up anyway.