UpsideDown Frisbees

[apples000]

Our team's been having some trouble figuring out how to pick up the frisbees from the ground. If we're picking up one in a corner, we'll need a sensor to tell if it's upside down then flip it if needed. Has anybody come up with a good way to flip/detect a flipped frisbee yet?

[Gregor]

How do you know you need to flip them?

[Sean Raia]

Shoot them vertically :yikes:

[elsenor]

Shoot them vertically :yikes:

Shooting them parallel to the ground will just bother you more than help you. However, shooting it vertically shouldn't cause a lot of problems because the wheel would only be touching the sides of the frisbee, not the faces.

[cgmv123]

How do you know you need to flip them?

Because they don't fly nearly as well when they're upside down.

[Gregor]

Because they don't fly nearly as well when they're upside down.

Who said they need to fly? Do you have a prototype shooter yet? How do you know they don't fly nearly as well upside down? Do you see my point?

[tj1673]

I'm not entirely sure of the disc that is actually being used because I have not gotten to see one yet, but, from playing Ultimate Frisbee, I can say that frisbees do NOT fly well upside down (unless you bomb them, which is terribly inaccurate and has poor consistency). Now, I'm not sure how well they would work out of a shooter, but I imagine that even with a consistent machine, they won't fly well upside down.

[Andrew Lawrence]

In some tests today, we found a correctly launched frisbee flies perfectly well, upside down or right side up.

[tj1673]

In some tests today, we found a correctly launched frisbee flies perfectly well, upside down or right side up.

Hm. Never would have guessed that. Good to know!

[ehfeinberg]

In some tests today, we found a correctly launched frisbee flies perfectly well, upside down or right side up.

Being an Ultimate Player, I can say that disc's do fly differently if they are upside down. When a disc is upside down, it tends to not fly as far and floats more. Also, a Frisbee thrown upside down tends to wobble to either side.

Because of this, a disc is only thrown upside down in Ultimate if the thrower wants the disc to float down slower. This technique (either through a hammer/thumber/scoober) is often used to get the disc around/over a cup.

When we go to competition, many of the human players will be throwing these types of throws in order to get the disk over the 8 foot high wall. With the float these throws generate, it is extremely difficult to get the disk into a vertical target. This makes the chance of a human player scoring next to nothing.

[tj1673]

Being an Ultimate Player, I can say that disc's do fly differently if they are upside down. When a disc is upside down, it tends to not fly as far and floats more. Also, a Frisbee thrown upside down tends to wobble to either side.

Because of this, a disc is only thrown upside down in Ultimate if the thrower wants the disc to float down slower. This technique (either through a hammer/thumber/scoober) is often used to get the disc around/over a cup.

When we go to competition, many of the human players will be throwing these types of throws in order to get the disk over the 8 foot high wall. With the float these throws generate, it is extremely difficult to get the disk into a vertical target. This makes the chance of a human player scoring next to nothing.

About what distance does it take for the hammers/bombs to level out when thrown "correctly"? Would it be feasible to throw them as a hammer and have them land in the alliance pyramid after leveling out?

[ehfeinberg]

About what distance does it take for the hammers/bombs to level out when thrown "correctly"? Would it be feasible to throw them as a hammer and have them land in the alliance pyramid after leveling out?

It defiantly is feasible for a Hammer hit/land in the top of the alliance pyramid. I could probably hit the goal pretty often. However, there is a pole and chain in the middle of the goal, with a piece of polycarb on top of the pole. This thing will cause a lot of the discs bounce right out. Also, I don't know how high the walls are for the goal, but most likely the disc would just the bottom of the goal and bounce out.

Clever idea, and I'll try my luck at accomplishing this feat.

[ProgrammerTori]

Shooting them parallel to the ground will just bother you more than help you. However, shooting it vertically shouldn't cause a lot of problems because the wheel would only be touching the sides of the frisbee, not the faces.

Remember the high goal is only a foot gap. The frisbee I think is approximately that size as well. If you shoot the frisbee vertically, getting a 12 in frisbee through a 12 in slot doesn't seem very likely. Shooting vertically will limit you to shooting at the mid goals or lower.

[protoserge]

Do you even need to pick them up? Make sure you take into account time to pick up, orient, store, retrieve your next frisbee and score vs. getting a full load from the feeder, getting to position, scoring, then returning to the feeder.

You may find that picking frisbees up is not worth the time and effort.

I'm not saying one way is incorrect, only that there are many things that should be considered when making decisions on how to play the game.


To help answer your initial question: have you touched/felt/manipulated an actual game piece yet? That will tell you pretty quickly how to go about what you want to be done, then you convert what you would do into machine motion.

[Daniel_LaFleur]

Remember the high goal is only a foot gap. The frisbee I think is approximately that size as well. If you shoot the frisbee vertically, getting a 12 in frisbee through a 12 in slot doesn't seem very likely. Shooting vertically will limit you to shooting at the mid goals or lower.
The disc is 10 5/8" and will fit nicely vertical in the upper goal, and may actually be able to skip in when it hits the top/bottom.

Do you even need to pick them up? Make sure you take into account time to pick up, orient, store, retrieve your next frisbee and score vs. getting a full load from the feeder, getting to position, scoring, then returning to the feeder.

You may find that picking frisbees up is not worth the time and effort.

I'm not saying one way is incorrect, only that there are many things that should be considered when making decisions on how to play the game.


To help answer your initial question: have you touched/felt/manipulated an actual game piece yet? That will tell you pretty quickly how to go about what you want to be done, then you convert what you would do into machine motion.

Considering the travel time to/from the loading zone and the number of discs that will be on the floor due to missed shots, it may be worth while to pick up from the floor (this, of course, assumes an efficient way of picking the disc from the floor).

In the end, your strategy/capabilities should drive this part of the design.

[Joon Park]

Another ultimate player here, completely agree with what ehfeinberg has been saying. Because ultimate is played more by the robotics population than basketball we'll see more "hail mary"s make it into the goals, but not much more. I wouldn't count on it being something you see every game; far from it, in fact.

Also, the 5 point goal is very misleading if you've ever played disc golf. In disc golf, if you hit the pole with the chains, you're pretty much guaranteed that it will fall in the goal. Here, that is not the case because of the different dimensions and the fact that a robot will be throwing them.

[DonRotolo]

from playing Ultimate Frisbee, I can say that frisbees do NOT fly well upside down (unless you bomb them, which is terribly inaccurate and has poor consistency). Now, I'm not sure how well they would work out of a shooter, but I imagine that even with a consistent machine, they won't fly well upside down.
Being an Ultimate Player, I can say that disc's do fly differently if they are upside down. When a disc is upside down, it tends to not fly as far and floats more. Also, a Frisbee thrown upside down tends to wobble to either side.
Ah, but what it you want to throw them only about 15 feet? Are the trajectories similar enough (or can be compensated) that it'll score in THIS game?
Do you even need to pick them up?

<snip>

You may find that picking frisbees up is not worth the time and effort.
Seriously? You seem to have concluded that it will be difficult to pick up frisbees, the floor won't be littered with them, and the cruise back to your feeding station will be both fast and easy.

I am sorry but I have to disagree on all points. Teams that can't pick up won't be in the top 1/3 of all teams.

[protoserge]

Seriously? You seem to have concluded that it will be difficult to pick up frisbees, the floor won't be littered with them, and the cruise back to your feeding station will be both fast and easy.

I am sorry but I have to disagree on all points. Teams that can't pick up won't be in the top 1/3 of all teams.

In all my time in FIRST, I have learned to never discount a single game play methodology when discussing how to play the game.

[ehfeinberg]

Ah, but what it you want to throw them only about 15 feet? Are the trajectories similar enough (or can be compensated) that it'll score in THIS game?

When I throw a disk upside down (a scoober) I can normally get the disk to travel 15-20 feet strait. But there is often much wobble on its way there.

Taken from Wikipedia itself

Upside-down
A disc thrown upside-down has a very different flight path than one thrown right-side up. The lift force does not enforce stable flight as it does on a right-side up disc, resulting in a more of a parabolic arc in flight. As with a right-side up throw, however, the flight path of the disc will curve toward the lower edge. This banking effect is most pronounced when the disc is at a 45-degree angle, and less pronounced when it is near-vertical, or near-horizontal.
Gyroscopic precession causes the disc to rotate toward horizontal through its flight path. Unlike a right-side up throw, however, an upside-down disc will not precess toward a stable flat state, and will in stead oscillate past horizontal and begin to bank in the opposite direction. This shuttlecock-like effect is known as "helixing", and is generally avoided due to the difficulty in controlling a helixing flight path. For this reason, an upside down throw is typically released with either clockwise rotation and the left edge up, or counterclockwise rotation and the right edge up. The longer the disc is expected to remain in the air, the closer to vertical it must be at release to avoid the helixing effect.

[Steven Donow]

In all my time in FIRST, I have learned to never discount a single game play methodology when discussing how to play the game.

In my opinion, when thinking about not designing with the ability to pick discs off the ground, there will be at least 1 extremely successful robot that isn't designed to pick discs up(much like 1503 in 2011). However, I believe that the majority of teams that can't pick up off the ground will have little success.

[slijin]

When I throw a disk upside down (a scoober) I can normally get the disk to travel 15-20 feet strait. But there is often much wobble on its way there.

I agree that scooper shots are much more wobbly and less stable than a normal back or forehand, but also remember that when we toss discs, the grip, flick, and arm motion all come into play. Depending on how a robot scores discs, the orientation may or may not be as critical.

[Jedward45]

However, I believe that the majority of teams that can't pick up off the ground will have little success.

I would not be so quick to rule out feeder-fueled bots. This game is a different animal than Logomotion or Lunacy.

The restrictions this year on entering game pieces changes that dynamic. Because frisbees cannot be thrown until last 30 seconds (when pyramid climbing likely reduces frisbee demand), the only remaining frisbees (excluding feeder frisbees) are the 28 initially on the field. Splitting this amount between two alliances, and assuming 50% are made, leaves 7 frisbees per alliance on the turf for robots to collect. Clearly, some of the remaining 90 white disks will need to be fed through feeder slots.

-Not to mention, frisbees may end up upside down or otherwise inaccessible

[sanddrag]

Teams that can't pick up won't be in the top 1/3 of all teams.How do you figure? There are 45 alliance station discs across 3 teams. That makes for 15 per team. That's only one disc per team short of 4 loading/firing sessions of 4 discs per session. If you figure 20 seconds round trip per loading/firing session, that's 80 seconds of the match used up, plus 5 seconds for getting out of auton position and into loading position for the first time, leaving 35 seconds for hang and colored scoring. The absolute best teams will get one or at most two more firing sessions in. I think a majority of qualification matches will not deplete the alliance station supply of white discs.

[falconmaster]

Our team's been having some trouble figuring out how to pick up the frisbees from the ground. If we're picking up one in a corner, we'll need a sensor to tell if it's upside down then flip it if needed. Has anybody come up with a good way to flip/detect a flipped frisbee yet?

We were playing with the frisbees a lot today and we play Ultimate and frisbees rarely land upside down. Could be wrong, but that is what I see...

[Teamcodeorange]

I hope that upside-down shooting is easy, so we won't have to automate disc flipping. :p

[PayneTrain]

I am sorry but I have to disagree on all points. Teams that can't pick up won't be in the top 1/3 of all teams.

To be fair I feel like a similar battle cry was echoed in 2011 only to witness* one large exception.

What I would suggest to teams is to spend a little bit of time trying to figure out the scope and flow of the game.

The challenge is your enemy. Know your enemy. Week Zero (Saturday/Sunday/Monday) is not a time to determine your strategy, fixate on nonessential rules (someone asked me about bumpers today. Don't ask me about bumpers until a host of other decisions are made in conjunction).

If you can afford it, maybe go out and buy some discs, construct makeshift obstacles as stand ins for the pyramids. Get with a team of students on rolling office chairs or push around some old robots on some carpet with all of these elements to feel out the game. You think about a lot of things when you become an active participant when creating a scenario based off the game. You get a sense of the game.

For example, teams will easily fall victim to the misconception that the field area is roughly equivalent to the Louisiana Purchase. If you take time to create a tactile or even make good use of the virtual simulation, you will find the "laws" of the game. The laws of the game are played out in the nature of the challenge and are not written in the rule book (like the field littered with more discs than an unkept gym closet). Discovering the laws after your robot is locked up does not a successful season make.

This would all possibly be better addressed in the general strategy thread we have already, but you can't steal second base if you haven't even left the batter's box.

For now, get some sleep for me while I wish you all good luck!

[wasayanwer97]

Though teams who have tested seem to report otherwise, it would seem that even if upside down discs didn't fly well, it would be easy enough for a shooter to just send it into the low goal for a quick point.

They are relatively easy to flip over though. Rolling a cart over it often flipped it back over. Perhaps just driving over one might do the same? You'd have to be careful for warping though...

[Joon Park]

In my opinion, the orientation of the Frisbee, either during launch or in flight, doesn't really matter if you're doing anything in the realm of less than 2ft. But I wouldn't really consider that "throwing," more of "lobbing" the disc.

If you're actually considering successfully and accurately throwing the disc over some significant distance, I can't imagine the discs being oriented any other way than right side up and being give a whole lot of spin: the way they're meant to be thrown.

[=Martin=Taylor=]

(The real question......












....which I was hoping this thread would answer)

Who has tried driving over flipped/rightsideup disks?

[Racer26]

Teams that can't pick up won't be in the top 1/3 of all teams.

Oh 1503, feel like showing Don your 2011 results? I seem to recall the same arguments being raised about your robot, and you have 2 more Blue Banners to show for it.

Don, I wouldn't be so sure. There's 51 DISCS in the ALLIANCE STATION. I think most teams won't be able to reliably hit their 17, never mind be able to pick up off the floor in a reliable manner that is efficient for feeding their shooter, within the new reduced robot envelope.

I MIGHT actually go so far as to say that many of the topmost teams won't have floor pickup. Throwing frisbees is a much different animal to throwing compliant things like foam balls. I think the robot-fired full court shot will play a significant role this year. If I can park my super-reliable full-court shooter in front of a FEEDER STATION, and just fire all 51 DISCS into a goal from there, I'm gonna win most Qualification matches.

[waialua359]

I would not be so quick to rule out feeder-fueled bots. This game is a different animal than Logomotion or Lunacy.

The restrictions this year on entering game pieces changes that dynamic. Because frisbees cannot be thrown until last 30 seconds (when pyramid climbing likely reduces frisbee demand), the only remaining frisbees (excluding feeder frisbees) are the 28 initially on the field. Splitting this amount between two alliances, and assuming 50% are made, leaves 7 frisbees per alliance on the turf for robots to collect. Clearly, some of the remaining 90 white disks will need to be fed through feeder slots.

-Not to mention, frisbees may end up upside down or otherwise inaccessible

Soo many truths to your statements. ;)

[ratdude747]

(The real question......












....which I was hoping this thread would answer)

Who has tried driving over flipped/rightsideup disks?

I'd have to see the exact frisbees this year, but I have a feeling that some cracked plastic might be involved.

[Paul Copioli]

Teams that can't pick up won't be in the top 1/3 of all teams.

Wanna bet? Case of mountain dew.

[jhusser]

Are team decided to pick up any frisbee no matter if its upside down or not. When we run into an upside down frisbee it would be easier to put it in the lower goal for one point instead of worrying about flipping it or shooting it upside down. You can drive up to the low goal and easily shoot them in and get an almost guaranteed point which is better than nothing.

[Anupam Goli]

I think the robot-fired full court shot will play a significant role this year. If I can park my super-reliable full-court shooter in front of a FEEDER STATION, and just fire all 51 DISCS into a goal from there, I'm gonna win most Qualification matches.

Don't give 469 any ideas. They might just end up doing this. Heck, I'm going to guess now that at least one team attempts this, and at least one team succeeds.

[ProgrammerTori]

I would not be so quick to rule out feeder-fueled bots. This game is a different animal than Logomotion or Lunacy.

The restrictions this year on entering game pieces changes that dynamic. Because frisbees cannot be thrown until last 30 seconds (when pyramid climbing likely reduces frisbee demand), the only remaining frisbees (excluding feeder frisbees) are the 28 initially on the field. Splitting this amount between two alliances, and assuming 50% are made, leaves 7 frisbees per alliance on the turf for robots to collect. Clearly, some of the remaining 90 white disks will need to be fed through feeder slots.

-Not to mention, frisbees may end up upside down or otherwise inaccessible

I do agree that the feeder slot will be the main source of frisbees this year, but don't think a robot who can't pick frisbees of the field won't be useful. Say a shooter on either team misses. Having a robot who can pick up missed frisbees can make up the difference in a game. If a team does figure out how to pick up the frisbees it could be a last minute game changer between two teams of equally shooting capabilities. I'm assuming a wash in the endgame, and both teams shoot pretty quickly. We all can probably guess a God not will be able to shot all 45 of their feeder frisbees pretty well.

One last note, game objects are limited this year more than they have been in the past. Last year, the balls returned to us, and in logo motion, number of game objects was irrelevant because there was only so many hooks. Make every frisbee count, and don't leave it to chance knowing both teams have an equal number of frisbees. What you can take away from them will be as vital as what we can score.

[Ian Curtis]

I am sorry but I have to disagree on all points. Teams that can't pick up won't be in the top 1/3 of all teams.

Man 25 in 2006, that team was awful! :D

I think the implication of Paul's challenge is that you can be very good and not pick up. But another thing you have to realize is that the bar to be in the top 1/3 of teams is actually set fairly low. By OPR last year if you scored your starting balls (even in teleop) and balanced you are well into the top 1/3.

[Jedward45]

I do agree that the feeder slot will be the main source of frisbees this year, but don't think a robot who can't pick frisbees of the field won't be useful.

Certainly a robot capable of collecting and/or flipping discs would be valuable, nobody denies that. The question is how much weight, manpower, space, and motors are you willing to sacrifice, and how much will you realistically be gaining from that sacrifice.

For some experienced teams it may be cost-effective to use a collecting system, but for the vast majority, the trade-off my not be in their favor.

[Alex.q]

I would think that if I had two strong shooters on my alliance, I would want at least want 1 floor picker to balance the alliance. Even if my two shooters are both fairly accurate, there will still be a good number of frisbees ending up missing, but then they will be right up next to the scoring wall. I would think it would be a useful robot that could pick up those missed shots and dump or lob them into the goals, even if it was just the first or second goals. I think the key will be knowing what to scout for in your alliance. Not every robot needs to floor pick, but I would venture a guess that an alliance without a floor picker will struggle in eliminations.

[Rishabhgadi]

When the human player does throw them, it's gonna be crazy and they are gonna fly everywhere! question,I didn't see where it said the human player can begin to throw??

[Reggie335]

Watch this video it might answer your question http://www.youtube.com/watch?v=iyE4Ir6dkY8

[nathan_hui]

Last 30 seconds. G35 implies throwing, since the slots are oriented to prevent effective throwing.

G35: DISCS may be fed onto the FIELD only under the following circumstances:
A. during TELEOP through the FEEDER SLOTS and
B. during the last thirty (30) seconds of TELEOP over the FEEDER STATIONS.