LIFT VS. LAUNCH
 

Hello all in FIRST World. I have a question cause I am curious like a cat and I dance on the event horizon of the FIRST black hole. I have had a few conversations with fellow Mentors from some other teams as well I have read a whole bunch of posts of teams that are going with a lifting design. Is it that teams decided that there was no way to effeciently launch a tracker ball? Not being able to see a way to load a launcher? My team almost immediatly ruled out a lifter, determing quickly that it would have to be just too complex and heavy to be efficient. Also for those lifter people what motors are you using to extend you lifting mechanism? Please do not take this as if I am saying one is better then the other cause frankly what do I really know. I was just curious.

Re: LIFT VS. LAUNCH
 

Our team will be building a catapult. We've built up a mock up with wood. It gets 7.5 feet consistently. It should get a bit more with the metal we hope. We also considered a lift, but we wanted to keep our center of gravity low.

Re: LIFT VS. LAUNCH
 

Our team is going with a lifter this year. We basically ruled out shooting the ball because we thought it would be very complicated to design and then very hard to control where the ball goes, and finally we wouldn't be able to put the ball on the overpass at endgame effectively

Re: LIFT VS. LAUNCH
 

I feel you with the whole endgame thing. That was discussed at length by my team however we concluded that the point differential 8 for a hurdle 12 for a place. Was just to small to change the whole design.

Re: LIFT VS. LAUNCH
 

Launching is cooler than lifting, and you can bet you are going to see some neat launch designs... as well as some noble attempts that just don't quite cut it. Mind you, you'll see that with lifters, hybrid code, and everything else, too.

We decided to go with an arm to do the lifting, in part because if you have a partner (or two) each capable of quickly placing the ball on the overpass and then quickly lifting the ball from the overpass then you never have to give up posession of the ball.

Consider:

Robot A is positioned on the far side of the finish line, ready to lift the ball from the overpass.

Robot B approaches the near side of the overpass, places the ball on the overpass.

Robot C is doing a lap with a ball in possession.

Robot A grabs the ball from the overpass (hurdle complete now) and proceeds to do a lap.

Robot B crosses the finish line (completing a lap), and turns around - ready to receive the ball after C places it on the overpass.

Repeat as needed.

It will take three co-ordinated lifters and some excellent driving, but it would be fun to see three good shooters go against three good lifters. I'll bet that ball possession would come out on top.... unless the shooters had some way of catching the ball after it went over the overpass and were able to do a similar technique to the lifters.

Jason

Re: LIFT VS. LAUNCH
 

All without ever breaking the plane of the finish line going backward (clockwise)?

Re: LIFT VS. LAUNCH
 

[quote=dtengineering;682224]Launching is cooler than lifting, and you can bet you are going to see some neat launch designs... as well as some noble attempts that just don't quite cut it. Mind you, you'll see that with lifters, hybrid code, and everything else, too.

We decided to go with an arm to do the lifting, in part because if you have a partner (or two) each capable of quickly placing the ball on the overpass and then quickly lifting the ball from the overpass then you never have to give up posession of the ball.

Consider:

Robot A is positioned on the far side of the finish line, ready to lift the ball from the overpass.

Robot B approaches the near side of the overpass, places the ball on the overpass.

Robot C is doing a lap with a ball in possession.

Robot A grabs the ball from the overpass (hurdle complete now) and proceeds to do a lap.

Robot B crosses the finish line (completing a lap), and turns around - ready to receive the ball after C places it on the overpass.

Repeat as needed.

It will take three co-ordinated lifters and some excellent driving, but it would be fun to see three good shooters go against three good lifters. I'll bet that ball possession would come out on top.... unless the shooters had some way of catching the ball after it went over the overpass and were able to do a similar technique to the lifters.

Jason[/QUOTE

This was discussed at length with our team. I see your point but I think you are assuming to much. This only works if you have three good lifters. My team has always assumed that your alliance partners can achieve nothing to very little and then design around those assumptions.

Re: LIFT VS. LAUNCH
 

Haha, so is Robot Casserole. We made a mock up of pvc and we hit our 14.5 ft ceiling. Testing at Building H should be very interesting. :rolleyes:

Re: LIFT VS. LAUNCH
 

Robot A would not be able to pick the ball off the overpass without crossing the finish line clockwise for a 10 point penalty. The finish line is on the far side of the overpass, so unless the team can pick the ball up while only contacting about 5 inches or so of the ball, I dont see how it can be possible. Not a bad idea though.
Joey

Re: LIFT VS. LAUNCH
 

Were you shooting the ball straight up? It will be fun to see you guys in Milwaukee this year.
Joey

Re: LIFT VS. LAUNCH
 

There is a way to do it such that no penalty is incurred. You have to have the right type of gripper, though.:D

Re: LIFT VS. LAUNCH
 

Isn't there a rule about the ball touching the ground before it can touch another robot?

Re: LIFT VS. LAUNCH
 

Or another robot:

Re: LIFT VS. LAUNCH
 

Our design allows for us to "catch" the ball as it is hurdled across.
We would not try to catch a ball that is launched... but we can catch a ball that is rolled or moved across the overpass by our alliance partner.

During design you must think about this from the very beginning of the design and not try to add it as an afterthought.

3 robots in the scenario above is exactly what we are designing for.
This doesn't mean we can't hurdle and acquire the ball by ourselves.
But we are not only hoping to see it in Atlanta... we are designing for it.
We may not get to do it until then but we will be ready....

This could be fun...

Re: LIFT VS. LAUNCH
 

We're going to try this, but the problem will be that this can be defended against pretty easily, just have a robot running back and forth across the place where the ball is going to land.

Re: LIFT VS. LAUNCH
 

No, we were shooting it foreward. That was just a prototype test. Our actual robot won't throw that high. From what I've read here on Chief Delphi, Milwaukee seems like it should be interesting this year. :)

Re: LIFT VS. LAUNCH
 

I don't see how this could work. The ball on the overpass hasn't crossed the finish line yet, so you can't hurdle it from the far side by grabbing it and keeping it.

Re: LIFT VS. LAUNCH
 

I had a nice explanation of why this would all work, based on the definition of "crossing" requiring all parts of the robot to cross the line, and the assumption that you were not penalized until you "crossed" a finish or quadrant line in the wrong direction, but re-reading the rules, specifically G22 kind of makes mincemeat of that idea. You get penalized just for breaking the plane of the line once you have "crossed".

Pity. The "bucket brigade" scenario would have been fun to watch and would have rewarded technical proficiency and teamwork. Not that it is 100% impossible, as the "scoring robot" could pass the ball completely over the finish line to the receiving robot... or for the receiving robot to grip the part of the ball that has passed over the finish line while the ball is on the overpass... or for a robot to be built in such a way that it can pick up the ball on the counter-clockwise side of the overpass without first having to completely pass over the finish line (robot turns around, extends a bar from it's "front", backs across the line leaving the bar over the finish line, reaches up and grabs the ball, then retracts the bar and moves away from the overpass in a counter-clockwise direction) but the combination of G22 and having the finish line directly underneath the "counter clockwise" side of the overpass makes it even more difficult than it would have originally been.

Jason

Re: LIFT VS. LAUNCH
 

There are some gripper designs that have the capability to render <G22> harmless in this situation. They'll need a very good driver/manipulator team to pull off the maneuver, though.

Re: LIFT VS. LAUNCH
 

I expect that is a strategy we may see in Atlanta this year. With all of the teams going with arm designs, there is bound to be a set of three that get paired up and can pull it off.

Re: LIFT VS. LAUNCH
 

Jason -
No need to be despondent. Keep that mental image in mind, but just make one minor adjustment. You started toward this scenario in your first message, but stopped short of fully developing it. Think about your "bucket brigade" of robots handing off the Trackball from one to the other by temporarily storing it atop the Overpass. But make the process faster. Rather than slowing down the process when the Trackball is stored on the Overpass, make Hurdling the part of the process with the highest-velocity Trackball movement. Rather than three well-coordinated, excellent "Super Lifters" you need three well-coordinated "Launcher/Catchers." Then your original scenario becomes:

Robot A is positioned on the far side of the finish line, ready to catch a Trackball.

Robot B approaches the near side of the Overpass, and launches the Trackball in a spectacular fashion. The Trackball describes a perfect parabolic arc over the Overpass as it heads toward Robot A (if you are thinking about this correctly, you should have a nice mental image of Max the dog in "The Grinch Who Stole Christmas," waiting outside the house for the Grinch to throw the massive bag of toys down to him from the rooftop after stealing them all from Whoville).

Robot C is doing a lap with a Trackball in possession.

Robot A catches the descending Trackball before it ever touches the ground in its whizz-bang-super-combination-Trackball-basket-and-catapult-launcher (it's a dessert topping! it's a floor wax!). The crowd goes wild! The Hurdle is complete, and the robot proceeds to do a lap.

Robot B crosses the Finish Line (completing a lap), and turns around - ready to catch the next Trackball as Robot C approaches and launches it.

Repeat until you win.


That is the ultimate "dream match" that I long to see. If not during the season, maybe we will see it at IRI. :)

-dave




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Re: LIFT VS. LAUNCH
 

Wow, you must be looking at our design drawings! (is that why we posted them?)

The ball catching stuff looks to be fun....we can't wait....

Re: LIFT VS. LAUNCH
 

our team is using a lifter/launcher on ours. and its turning out very promising so far almost done too:)

Re: LIFT VS. LAUNCH
 

Our team is making a lifter, we were thinking about launching the ball, but after some discussion with other schools we decided it might be considered dangerous. thoughts?

Re: LIFT VS. LAUNCH
 

It can be very dangerous to make a mechanism that is capable of launching a ball that high, so you would need to go to a lot of extra trouble to make sure your design is safe. As I see it, the danger is not with actually launching the ball...the danger is that someone could have their bodily parts in the way of the mechanism when the ball is NOT in it, and it could give them a severe blow.

We figured out a way to use an air powered catapult that moves slowly if there is no ball on it, but with a ball in place, it is able to launch the ball quickly.

This is not an easy thing to design....so if you go this route, you really need to think about it carefully. We are using restrictor valves to keep the cylinders from filling quickly, and using an arm on top of the ball to hold it down, and the ball holds the catapult arm down. The system can only build up pressure when the ball is in place, and launching the ball uses up all this pressure.

Re: LIFT VS. LAUNCH
 

Even though its is safe without a ball, what happens when you finish a match and the ball is on your robot and the catapult is pressurized, that scenario is what scared me away from using a catapult

Re: LIFT VS. LAUNCH
 

First of all, kudos to all the teams who have managed to build a catapult not only capable of simply holding/controlling the ball, but launching it into the air. Our team considered this at the beginning of the season, and decided that it would essentially be too complex (something we have had problems with in the past).

So, we decided to build a relatively simple forklift mechanism with a rotating "grabber" that the ball simply rests in (A teammate has the inventor drawings:( ). A winch pulls a cable (winch is just a plastic attachment to a motor (window i think) that lifts the "grabber" to 6'4" (forklift is bent at start, pneumatic piston straightens). At that height are two 10" stroke, 3/4" pistons that push the ball onto the overpass (12 pts. at end of match) we then move a few inches, push again (on the ball on the overpass) and the ball comes off the overpass, scoring a hurdle.

While we have no "catcher" design, we can regain control easily, and perhaps even "pass" the ball to another robot (hard though).

In short, our team is all lift.

Re: LIFT VS. LAUNCH
 

The whole idea of the catapult appealed to our team however the designs that we could come up with where all dangerous and to complicated. However we have developed an idea that launches the ball, More like a ballista. we have tested a scale model and it worked perfectley with little danger to opperatores and other robots. So we think that our design has the capability to launch quickly and very effectivley,
Is there anyone else that is using a ballista/crossbow design? Just curious.

Re: LIFT VS. LAUNCH
 

The catapult will be pressurized with a single acting solenoid valve that releases the "up" pressure when the robot shuts off.

Re: LIFT VS. LAUNCH
 

Over the weekend some of us on the team began experimenting with different ways to get a track ball over the overpass. Our original ball did not last long enough to be used on our full sized practice overpass. Our new balls arrived Friday.

Since we had no robots ready to play with we were trying different things with human handlers. We found out pretty quickly that with practice and good timing the balls could be easily kicked over the bar.

I figure if a human can do it in their own strength, then the act itself is not inherently dangerous. Having been hit by a couple of these flying objects, I'm more worried about damage from the fall if they should knock me over than being hit by the ball itself.

It is still possible to store or release the necesssary energy in a manner that could result in injury, or to have the energy containment system fail in a catastrophic manner. That is the sort of thing you need to be careful of.

ChrisH

Oh and by the way, the BeachBot practice field (funded by SCRRF) is open to anybody that wants to use it from 10-4:30 on Saturdays and other times by appointment. Details are in the newsletter sent out by the Regional Committee chair, Nancy McIntyre.

Re: LIFT VS. LAUNCH
 

We started out lifting the ball up to the over pass ( our robot will just go under) and shooting it over with a 1.5 pneumatic. Using the garage compressor at 60 psi we were able to throw it 3 ft horizontal and vertical just enough to clear the rack. When we tried it with the robot compressor it would only lift the ball and not throw it. So we are just pushing it up onto the over pass. Most people don’t know this but if you push it over at the spots between the ball locations the pipes are only about 12 inches apart and the ball just rolls off with little effort. So we can push it up and over with out hardly slowing down. Some drawings are at http://www.team1322.org/team_news.htm

Re: LIFT VS. LAUNCH
 

Why, as a matter of fact we had a team meeting on Monday to discuss the problems with the arm (80" limit, mostly), the crossing the plane when you take it off from the back, and to revisit some of our earlier ideas.

Tonight we had a prototype pneumatic launcher in the works and are looking at how to launch (and catch) the ball effectively.

If even two robots can do this working together they are going to do well. They should be able to lap almost as fast as the "racers", at least as fast as the herders, and will be pulling in hurdles all over the place.

I'll keep my eyes open for a match like that.

Jason

Re: LIFT VS. LAUNCH
 

I would love to see 3 launchers on a team, but i don't think that it will happen, i think the most you will see is 2 on a team. (Especially with the serpentine draft)
And i want to see how well and fast these robots can launch the ball over effectively and still be as fast as a lapper. With my calculations a GOOD lapper can do a lap in 10s or less. A launcher with a GOOD launch/catcher will be 17s+ and a hurdler will be 24s+ (Just my rough estimates.) So i would like to see all of the strategies teams will come up with during the season.

Re: LIFT VS. LAUNCH
 

How would you plan on loading your catapult?