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.

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.

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

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.

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.


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.


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

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:

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.

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

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

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

Or another robot:

and then contacts either the floor or another ROBOT before re-contacting the originating ROBOT.

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…

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.

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. :slight_smile:

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.

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.


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.

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.