# fun with shooters...

Hello again everybody…

I was talking with another team some time ago, and they boasted the ability to shoot the balls in “Toss Up” across the field with a “gun” they manufactured. This made me think back to the intro video with the catapult robot showing the game off. I personally believe that there are too many variables, and even though the trajectory could be calculated mathematically, the balls could easily miss or bounce out of the target zone (which I assume would be the far scoring zone, across the 12" high barrier). Plus, if one wanted to try for the cylindrical goals, shooters would have some difficulties… For these reasons, my team will most likely use rollers, like the “NZ” robots in Gateway.

The question is this:

Are you planning on shooting the balls, or collecting them “Gateway style”? Why?

(poll is above)

We will not, but look forward to playing with and against those who can since it will certainly make the game fun.

Our logic for not doing it is the fact that if we knock the 2 big balls into the goal zone during autonomous that only leaves 2 balls in the starting area. If we leave 1 ball to hang with that only leaves one to get over the 12" goal which we can do fast enough (not as fast as tossing). To us, the thought of hanging with a big ball for 20 points outweighed the tossing a big ball for 5 points. With the 3 bucky ball limit our intake will pick the bucky’s up plenty fast to make the added weight and complexity of a tossing or shooting mechanism not worth the effort or motor allocation. The weight and expense of using pneumatics did not make sense to us either.

There will be teams that do it and do it well, and we can’t wait to see them.

No, none of our teams are building shooters this year. We’re going for filling the cylinders, not just having massive numbers of objects in the goal zone. They’re worth 2x-2.5x in the Cylinders compared to on the floor around them.

I think that the 24" goals are by far the most important part of the game, and attempting to shoot into the goals is not going to be worth it at all.

I think the best robots will be able to both shoot and quickly score the cylinders. That way a robot can stay in the goal zone and descore their opponents balls quickly.

I agree. If you can stash quickly, guard your points by camping in the goal zone to protect the goals, and shoot opponents’ objects out of the Goal Zone, then it will be very difficult to beat you.

With three teams, there is a lot of freedom to try new ideas. We were thinking of creating 2 robots that could go under the 12" bars and score on the 24" goals while having the third robot be able to easily hang and shoot balls to our shorter robots. Having a robot that can do everything will ultimately lead it to not being the best at anything. Splitting up the tasks make it much more manageable.

I don’t think you need to throw anything. The big balls can just be set over he bar, and the buckyballs can be pushed under it. I don’t see throwing as a huge factor, but I also will look forward to being hit by the flying objects

If you ignore the actual act of stashing buckyballs for a second, throwing is inarguably faster than traversing the field. It definitely has a place in this game. An alliance could set up with a scoring robot in the goal zone and a catapult in the far zone, to quickly relay buckyballs down the field. Later in the game, a last-second cross-field toss of an opponent’s big ball from the goal zone could be a difference maker.

Teams may want to look back to some more adventurous clean sweep teams for inspiration on how to do this.

Gateway style?

If you could have two robots, one that can transport or shoot big balls and bucky balls into the Goal zone with the advantage of hanging and the other able to kick out opponents balls out of the Goal zone and score in the stashed goals, then you can have a huge team advantage against the teams that are constantly going back and forth from each end of the field.

I don’t think you will see any teams successfully pull off a “shooter”, with rotating wheels and such (maybe a flywheel ect.) We tried to do this with VEX, prototyping for FRC rebound rumble. Even with 8x393 on a dual flywheel system we were unable to shoot scale foam balls (Clean Sweep green balls) farther than 2 feet.

That being said, I think catapults are very feasible. I had one concept where to “reload” the catapult, one would simple drive into the barrier, forcing the elastic “scoop” back to the floor. No motors required, just a piston to lock the scoop into place. This obviously poses the problem that you have to be at the barrier to reload. I believe it was 4476 who had something like this in sack attack, where their PTO high capacity basket was reloaded by driving under the trough, forcing it back in place.

You can shoot balls easily with 1 motor. My team did this in FTC. It would only work for buckyballs though…

Here’s an example of shooting robot that the VEX interns built last summer. This robot as designed to play the 2012 FRC game, which is normally played by robots that are up to 28"x38"x60", and utilize industrial strength motors.

I have a general concept going for the 2425 robot. Hopefully it goes well. It’s similar to the rebound rumble bot and a clean sweep robot. I’ll release details when things flesh up more

My team is working (just on solidworks for now) on a rubber band powered shooter that set ups slowly but uses only one motor. We believe that throwing the bucky balls is a great avantage because they move faster across the field in the air than carried by a robot (especially with the bump). I don’t know yet if we will camp in the scoring zone and block while throwing the bucky balls back in the hanging zone

aiming at the pilot is also a possibilit :rolleyes:

The bump is NOT a big deal at all. I have no idea what people are talking about. Every drive we build goes straight over, from 1:1 to 2:5:1 speed drives. Omnis, high traction, or Mecanum wheels, it doesn’t matter.

And shooting things deliberately at the opposing drivers is a lame strategy, if anyone WAS actually planning to do that.

The way I see it, the arguments FOR shooting all revolve around moving the balls faster across the field. This, I believe, completely ignores one of the most crucial aspects of Toss Up. The Goals.

No one is arguing that the goals are insignifigant. But in order to score in the goals, you need to move balls down the field first, as most of them start on the end of the field opposite the goals. You can do this with a traditional design, but you can do this faster with a shooter if the shooter is on one end of the field, and a goal-capable robot is already on the other.

When building a catapult, there are 2 main questions that bother me.

What path do you want your arc to follow?

I thought of 3 paths, but i’ve fancied 2. the first path is have an extreme angle up and let gravity bring the balls down. I don’t really like this path cause it limits your distance. However i think it would be really simple to build. the second path is the general arc. Have a nice path which flows nicely and rebounds off the wall to stop. I kind of like this because of it’s steady nature, however i think it has blind spots where the barrier will get in the way and bypass the wall completely. The third path i thought of was having a steep path like a bullet. A forcing route which causes the ball to roll out and stop against the wall. This path is reliable enough to avoid the barrier and prevent overshooting, but there’s always the weird unpredictability of rolling bucky balls (which may be ok cause the robot has funnels, but it places blindspots in alliance strategies).

the other question was
How will fluctuations in force affect shooting?

Fluctuating power is pretty much going to happen, but idk whether the lift should have more power near the end, middle, or beginning of the shot. I’m also not savvy enough in this type of physics to understand how force plays a role. Even though i know velocity and angle are the biggest contributors, isn’t there a relationship between force, momentum, and speed?