Catapult?

[Marcel]

The problems I see with a catapult is that you can only set it to shoot at 1 angle I cant think of any way to change the angle in the middle of a match meaning you'll have to be the same distance away from the goal at all time. You cant set up to shoot 2 feet away and than be like 4 feet away and hope to make a goal. Also you'll only be able to shoot once, reload, and shoot again. There are much better designs that allow you to fire more than 1 in one load. ^_^

But thats just what I think.

[Eric Scheuing]

The only good catauplt would be a tribuchet, but if you used that, good luck aiming/firing at the goal consistently.

But seriously, if someone's team could pull off a catapult with... say 75% accuracy, I would be amazed.

[Rick TYler]

Originally Posted by Eric Scheuing

The only good catauplt would be a tribuchet, but if you used that, good luck aiming/firing at the goal consistently.

Actually, a trebuchet would be an accurate and consistent, but really impractical device for a robot. Trebuchets rely on a counterweight to pull the arm down. In a robot, where every ounce is critical, anything relying on a counterweight is a Bad Idea. Likewise, I cannot think of any practical way for a robot to reset the sling of a trebuchet after each shot. A rotating wheel, or the energy of a wheel imparted to a belt, is a much more appropriate mechanism for a robot. Even a mangonel or oranger would be easier to build than a treb, even if you have to design for the end-of-stroke shock.

[Eric Scheuing]

Originally Posted by Rick TYler

Actually, a trebuchet would be an accurate and consistent, but really impractical device for a robot. Trebuchets rely on a counterweight to pull the arm down. In a robot, where every ounce is critical, anything relying on a counterweight is a Bad Idea. Likewise, I cannot think of any practical way for a robot to reset the sling of a trebuchet after each shot. A rotating wheel, or the energy of a wheel imparted to a belt, is a much more appropriate mechanism for a robot. Even a mangonel or oranger would be easier to build than a treb, even if you have to design for the end-of-stroke shock.

I suppose, but a trebuchet would be frickin awesome.

Play Age of Empires?

[Jimbo5051]

Im am not completely sure but I dont think that catapult is legal because you can not use anything that uses a sudden stop. But I do think you could use a trebuchea.

[Matt Gent]

-a catapult design does not have to come to a sudden stop
-the energy stored in the arm's rotational motion doesn't have to be lost (it can be restored into its original form)
-an effective & accurate catapult can be made that is not a trebuchet (ie doesn't use weight @ height to store energy or an arm/sling)
-trajectory could be changed in-match, but it becomes complicated. With an intelligently selected single trajectory it is possible to score at a wide range of distances from the center goal.
-a catapult can be implemented with a rate of fire of > 1 ball/sec
-a clutch or similar device is not necessary to "k"ock the mechanism when driven by a motor
-a working prototype using a whammo-type jai-alai cesta achieved much greater than 12m/s and has many variables for adjustability.

[Tim Arnold]

Check our catapult-like device out in prototype: http://marsbot.org/files/arm_demo.zip

We finally got our hardened shaft and everything is coming together now. I will try to post a video of it throwing tommorow (assuming it can do that yet )...