399's ramp release.
 

http://www.youtube.com/watch?v=qYIqy0AYyGg

Sorry for the bad quality, long story.

This is our current prototype for the ramp release... It's really hard to drive up right now, it needs reinforcing... and probably a wall. It's also not our final design, we have another group working on a lift that will actually lift the robot, this is just less parts. We aren't sure which will weigh more yet. The whole thing falls down after pulling a pin, which we plan do just do with a servo. Lexan is being used to spring it out, it's pretty sweet.

Re: 399's ramp release.
 

That looks good so far, are you going to have any control over the ramp once it falls down?

Re: 399's ramp release.
 

Looks sweet. Two questions...

1) How much does that ramp weigh?
2) What material are you using?

Our team has something like that planned, but we are going to stress on weight depending on what we use.

Re: 399's ramp release.
 

As of right now with this design there is no plan to. the robot would have to climb up and be supported on the platform, which could be a problem. Like I said we have another design being worked on which would be just the ramp portion, and would be powered to lift the robots. They still have to climb the ramp, but not the entire way, and we think it may be a little easier on the robots.

Right now it weighs around 14 pounds. We're just using some sheet aluminum (sorry I don't know what exact thickness etc, I'm technically a programmer ;P) with angles for supports. A robot can drive up it fine (as in it can support it) but it's a little small and tough to position yourself on.

But yeah, weight is definitely an issue for us right now... we're trying to do a little bit too much. All is well though.

Re: 399's ramp release.
 

We are using sheets of .050 thick aluminum backed with 1x1x.125 angle aluminum all riveted together with number four rivets which hold around 650 pounds of sheer force.

Re: 399's ramp release.
 

whats your ramp angle?

Re: 399's ramp release.
 

approximately 19 degrees and it is around 12 and a half inches tall

Re: 399's ramp release.
 

sorry for the late reply, but can you further elaborate on the lexan "spring"
just wondering...

Thanks :)

Re: 399's ramp release.
 

Well, basically we found out you could use lexan as a springing mechanism, if you bend it, it'll snap back into shape. We connected the lexan to one part of the ramp, and bent the other part down (it's hinged). then we stuck a pin in the bottom of the ramp... there's a lot of force on that pin, from one piece of lexan (we just cut some small strips). In the video there were two pieces... Pull the pin, then the lexan snaps back into a strip, forcing it to unhinge.

Sorry for the rough explanation, it's kind of hard to explain. Just go get a piece of lexan, bend it, then release one end and watch it snap back. You can use it like a leaf spring, works great.

Re: 399's ramp release.
 

"pull the pin" - note that <R46>, as amended by Team Update #3, prohibits solenoids. No rationale, just the prohibition.

We are using expanded aluminum supported by aluminum angles along the edges. Light; mostly open space. Is it OK to let the ramp crash down? We plan to lower the ramp gracefully using a motor unwinding a support wire, with a coil spring assist.

Re: 399's ramp release.
 

Please re-read--it prohibits "electric solenoid acutators". Nothing prohibits using small pneumatic cylinders or servos, or even a motor, for pulling a pin.

And yes, the ramp may crash down.

Re: 399's ramp release.
 

Yeah, we plan to use the dual action solenoid to pull the pins, one for each side. We tried using servos but the way we had it rigged currently the servo didn't have enough power to pull it (I hooked it up through a vex controller, still uses 7.2v batteries and everything). Although the solenoid is heavier than the servos, it will more than likely be more reliable.

Re: 399's ramp release.
 

Looks really nice and simple!!! although I couldn't tell what is was made out of so can it take that kind of impact repeatedly?

Re: 399's ramp release.
 

right now it's aluminum, and it still looks fine after ~20 pulls. We think it's a tad too heavy so we're trying some other stuff right now. We also lowered the amount of lexan to one piece, so it doesn't slam as hard. it goes out a little slower and is less violent.

You should see our miniature version of this though, that thing really slams out. All of our mentors were worried about the safety of the large one, lol.

Re: 399's ramp release.
 

interesting.... nice idea


thanks for the explanation and good luck in the competition:D