Hey guys! This is my first post here, so please forgive me if I’m a bit of a noob. This season was my first year in VEX (and robotics in general) and I’m still a bit so-so regarding understanding mechanical systems. More specifically, I’d like to get a better understanding of 1103’s two tiered elevator (Vex Robotics Competition Team 1103 explaining their robot design 1/22/11 - YouTube) as well as two tier elevators in general. I saw a few of them at FRC this year, and I was quite impressed. After seeing that it’s capable using the VEX platform, I’ve been even more anxious to learn about how they work. Anyone wanna help me out?
) as well as two tier elevators in general. I saw a few of them at FRC this year, and I was quite impressed. After seeing that it’s capable using the VEX platform, I’ve been even more anxious to learn about how they work. Anyone wanna help me out?
Thanks in advance…
It looks as though they are using the same sort of mechanism that you find on extension ladders in your local hardware store. One difference is that the ladders in the hardware store only have one extending piece and the robot has two.
I think I saw heavy duty chain that loops through the extending pieces like the ropes do in extension ladders to cause the extension, and the chain gets coiled up on a spool (Polycarb?) on the base of the bot.
I don’t have any URLs handy, but if you go to the [www.ChiefDelphi.com site and start doing some searching in the "Whitepaper"s archive there, you should be able to find 2-3 presentations (probably in PowerPoint format) describing how to trade-off the different characteristics of ways to accomplish these sorts of extensions. The way you run the rope/chain/cable through the extending pieces has important effects on the way the entire mechanism performs.
Blake
PS: Making the enitre bot of of aluminum instead of steel (that’s what 1103’s metal looked like in the video) has important effects too…](www.ChiefDelphi.com site and start doing some searching in the "Whitepaper"s archive there, you should be able to find 2-3 presentations (probably in PowerPoint format) describing how to trade-off the different characteristics of ways to accomplish these sorts of extensions. The way you run the rope/chain/cable through the extending pieces has important effects on the way the entire mechanism performs.)
I’m working on using 17.5" C-Channel to create an extending device that will be 32" bottom to top using two C-Channels; and if I hold my tongue just right as I design and assemble it I should be able to add a 3rd piece of C-Channel to get it up to 47".
There won’t be any of the Vex slide rails in it (unless of course they are now selling 17.5" slide rails and my project becomes moot). That should save some weight.
Reaching those hieghts will mean that the C-Channel pieces only overlap by 2.5". That will mean that rigidity will be a problem under heavy loads (especially when the 3rd is added). However, that is the case in just about any extending mechanism.
If I succeed and it gets used/copied by me or my team, I’ll keep the playing field level by making the info public.
Blake
[EDIT] FYI: The 32" C-Channel extension starts at 17.5" long. The best I can dream up right now for a 47" extender made only from 3 pieces of 17.5" C-Channel and a few modest brackets (equal to 12.5" or 15" of additional C-Channel)) will start at 20" long.[/EDIT]
I’ve done some thought experiments along those lines, if you’d like to collaborate.
Two 1x2x1 C channels interlocked
Two 1x2x1 C channels facing each other
1/2" spacers as rollers inside the C channels
crimped over C channels with small spacers as trapped rollers
Among the 70 college robots for Roundup, there were 6-8 different methods for reaching the 30" wall goal with the bottom of a 17" needle, so there are some prototype examples to look at there. Most common was a linear slider extension before or after a 4-bar arm.
If you check out our photos of Bravo (and Zulu), you can see how we tried to use linear sliders to reach the 30" high goals with hopefully enough detail. (Apologies for bad photo quality… my camera isn’t that great and we probably won’t be using it anymore).
We didn’t end up using those robots because we found that having a really heavy intake and a set of sliders at the end of a 4-bar makes it really unstable and wobbly.
