Re: telescoping arm
 

Awesome video and comments....

Re: telescoping arm
 

This is a helpful little tidbit, maybe:

The less telescoping pieces, the better. Two would be enough to reach the bar. As my team discussed; more than 2 would be impossibly difficult. Rmeember; it gets stronger and weaker as each telecoping piece size decreases.

Re: telescoping arm
 

Roccobot 2K

Roccobot 2K2

We used a two piece telescoping tower that is able to tilt all the way down. The good thing about Roccobot 2K was that it had a nice base, and it was able to evenly distribute weight even when extending to retrieve the big round balls. But it was not very strong, but did its job well. On Roccobot 2K2, we improved the arm design, but we were unable to maintain stability and balance when using the arm. Note that it had three wheels. But we made sure that if Roccobot 2K3 tipped over (which it has during competition) that it was able to right itself up easily using the arm.

Re: telescoping arm
 

WOW no one mentioned us team 25 in this artical i though we built one of the best telescoping arms ever made for first. Well if you need to see what we did get a hold of wayne.

Re: telescoping arm
 

Our telescoping arm made use of a pully system with extruded aluminum attatched by plastic sliders. We used pistons to extend. Very effective.

Re: telescoping arm
 

thats right, if i remember correctly, we (team 25) built a telescoping arm that reached about 12 feet out in order to steal the black balls from the other teams bin and then put into ours (2000 game), im suprised as well that no one has mentioned us....

Re: telescoping arm
 

I don't mean to be rude, but why not mention yourselves? If you'll notice, most teams are mentioning mechanisms they built themselves. I'm not sure why you see it as everyone else's duty to talk about your team (and I'm not just referencing this thread. Another memeber of your team has been posting "Well we did this, why didn't anyone say anything about that?" on other threads, too)? I know you're a very old and respected team (25 is a very low number haha), but honestly, not everyone is going to know you built some (apparently) amazingly fancy mechanism. If you want it to be known, then say so.

I've located some pics and videos of 442's arm from 2002 and I'll be posting those soon (hopefully).

Re: telescoping arm
 

Our team built two 4 staged telescoping arms in 2001 which could put the balls on top of the goals while the goals were on the ramp. Here are some pics

Practicing capping goals

Don't really need 4 stages

Oops ... the red one ended up on the floor

Kinda see how they work … best pic I could find

Under the bar

In the Easter spirit

Here are some of my memories of the arms that might help

-Globe motor was used to extend arms
-Surgical hose was used to "assist" the globe motor
-Window motor was used to lift arm (about 6" moment arm with 1" hub) … arm had to fit under bar
-Seat motor was used for turret
-Spectra string was used to "pull" things
-An Eagle Scout tied all of our knots … pretty frustrating when a knot lets go.
-First stage was pinned to turret
-Globe motor "pulled" second stage into place (up or down … did not depend on gravity)
-Third stage strings were attached to second stage ... not directly to motor
-Likewise, fourth stage was attached to third stage
-The cross section was a triangle with flat corners
-Delrin blocks (Teflon was cost prohibitive) were used as anti-friction blocks and "pulleys"
-The aluminum used for the arms was 0.032" sheet
-Bending the triangular sections is definitely an art but can be mastered with a good sheet metal break

Although the structure of the arm was very strong, the actuators were all fairly weak (using all of the strong ones on the base and balancing mechanism). This was okay because it was a 4 team alliance with no defense. This year, you need to have more powerful positioning actuators; thus, this year we are thinking about simply using our base to point the arm or go to a very strong turret.

All in all these arms performed very well even though our main strategy that year was to balance both of the goals. Telescoping is a good way to go and if you go this way, try to leave yourself a solid week to get out all of the kinks & binds.

Good luck,
Lucien

Re: telescoping arm
 

All these telescoping arms are SWEET. I think I have the general idea of how they work, but does anyone have any specifics? A design sketch would be great.

Re: telescoping arm
 

I don't know if this helps but this is the way we did it for three years 2000, 2001, and 2002 this is the 2002 one inch version, It drives whith chain or cable. and except for 2000 (cable) it is very reliable and compact.

Re: telescoping arm
 

Acutally I saw 25's arm on another thread. It was very impressive. I don't remember which thread. You would have to search.

Re: telescoping arm
 

By any chance do you remember how much the 2 pieces weighed?

Re: telescoping arm
 

I'm afraid I do not remember how much the two pieces weigh, but I could ask my teammates and find out. But before I do, which robot you would like to know the weight of those two pieces?

Re: telescoping arm
 

The 2000 robot arm

Re: telescoping arm
 

Maybe a totally inovative method is required , we have a secret method that might stun you at its simplicity :yikes:
How about the parraleelagram method?