Chief Delphi

Chief Delphi (http://www.chiefdelphi.com/forums/index.php)
-   Technical Discussion (http://www.chiefdelphi.com/forums/forumdisplay.php?f=22)
-   -   233 telescoping arms how do they work? (http://www.chiefdelphi.com/forums/showthread.php?t=116765)

Travis Schuh 09-05-2013 01:02

Re: 233 telescoping arms how do they work?
 
Quote:

Originally Posted by coalhot (Post 1273423)
From one of the post photos threads. Look at 254's set, there are a few really good shots of the arm, and the bearing assemblies it rides on.

That exposed bearing assembly pictured in the referenced photos is for the simple level 1 hanger (hook on the end of a piston), which is entirely separate from the 233 climber arms. I am pretty sure that the 233 climber arms use bearings for only the front-back sides and use plastic on the other two sides.

-Travis

Jeffy 09-05-2013 01:46

Re: 233 telescoping arms how do they work?
 
Links that helped me solve this problem:

Take a long stare at a few of these and you will figure out how they work.

https://www.dropbox.com/sh/3fxabc28nvvkcr8/A2tQie9tgK
specifically: https://www.dropbox.com/sh/3fxabc28n...f:DSC_0149.JPG

Also: http://www.chiefdelphi.com/forums/sh...ng+a+clim ber

Good luck!

JesseK 09-05-2013 09:01

Re: 233 telescoping arms how do they work?
 
2 Attachment(s)
233's 2011 Arm was a beauty to behold. Good luck to anyone who wants to make one :D

akoscielski3 09-05-2013 10:11

Re: 233 telescoping arms how do they work?
 
Can we please get a CAD model of those? Or extremely detailed pictures? It's so hard to see what is going on in there :P

Doug G 09-05-2013 11:13

Re: 233 telescoping arms how do they work?
 
Why is that when I look at 254's machine to see how they did something, I come away with more questions than answers... that machine and its mechanisms are so condensed, it's just insane.

Triple B 09-05-2013 16:00

Re: 233 telescoping arms how do they work?
 
I can only speak for the 233 arm on this topic. First off, a gearbox is attatched to the outside of the largest box (4d0 x 4d0 x d125 al box) at the bottom of the tower. It has a shaft that transfers power to a sprocket on the inside of the box. At the top of the box is an idler sprocket which is also the tensioner for this chain. We will call this chain 1. Chain 1 is attatched to the outside of the next box (2d5 x 2d5 x d125 al box) thru what I call the "chain anchor". The motor/gearbox drives this stage in and out directly.
The gearbox has a 10 turn pot attatched which controls the limits and also the PID control for ramping up and down the power as the tower nears its limits at each end of its travel. Now here is where it gets a little tricky, the opposite side if the 2d5 box has a shaft in the bottom with a sporcket on the inside and the outside, this is what drives the final stage of the tower. It also has an idler at the top which also acts as the tensioner for these 2 chains.
The chains both have a "chain anchor". The chain on the inside of 2d5 box is attached to the bottom of the final stage (1d0 x 1d0 x d125 al box). The chain on the outside of the box is attatched to the inside of the 4do box. The key is that the anchors are on opposite sides of the chain, this allows the second stage to use the anchor to drive the chain which extends the final stage at the same time. This is a very lengthy post and I may not of explained the subject completely but it has started an open line of communication. Ask any questions you may have and i can explain why Charlie did not like the delrin bearing blocks from 2k10.

Mike D "233 for life"

ASmith1675 09-05-2013 16:36

Re: 233 telescoping arms how do they work?
 
Awesome stuff. Thanks for all the info about these mechanisms.

When we've built these cascaded telescoping lifts/arms in the past, we've used a winch system for the first stage. What I'm having trouble wrapping my mind around with both of 233's and 254's telescoping arms is where the extra chain/timing belt, goes when these mechanisms are extended. Or are just the cascaded sections using the timing belt/chain?

Always trying to come up with better solutions, and these are the type of mechanisms we're all striving to make (in some small way).

Pat Fairbank 09-05-2013 17:43

Re: 233 telescoping arms how do they work?
 
Quote:

Originally Posted by Smitty1707 (Post 1273716)
What I'm having trouble wrapping my mind around with both of 233's and 254's telescoping arms is where the extra chain/timing belt, goes when these mechanisms are extended.

In this year's arms, the other end of the belt comes off the bottom pulley and then goes back up inside the bottom of 1x1 tube (the last stage), where it is clamped.

This section of belt (from the pulley to the bottom of the last stage) is what takes all the tension when the arm is being retracted. This way, the force exerted by the weight of the robot while climbing is just transmitted through the (large) bearings and shaft supporting the bottom pulley, and not on any of the tiny ones where the belt doubles back on itself.

The beauty of using a telescoping arm for hanging, in my opinion, is that there are no moments exerted on any of the stages during retraction.

CENTURION 09-05-2013 18:41

Re: 233 telescoping arms how do they work?
 
If I'm reading this thread right, the arms are basically a condensed version of this right?

Lil' Lavery 09-05-2013 19:05

Re: 233 telescoping arms how do they work?
 
Quote:

Originally Posted by CENTURION (Post 1273747)
If I'm reading this thread right, the arms are basically a condensed version of this right?

That's similar to 254's arm, in that it is a multi-stage, continuous lift.

If I understand MikeD's post correctly, 233's multi-stage arms are essentially cascaded lifts, but the second stage does not return to the original power source (and is instead driven "passively" by a sprocket that is turned as the first stage extends).

The key difference for both arms is that all the stages are nested within each other, which presents numerous challenges and advantages.

CENTURION 09-05-2013 19:54

Re: 233 telescoping arms how do they work?
 
Quote:

Originally Posted by Lil' Lavery (Post 1273754)
That's similar to 254's arm, in that it is a multi-stage, continuous lift.

If I understand MikeD's post correctly, 233's multi-stage arms are essentially cascaded lifts, but the second stage does not return to the original power source (and is instead driven "passively" by a sprocket that is turned as the first stage extends).

The key difference for both arms is that all the stages are nested within each other, which presents numerous challenges and advantages.

Ah, okay, yeah we used a cascade like the 233 one you describe in 2011 to raise/lower tubes.

Yeah, the nesting sounds very hard to do. Maybe if I get bored over the summer I'll CAD up something :D

Tom Line 09-05-2013 21:05

Re: 233 telescoping arms how do they work?
 
Quote:

Originally Posted by CENTURION (Post 1273764)
Ah, okay, yeah we used a cascade like the 233 one you describe in 2011 to raise/lower tubes.

Yeah, the nesting sounds very hard to do. Maybe if I get bored over the summer I'll CAD up something :D

The nesting is only really difficult if you want to put it into a very small package. Pink's arm and Poof's variation show true engineering elegance in packaging, from the wide rollers to the usage of belt (low profile) to the threading of the linear springs through the system.

The question that you'll also have to answer is the orientation of the constant force springs. Do you use them to extend the arm and only pull one way with your motors? Do you use to retract the arm so they help you lift the robot, but power the arm in both directions?

It's a really awesome design that I wanted to understand to put it in our 'toolbox'.

MichaelBick 10-05-2013 04:14

Re: 233 telescoping arms how do they work?
 
If somebody is still having a hard time understanding how the poof's arm works, I took many pictures which are posted here: https://drive.google.com/folderview?...&usp=sha ring

Triple B 10-05-2013 09:34

Re: 233 telescoping arms how do they work?
 
In our application we use the constant force springs to assist the extend function only. It offsets the weight of the manipulator on the end of the tower/elevator. The motor/motors have plenty of power for lifting the robot and we use a locking type ratchet to hold the weight up after the buzzer but the idea of having the motor/motors stalled out to hold position while the tower is extended is not, in my opinion, a healthy one. This year we did an elevator and used constant force springs to assist the elevator in lifting our shooter deck, it weighed in at about 18lbs. I find it ironic that we did an elevator and the Poofs did telescoping towers this year

Mike D "233 for life"

Nemo 10-05-2013 09:43

Re: 233 telescoping arms how do they work?
 
To the people who have posted in this thread: I just want you to know that after the school year ends, I'm going to devour the information in this thread, including both the pictures and written explanations. I am looking forward to trying to figure out the guts of one of these arms and working with some students to create a model of something we could build. Thanks very much for all of the posts.


All times are GMT -5. The time now is 16:52.

Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Copyright © Chief Delphi