Adjustable robotic links 5

[FeX32]

Simple question guys.

Anyone come across legs or links that have an adjustable length?
For example, there exists synthesis methods for 4-bar linkages in which adjustability of a link provides several advantages.
Has anyone seen a practical version of an adjustable link? For mechanisms or robots.

Thanks and cheers!


Fe

 

[rb1957]

if you're manually adjusting the rod length, you could add segments ... any extending rod (telescoping, threaded, ...) would be limited to dubling the length.

adding segments would be easier than nesting more than two tube together.

i've presumed these rods are compression loaded; any chance these things will be loaded in tension only ? that' d open up a whole different set of solutions.

 

[unclesyd]

I have a walking stick that has the holes on 3/4" centers for the spring loaded detent, so you can make 3/4" increments where locking collar locks it in.
Aside from the walking stick approach here is osme additional
information that be of interest to you.

http://valco.thomasnet.com/category/snap-buttons?&plpver=10

http://www.testrite.com/browse/telescoping-aluminum-tubing/telescopic-lock-types/

 

[MikeHalloran]

Dumb question:
How does the robot controller 'know' the length of the arm after you've changed it?


Mike Halloran
Pembroke Pines, FL, USA

 

[FeX32]

any chance these things will be loaded in tension only ? that' d open up a whole different set of solutions.

The robot is to be potentially used for high speed applications. Thus, the loading will be tension and compression. From my modeling the closest loading condition is the "repeated-reversed" condition. Imagine something like a delta robot (not exactly, but it's the closest I could find):

http://www.youtube.com/watch?v=foTE0Mau5a8

And add about 10kg to those ping pong balls.
I wish I could tell you guys more information about the robot, but I can't leak the designs for reasons I'm sure you guys understand.

so you can make 3/4" increments where locking collar locks it in.

I agree that this variation of a telescoping tube idea is indeed a potential solution, particularly because of the large difference in lengths I require for re-configurations.
So, I have decided to model at least 2 different solutions, one of which being this.
Then later I will conduct a feasibility study on each of the designs likely be experiment.

Thanks!



Fe

 

[FeX32]

How does the robot controller 'know' the length of the arm after you've changed it?

Not a dumb question IMO, more like fundamental but important.
Initially, it will be changed manually in the control architecture. Potentially, the robot is to be re-configured for certain "blank" due to "blank" (sorry) and may be fitted with a simple sensing mechanism (maybe something like Hall sensors) to provide a signal of link length.


Fe

 

[sreid]

You might be able to combine the detent adjustment for corse length with a threaded adjustment for the fine length.

 

[unclesyd]

Went to the big red box and saw several of these. Again depending on your requirements one of these may work. They are infinitely adjustable.

http://paint-and-supplies.hardwarestore.com/47-345-extension-poles.aspx?viewAll=yes&sortBy=

 

[FeX32]

Thanks again everyone!


Fe