Snake Arm Robots

[Richard Wallace]

This is cool. I wonder if a FIRST team could build something along these lines for some future game?

[miketwalker]

1875 made an amazing attempt this year with an idea one of their students had to do something like this. They found a way to do a version of what you are talking about for super cheap using a boat antenna ($15) some simple CNC'd X brackets to run cables up the antenna with, and mounts at the base. At the Florida Regional they were having problems staying within the starting dimensions (they would bend it around to look almost exactly like a question mark to start with and then it would spring out at the start of the match) as well as controlling it (they had one person controlling the 4 motors himself if I'm not mistaken, so considering they had no sensor feedback it was really, really, really innovative and definitely something I think should be pursued more). For the "complex" movements it achieved (360 degree turret arm that could extend out 8 feet or so from the robot) with such simplicity (4 cables and a boat antenna) it was quite a nice development within FIRST. I know a big issue with it was the spring force of the antenna is what was used to naturally make the arm go back up as the 4 other cables were released, so it was fine to pick up something like a tube, but to pick up a Tetra would probably be impossible (at least with a boat antenna) just since the weight is so massive in comparison to those tubes.

Here are some pre-ship photos of their robot, I wish I had some from the competition, but like I said they did have some problems with it and you can get the basic idea from these... very cool stuff.

http://www.chiefdelphi.com/media/photos/27108
http://www.chiefdelphi.com/media/photos/27096
http://www.chiefdelphi.com/media/photos/27078

[Jack Jones]

But does it recieve HDTV?

[Rich Ross]

Richard, i feel like a "snake arm" is not practical for FRC robots.

1) it doesn't look all that robust to me
2) it looks pretty heavy
3) It is sooooooo slow. This company (OC robotics unless my brain is jumbling things again) builds these things professsionally, and it takes a full minute to look at the underside of a car. Between the way these things are controlled and the way that the motors are mechanically set up, its not that beneficial overall as far as i can see.

[Qbranch]

Are there any videos of one of these flex arms running? Or one of 1875? I've never seen one actually run... but if they are as slow as i've herd I'm unsure how useful they could be.

However... the K-sub-WOW on this type of manipulator is runnin high...

-q

[Cowmankoza]

Originally Posted by Rich Ross

Richard, i feel like a "snake arm" is not practical for FRC robots.

1) it doesn't look all that robust to me
2) it looks pretty heavy
3) It is sooooooo slow. This company (OC robotics unless my brain is jumbling things again) builds these things professsionally, and it takes a full minute to look at the underside of a car. Between the way these things are controlled and the way that the motors are mechanically set up, its not that beneficial overall as far as i can see.

I agree on the robustness factor, however I have seen methods in which an air bladder is placed on the "snake arm", the arm is sectioned and in effect limp, but when the air bladder inflates it extends the structure and makes it rigid, im sure that you can have more bladders, say on the side of the arm to give it a side to side motion. Therefore the weight is dropped drastically and as for speed, that is directly related to the volume and pressure of air being put into it.

As for FIRST robots, it seems unpractical to use an air bladder due to the limited volume we can store, as well as the question on wheter or not its legal (I doubt it).