Grab Tube on the Run!

[rsisk]

Love the arm action, beautiful!

[Carter12s]

Wow that is cool. Can I make sure I am getting this right thou? you have a stationary gear mounted at the pivot point of you shoulder, so that as you rotate, the chain linkage from this gear to the wrist would keep the wrist at a constant relative angle, except that by using two different sized gears you get the angle of the wrist to change as a function of the angle of the shoulder! That is really impressive!

The only place I have seen a similar system is inside the explosive ordinance disposal arm used on Foster-Miller TALON robots. Even thou I work with a talon and the arm almost every day, I never thought to use it on our FIRST robot, and the TALON system is simpler since because they use same sized gears they simple keep the joints relative angles the same.

That is just fantastic to see! If I can ask what gave you the idea to use a linkage like that?

[Mike Schreiber]

Originally Posted by Carter12s

Wow that is cool. Can I make sure I am getting this right thou? you have a stationary gear mounted at the pivot point of you shoulder, so that as you rotate, the chain linkage from this gear to the wrist would keep the wrist at a constant relative angle, except that by using two different sized gears you get the angle of the wrist to change as a function of the angle of the shoulder! That is really impressive!

I have seen similar techniques used before, It is a cool way to do it, RUSH 2007 pre-ship had the same concept, but using timing belts instead the upper joint was eventually cut for weight. This year 3450 is doing the same thing but with steel cable and our pivot point is at the base, so we have two longer joints. It is basically just a four bar linkage but the chain/belt/cable act as your bars.

I like the design looks cool, looking forward to seeing more.

[Navid Shafa]

Love the arm design. It might just be the video, or me, but it seems that your drive is twitchy at low speeds when you came up to the peg. Looking great!

[s_forbes]

Originally Posted by Carter12s

Wow that is cool. Can I make sure I am getting this right thou? you have a stationary gear mounted at the pivot point of you shoulder, so that as you rotate, the chain linkage from this gear to the wrist would keep the wrist at a constant relative angle, except that by using two different sized gears you get the angle of the wrist to change as a function of the angle of the shoulder! That is really impressive!

The only place I have seen a similar system is inside the explosive ordinance disposal arm used on Foster-Miller TALON robots. Even thou I work with a talon and the arm almost every day, I never thought to use it on our FIRST robot, and the TALON system is simpler since because they use same sized gears they simple keep the joints relative angles the same.

That is just fantastic to see! If I can ask what gave you the idea to use a linkage like that?

That analysis of our arm is correct; the static sprocket at the top of the mast provides the rotation for the secondary arm member. There is a ratio of 1.5:1 to give the arm the motion seen in the video.

Not quite sure exactly where the idea came from... to quote professor Farnsworth: "It came to me in a dream, and I forgot it in another dream". I think SPAM's robot from '07 may have played a subliminally inspirational role.

We're hoping that everything will pan out well for the AZ regional in a couple of weeks. The bot in the video is the practice robot; we still have to adapt everything we learn from it to the competition bot on Thursday morning!