Manipulators: Claws vs rollers?

[ttldomination]

Originally Posted by Koko Ed

We did pretty good in 2007 so we're gonna try to stick with our claw design as much as possible from that year with some inspiration from our even more successful 2008 bot for the elevator.

Could someone explain the lift in this image? It seems like the ropes simply go from the bottom of one stage to the top of the other, so how does it all go up exactly?

Thanks,
Sunny

[Koko Ed]

Originally Posted by ttldomination

Could someone explain the lift in this image? It seems like the ropes simply go from the bottom of one stage to the top of the other, so how does it all go up exactly?

Thanks,
Sunny

You mean the 2008 bot?
Those are slide rails that are designed for use in a copier drawer were used for the elevator.
Just be warned when using them that they can give out (check out 7:52 into the video. Ironically we won the Quality Award after this happened).

[ttldomination]

Originally Posted by Koko Ed

You mean the 2008 bot?
Those are slide rails that are designed for use in a copier drawer were used for the elevator.
Just be warned when using them that they can give out (check out 7:52 into the video. Ironically we won the Quality Award after this happened).

I'm more curious about how the actual lift was obtained. Like, it seems that the rope runs from the bottom of one stage to the top of the previous stage. How would you pull that up?

- Sunny

[Koko Ed]

Originally Posted by ttldomination

I'm more curious about how the actual lift was obtained. Like, it seems that the rope runs from the bottom of one stage to the top of the previous stage. How would you pull that up?

- Sunny

No rope.Chains moved the mechanism up and down..

[Wayne TenBrink]

We looked at a claw and a gripper, and made quick ptototypes of each. We are going forward with a claw, but not everyone has full confidence at this point.

A claw is a lot simpler and the parts that are exposed to damage (extended) are easier to fix or replace. It is lighter. A claw can't rotate a tube after picking it up, but this year most or all tubes will essentially be horizontal on the floor. We can do any necessary rotation with the arm. A claw can be made to pick up a tube that is in contact with the robot - and robot/tube contact should orient and locate the tube for pickup. A claw requires fewer wires running out to the tip of the maniplator. It is easier to modify the details of a claw (grip materials, length of the fingers, amount of clamping, etc. Hopefully, our claw will be done soon enough to build a roller claw if it doesn't work!

I expect the tubes to be inflated quite tight. Inflation pressure really changes the dynamics of the pickup. Whatever you use, be sure it can be adjusted for, or is relatively unaffected by tube pressure.

Finish early - then practice, break it, improve it, repeat.

[pfreivald]

Originally Posted by Wayne TenBrink

I expect the tubes to be inflated quite tight. Inflation pressure really changes the dynamics of the pickup. Whatever you use, be sure it can be adjusted for, or is relatively unaffected by tube pressure.

I was convinced with a claw when it was used to pick up a completely uninflated tube with incredible ease... While running.

Originally Posted by Wayne TenBrink

Finish early - then practice, break it, improve it, repeat.

No such thing as finishing early!

[jblay]

What are peoples thoughts on how fast they think the roller should run to adequitly pick up the tube?

[pfreivald]

Originally Posted by jblay

What are peoples thoughts on how fast they think the roller should run to adequitly pick up the tube?

...as fast as it needs to...

No, really. Depending on the material surface, diameter, and geometry of your roller claw, that answer is going to have a lot of play.

Design, prototype, test, critique, redesign, re-prototype, test, critique, redesign, re-prototype, test, cry a little, critique... Repeat these steps as necessary!