pic: FRC488 - Lifts Raised 1

[Madison]

Originally Posted by Joe Johnson

No arm? Bold indeed.

What motors are you using to lift 2 190lbs 12inches in 2 seconds?

Force = 380lbs = 1700N
distance = 12 in = .3m
Work = 4600in-lbs = 510 Joules
Power = 260 Watts

You had better say something like "The Big CIM" or 2 FP's or something else that adds up to enough power to do the job.

Joe J.

Originally Posted by Lil' Lavery

They're using gas springs.

Each lift is driven upward by two 125 lbf. gas springs. Each spring is held closed through the match by a servo-driven latching mechanism that is designed to distribute the force of the springs into structural members of the lift rather than directly against the servo.

You can see a quick video taken without the latches attached that shows two students setting and releasing the lift here: http://www.youtube.com/watch?v=okYnM1a5T-E

I have another question. How do you tie the front an the back together? If I am a very heavy robot in front and light in the back will you lift me still or will the platform $@#$@#$@#$@#?

Do Tell.

Each spring drives a four bar linkage such that there are two linkages per lifting mechanism. Those linkages are tied to one another in several places throughout -- three crossbeams supporting the polycarbonate platform attach to the upper horizontal member of the four bar, a single crossbeam connects to the bottom of the four bar, and a larger crossbeam connects each side at the gas spring end to give rigidity near the points that allow the lifts to rotate from vertical to horizontal while being deployed.

The platforms are very good at handling uneven loading, as you can see for a moment in the video linked above when the students press downward unevenly. We've tested the lifts with three 50 lbs. sandbags in as many different locations as possible. As a result of such testing over the last week, we identified some problems with lifting robots with CGs in certain places and redesigned and rebuilt the mechanisms to compensate.