Iterave design, 2011

[GearsOfFury]

Thanks for sharing, this is a neat idea.

You mention the FP motors. Just so your team is clear, if these motors are direct from the manufacturer (e.g. KOP or AndyMark) and have not been modified (pinion gears, etc.), they qualify as COTS, and are not FABRICATED ITEMS, and do not count against your 30 lbs:

FABRICATED ITEM – any COMPONENT or MECHANISM that has been altered, built, cast, constructed, concocted, created, cut, heat treated, machined, manufactured, modified, painted, produced, surface coated, or conjured partially or completely into the final form in which it will be used on the ROBOT.

<R33> Teams may bring a maximum of 30 pounds of custom FABRICATED ITEMS (SPARE PARTS, REPLACEMENT PARTS, and UPGRADE PARTS, plus all WITHHOLDING ALLOWANCE items) to each competition event to be used to repair and/or upgrade their ROBOT at the competition site.

[Jeffy]

How is that single roller claw working for you? We prototyped something like it and couldn't find a way to overcome the tubes turning upon entry.

[Hawiian Cadder]

the single roller works fairly well.

the roller is a polycarbonate tube, which is attached to the drive axle with rubber bands. this gives it 1.5 inches of tolerances where it moves to accept different sizes of tubes.

the "sensor" on the roller is only C-A-N, the free current of the roller is 2-4, as soon as it exceeds 14 amps, we know a tube is securely held.

we looked at a variety of materiel for the bottom of the roller. regolif, was very promising, however we found that polycarbonate coated in duct tape works nearly as well, and is significantly lighter. regolif is also not COTS as far as i know.

the width of the roller also helps it to not turn the tubes. it does turn them up a little at the beginning, but when they get sucked in far enough they are forced to line up with the bottom of the manipulator.

the fisher prices have had their gear pressed off, and a new one put on. we were not sure as to the legality of that. there is also not much that can be changed. the original CAD will work just as well as the other two, once we get the lift to stop binding. our withholding allowance has a couple of new sliders, as well as spare axles. our the COTS items we are taking are a lighter digital sidecar ribon cable. a new encoder for the lift. and a few other things to cut weight.

i think were good, but does anyone see a problem with continuously stalling a rs550 at 14 amps?

[Jeffy]

Originally Posted by Hawiian Cadder

i think were good, but does anyone see a problem with continuously stalling a rs550 at 14 amps?

Absolutely. The BB motors get their cooling from a fan attached to the armature, if the motor is stalled, no cooling. We had a deffective gearbox with a 550 for the arm on a 20 amp fuse. It got unbearblely hot within 30 seconds and thermal shut off in under a minute.

What have your tests shown?

[Hawiian Cadder]

we did not have a whole lot of time to test it. 14 amps is not too much. i will talk to the programmers and see if we can change it to test for a tube every second or something.

[Alan Anderson]

Originally Posted by Hawiian Cadder

14 amps is not too much.

14 amps at 12 volts is 168 watts. You'll fry the motor in short order if it isn't spinning and cooling itself.