Aluminipede, a small walking machine

Postby LeChatNoir » Fri Jul 23, 2010 9:56 pm

Looking great!!

I mean, really.

I love the down-to-the-wire last few weeks of crunch time. It’s as exciting as it is terrifying.

Re: milling a slot. I don’t have broaches, so if I need a keyway in a collar or something I just cut it on the mill, starting slow with plunging and advancing, then plunging again until the keyway is cut to depth. This is better than side milling into it all at once, since that is a lot of pressure on a small diameter mill, usually resulting in breakage.

One might think that the keyway should be the depth of half the keystock, plus half the diameter of the mill, however this always results in a loose key. Split the difference by advancing beyond half the depth by 0.050â€
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Postby bigbluedoggy » Fri Jul 23, 2010 10:09 pm

Listen to the cat! He one clever kitty!!
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Success!

Postby rodiponer » Sun Sep 12, 2010 10:30 pm

It walked! At Burning Man! It didn't make it to the DMV, or even out of Kidsville, but I am so happy that it walked at all, and on the playa at that.

Here is a video of it's first steps, ever, on the playa:
[youtube]http://www.youtube.com/watch?v=VyvhvTAMWCc[/youtube]

Thank you, everyone here, who helped me figure out the technical details. I didn't, and still don't, really know what I am doing. But with you guys help I was able to get the machine this far.

LeChat, it was wonderful to meet you and your wife. I'm glad we randomly met. Thank you again for your help here, and perspective on playa-- that it can take two years to make a vehicle that does more than go around the block, three years to get out to the trash fence. And Sail Man, thanks again for helping get this thing back in the trailer-- you are truly stronger than four hippies! :)

I think, with some more time in the garage, this machine is likely to make it past the Esplanade next year.

But first it is going to rest, in storage, for a couple months. The month long mad rush to finish it in time, of late late nights and waking up early in the morning to do it all over again, got a little crazy even by my standards of live-eating-and-breathing the projects I do, and I need a little vacation from being a mad scientist for a while.

The main problems are:
- It needs feet. Though I love the foot prints it made, it was sometimes punching through the crust of the playa and sinking 4 or 5" into the playa (!).
- Sinking into the playa increased the loads on the crankshaft, because the legs would touch the ground before they had stopped moving forward, so the weight of the machine was taken sideways on the crankshaft support arms, which caused a weld on a crank shaft support arm to tear off. Just making the legs required 544 one inch long aluminum welds, so I thought I was pretty good at TIG welding aluminum by the end of this. I have the stack of dimes look, at least. But I am not. The weld that tore had no penetration and was just filler rod laid onto the surface… I need to reinforce the crank shaft support arms with brackets that are riveted or bolted on. And then reinforce them again with some sideways tubing, for good measure.
- The nylon bearings I used in the leg joints have too much play in them. The legs were sometimes able to rub against each other, even with 2" of separation. I am going to try replacing the nylon bearings with bronze bearings, which are much tighter. And if that doesn't work, I will have to go back to making clevises to make a set that will take a larger hip axle (if I move up from 3/8" rod to 3/4" or 1" rod, which will allow less movement in the leg joints).
- Idler pulleys on the chain, so that we don't have to make the chain as tight as it was to keep it from skipping. This will work, right?
- Optical encoders on the motors, so that the motor controller will keep the left and right side at the same RPM. Currently, the motors are given a voltage and allowed to vary their RPM slightly as the torque requirements change, which means the machine yaws slightly when one side needs slightly more torque.
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Postby Shoeshine » Sun Sep 12, 2010 11:10 pm

Nice Rodi.

Sorry I never had a chance to make it out your way.

I kind of got -stuck in- doing work for megatropolis.

Looking fucking fantastic.

Would still love to do a meet-up in SD if you are game.

Chris
aka "Shoeshine"
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Postby masho » Sun Sep 12, 2010 11:47 pm

I was wondering what happened to this. Looks fantastic. I love the visual on you leg motion, the overlapping triangles look great. Good luck with your tweeks + revisions.
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Postby Sail Man » Mon Sep 13, 2010 8:21 am

Matt, thanks for the kind words. It was def. a pleasure to help you with this on playa in any way possible.

And it was great to see her? in action. BTW, what's her name? :D

After all you did to get her this far, I can only imagine the tweaks that you have to do, imagining far less labor and time intensive this time around, will only insure that she walks much further next year. And I am looking forward to seeing that.

Kudo's on a most awesome project.
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Postby LeChatNoir » Tue Sep 21, 2010 7:46 pm

Rodiponer,

It was a joy to meet you and your family. And thank you for posting the video. It is exceptionally cool and beautiful to see Aluminipede in motion. It takes a special sort of crazy to keep throwing one’s self at these types of things, but that’s ok. You won't be able to look back on your life and say it was uninteresting.

It makes me very happy to have been of help to you and I look forward to keeping up with your project’s evolution. I hope to see it in person next time.
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Postby Tiahaar » Tue Sep 21, 2010 11:01 pm

Wow amazing great job on Aluminipede!! The leg motion in the video is so nice and smooth, what a contrast to that other beastly big stomping walking machine (which is also most awesome...though seems to frequently bash itself apart). Love the linkages. Hope to see this 2011!
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