noodleFeet : All Wired and Ready

When your baby is learning to walk, you make sure its near soft things and away from stairs so that when the inevitable fall occurs, they don’t collapse into pieces. When your baby is a robot learning to walk, bungie chords and harnesses are also needed. And in the case with noodle, who is delicate and wobbly like a skittish baby fawn, I am sparing no precaution!

The noodle Harness

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Robots get rigging. Mark took the time this weekend and installed a guide wire on the ceiling over our work table. A “leash” hangs down from this wire and clips on to noodle’s smashing neon-yellow harness which wraps around all four of his legs. If he loses his balance, he won’t have very far to fall before the leash pulls tight and catches him.

Calibration!

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Before assembling noodle for his big day, I had to calibrate all of the servo motors to 90º. Only then could I screw the gears to the motor shafts, as well as connect the pulley bits from the secondary servo motors on each leg to the bendy bits.

In the end, once all of the final parts were attached to one another,  I was pleased with how solidly he stands on his own. Hopefully I can figure out the right way to distribute balance so that he can lift up his feet and walk.

Wiring up the Bread

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Lastly, this afternoon I taped an Arduino down to the end of a breadboard and fashioned some male headers so that the servo motors could easily plug-in and tether to their appropriate pins. The breadboard itself is taped directly to the leash so that it will move with noodle as he walks… or falls.

When is he walking?

So, he’s poised and ready. The big moment will either come tonight some time or tomorrow after Mark is home from work for the weekend. Either way, I’ll be sure to take LOTS of footage of my wobbly child as he navigates across the table for the first time. =O

Wish us luck!

noodleFeet : Goes Metal

I’ve relied on 3D printing for so many of my prototypes lately, and have finally come to a point where plastic won’t cut it any longer. I require metal, in this case aluminum. The likes of which I ordered from McMaster-Carr and received in the mail last week. I literally spent the majority of the weekend meditating over how to measure my cuts and holes… as for the first time in a long time, their accuracy and placement was entirely up to me and my calipers, not some Cartesian goo plotter as I’m so spoiled by…

While everyone was downing beer and watching the Stuperbowl, I was in the garage with Mark playing with his father’s ancient drill press. He eyeballed one axis, I checked it against the other, and we were able to punch the 24 holes needed on the four pieces of aluminum tubing which would soon be noodleFeet’s strong new legs.

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As you can see, I printed out little strips of paper with lines where holes needed to be drilled. It only occurred to us immediately after we finished how much easier this would have been if we had 3D printed a jig for drilling the holes instead… So alas, 3D printing could have potentially saved the day. Thoughtful or not… we did a pretty good job.

Once the aluminum femur was assembled, I realized I was going to need stronger springs. These flour legs are going to support eight motors, a board, and eyeballs; a decent amount of weight:

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The calf bit is essentially a bone buried within the noodle material. However, with my last prototype, the bone kept sliding out the clearance slot I cut in the noodle. So to remedy this I made these little braces that look like pac-man heads… which keep the bone centered within the tube and prevent it from popping out where it isn’t suppose to:

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The rare and beautiful white noodle was harvested by Mark from the great noodle beast itself. I cut the pieces to length with a Japanese saw and carved the appropriate clearance slots so that the legs can fold in on themselves like they should:

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The new servo and leg bracket is THICK. It is complete with roller bearings spaced a decent amount apart vertically to keep the intersecting pipe from wobbling around (as with my first prototype):

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The eight roller bearings hold the pipes perfectly parallel to one another and allow them to turn nice and smoothly. I also added stronger springs to tension the legs outward, so the new prototype is a little monster. Although… he looks sort of helpless up-side-down on my bench right now:

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At this point, Feet is nothing but a pile of feet. He needs eyes, and that is exactly what I’m going to do next… and maybe a brain. Over this weekend I’ll likely hook an Arduino up to his servos and figure out a walking pattern too.

I honestly have no idea what it’ll look like when he walks, but I’m hoping due to the springs counterbalancing his weight that he’ll have a little bit of a bounce. That’d be cute.

I also don’t know if he’ll be able to balance himself when he walks. Once summer happens and the noodle is less rare, I will go harvest some 4″ stock (in neon yellow) from Walmart and cut my prototype some new fat feet. That way he makes more contact with the ground and is less like to fall. Like training feet.

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Hopefully by my next update he’ll be moving some… like a robot aught to. Cheers!

noodleFeet : Proof of Concept

Last week I started building a new robot who I’m calling noodleFeet! He is essentially a spider-type walker who will locate nearby legs, approach and then lean on them. In addition to having that specific purpose, he needs to look a particular way. I’ve been drawing him in the margin of my notes for weeks now, so he’s become something of a character to me:

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In order to make a robot that does these things, I need to design the mechanism itself and how it will be attached to the motors driving the motion (challenging and fun). At the same time I need to learn about Open CV and figure out how to make a computer recognize all the different shapes that legs come in. This will involve a camera and some coding (hard and not fun). With these two elements combined, I’ll eventually end up with a leg hugger…… or leaner. I’ll talk about the details of those steps when I get to them.

To get started, my challenge for the weekend was to solve how to make the legs of the robot itself. I wanted to come up with a reverse knee-joint capable of folding into a single-stick. This took about three of four revisions to get right, at which point I went on to 3D print four copies for the proof of concept.

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The proof of concept is nothing more than a rough servo bracket that holds all of the motors in place at the point where the four legs attach to them. With these parts alone I was able to construct something that looks surprisingly already very much like the end product I’m aiming to create. It still isn’t a working prototype however. For this, my concerns were mainly measurement and proportion:

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I’ve gotten away with using 3D printed parts on many of my projects, but for this one plastic isn’t going to cut it. Even though the design is mechanically sound (I believe) and I could have wired some servo motors up to see some motion, the flimsy plastic legs don’t seem like they’d be able to support the combined weight of the motors… so I didn’t. Because of that, the next step is to replace the crucial parts that support the most weight with aluminum pieces. So I’ve gone ahead and ordered some hollow pipe and bearings for a more sturdy, motion-ready second prototype. In fact… the materials arrived today, so it’s a good thing I got documenting this out of the way!

Hopefully with my next post I’ll have video of noodleFeet making his first steps… or wiggles. You can see him in this illustration I recently drew to the right of our car:

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mechaFeet : Prototyping with Algodoo

I had to wait this week for the sensors I ordered to come in the mail before I continued progress on Jelly. With Jelly on hold, I couldn’t save myself from starting on yet another project idea I’ve had fermenting in my mind for a while now. It involves building a pair of mechanical chicken (or raptor) legs that can stride in sync with one another; both legs driven by the same moving part. The thing that initially inspired me to make a mechaChicken was this quirky and utterly gorgeous mechanical hand ostrich thing by Tim Lewis called “Pony” (that and all the stupid bipedal robotic dinosaurs that are in the stores for Christmas this season).

My problem is that I don’t have a whole lot of experience with big kid mechanical motion, so it took a lot of meditating on before I even got started.

Two nights ago, I laid in bed and mused over parallelograms. When I woke up, my mind was running an animation loop that I must have seen somewhere at some point in my life. In any case I understood what sort of shape I needed to build to get the movement I wanted. So, I rushed to the closest scrap of paper and drew it before the idea escaped:

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After I made the doodle I played geometry Sudoku with the lengths of the pieces. Once I was satisfied with my own logic, I designed the segments in CAD and printed the eight individual bits to test. I eagerly screwed them together to find that the ‘mechanical leg’ moved EXACTLY like I thought it should… the proportions needed to be tweaked a bit, but it worked:

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This wasn’t good enough in itself though. Now I had to figure out how to drive the leg in order to execute the motion correctly (which isn’t as easy as you’d think). After spiral-graphing the top of the ‘thigh’ in motion by manipulating the ‘foot’ of the piece, I saw that the thigh tendons were arching in circles, so I knew I needed to create a wheel of some sort… which I did, but it sucked:

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Sucky wheel sucked because I didn’t take into account that the tendon piece of the leg would need to clear past the center of the hub, flush with the wheel itself. Of course, I had a screw mounting the wheel in place, so the head of that said screw got in the way… ruining my night. Easily remedied… but… Bleeeeeeeh very fussing. so much tedious.

Around now, Mark suggested that there ought to be some sort of 2D motion simulation software out there in the ether that I could use to test my ideas. I was starting to wonder that too… as I was minutes away from hopping on Little Big Planet to make use of their physics tools, tehe.

Last night, after some hunting, I found Algodoo. What a wonderful discovery… It allows you to draw out (literally) your arms, connect the joints with screws and drive them with motors, just like life but without the toil of actually building the prototype. What do I mean? I made this in about 5 minutes and it gave me the exact same feedback:

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In my video I give a brief introduction to the software while explaining how to make my chicken leg. As of right now, I still haven’t figured out what kind of motion will properly drive it, but I’m well on my way to getting there (without wasting PLA!)