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MegaQuad MKII

Obstacle avoidance via ping, hand tracking (eventually)

The old bot had 3DOF per leg using 9g servos :( I'm using Inverse kinematics for his movement. I just started programming him and got the IK working for one leg. The ping((( is just stuck in the mega2560 for now. I'll be adding a tilt/pan head when I get more servos, and the wiring needs some cleaning up :p I just found out about LMR last week and so far it's awesome! The thing underneath him in the picture is a stand I made with my 3d printer to get his legs working correctly, very handy. More to come.

    ****    UPDATE    9 - 23 - 12    ****

     Well the little guy above is no more, as you can see in the picture below, he went through the disassemble process. The reason for this was I thought I had a pile of bad servos. Upon powering the servos the bot would go into an epileptic fit. At first I thought that the pots were dirty, but a teardown revealed that they were fine.
     My original intentions were to build a V2 bot when I got the code working for the V1 bot, but things change and you just have to adapt sometimes. As it turns out, it wasn't the servos that were bad, it was the cheap oxidized jumpers that were the bots untimely demise. This wasn't realized until it was time to center the new SG-5010's for the leg assemblies, and THOSE were acting erratic and having convulsions as well.
     At the end of the day at least I have a small pile if micros' for future bots, and a good start on V2. I'm currently prototyping a power distribution board while waiting for the Mega PotoShield to show up from Adafruit Industries. I tried etching my own board for powering all of those servos, but most of the traces ended up being open and overall it just wasn't worth trying to save. I'll show some pics just to try to justify the long slow updates . :P

The carcass of MegaQuad Mk1
The parts needed to assemble a leg.
When you don't have the right tools, sometimes you have to make the right tools.
I put a pivot on the back of the servos in this design.
Here is a size comparison with the old bot.
More parts printed and almost ready for assembly.
All the legs attached pretty nicely.
Ahh, that's better, now he can see where he's going.
Still needs the servo board I'm putting together and lots more programming.
Eye level view.
Well, that's all I have for now. Thanks for stopping by, And I'll have some video on the next update. Hopefully it will be sooner than later....
 Oh wait, here are those pics of the servo power board fail. :P I guess I owe it to ya if you made it this far through the post. :)
The board before etching, all sharpied up, or so it appears :( 

View of the board mostly populated (no signal jumpers, yet), but not soldered. Hence the dangling screw-terminal. :P

View of the back, notice the over-etched traces.
Thanks again and be sure to click on the collect link above.

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Wow, nice work on your Reprap. Thats is one very cool Quadruped. I might drop you a note for the drawings, when I get my own Reprap up and running.

When I get it programmed and a cool video made, I'm going to put it on Thingiverse. Glad you like it. :)

It look like a jumping spider! With half the legs and a quarter of the eyes, of course.

Having a 3D printer at hand makes robot building even more fun - I see. This green quadruped rocks.

Any information on how you control the servos? Do you use an Arduino servo shield or have you soldered something from scratch?

Thanks NilsB, Yes it is quite fun. I wish I had more time for it.

I'm actually using a proto-shield with a breadboard on it, until I finalize the bot and design a PCB for it. It will be my first legged bot and first custom PCB so this bot is more of a "get my feet wet" kind of build. I'm happy to learn about LMR so I can keep up my motivation and see it to completion. I'm prepared to learn from many mistakes.

All the best



That is a nice way to get your feet wet in the field of legged robots and PCBs.

Thank's for sharing this green beast... and welcome to LMR!

I think that is the reason I can't get this to show up as updated. Hmm, guess I'll have to bump it. But anyway, finally after a month and a half, an update!

Very cool design , looking forward to see it walk !

3d printing enables such great builds!

How thick are the various parts ? (I usually consider any print with a thickess > 3 mm to be robust enough at 50 % infill , but I wonder if  it is thick enough for these "leg parts")

The parts are generally 3mm thick, printed at 20% infil. They are quite strong. I printed the bot with PLA so it is quite rigid at this thickness. I could definately see a servo horn tear off before a leg broke, and it is still quite light. ~300g of PLA for the whole bot.

that's a nice looking quad ! :)