The Atrax - A Tarantula inspired octopod

I whished to try building a multi-leg robot looking like as good as possible at a Tarantula.
I thought that one of the easiest ways for me, was probably starting and adapt

  • the famous Zenta’s PHOENIX project
  • Xan’s Basic code for the Basic Atom Pro
    Zenta’s Phoenix Excel Program (PEP) for OXYOPUS is useful too for the postures
    Some great thanks to both of them! :smiley:

Let’s see the plan: it was cool to try reduce the cephalothorax to the minimum size, just sufficient to allow coxa servos move correctly.
In fact, a small body and long legs will look fine like a spider!Plan of body.JPG

Looks like you’ve got a good start on an octopod design! I hope you thoroughly checked out the range of motion of the legs!

There are a few other threads on octopods on this forum you might want to check out.

viewtopic.php?f=8&t=3085

Jim was considering fabricating a test chassis from a plan I submitted. I wonder where that is? ;>)

I have milled chassis for my 'Quad and 'hex robots, but the octopod I designed is just too big to mill on my CNC’d Sherline.

Alan KM6VV

Thanks Alan! I’ll read these threads in details…

Mine is not circular, and in fact, the space for coxa moving will just be OK.
For the first one, it seems better for me build it of wood: the easiest material to work with for a beginner…

Nice looking parts!

I don’t do much with wood, but I’ve heard some of the spruce plywoods used for models can be quite strong. You should also be able to cut parts out of Lexan, which I think can be worked similarly. I like metal. 6061-T6 machines quite well.

Alan KM6VV

As shown on pictures, the SSC-32 card (connector to the front on the Phoenix) is turned 90° on the right , presenting the DB9 connector on the right.
2 pair of Rear legs + the abdomen are powered by one 6V NI-MH battery, via VS1
2 pair of Front legs + the fangs are powered by one 6V NI-MH battery, via VS2

The space for these 2 batteries was negotiated as follows:


Then, let’s try the abdomen, just to see how it looks…Abdomen.JPG

It’s become buried under a T-Hex clone, a ground contact leg switch, a mini T-Slot construction system, etc. Sorry I will try to get to it soon.

Hi McSpider,

Interesting build! How did you manage to cut out the wooden pieces so beautifully? They look like they where cut out with a CNC machine. Am I right?

One of the pictures shows the tibia. What are the 3 little pins sticking out? They look like jumper pins. Are you planning on adding sensors on the tibia?

You’re design looks pretty heavy. What servos are you planning on?

Xan

Hi Xan
Unfortunately I don’t have any CNC machine. My best friends were just a drill press and a little Dremel saw for that. But it needed a bit time and a lot of Swiss precision in my work to obtain this result! That’s it. :wink:

You are right: I put some microswitches on each tars. I hope that you’ll maybe take care of this option in the future version of your code. Right? :wink: They are state control leds … just for fun for the moment!
(tars on ground -> green, and lifted -> red)Tars.JPGTars - Leds side.JPG

Amazing craftsmanship! The edges of the wood is very clean and no splintering what so ever. I can’t imagine trying to cut that shape free hand using a dremel saw.

I’m using the Hitec HS 645 for the legs, and HS 475 for the fangs and the abdomen.

Let’s see the fangs: I needed 2 ASB-06 ] brackets folding a bit, just to reach an 40° angle. By this way, it looks a little bit like an Australian Atrax now!

Hey! You’re holding out on us. Let’s see some more pictures of the thing, but back up a bit. :wink:

Nice Chelicera! Or are those Palps? I really don’t know much about spiders. but it should be interesting to see your spider move!

Alan KM6VV

How thick is your wood? The local Lowes home improvement center has 24"x24"x5.2mm sheets of Lauan plywood for ~$3. Just wondering if you are using something similar.

Hi, anyway, I’ll upload a video Alan, coming soon for sure!

You’re right zoomkat, in fact I bought a plywood plate for ~$3 or something like that. The thickness is 3 mm for all parts, instead of 2 mm used for the Phoenix’s aluminium parts. But I observe that is not too thick. The total weight of the spider gives about 3 kg !! I’ll use Aluminium for the next one for sure. I used wood for some trials, because I was not so sure about the possibility for 2 more legs implementation.

By the way, I put a 4 pole switch directly as a quick switching facility to allow connecting
position 1 -> SSC-32 at the BB2
position 2 -> SSC-32 at the PC
That’s very useful: no jumpers to change any more!
The sheme looks as follows:

Then the The LED interface card is ready:

Hey there ya go! That’s one nice arachnid bot! Nice work! 8)

That looks rather menacing :smiley: Can’t wait to see it walking.

-1

OK, Atrax, aka the Australian Funnel web spider!

Nice implementation!

Once upon a time… ?

So are you in France, or Australia? In either case, welcome!

Alan KM6VV

Edit: OK, Switzerland!

Hi,

Wow, every part are simply excellent work and great craftmanship! 8)
Great to see an octopod again, I just love seeing it come together. The pinchers/palps looks really scary. :smiling_imp:

Now we are just waiting for a video… :smiley: