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A-pod, an ant inspired hexapod

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Guru ( offline )
Posts: 2120
Posted: 2009-01-06 19:28 
Hi all roboteers!

Lately I've been working with a new hexapod. This is my third hexapod project. And this time I wanted to make something very different.

I've always been inspired by insects and especially ants, check out Alexander Wild Photography of ants and you'll see what I mean.

I've not tried to copy any ant, I think that would be almost impossible with the large legs compared to the body. I also wanted to use 645 servos for the coxa, femur and tibia. But I wanted A-pod to have the following:

    A large and a very flexible head, ideal 3 DOF
    Large mandible that can grab around a bottle/can
    A thorax, the main body with a natural shape for all legs and main battery
    A 2 DOF controlled Abdomen (a tail, gaster) holding all electronics

So far I'm done with the coxa, femur, tiba, mandible, head and body parts. I've not made the abdomen yet, soon to be made :wink:

This time I've choosed a very different coxa design, I know it has some cons. I wanted to place the femur servo joint very low and also increase the horisontal distance between the coxa and femur joint. Making this distance to large have also some cons but I think this are going to work ok. Here are some pics of the coxa design:

The coxa are made of three parts:



Completely mounted with the femur servo:



Here are the femur and tibia parts. I've used the same material I used for my original Phoenix, ABS texture plastic 5mm. The little 1.3mm hole at the end of the tibia (tars) are for calibration.



I've no pictures of only the head/mandible section yet, but I think you'll get the picture of how I designed it using black SES brackets and some custom made plastic parts. I'm going to add some rubber to the inside of the mandibles to make it easier to grab and hold objects.

Here are some pictures of the body with mounted head and legs. I placed the black dummy dome just for making it a bit easier to imagine how it would look like with the abdomen.



















The last pictures demonstrates how flexible the head are going to be.
Pardon the messy wires. But I've a lot of work left :wink:

Please let me know what you think.

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Novice ( offline )
Posts: 63
Posted: 2009-01-06 19:46 
wow that is awesome! I would love to see a video of it in action once it is up and running! 8) :mrgreen: also, that is great work with the materials, and the molded body. how does everyone get such perfect pieces?


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Guru ( offline )
Posts: 4921
Posted: 2009-01-06 20:40 
Looks great! I hope I don't run into it in the dark! You do great work!

Kurt


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Posts: 81
Posted: 2009-01-06 22:19 
You've done it again, Zenta! Another masterpiece.

I'm sure this one will as much a success as the Phoenix is.

Like the others, I'll be waiting for the first video of it.

Oh yea, you can't have just one; you're going to have to build a colony of them.

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Guru ( offline )
Posts: 1130
Posted: 2009-01-07 03:53 
WOW! Truly awesome work Zenta!

I was happy to see the previous that you’ve send me some time ago but the end result is even better that I’ve could imagine! Great work with the body part. I have no idea how you managed to get the moulted shape in there and still keep the servo wholes in the right places. The head with the mandible really gives it character!

But the best of all…

It can fetch you a beer!!

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Guru ( offline )
Posts: 2120
Posted: 2009-01-07 07:06 
PrinterFace wrote:
wow that is awesome! I would love to see a video of it in action once it is up and running! 8) :mrgreen: also, that is great work with the materials, and the molded body. how does everyone get such perfect pieces?


Thanks!
I'll post some information and pictures later of how I made the upper body part.

kurte wrote:
Looks great! I hope I don't run into it in the dark! You do great work!

:lol: Thanks Kurt! Yeah lets not hope that...

Thanks Core2! I think we all have to wait a while to see any video.

Xan wrote:
WOW! Truly awesome work Zenta!

I was happy to see the previous that you’ve send me some time ago but the end result is even better that I’ve could imagine! Great work with the body part. I have no idea how you managed to get the moulted shape in there and still keep the servo wholes in the right places. The head with the mandible really gives it character!

Thanks Xan!
I didn't have time to take more pictures before my christmas vaction, so pardon me for not posting more pics for you :wink:
As I mentioned I'll post information about the upper body plate. Actually its rather easy.

Xan wrote:
But the best of all…

It can fetch you a beer!!

Oh yeah! 8)
Finaly I've hopefully managed to make a "useful" hexapod that actually can DO something :lol:

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Kåre Halvorsen, Zenta
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Zenta's blog
http://zentasrobots.com/
Zenta's YouTube channel
http://www.youtube.com/ZentaOlbaid
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Expert ( offline )
Posts: 536
Posted: 2009-01-07 11:03 
:shock: Holy cow... Not quite what I expected to see on a Wednesday morning, but in a good way!

Is this the Queen or just a worker? :lol:


In any case, I'm interested in how you pulled it all off, nice work :D

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Guru ( offline )
Posts: 3301
Posted: 2009-01-07 12:44 
well you have been busy. i see why the work on you felix 4x4 has stopped!
excelent work zenta.
once again you have inspired!

the web link is cool. i like all the bugs too. i have some images ill post soon. you will love them!

well done. j

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Guru ( offline )
Posts: 2158
Posted: 2009-01-07 13:12 
it is pretty cool and your ability to design and fabricate tight fitting metal parts is demonstrated once again. your comment about having a hexapod that can do something got me thinking about the can of soda pictures. I would guess the weight to be around 0.35kg or so and it seems like having that mass way out front in the mandibles would seriously alter the CG of the body and really load up the front legs. It seems like an ant would have the same issue so I wonder what is it about their geometry that allows them to lift the seemingly incredible amounts of weight they do (relatively speaking). it looks like this design has legs all the same length while I don't believe that is the case for the ant. is there possibly any benefit to adjusting the ratios of the legs to approximate that of an ant? I'm sure it makes the IK 3x as much since you would have 3 different "constants" that are now different between forward, mid, and aft legs. just thinking out loud... :roll:


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Posted: 2009-01-07 13:15 
Quote:
I WROTE
Quote:
i have some images ill post soon. you will love them!

http://www.lynxmotion.net/phpbb/viewtop ... highlight=

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Jonny Poole,
Freelance Concept Art & Animatronics, 3D Art and 3D Modelling, as well as Physical Modelling, Mechanical design, and illustration.
http://www.innerbreed.co.uk
Create, Innovate, Inspire.


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Guru ( offline )
Posts: 9256
Posted: 2009-01-07 13:56 
Hey Zenta, Nice work. Can't wait to see it in action. ;)

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Posts: 2120
Posted: 2009-01-07 16:05 
Thanks to you all for your comments!


EddieB wrote:
I would guess the weight to be around 0.35kg or so and it seems like having that mass way out front in the mandibles would seriously alter the CG of the body and really load up the front legs.:


Thats very true about the CG when lifting something very heavy with the mandibles. I think the solution would be to reposition all legs to compensate for the new CG. Probably by moving the middle and rear pair of legs more forward. Also reducing the horisontal distance from the femur joint to tars would increase the ability to carry more load.

I'm looking forward to try this for real :twisted:


EddieB wrote:
It seems like an ant would have the same issue so I wonder what is it about their geometry that allows them to lift the seemingly incredible amounts of weight they do (relatively speaking). it looks like this design has legs all the same length while I don't believe that is the case for the ant. is there possibly any benefit to adjusting the ratios of the legs to approximate that of an ant? I'm sure it makes the IK 3x as much since you would have 3 different "constants" that are now different between forward, mid, and aft legs. just thinking out loud... :roll:


I've been thinking of using different lengths of the legs and I dont think the IK would be any trouble. But I didn't want to reduce the length of any legs, I would prefer to make some of them longer but that would require stronger servos. Maybe a 5990 TG version would be cool? But very expensive too :oops:

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Kåre Halvorsen, Zenta
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Zenta's blog
http://zentasrobots.com/
Zenta's YouTube channel
http://www.youtube.com/ZentaOlbaid
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Guru ( offline )
Posts: 2158
Posted: 2009-01-07 16:59 
zenta wrote:
I've been thinking of using different lengths of the legs and I dont think the IK would be any trouble. But I didn't want to reduce the length of any legs, I would prefer to make some of them longer but that would require stronger servos. Maybe a 5990 TG version would be cool? But very expensive too :oops:

yeah, perhaps if you don't need the full range of motion of the servo then you could construct an indirect drive that trades torque for range of motion through leverage? I am thinking RobotDude has posted images of some experiments he has done along these lines with SES components in the past...


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Posts: 36
Posted: 2009-01-08 18:34 
 Post subject: New ant
Great job, Zenta!! :D :D :D Can't wait to see it a crawlin'.
Have you ever seen the "Bill Ant Project" It was posted online several years ago, as a graduate project. It has an articulated head as well.
Love the work on the coxa joints --- are you sure you don't have a CNC machine shop ? :P

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Posts: 2120
Posted: 2009-01-12 17:59 
 Post subject: Re: New ant
brlippincott wrote:
Great job, Zenta!! :D :D :D Can't wait to see it a crawlin'.
Have you ever seen the "Bill Ant Project" It was posted online several years ago, as a graduate project. It has an articulated head as well.
Love the work on the coxa joints --- are you sure you don't have a CNC machine shop ? :P


Thanks brian!

Yes I've seen the Bill Ant, great project with good documentation too!
Yeah, Im pretty sure I don't have any CNC machine shop. :wink:

_________________
Kåre Halvorsen, Zenta
-----------------------------------------
Zenta's blog
http://zentasrobots.com/
Zenta's YouTube channel
http://www.youtube.com/ZentaOlbaid
-----------------------------------------


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