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Project Oxyopus, an octopod robot

#1

Hi!

Some of you have probably noticed that I’m working with a new multi-legged creature in my Phoenix thread lynxmotion.net/viewtopic.php?t=2743&start=195.

First, I must say that this project has been more of an experiment since I have choosed to try some cheaper servos. Of course you almost always get what you pay for. The servos I’m using does not have the same quality and precision like you get from Hitec or Futaba. But they are strong and have MG geartrain. Here is a picture of my new coxa design: http://i214.photobucket.com/albums/cc6/ZentaOlbaid/OxyopusCoxa.jpg
Having low weight in mind from the beginning of this project has been very important. These servos has a relative low weight (low quality = low weight? :laughing: ) The low profile servo has a torque of 7,4 kg and the standard sized servo has a torque of 9,7 kg and their weight is 33gr and 48gr. I’ll also use this low profile servo for the tibia part.

The coxa design is very simple, but has very low weight and was quite easy to make.

To day I made the body part, here is a picture of them together with Phoenix for comparing:
http://i214.photobucket.com/albums/cc6/ZentaOlbaid/OxyopusVSPhoenix02.jpg
Also a overview picture of all servos, spacers for mounting the bodyplates together ++:
http://i214.photobucket.com/albums/cc6/ZentaOlbaid/OxyopusParts.jpg
As you can see I’m using two 2S 1700 mAh LiPo’s for powering Oxyopus. I’m also using two voltage regulators. Each regulator can handle 8 amps constant and 12 amps in a 20 sec burst. I think 16 amps would be enough? There are two reasons for using a regualtor for LiPo’s: 1. The 8,4 voltage they deliver after charging might be too much for the servos. 2. When discharging LiPos you MUST monitor voltage. These regulators has a LED who starts to blink when the voltage reaches about 6,7v. Very useful! 8) Here is a closer pic:
http://i214.photobucket.com/albums/cc6/ZentaOlbaid/OxyopusPower01.jpg
The body is not completely mounted, but I just had to try how it would look like with the coxa parts:
http://i214.photobucket.com/albums/cc6/ZentaOlbaid/OxyopusBody01.jpg
Another pic together with Phoenix again:
http://i214.photobucket.com/albums/cc6/ZentaOlbaid/OxyopusVSPhoenix01.jpg
I’m not pleased with the cream white colored servo horns, I think I’ll paint them black. Do you agree? :unamused:

Ok, that was all for this time. I’ll soon start designing the femur and tibia parts, I have made alot of drawings but I’m not 100% satisfied yet.

I’ll post more information later.

#2

Most excellent design! I’m actually looking at upgrading my Johnny 5’s batteries to all LiPo, and was also going to implement the use of BEC’s. Can’t wait to see it with legs.

Once again Zenta, absolutely amazing work, made even more amazing by the fact that it’s hand cut. /applause

#3

Hi Kåre,

Nice job! but if it’s an OCTAPOD, shouldn’t it have a few more legs? ;>)

I can see why you’d be anxious to get everything made up. It’s gonna look great!

Do you have a ball bearing on the underside of the coxa frames?

I noticed that each leg pad extends non-symmetrically from the body. makes sort of a “streamlined” look to the body. Nice effect.

I see the SSC32, but no controller board. ABB?

Alan KM6VV

#4

I think you’re looking at his Phoenix that is next to it for size reference :stuck_out_tongue:

#5

Wow , this is a great desing! First real octopod I’ve seen for a while, and I see you’re going more the way of small lighweight inexpensive servos for a lighweight rbot more than the traditional beefy body with beefy servos that en up costing you an arm and a leg.

I know I already said it but I love this design! it’s nice and sleak. i have a feeling it’s going to walk pretty fast! i can’t wait to see it walking, t will be almost hypnotizing to see the eight legs advance in perfect coordination!

and, finaly I completely agree with you about panting those thing black, it just dampens the style. :laughing:

Can you show us you’re drawings of the femure and tibia?

#6

First, I must say you have many tallents! Fantastic work!

I agree with you 110%, those bone colored servo horns need to be painted black. The aesthetics are EXCELLENT!

#7

Ah yes!

thanks for pointing that out!

Alan KM6VV

#8

Wow, you’ve made extremely well use of those low profile servos. Never understood the meaning of those until now! :smiley:

#9

Hi!
Thanks for all yours nice comments!

Alan: I choosed not to use ball bearing on the underside of the coxa part. I used ball bearing on my Phoenix. On Oxyopus I have used some custom made brass bearing, you can see them integrated on the picture of the lower bodyplate. I think they will do the job. I’ll mount the SSC32 inside the body this time. And hopefully there is some space for a motherboard too, in the future :wink:

Tyberius: Yes, I hope the LiPo’s and the BEC’s will do the job.

Sam: I’m looking forward to see it walk too :smiley: . I’m not sure about the speed though :confused: . But since the total weight of Oxyopus without the battery are almost the same as for Phoenix, it will have a very good weight/power ratio. I think the total weight for Oxyopus will be a little bit over 1,9 kg. Phoenix’s weight is 1,8 kg.

Here are two pics of them on the scale:
First Phoenix complete with battery:
http://i214.photobucket.com/albums/cc6/ZentaOlbaid/PhoenixVekt.jpg
Oxyopus with all servos, regulator, LiPo’s and a bunch of Phoenix’s old tibia parts just for adding some weight:
http://i214.photobucket.com/albums/cc6/ZentaOlbaid/OxyopusVekt.jpg

#10

Another awesome project… Zenta is leaving the hobby robot community in the dust…

#11

Wow, thats really amazing work.

#12

Very Very Cool!!

I can’t wait to see how its styled when everything is together!

#13

If the horns are nylon you can dye them black. Paint will not adhere to nylon. :frowning:

Are those BlueBird servos?

#14

Hi Jim!
Thanks for the tip. But I’ve already sprayed them black. It seems OK and I have already monted them but I had to be careful not to fasten the srew to hard, some of the paint did (as you mentioned) crack of.

What should I dye them with?

The servos are called HXT 9610MG and SSV-9764MG.

#15

Here in the states we use a product called Rit Dye. It’s designed for clothing! but hobbyists have been using it to dye nylon forever.

lynxmotion.com/images/html/build008.htm

I’ve never heard of the servos. Let us know how they work. :smiley:

#16

Ah! I see. I’ll have to check that out.

To day I made templates (of aluminium) for the tibia and femur parts.
I don’t have any pictures yet. I’m going to use those cream white servo horns on the femur parts too. And I want them black too.

#17

HI!

Thanks again Jim!, for the tip about dyeing the servo horns. It worked very fine! 8) It was simple, but a bit messy.

Ehm… you should hear my wife when she caught me in the kitchen: Hey! That’s my finest pot you are using there!! :imp:

Anyway I’m finished with two set of tibia’s and femur’s, I’ll soon post some pics.

#18

LOL … I used a kitchen pot last time I dyed a set of RC truck wheels. I just ran it through the dishwasher and put it back in the cabinet. :smiling_imp:

#19

Hi!

I’m just finished with two set of legs. The femur and tibia part are made of the same plastic material as the body and Phoenix.

As you can see I’ve choosed another design of the leg parts. This gives the legs a very flexible motion.

But the legs are not so stiff as if I made them of aluminium.

This picture is a good example of why I choosed those low profile servos on the tibia parts:

And a overview picture with the templates of aluminium and som dyed horns, I used a dyer called DYLON:
http://i214.photobucket.com/albums/cc6/ZentaOlbaid/OxyopusLeg01.jpg

#20

wow! This octopod is wonderfull! I love how thw curve in the femur would give more flexibility and looks really cool with all those curves, looks like a spider-web :laughing: or like the batshaped weapons of batman…

It adds lots of style! thumbs up :exclamation:

But, what I didn’t exacly get is, you use low profile servos on the tibia because the legs don’t have a lot of space between each other, so you need the smalest servos to get the biggest gait you can get?