Not a bad idea. Haven’t really even started to think about the programming! LittleDog’s abilities would be a formidable goal!
I’d like to see how the additional six DOF are implemented. Maybe incorporate a few of 'em myself.
Here’s a paper that may be of interest:
ihmc.us/~jpratt/publications … tleDog.pdf
boltoneng.com/portfolio/p_little_dog.htm
reports-archive.adm.cs.cmu.edu/a … 07-148.pdf
stanford.edu/~kolter/pubs/kolter-icra08.pdf
Alan KM6VV
Hi,
thanks for the links Alan, I’ve got to study the gait part soon.
I’ve been working with the 4 DOF kinematics. First I’m going to use precalculated sequences (like I did for Phoenix). I’m not finished with all of the kinematics. But most of it are solved. This is a screen dump from my PEP version for a 44 Quad. The picture are showing the quad doing a 44 DOF kinematic body rotation:
I’ve to finish the pitch and roll rotation too. And I’ve not started with the gait part yet. I also have to make a battery holder and calibrate all legs.
Looks greaaaaaat!
Good job Zenta, it’s a wonderfull dog! It must be fun to try to make 3 of them and compete in some soccer event. With 4 DOF they must walk pretty well and be able to kick the ball. You just have to had a head with a camera and sensors!
you could also make a kind of AIBO! 
I thought it was a cat with the name Felix… I agree about the wonderful part though. 
Well, I guess it depends on the kind of silicone/fur and head he puts on to it later 
I saw that you are using the 5645. Do you think it could work with the 645 (133oz.in of torque compared to 168? ) ?
Hi,
thanks for you nice comments!
Yes the name Felix came from Felix the cat but I agree that my Felix does not look like any animal so far
The 645 would probably work (mechanical they are the same servo).
Hi!
I’ve just finished calibrating the servo’s for Felix. Also made a simple battery holder for one 7,4v 4000 mAh LiPo’s. The LiPo supply both servos and electronics for power.
This is a video of Felix doing complete 4 DOF per leg body rotation: youtube.com/watch?v=GceQQENO-mo
You might see that every servo works together to make the rotation. This was also a test of the towerpro MG996R I’m using at the tibia parts. And to be honest I’m not satisfied with them, I’m gonna replace them with MG645’s later.
Have not tried the walking part yet, so far it’s a real challenge! Have to study that part first.
That is seriously awesome. This is easily my favorite of your projects.
Hi Zenta,
Great video! very smooth moves! I bet that it is/was hard to get the IK up and running! The gait will be brain breaking as well! Uuuhh I mean a big challenge 
Xan
Hi,
Thanks A-bot and Xan!
Yes the kinematics was a challenge and yet not 100% completed. One problem is that one position has several solutions, so I’ve to priority the kinematics. My math skills are limited so I’m still just using plain trigonometry to solve the kinematics.
Hi Zenta,
I was wondering where you got those 7.4V 4000 mAh LiPo’s from? Or did you package together a group of 4 - 3.7V 2000mAh ones yourself?
I want to put together a larger stack for running a hexipod I’m building, but I’m still trying to find out exactly what I need in the way of temperature monitoring and voltage tracking for charging them.
Thanks,
Hi kirk,
Zenta got those from towerhobbies.com. I’ve got the tip from zenta as well and ordered my package there as well. I didn’t know exactly what I needed for the lipo so I started a thread at there forum and got some good help!. Here is a link to the topic. Read trough it and I think you’ll get a answer on most of the questions!
And the Lipo I purchased is really worth the money!
Good luck!
Xan
Thanks Xan,
I was kind of supprised when I saw a reply at 3:00 in the morning, glad to see I’m not the only one up at that time
I’ll check out the forum and see about upgrading from NiHM, I may stick with them for a while until I have a little more to spend on some larger LiPo packs.
Hey Xan,
How happy have you been with your Turnigy Accucel-6 Balance Charger & Discharger? I’m thinking I may be better off ordering that, compared to the $80 unit I was going to be ordering.
Also any idea if the Turnigy 8-15A UBEC for Lipo would work with NiHM cells? In my mind I don’t see what the problem would be as long as the voltage of the NiMH packs are within the same voltage range. I’m thinking those may be better than the Adjustable 5vdc - 6.5vdc Regulators as I can use them when I upgrade to Lipos later on.
That charger is truly awesome! It’s a really need charger with a lot of functions and settings. Easy to use with almost all batteries! (Pd, Nicd, NiMH, Lion, Lipo) It is easy to setup and use your custom charging program tuned for your battery. I think it’s a great deal and I haven’t used my “oldâ€
As of a few days ago I had decided on the following charger: robotshop.ca/home/products/r … arger.html, from RobotShop as that is where I’m getting a lot of my parts from.
I think I’ll maybe stick with the 5v-6.5v regulator for now, and see about a upgrade to all the power systems later. I don’t know if I can take the wait of a few weeks or more to get some stuff from Hobbycity, I’m just itching to start building everything, maybe I should hold off completely and just run it with a cord to a bench power supply.
As for the 12V needed to run it, a modified computer PS seems to be the best option for me. Should only take a few hours to set one up from an old PS.
I also wanted to say your hexipod looks great. I really like the all black look with blue LED’s. It is very much what I want mine to look like.
Thanks for anwsering all my questions. Electrical and mechanical work is not new to me, but running stuff from batteries is.
I don’t know if this charger can charge lipo batteries as well but I didn’t had a lot of time so I could overlooked it. It looks like the charger has almost got the same features as the one on hobbycity.
I can imagine that you can’t wait to get it up and running using a wire should be a good idea to start with. My first hex BlackWido has a NiMH battery which gives me 25 min of runtime. This is much to short while programming so I used a wire to do some testing on my desk. But if you want to walk with a power supply, be sure that it can deliver enough amps! Walking at full speed can take up to 12 amps at 6V.
I don’t know what type of regulator that you are using but be sure that it is a switching regulator. This has a much better effectivity! The non-switching regulators will dissipate all the power. So regulating 12V to 6V will give a effectivity of 50%!! It will keep you warm at the winter but you also need supply that can give 24A at 12V
Thanks for the comments! I really appreciate it!
No problem at all! I’ve been there and there where people to help me out so I’m happy to somebody else at my turn
Xan
I really think I want to get either a single or pair of Turnigy UBEC’s to run the motors on the hexipod, as I want to run 18x 645’s, so the peak current could be as high as 8A.
I just don’t want to deal with the hassle of import taxes from hobbycity compared to robotshop.ca being in Canada. Plus I’m trying to limit myself from spending way to much It is really to easy with this kind of stuff, there are just so many cool things that can be added to projects, if only cost wasn’t an issue. I have to limit myself, and first get it walking, etc then I’ll see about some sensors, and maybe some balancing software for complex terrain, but that will be months/years down the road.
I think I’ll setup a 5V input for testing purposes, not exactly the same but I can easily get 10A+ out of a PS and that’s basically free as I have a few laying around.
I really want to get into the programming of it as well. I’m going to try and start from scratch for now and setup all the Inverse/Forward Kinematics for the system, doesn’t seem much more complex than the 6DOF arm’s I did it for in school. I picked up an Atmel 32-bit process on a prototype board a few months ago at a seminar. I’m hoping I can set that up onboard to run all of the software.
Hi,
I’ve not got much time for robotics lately but I’ve been working with Felix a bit and have replaced the tibia servos with 645MG (I gave the Towerpro’s to my dad ). And i was amazed how much smoother and accurate the result was. So no more crappy Towerpro’s for me.
I’ve also worked with the PEP Felix version for live control. I’ve not tried to make Felix walk yet, but I promise that my next video of Felix will include walking.
I added some new sequences to the Felix project. Here is a little demo of Felix together with Phoenix.
