Prismatic joints don't seem to be very popular on walking robots so wanted to try them out and find out why.
Hi there @demej00,
Thanks for sharing your project!
I saw your initial post which had only the leg.
I have to say it’s quite satisfying to see it added on a robot!
Haft-Quadruped is a good name for it!
Thanks Mariane. It is satisfying to see it lift its feet off the floor. It was funny to see the legs walk up onto the carpet but the wheels needed a little assist. I have another leg built and one more to go. Looking forward to have a full quadruped. Programming a walk shouldn’t take long but will be interesting to play with some different gaits.
Oh wow!
That’s an amazing concept here.
The mechanism created by the servo to achieve linear motion is really inspiring.
Thank you pj! I couldn’t afford a linear servo which I thought I could find pretty cheap on taibao.com but no luck. I now have the quadruped working with 4 legs and am playing with gaits. Will post a video when I get something interesting. It looks like a robot using 4 crutches.
Even more satisfying now! Lovely idea.
Your robot is a good example of how a project can evolve and become greater than it was, even though it was amazing at first.
Thanks again Mariane. I wish someone with real mechanical skills and equipment would evolve it further. I probably will just tinker with the code a bit and then move on.
Decided to place update here as I don’t like my project to jump to the head of the line when I update it.
Have discovered that SG90 servos are really inadequate for operating as the hip joint on my robot - they are floppy and sloppy and the gears loosen up quickly which makes the robot start turning when I want it to walk a straight line. Trying SG92Rs which use carbon fiber reinforced gears and wow, what a difference - much stronger. Will use these in the future for all my projects or MG90s.
Now I want my robot to walk with a smoother gait and feel I need to swing the battery underneath the frame to keep it balanced on the three legs forming a stable tripod.
Also will use RemoteXY software and bluetooth to control direction and speed.
Perhaps raising the servos so the frame sits lower will also lend it more stability.
Also wonder if narrowing the stance will make for smoother gait.
All questions to be answered in time and no hurry I guess as I don’t have anything else I want to work on right now.
This is so great! do you have any tips?
Thanks! Well I haven’t done much with it lately as I got sidetracked on another project. But I found out that you shouldn’t use the SG90 servos for the hips as the plastic linkage is too floppy - need at least SG92Rs or MG90s.
I think someone with some real mechanical skills could build some solid prismatic legs. I always build with cheap materials.
I need to order a voltage regulator to allow use of a lipo battery and get rid of the tether.
Also, I haven’t developed any good turning code yet - I can increase the distance on one side and decrease it on the inside and that works - just kind of a slow turn. So lots of coding algorithm development could be done - don’t know when I will get to it though.
Is it possible to 3-d print parts? (If you like hat idea, you might want to check out my post) thanks!
I just never got into 3D printing and live in such a small apartment that I have no room for the printer. Just rely on hand tools and simple materials. Wish I had the expertise or motivation to get into but just won’t happen as I have too many other interests and hobbies.
It’s cool to see how the robot is growing from 1 leg to 2 and 4 legs 
I wonder if there will be more of this “growing” 
That’s an awesome project. It is getting bigger and bigger. Can’t wait to see it finished.
Congrats @demej00 !
Thanks. I don’t really know what to pursue on it now. More radical steering or directional control would be interesting I guess.
Thank you. I guess it is gone far enough for my interest. Would live to see someone with 3D skills build a nice one though. I have no skills and no room for a 3D printer.
But just want to let you know, now that I thought about it a bit, you have motivated me to do the following at least: I am going to make the rear servos steerable also, without going through the trouble of making it servo controlled for now at least, and see exactly how extreme an angle I can make this thing turn. Can it do a 360 turn within one or two body lengths. I think that would be cool.
It would be cool Step by step
Very nice robot! I like your DIY linear servo. You should definitely continue improving it
@abram Thank you. I probably will at some point but working on another couple ideas that I just can’t get out of my head right now. Robots are addictive - they invade your sleep.
