Felix a four legged robot

First robot, work in progress. I've written a couple of posts about the design and gait implementation on my blog (http://www.burningservos.com), video and additional info will follow.

Added video of trajectory and IK test.

Completed the body assembly. Here a couple of shots of Felix posing for the camera:

Eventually walk around

  • Actuators / output devices: 8 Tower Pro MG995 Servos
  • CPU: Arduino

This is a companion discussion topic for the original entry at https://community.robotshop.com/robots/show/felix-a-four-legged-robot

Awesome! I have been

Awesome! I have been thinking about building a mechanism like this since I saw the Titrus III robot. 

And finally someone who uses Processing.

But it looks a bit complicated. What is the second servo horn on the lower servo for?

Couldnt you just connect the upper servo too the knee or does this simplify the IK? 

That’s super cool for a first robot, can’t wait for more updates!

Two reasons for the design

Thanks, I have two reason for the extra linkage, first as you pointed out it simplifies the IK.
By using the hip as a common rotation point I can use the resolved IK angle for the knee directly to set the position for the servo.
The other reason is that this is the first design iteration. Once I have the geometry, gait and controls right I plan to make an enclosed leg design, something more organic. I consider the current iteration sort of a skeleton.

Excellent leg

Excellent leg design…

excited to see your progress…

Something I continue to wonder about is if the connectors from the servos to the skeletal points were under spring tension, you could then do excitingly smooth gates.   A cable spring versus a solid rod would be the difference, but with springs incorported, there should be certain harmonics which the little beast could move which would be more effecient than others…

Admire your work…

BTW if you ever want to try to incorporate your bot into a borg through communication, let me know @ http://myrobotlab.org 


My brother said that i looked like a cat and asked if it could land on it’s feet when dropped. Good thing he asked before trying =)
Springs are a very good aproach. The robot Cheetah-Cub (http://biorob.epfl.ch/cheetah) use a spring system where the knee actuator is only use to clear the leg from the floor with a cable. There is no torque required to keep the robot upright, pure springs. But their focus is dynamic gaits. I’ll try to get static gaits right first.
I’ll experiment with something similar at some point. Ideally to make Felix more robust and cat-like.

Very good for a first robot post.

I like the design. I am wondering though, if you would not burn out servos getting the gait right. It looks like if you do not have your wits when coding the servos could end up fighting eachother.
Then I see your website is called burning servo, lol.

That is so cool! I can’t

That is so cool!  I can’t wait to see what it can do…



That is so cool! I can’t

That is so cool!  I can’t wait to see what it can do…




Love the design and execution. Beautiful build work there. Congrats.

Love it

Automaticaly added to the to-do list :slight_smile:

It looks really great, and I

It looks really great, and I love the idea of making the legs light by putting all the servos on the body. Did you manage to make it walk?