Quadruped Robot Basics

In this video I explain some basic theory regarding quadruped (four-legged) robots.

ROS : Noetic

The project is here

[ErrorClements.]

Thank you so much!Trying to get into robotics, so here we go

[Paul-rsgd]

Great video, thanks ! Getting a stable gait is a lot harder than it seems at first. I succeeded after quite a lot of trial and error. I still have not got my dog to turn on the spot, but I am working on it. The geometry of turning circles and foot placement is interesting, could you do a video about that...

[sally]

Thanks so much for this amazingly informative video! I've had a look at your other uploads and they're all incredible resources for anyone into robotics, you've definitely earned a new sub for all the work you must have put in in order to produce these. Although I understood ‘enough’ to follow along, I keep getting stuck at the graphic you showed at 4:10 and can't fully get my head around what it means. What does Kp, or the s, 1/s stand for? steps? I'm probably overlooking something very easy here

[teerthraj_verma]

Thanks
Its really hard to find such video where gaits, motion is explained in detail.

[maenhp]

This is so cool, really appreciate it!
Could you recommend a paper to read regarding the dynamics of quadruped? Thanks

[rutgervisscher]

Would be really interesting to see a video on the actual programming of the gait, how to go from the IK to the gaits... Or am I missing something here...

[simonjeppesen]

I think there's a "mistake" in the inverse kinematics. The angle you have represented in with a blue semi-circle is not atan(y/x) but pi-atan(y/x) so it would probably be easier to understand if you wrote theta1 = pi-atan(y/x) -atan(AG/OA) where pi-atan(y/x) would be blue to match your drawing. Thank you again for the great video, I just rewatched it. Best from Simon.

[mikaeltrana]

Really love your videos! This helped me out a ton when building my own quadruped and getting it to move correctly in Gazebo. I was wondering, I would like to give it a try to enable it to handle stairs as well, perhaps through some kind of reinforcement learning. What would you recommend to start looking into for solving something like that? Thanks again for the great content!

[juggernaut]

Thank you so much for this tutorial! Its a wonderful introduction to quadruped robots and really helped me out. Have you published any paper or document about your work? I would like to reference and give credit to you.

[thecongo]

Thanks for the video. I have tried to make a moving quadratic, the legs are moving but the quadratic isn’t moving

[fengliu]

Thanks, I've learned a lot from your vedio!

[EtrnalFir]

Hi, I am getting an error when running the script. "Could not load controller 'rear_left_shin_joint' because controller type does not exist"

[ashwathwatchesyou]

Hey, I've followed the instructions perfectly and have changed the chmod permission to allow gazebo to access the controller scripts. I have also installed the ros-noetic-control and controllers libraries. But the robot still cannot do the stand up function or change its pose. It just stands there in the crouch pose. Am I doing something wrong? Please help and thanks in advance.

[mustafagorur]

Hello, how can I control the robot from the computer, the gazebo opens but I cannot move it.

[oracid]

Great video ! Thank you for sharing. Do you think this could work if I install Gazebo for Windows 10 ?

[towerboi-zgit]

Very nice work! By the way, are you planning to have a github for this pkg? I think it's a good opportunity if you or someone would like to upgrade or debug something. One I have tried is migration from ros to ros2 humble env. Also, you may fixed it already, but at the beginning when I down load the code, there is some incorrect path to the mesh files in the urdf file, so it would be great if you have updated it already.

[lixiaokang]

Hello, thanks for the great video.
I use Ubuntu 18 and ROS melodic. When launching the file, there are some errors. "ImportError: dynamic module does not define module export function (PyInit__tf2)" and "ERROR: cannot launch node of type [joy/joy_node]: joy". Do you have any clue to fix these? Thank you!

[simonjeppesen]

Hey there. Great video, loved it! We are working on building a quadruped robot, do you have any useful references you could share? We have already made the mechanical construction we are soon to implement gait controllers and probably WBC and MPC (if we have time). I am sure we can use some of your code to establish a simulation thank you!

[neo]

Thank you for your great video! Can I ask some problem?
I want to install catkin. But The problem is not solved.
(catkin : depends: python3-catkin-pkg (>= 0.4.14-2) but it is not going to be installed)
I used in Ubuntu 20.04. (Ryzen 5900HS + RTX 3060 Notebook).

[OverClockedShow]

Hello. thanks for the great video, very well explained
I also had an error when running the script. "Could not load controller 'rear_left_shin_joint' because controller type does not exist" but when I manually run joypad.py and robot_controller_gazebo.py manually and then "roslunch" the project it works perfectly.
I'm not familiar with ROS nor catkin. do you think you can take a look at it? thank you so much for sharing.