# Passive Walking Video

I took simulations of passive walking using the software of computer algebra system (CAS) and got a good result in which a simple robot kept walking forever from the simulations, then I worked making a video to see the motion of the result visually and finished it. When I made the video, I used this Python script to import the result data of the simulations into Blender and to create IPO curves for animation.
I want many comments about what you think. Any suggestions or criticism are also appreciated.

Script for importing:

The animation looks nice, but as far as i know physics shouldn’t the walking thing stop because of the friction on the axis? One other thing about that animation, why is the model falling through the plane, it would look nicer if it would just stay there.

Thanks for your reply. You have a good point. The robot should stop by friction in real world, but I assumed ideal conditions for simplicity when I derived the motion equations and didn’t consider any friction on the axis. Also I think that it will walk well if there is some amount of friction because the robot is walking down the very gentle slope in the simulation as you can see at around 0:35 in the video. For passive walking, slopes are always necessary to get energy and walk forever.

it’s interesting, but really telling about this it would go forever is a nonsense.it’s also quite long for what it shows. but a nice and interesting entry still.

Nice video. How about adding an Empty with an Copy Location Constraint to the walker ( only copying x and y) and then changing the Track To Constraint of the camera to track this empty. This would eliminate the up/down-motion which is very distinct at 00:23.

As mentioned, practically speaking, you need an ankle, a knee, or a cam inside the hip to lift the forward-recovery stride leg up to clear the ground.

From a data-import point of view, the work is awesome in porting the CAS data into Blender. I can see this extending for use in computer simulated explosions, collisions, etc, where you have the power of a finite element analysis software/computer run and spit out the data, and then use Blender to visualize the data.

pildanovak, thanks. Yeah, the robot will not go forever in real world but it kept walking stably and took at least 1000 steps of walks in my simulations on CAS. I really don’t know the stability for walking from any algebraic points of view because the mathematical analysis is too difficult for me using long motion equations. In any analyses, such a kind of model will be still unrealistic. Also I certainly have to consider the length of the video.

foom, your idea is very good. I simply used only TrackTo Constraint to the camera. The up-down noisy motion of the camera must be reduced for a video. I will use your idea when I make the next video.

PapaSmurf, thanks. I know the need for an ankle or a knee and this model can’t really switch its legs on a flat slope because the moving leg rubs with the ground when it goes in front. I used this model to analyze the motion algebraically with the simple equations. (I couldn’t do that, though.) As you said, it needs some improvements and 1 or 2 months ago I tried to take new simulations with another 2 types of models to avoid the problem of the rubbing legs. One model has knees and the other has sphere-shaped legs. First, I tried to analyze these more complicate models with the derived motion equations which have over 1000 terms. And I gave up. So I changed the approach and used the physics engine Bullet in Blender. The threads on what I did with Bullet are here and here. It worked well and needed no equations for it. I like the style that all that I have to do is make a model and physics settings and press P key to start the simulation.
When importing some data into Blender, how do people do that and what kind of tools do they use, in general? I really want to know about that.

Lol mean video. Like the transitions
It made me laugh seeing it fall over when its leg swung forward and then came back and kind of just missed or went through the floor and it fell over
Twas a bit long tho

Anthony, thanks. I’m glad you liked it. I found out the robot would fail in only these 2 types after repeating simulation a lot to search the patterns of the failures. I understood the video was a bit too long. I made it for the purpose of introduction to ordinary people who know physics well and who start to learn physics and who even don’t know about physics very much. I felt like a video which length is 4 minutes should be good for them to look blankly at without considering the difficulty, but now I realized it was long enough to bore them from your mentions.

Glad I could help or something

:eyebrowlift: Maybe it’s a greatest help. :eyebrowlift:

I still wonder how Blender users do to import some data into Blender and what kind of tools they use… This time, I decided the data type as CSV format and I used the script which I made to import the CSV data. If there are another well-known way to do that, please let me know some key words, links or your thoughts on it.