Instructables

Please explain Theo Jansen Mechanism?

We all have seen the Theo Jansen Machines and they are JUST AWESOME!
I'm trying to build one.

What is the the theory and mechanism behind Jansen's machines?
Please explain.

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rickharris2 years ago
A relatively simple 4 or 5 bar mechanical linkage. The movement is created by the relative lengths of the struts - Your best bet is to study the many youtube videos of these mechanisms - There are animations out there that show it clearly.

http://www.youtube.com/watch?v=CufN43By79s

http://www.youtube.com/watch?feature=fvwp&NR=1&v=PWm4VMR8D0w

http://www.youtube.com/watch?NR=1&v=NM4q-f68TlY
sarveshk (author)  rickharris2 years ago
Nice videos rickharris!
I'm getting the Jansen mechanism, expecially the third one is very detaile!
Kiteman2 years ago
What do you want explained?

If you want to build one, look at the Jansen walkers already on this site, or take the measurements from Jansen's site or videos.

sarveshk (author)  Kiteman2 years ago
Dear Kiteman,
I already have plenty of tutorials for making Jansen Machines.

But, I wish to know it's phenomenon, it's theory and explanation of the mechanism.
It's very easy to laser-cut the drawings and assemble them, but there is no fun in building something without knowing how physics and maths work, isn't it? :)
Even Jansen himself says that the best way to explain the leg is to make one.  The "maths" of getting the leg right was pure experimentation, thousands of iterations to produce the now-classic proportions:

Legs

The real trick is the energy system

sarveshk (author)  Kiteman2 years ago
Thanks Kiteman! Now I understand, that not every practical structure is bulits using pre-derived maths n phy, sometimes maths n phy theories are based upone such structures. :)
AFAIK, Jansen employed some random searches (of linkage lengths?) and optimized the base linkage. The tricky part was coming up with the base linkage. From there optimizing by computer is relatively straightforward. Here is a thesis by a person who optimized this linkage with different criteria, creating a superior linkage for some applications:

http://www.amandaghassaei.com/files/thesis.pdf