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Jansen Linkage Tutorial

The Jansen linkage is an 11-bar planar leg mechanism designed by Dutch artist Theo Jansen. It converts rotary motion into smooth walking motion.

Key Insight: The "Holy Numbers" are 13 carefully optimized link lengths that produce an ideal walking trajectory.

The Holy Numbers

ParameterValueDescription
a38.0Crank radius
b41.5Crank to B link
c39.3B to C link
d40.1Crank to C link
e55.8B to D link
f39.4C to D link
g36.7D to E link
h65.7E to foot link
i49.0M to E link
j50.0M to B link
k61.9D to foot link
l7.8X offset (O to M)
m15.0Y offset (O to M)

Step 1: Fixed Points

The mechanism has two fixed pivot points: O (origin) and M (offset from O by l and m).

Interactive Linkage Construction

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Fixed pivots (O, M)
Crank (rotating)
Upper linkage
Lower linkage
Foot point