Three linked ideas, in order: a mechanism that walks on its own geometry, a bistable unit that always settles into one of two shapes, and a mechanical adder built by wiring two of those units together — logic performed with no electronics at all.
the mechanism
A Leg That Walks Itself
Turn one crank in a circle, and a simple four-bar linkage traces this looping path with its foot — stepping forward, lifting, and resetting, forever. This is the same principle behind Theo Jansen's Strandbeesten and the Jansen linkage I simulated for the thesis: one motion in, a walking gait out.
bistability
A Switch With Two Homes
A hinged mechanism with a biasing spring won't rest in the middle — it settles fully to one side or the other, +θ₀ or −θ₀, and stays there until pushed hard enough to flip. That's the whole idea behind a bistable mechanism: two stable shapes, one unstable tipping point between them.
mechanical logic
Two Switches, One Adder
Wire two bistable units — A and B — into a shared linkage, and
their spring stiffnesses become weights. The output position is
literally 0.4·A + 0.6·B, computed by geometry alone.
This is the mechanical "neuron" from the thesis, and a small step
toward mechanical logic gates.
further extension
From Switches to Gates
The same two switches, gated at a threshold instead of weighted, behave like real logic gates — shown here beside their standard schematic symbols. This wasn't built in the thesis, but it's the natural next step it points toward: purely mechanical AND, OR, and NOT.
scaling it up
Six Switches, One Network
The same idea, bigger: six switches (I1–I6), each pushing a rod onto
a pivoted beam at a point spaced by its own weight — a mechanical
balance computing Σ weight·input entirely through
geometry. Logic gates aren't a separate trick bolted on afterward —
they're the same number read differently. "All six on" is just that
sum reaching 1.00; "any one on" is it clearing the smallest weight;
a plain majority vote is it crossing 0.50. One beam, three lines
drawn across it.
Built with Direct Stiffness Method and Lagrangian mechanics solvers in Python. The same constrained rigid-body kinematics shows up in my day job now — scenegraphs and rigid-body transforms for exploded views in production CAD software.