Using Theo Jansen's "Golden Ratio" imitated limb linkage, combined with a "coaxial variable-speed gear," resulted in a quadrupedal walking creature.

Non-Circular Gears

Due to the imitated limb linkage, the mechanism fails to maintain a three-legged standing position under the crank's constant transmission, especially with four legs. (Theo Jansen's models typically have six legs.) Thus, a non-circular gear mechanism is required to achieve the effect of "coaxial variable-speed." With a quadrupedal structure, the speed needs to allow for at least a 1/4 lifted leg and 3/4 grounded leg, creating a time difference.

Simulations