Weak actuators generate versatile locomotion patterns without a brain

This article describes a minimalistic legged robot that generates three-dimensional gaits using a purely physical mechanism, without a sensor or microprocessor. The robot has an extremely simple body structure composed of modular units and an elastic spine. By arranging these units, we can investigate the effect of a morphological parameter — the number of legs — and interlimb interaction via spinal flexibility. A simple oscillator model is applied to generate gaits. This model delays and synchronizes the phases of the legs by exploiting only the mechanical passivity of the DC motors corresponding to each leg.