Passive Dynamic Walking

There exists a class of two-legged machines for which walking is a natural dynamic mode: Once started on a shallow slope, such a machine will settle into a steady gait quite comparable to human walking, without active control or energy input. Interpretation and analysis of the underlying physics is straighgorward; the walking cycle, its stability, and sensitivity to parameter variations are easily calculated. Experiments with a test machine verify that the passive walking efSect can be readily exploited in practice. While the dynamics are most clearly demonstrated by an unpowered machine, they also promise to make powered walkers efjicient, dextrous, and easily controlled.