A Three-Dimensional Passive-Dynamic Walking Robot with Two Legs and Knees

Abstract

The authors have built the first three-dimensional, kneed, two-legged, passive-dynamic walking machine. Since the work of Tad McGeer in the late 1980s, the concept of passive dynamics has added insight into animal locomotion and the design of anthropomorphic robots. Various analyses and machines that demonstrate efficient humanlike walking have been developed using this strategy. Human-like passive machines, however, have only operated in two dimensions (i.e., within the fore-aft or sagittal plane). Three-dimensional passive walking devices, mostly toys, have not had human-like motions but instead a stiff legged waddle. In the present three-dimensional device, the authors preserve features of McGeer's two-dimensional models, including mechanical simplicity, human-like knee flexure, and passive gravitational power from descending a shallow slope. They then add specially curved feet, a compliant heel, and mechanically constrained arms to achieve a harmonious and stable gait. The device stands 85 cm tall. It weighs 4.8 kg, walks at about 0.51 m/s down a 3.1-degree slope, and consumes 1.3 W. This robot further implicates passive dynamics in human walking and may help point the way toward simple and efficient robots with human-like motions.

Humans exploit the biomechanics of bipedal gait during visually guided walking over complex terrain

“…This approach to the study of locomotion has its origins in research on passive dynamic walking robots. These simple, mechanical bipedal robots capitalize on the physical dynamics of bipedal gait in order to walk with no actuation down a shallow slope [4][5][6][7]. Minimal actuation in the form of footsprings or hip actuators allows these robots to walk over flat ground with an energetic cost of transport that is comparable with a human and is an order of magnitude less than the cost of transport of traditional walking robots [8].…”

Robotics and neuroscience: A rhythmic interaction

“…In the context of rhythmic locomotion, passive strategies have inspired passive-based designs with small active power sources to walk on level ground, revealing the prominence of passive stability in the architecture of the human locomotor system (see e.g. Collins, Ruina, Tedrake, and Wisse (2005), Collins, Wisse, and Ruina (2001) and Kuo (1999)). …”

Online generation of cyclic leg trajectories synchronized with sensor measurement

“…To justify this point of view, we have to refer to another class of mechanical systems: the passive walking machines. Indeed, let us consider the case of a planar compass, walking above a slope, with instantaneous and inelastic step transition, as addressed in [24] and several others [25,26]. It then can be shown that, for a given slope, such a system exhibits a limit walking cycle (see Fig.…”