Extreme dynamic symmetry enables omnidirectional and multifunctional robots

2026-05-27

AI Summary

This work addresses the limitations of conventional robot designs that emphasize geometric symmetry while neglecting dynamic symmetry, thereby compromising agility, robustness, and versatility in complex environments. The authors introduce the concept of “dynamic symmetry,” achieving near-limit dynamic isotropy through uniform centroidal acceleration capabilities, and pioneer the extension of symmetry from morphology to dynamic actuation. Guided by this principle, they develop Argus—a spherical multi-legged robot with radially arranged linear actuators—and establish a quantitative framework for assessing dynamic isotropy, alongside corresponding modeling, control, and distributed perception methodologies. Experimental validation on a 20-legged prototype demonstrates direction-agnostic locomotion, rapid traversal over deformable terrain, strong disturbance rejection, high energy efficiency, and sustained operation despite partial actuator failures, collectively yielding significantly enhanced overall performance.

Abstract

Symmetry is a central organizing principle in natural systems, yet its use as a unifying design strategy in robotics has largely remained limited to geometric form. We show that symmetry can instead be leveraged at the level of dynamic actuation capability. We introduce dynamic symmetry, the uniformity of a robot's attainable center-of-mass accelerations, and formalize it through a measure coined as dynamic isotropy. Across more than 1000 simulated morphologies, we found that higher dynamic symmetry consistently improved trajectory tracking, task success, robustness, resiliency, and energy efficiency, with the benefits becoming most pronounced as dynamic isotropy approached its theoretical limit. To study this regime systematically, we developed Argus, a family of spherical robots designed to explore the effects of increasing dynamic symmetry. Members of the Argus family vary in their actuation geometry and dynamic symmetry level while sharing a common architectural principle: radially oriented linear actuators that directly shape the robot's center-of-mass dynamics. Among them, we built a physical 20-leg Argus variant that achieved near-extreme dynamic isotropy and demonstrated orientation-invariant locomotion, agile traversal of cluttered and deformable terrain, rapid self-stabilization, and resilience to partial actuator failures. Its distributed sensing further enabled omnidirectional perception and object interaction during continuous motion. These results show that designing robots for symmetry not only in morphology but also in their attainable dynamics provides a powerful and general pathway toward agility, robustness, and multifunctionality in uncertain terrestrial and extraterrestrial environments.

Problem

• dynamic symmetry
• robotics
• omnidirectional locomotion
• robustness
• multifunctionality

Innovation

• dynamic symmetry
• dynamic isotropy
• omnidirectional locomotion
• radial actuation
• resilient robotics