Soft limbs of flexible tubes and air enable dynamic, autonomous robotic locomotion

(Press-News.org) Using only airflow and simple physical design – resulting in a structure that looks like a roadside “inflatable tube dancer” – researchers have developed soft robots that achieve coordinated, autonomous movement without relying on complex electronic controllers. In nature, animals often move with remarkable efficiency. They do this by seamlessly integrating the nervous system, body mechanics, and environmental interactions. This decentralized coordination allows animals to move efficiently without relying on constant direction from the brain. In contrast, most robots depend heavily on centralized processors to orchestrate their movements. While rigid and soft robots can exploit body dynamics or shape changes to move and avoid obstacles, many remain limited in adaptability due to a lack of limbs or reliance on slow, sequential control mechanisms. Moreover, their bulky, analog-like design introduces energy inefficiencies and slow response times, limiting their practicality and autonomous capabilities in complex environments. To achieve rapid movement without relying on a central processor, Alberto Comoretto and colleagues developed a self-oscillating robotic limb powered only by a continuous stream of air. The limb consists of a bent silicone tube, which – without airflow – remains in stable, kinked positions. However, when steady airflow is introduced, it spontaneously oscillates between kinked states, performing rapid stepping motions at frequencies reaching 300 hertz. This motion arises from a feedback loop between pressure, kink formation, and tube resistance – akin to a mechanical “heartbeat.” By physically linking multiple limbs and exploiting environmental feedback, Comoretto et al. achieved synchronized gaits without any electronic control, enabling the robots to move at speeds exceeding those of comparable soft robots. They could also amphibiously enter and move in water through an automatic change in gait. For interested reporters, the authors have provided a number of videos illustrating the robotic platform’s capabilities.

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