Design and control of a ray-mimicking soft robot based on morphological features for adaptive deformation


Underwater tasks are diversified and articulated. The environment in which they must be accomplished is often unconstrained and unpredictable. Operating AUVs assuring safety of the robot and of its surrounding is therefore very difficult. On the other hand, many fishes are able to easily move in the same environments. A crucial factor for this capability is their body, which consists primarily of elastic and soft structures that enable both complex movement and adaptation to the environment. Among the most efficient swimmers we find rays, which show abilities like high speed turning and omnidirectional swimming. In this paper we propose an underwater soft robot based on the morphological features of rays. We mimic both their radially skeletal structure with independent actuators for each bone and the compliance of their fins. This flexibility of the structure provides an adaptive deformation that allows our robot to swim smoothly and safely.

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    The tail is currently unactuated and unused. Future experiments will evaluate its possible usage for helping fast movements similar to the ones of real rays.


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This research was supported by “Program for Leading Graduate Schools” of the Ministry of Education, Culture, Sports, Science and Technology, Japan.

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Corresponding author

Correspondence to Kenji Urai.

Additional information

This work was presented in part at the 20th International Symposium on Artificial Life and Robotics, Beppu, Oita, January 21-23, 2015.

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Urai, K., Sawada, R., Hiasa, N. et al. Design and control of a ray-mimicking soft robot based on morphological features for adaptive deformation. Artif Life Robotics 20, 237–243 (2015).

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  • Underwater robot
  • Soft robotics
  • Bio-mimetics
  • Morphological computation
  • Batoid fishes