A Year at the Forefront of Hydrostat Motion

Abstract

Currently, in the field of interdisciplinary work in biology, there has been a significant push by the soft robotic community to understand the motion and maneuverability of hydrostats. This Review seeks to expand the muscular hydrostat hypothesis toward new structures, including plants, and introduce innovative techniques to the hydrostat community on new modeling, simulating, mimicking, and observing hydrostat motion methods. These methods range from ideas of kirigami, origami, and knitting for mimic creation to utilizing reinforcement learning for control of bio-inspired soft robotic systems. It is now being understood through modeling that different mechanisms can inhibit traditional hydrostat motion, such as skin, nostrils, or sheathed layered muscle walls. The impact of this Review will highlight these mechanisms, including asymmetries, and discuss the critical next steps toward understanding their motion and how species with hydrostat structures control such complex motions, highlighting work from January 2022 to December 2022.

Maximum trunk tip force assessment related to trunk position and prehensile ’fingers’ implication in African savannah elephants

“…However, their gripper and all other existing two-finger soft-robotic grippers have a symmetrical constitution with fingers of the same shape and deploying the same force [examples: [38][39][40]. There are already asymmetrical robots mimicking the trunk body, similar to the non-homogeneity of the elephant trunk during stretching, which is not due to muscle but to asymmetries in the properties of the skin [14,34,41]. This study also highlights the benefits of asymmetries in terms of shape and force between the two fingers, which could lead to more versatile robotic grippers that are efficient gripping without having to deploy greater force.…”

“…The grasping systems of animals, including elephants, have been selected through evolution for their effectiveness in responding to functional, morphological and environmental constraints. These capabilities have inspired robotic engineers to incorporate bioinspired technologies into their designs [13][14][15][16]. Thus, for the past two decades, the full range of abilities of the elephant's proboscis has inspired research in soft robotics, specifically in manipulative and grasping robots.…”

Elephants develop wrinkles through both form and function

“…Elephant trunks are described as one of the three prominent examples of muscular hydrostats along with octopuses' arms and reptile or mammalian tongues [1][2][3] . A key aspect of the functionality of the elephant trunk is the immense motility and flexibility of this organ.…”