Bioinspired reconfigurable soft robots for underwater multimodal locomotion and manipulation

Sponsor: United States Department of the Navy (DON)

Award Number: 50209679

Co-I/Co-PI: Tommasso Ranzani

Inspection and sample collection on the ocean’s threatened reefs requires dexterous machines with a low impac,. Soft robots are ideal for this purpose. Current soft robots for underwater grasping use silicone actuators. While these allow for,the safe manipulation of corals and other delicate aquatic objects, the dexterity of such actuators is reduced. Examples of such dev,ices in the state of the art are limited with regards to complexity of motion and have featured primarily in robots which are signif,icantly rigid. Other works have demonstrated soft robots capable of swimming like fish, but, much like their natural counterparts, t,hese do not provide any object manipulation capabilities. Soft robots modeled after cephalopods have sought to recreate the highly m,aneuverable jet propulsion navigation of such creatures, and octopus tentacles are a popular inspiration for dexterous, multi-DoF ac,tuators. However, few devices exhibit both locomotion and manipulation. Additionally, locomotion tends to be specialized towards swi,mming or crawling on the seabed with limited capability to switch among the two modalities.The undersea environment requires novel r,econfigurable soft robots, built via advanced manufacturing paradigms to embed a wide range of materials and functionalities includi,ng sensing, actuation, and on-board control.This proposal will address the challenge of multi-modal locomotion and manipulation for,soft underwater robots. We propose a soft octopus-inspired robot with five foldable multi-DoF arms for object manipulation and legge,d locomotion on the seabed thus providing unprecedented dexterity and reconfiguration capabilities. The robot’s five tentacles will, will be combined with a jet propulsion system to provide multimodal locomotion both near the seabed and while swimming. The tentacl,es will also be foldable when not needed to minimize their impact on the robot’s motion. In order to be able to control the multiple, DoFs of the robot with a single pump, onboard fluid logic will be embedded in the robot, drastically reducing the reliance on bulky, input tubes and the need for dedicated electromechanical components for the individual control of each of the robot’s DoFs.This pro,ject will leverage the PI’s prior work in the development of dexterous soft actuators built using thermoplastic elastomers. Such act,uators are nearly flat in their unactuated state, can expand over 50 times their initial height at pressures of 20 to 30 kPa, and ca,n deliver forces on the order of several newtons. Prior works show that multi-DoF structures can be obtained by combining multiple e,xtension actuators together in a single tentacle. Sensing and suction elements incorporated into such structures will help the robot, further emulate the dexterous manipulation abilities of cephalopods and monitor contact forceswith the surroundings.Control of the,pressure delivery to the tentacles will be accomplished using novel custom valves at the point of actuation building upon the PI’s p,revious works. By incorporating electronically con- trolled magnetic valves, we will be able to control the pressure into an arbitra,ry number of actuators using a single pump and the surrounding water. Specifically, we propose a novel valve architecture using elec,tropermanent magnets and magnetorheological fluid. Our new design will enable to control air and water powered soft fluidic actuator,s using an architecture similar to those already used in microfludics while retaining the ability to be electronically modulated and, reprogrammed like pressure activated valves.Approved for Public Release

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