SanD-Worm: a soft bodied Swimming & Digging robot
Abstract
Robots capable of exploring the sea-floor environment have many potential applications of relevance to the Navy including structural inspection, surveillance, environmental monitoring, and exploration. However, current aquatic robots are either only capable of swimming through water, or have limited digging capabilities. Many marine animals, by contrast, skillfully transition between swimming and digging to hunt or evade predation. In particular,polychaetes (bristle worms) are an abundant class of annelids capable of a variety of locomotion behaviors well adapted to life at the ocean oor. By propagating transverse or longitundinal waves through their soft bodies, in coordination with motions of small protrusions called parapodia along their bodies, polychaetes can swim eeffectively through water, and dig through sandy or muddy substrates. Inspired by polychaetes, in this proposal we will discover the basic principles required to design, build, and test an aquatic soft robot for sea-floor exploration that has two fundamental locomotion capabilities: 1) swimming locomotion in water, and 2) digging locomotion within the granular substrate of the sea-floor. We call this Swimming & Digging robotSanD-Worm". SanD-Worm will use combinations of body undulation and parapodia actuation to achieve swimming and digging behaviors. In the proposed work, we will perform experiments to determine optimal actuation parameters, as well as the sensor locations and modalities required for feedback control of the robot.The design and operation of SanD-Worm will build upon insights that PIs Gravish and Tolley have gathered from a preliminary investigation in which they built a digging soft robot for dry granular material. The mechanical design of SanD-Worm will use soft exterior materials such as silicone and other elastomers to achieve a soft, expandable exterior body. Rotational actuation in each segment of the robot will be provided by either soft bending actuators, or brushless DC motors. The operational actuation parameters such as amplitude,frequency, and multi-actuator coordination will be determined experimentally through laboratory tests. A fundamental area of research for success in this project is determining how body movements weaken or strengthen submerged granular material; weakening is required for reducing drag force on the body, and strengthening is required to generate forward thrust. The design and testing of this system leverages the combined expertise of the PIs in the physics of granular flow (Gravish), and the design and control of soft robots (Tolley).The project will be performed in four phases (swimming, digging, swim-to-dig transition, and subsurface navigation) culminating in a robot demonstration of locomotion capabilities in year three.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- May 08, 2020
- Source ID
- N000142012373
Entities
People
- Michael T Tolley
Organizations
- Office of Naval Research
- United States Navy
- University of California, San Diego