Robotic hand design for remote ocean exploration : active selection of compliance and contact conditions
- Mobile robots expand human reach into new and difficult environments, such as space, disaster sites, and the deep ocean. Robotic operations are typically executed via end-effectors, i.e. hands or grippers. Compliant underactuated hands are a useful solution in unstructured environments. This class of grippers trades off dexterity and simplicity to permit a range of grasp types and afford physical robustness without the complexity of a fully actuated design. This thesis presents the design, implementation, and testing of versatile and resilient compliant hands. The immediate application is the Ocean One submersible humanoid robot, which is intended to bring intuitive telepresence to marine exploration. Underwater vehicles take the place of divers, especially at unsafe depths, and expand our access to untapped marine environments. Relevant applications range from oil rig maintenance to ocean archeology and marine biology. Underwater environments present challenges that require special consideration when designing and controlling hands: slippery biofilms are commonplace, water currents can make reaching for flexible objects inaccurate, and buoyancy can make it easy to accidentally push floating objects away while trying to grasp them. Ocean One may need to acquire and hold a range of objects, from delicate sea creatures and priceless artifacts at shipwrecks to heavy structures and tools. By virtue of the kinematics and joint stiffnesses, the hands created for this work can perform precision fingertip pinches and strong wrap grasps. In addition, two mechanisms change the hand's passive behavior during grasping: (i) a dual-stiffness spring-winch transmission changes load-sharing characteristics between the fingers, and (ii) fingertip suction flow influences where contact occurs on the fingers and the amount of friction associated with each contact. These mechanisms alter the compliance and contact conditions of the underactuated hand, significantly influencing grasp behavior and enabling more versatility. Suction flow also acts as a simple and robust solution for tactile sensing, providing information about the finger-object contact conditions without the need for additional wiring or electronics at the hand. Improved dexterity of underactuated hands could allow them to function more effectively during unstructured and wet manipulation tasks.
|Type of resource
|electronic; electronic resource; remote
|1 online resource.
|Stanford University, Department of Mechanical Engineering.
|Cutkosky, Mark R
|Cutkosky, Mark R
|Statement of responsibility
|Submitted to the Department of Mechanical Engineering.
|Thesis (Ph.D.)--Stanford University, 2017.
- © 2017 by Hannah Sharpe Stuart
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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