Multidimensional Tunable Mechanics Using Jamming

Abstract

Jamming is a structural phenomenon that provides tunable mechanical behavior. A jamming structure typically consists of a collection of elements with low effective stiffness and damping. When a pressure gradient, such as vacuum, is applied, kinematic and frictional coupling increase, resulting in dramatically altered mechanical properties. This results in a number of functional capabilities useful for robotics applications including: tunable stiffness, tunable force threshold, tunable dynamic response, reversible plasticity, shape locking and variable kinematics. Engineers have used jamming to build devices from conformable grippers to tunable-damping landing gear. This thesis presents a multidimensional approach to the modeling and design of jamming-based structures. It proposes novel jamming-based structures with programmable tunable mechanical properties in specific degrees of freedom, enabling hybrid force/position control during robot-environment interaction. It introduces a rigorous framework that systematically guides the design of jamming structures of major types (i.e., grain, fiber, and layer) for target applications. It characterizes and compares the force-deflection behavior of these structures in fundamental loading conditions (e.g., tension, shear, and bending). It describes the parameters that go into designing, fabricating, and actuating a jamming structure (e.g., scale, material, geometry, and actuator), along with their effects on functional metrics. It introduces three strategies to expand on the design space of jamming structures, and utilizes each of these with experimental case studies. Finally, it utilizes jamming-based structures to explore how people haptically engage with state-changing objects. Collectively, this thesis elaborates and extends the jamming design space.