Fluidic Camming for Grasping

Abstract

Soft robotic grippers offer certain advantages for grasping objects and anchoring into environments compared to traditional rigid grippers. For instance, their conformability enables handling of delicate objects with simplified sensing and control, and their compliance allows them to be robust to impacts. However, soft grippers generally face two significant challenges: (i) an inability to apply large grasping forces, and (ii) the use of large and cumbersome pumps and power supplies, particularly for pneumatic systems. Here, we propose “fluidic camming,” in which the force pulling on a gripper device pressurizes its actuating fluid, which, in turn, applies pressure to the grasped surface. The larger the pulling force is, the larger the grasping force automatically becomes. Fluidic camming results in the ability to grasp with very high squeezing forces. The presented devices are lightweight, work across a large range of feature shapes and sizes, perform both negative and positive-space grasping, and do not require pumps, batteries, or disposable canisters to generate system pressure. This technology is especially interesting for anchoring robots or humans to negative spaces in environments, such as cavities on a rock face, or as a gripper for gently manipulating a wide variety of both heavy and fragile objects. A device with mass 55 g anchored 667 N to a parallel-walled cavity; another device, capable of negative and positive feature grasping, successfully lifted both a chicken egg and a 222 N weight.