A Soft, Fast and Versatile Electrohydraulic Gripper with Capacitive Object Size Detection

Abstract

Soft robotic grippers achieve increased versatility and reduced complexity through intelligence embodied in their flexible and conformal structures. The most widely used soft grippers are pneumatically driven; they are simple and effective but require bulky air compressors that limit their application space and external sensors or computationally expensive vision systems for pick verification. In this study, a multi‐material architecture for self‐sensing electrohydraulic bending actuators is presented that enables a new class of highly versatile and reconfigurable soft grippers that are electrically driven and feature capacitive pick verification and object size detection. These electrohydraulic grippers are fast (step input results in finger closure in 50 ms), draw low power (6.5 mW per finger to hold grasp), and can pick a wide variety of objects with simple binary electrical control. Integrated high‐voltage driving electronics are presented that greatly increase the application space of the grippers and make them readily compatible with commercially available robotic arms.

Elephant trunks use an adaptable prehensile grip

“…Artificial muscles composed of silicon elastomers can actuate rigid grippers to pick up objects. One artificial muscle, known as hydraulically amplified self-healing electrostatic actuators (HASEL) [15], can grasp various objects and use its own feedback to estimate the object's size [29]. Fluid-filled toroidal tubes can grip, catch, and convey objects [30].…”

Elephant trunks use an adaptable prehensile grip

“…Artificial muscles composed of silicon elastomers can actuate rigid grippers to pick up objects. One artificial muscle, known as hydraulically amplified self-healing electrostatic (HASEL)[15], can grasp various objects and use its own feedback to estimate the object’s size [29]. Fluid-filled toroidal tubes can grip, catch, and convey objects [30].…”

Biodegradable electrohydraulic actuators for sustainable soft robots

“…We characterized the normal force exerted by the tips of individual pincers comprising grippers using previously established methods ( 52 ); a pincer was exposed to constant DC voltage signals for 4 s, during which normal forces of the pincer tip in relation to distances ranging from 0 to 25 mm from the resting position were measured using a dual-mode lever system (Aurora Scientific 310C-LR, Canada). We attached to the lever system a custom 3D printed lever with an arm length corresponding to the radius of curvature of the pincer tip.…”