A Multimodal, Reconfigurable Workspace Soft Gripper for Advanced Grasping Tasks

Abstract

A new generation of soft functional materials and actuator designs has ushered the development of highly advanced soft grippers as adaptive alternatives to traditional rigid end-effectors for grasping and manipulation applications. While being advantageous over their rigid counterparts, soft gripper capabilities such as contact effort are mostly a consequence of the gripper workspace, which in turn is largely constrained by the gripper design. Moreover, soft grippers designed for highly specific grasping tasks such as scooping grains or wide payloads are usually limited in grasping other payload types or in their manipulation versatility. This article describes a reconfigurable workspace soft (RWS) gripper that exploits compliant structures and pneumatic actuators to reconfigure its workspace to suit a wide range of grasping tasks. To achieve desired kinematics, finite element analysis (FEA) studies are conducted to dictate actuator design and materials used. Various grasping modes and their reconfiguration of the gripper workspace are presented and characterized, including the gripper's capability to reliably scoop granular items with radii as small as 1.5 mm, precisely pick items as thin as 300 μm from flat surfaces, as well as grasp large convex, nonconvex, and deformable items as heavy as 1.4 kg. The RWS gripper can modify and increase its grasping workspace volume by 397%, enabling the widest range of grasping capabilities to date achieved by a single soft gripper.

Transporting Dispersed Cylindrical Granules: An Intelligent Strategy Inspired by an Elephant Trunk

“…Compared to the traditional two‐fingered profile, this SPA is characterized by a one‐body design paradigm that results in lengthy fingers and wider finger pads, facilitating sweeping of scattered granules and the grasping of gathered cylinders. [ 13 ] The fingertips with a descending thickness from 15 to 3 mm ensure consistent contact with granules while manipulating, which enhances pinching of small targets. [ 31 ] Moreover, they form a tight seal against the ground, preventing any leakage of cylinders even under large bending deformation.…”

“…[11] The second approach proposes pre-stacking the granules in a container (Figure 1Bii); however, it is challenging to encapsulate the unconstrained granules. [12,13] The third approach involves the use of an array of grippers on uniformly ordered granules (Figure 1Biii), which may exhibit low robustness for taking up disordered ones. [14] Therefore, a practical technique for effectively handling scattered granules remained unexplored.…”

DenseTact: Optical Tactile Sensor for Dense Shape Reconstruction

“…Such grippers are capable of gripping either tennis ballsized or micro-sized objects, but fail to grasp smaller and Manipulation of smaller objects has been extensively explored from multiple perspectives. Specialized grippers that precisely handle small, flat, and thin objects include grippers with diverse grasping modes [5], digging grippers suited for cluttered environments [6], and grippers with retractable fingernails [7]. Concurently, numerous strategies have been introduced for grasping objects on flat surfaces with two fingers.…”

Topologically Optimized Fingerless Versatile Gripper Actuated by a Shape Memory Alloy Coiled Garter Spring

“…By leveraging the instinct properties of hyperelastic materials, soft grippers can handle various objects while maintaining safe and compliant interactions with their environment. [11,14,[16][17][18] Due to the inherent characteristics of soft materials (i.e., large deformability, high compliance, inherently safe, dexterous and versatile, simple fabrication, low cost, etc. ), highly adaptive and robust grasping mechanisms have been demonstrated.…”