A Soft Enveloping Gripper with Enhanced Grasping Ability via Morphological Adaptability

Abstract

Grasping objects of various sizes, shapes, and rigidities are an essential capability for robots to interact with the environment and people, especially in unstructured scenarios, which has been attracting intense attention from researchers over several decades. Since different objects have different geometries and materials, even if the same object poses differently, a universal gripper is expected to always find the feasible points on the objects to effectively grasp them. [1][2][3] Inspired by the extraordinary dexterity, adaptability, and multimodal perception of the human hand, anthropomorphic grippers which are equipped with multiple fully actuated fingers and sensors were developed to achieve grasping objectives by actively changing their grasping gestures and adjusting the gripping force. [4][5][6][7] These grippers can achieve complicated manipulation tasks, such as cutting, stitching, and in-hand manipulation. However, the complicated structure and control strategies, as well as the extravagant prices impede their further application in grasping. Underactuated grippers, whose actuators are less than the degrees of freedom, were developed to reduce mechanical complexity and improve compliance. These grippers are usually driven by cables, such as the prosthetic hand with fingers connected by one cable and actuated by one motor, [8] or linkage such as the famous five-bar mechanisms. [9] With the passive elements, the underactuated grippers can, to some extent, automatically adapt their fingers to the shape of the objects, so they can more effectively grasp objects than the fully actuated grippers. However, it is challenging for the abovementioned grippers to safely handle soft, fragile, or unfamiliar objects because of the rigid contact surfaces.Recent advances in soft grippers have opened an avenue to overcome the inadequacies of rigid grippers. [10] Compared to rigid grippers, soft grippers are inherently adaptable and safe, and with the aid of smart materials, allow for greater design flexibility in actuation methods, such as light induction, [11] thermal reaction, [12] chemical stimulation, [13] electroactive polymers, [14] and electromagnetic driven. [15] These smart material-actuated grippers are only suitable for gripping micro-objects and operating in specific environments. In contrast, soft pneumatic grippers made of silicone rubbers have better application prospects due to the advantages, such as low cost, robustness, and

Underactuated Humanoid Peeling Approach for Pickled Mustard Tuber Based on Metamorphic Constraints

“…This article addresses the challenges posed by the highly distorted and heterogeneous structure of pickled vegetable skin, as well as the random distribution of fibrous structures. Drawing inspiration from the dexterity, adaptability [19], multimodal perception capabilities [20], and synergistic effects of human hands and fingers [21], a human-like pickling robot based on the "insert-clamp-tear" process is designed with underconstrained architecture constraints. A modular force analysis is conducted using variable configuration constraints to optimize different flexible deformation forces based on the clustering analysis of different pickled vegetable shapes.…”