Design of Soft Grippers with Modular Actuated Embedded Constraints

Gabriele Maria Achilli,Monica Malvezzi,Gionata Salvietti,Maria Cristina Valigi

doi:10.3390/robotics9040105

Gabriele Maria Achilli, Monica Malvezzi + Show 2 more

Open Access

https://doi.org/10.3390/robotics9040105

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Journal: Robotics	Publication Date: Dec 6, 2020
Citations: 19	License type: CC BY 4.0

Affiliation: University of Perugia, University of Siena

Abstract

Underactuated, modular and compliant hands and grippers are interesting solutions in grasping and manipulation tasks due to their robustness, versatility, and adaptability to uncertainties. However, this type of robotic hand does not usually have enough dexterity in grasping. The implementation of some specific features that can be represented as “embedded constraints” allows to reduce uncertainty and to exploit the role of the environment during the grasp. An example that has these characteristics is the Soft ScoopGripper a gripper that has a rigid flat surface in addition to a pair of modular fingers. In this paper, we propose an upgraded version of the Soft ScoopGripper, developed starting from the limits shown by the starting device. The new design exploits a modular structure to increase the adaptability to the shape of the objects that have to be grasped. In the proposed device the embedded constraint is no rigid neither unactuated and is composed of an alternation of rigid and soft modules, which increase versatility. Moreover, the use of soft material such as thermoplastic polyurethane (TPU) reduces the risk of damage to the object being grasped. In the paper, the main design choices have been exploited and a finite element method (FEM) analysis through static simulation supports a characterization of the proposed solution. A complete prototype and some preliminary tests have been presented.

Highlights

Robotic grippers are composed of an assembly of rigid joints and links [3]
A robotic gripper is normally used to grasp object placed in a definite space; research in this area of robotics led to the development of devices able to recognize targets as an object, or an obstacle and create the best path planning strategy to complete assigned tasks [5,6,7]
This paper proposes an upgraded version of “The Soft ScoopGripper” [38], a modular, underactuated soft gripper with embodied constraints (Figure 1a)

Summary

Introduction

Robotic grippers are composed of an assembly of rigid joints and links [3]. The actuators can directly be applied to the links or the joints. The actuators can be placed at the gripper base using cables or tendon-like structures. Robotic grippers can use different types of sensors, such as encoders, torque sensors, or accelerometers, to obtain information about position, velocity, and distance from the object [4]. A robotic gripper is normally used to grasp object placed in a definite space; research in this area of robotics led to the development of devices able to recognize targets as an object, or an obstacle and create the best path planning strategy to complete assigned tasks [5,6,7]

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