A Novel Soft Bending Actuator Using Combined Positive and Negative Pressures.

Mohammad Fatahillah,Namsoo Oh,Hugo Rodrigue

doi:10.3389/fbioe.2020.00472

Mohammad Fatahillah, Namsoo Oh + Show 1 more

Open Access

https://doi.org/10.3389/fbioe.2020.00472

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Abstract

Most soft pneumatic actuators for producing bending actuation have made use of either positive or negative pressure and adjusted their design in consequence. In the proposed paper, a novel soft bending actuator using combined positive and negative pressures (PNP) where the bending force of a negative pressure actuator and a positive pressure actuator is combined into a single actuating structure. This actuator is capable of producing a blocked force as high as 150 N at a combined positive pressure of 60 kPa and negative pressure of 60 kPa while still being able to produce large bending deformations. It was found that the equilibrium angle of PNP actuation is lower than using only negative pressure but that the actuator can produce larger forces at angles below the equilibrium angle of using positive pressure only. The actuator can use PNP actuation to produce large forces at lower bending angles and negative pressure actuation for producing large bending angles. This actuator was implemented in a soft robotic gripper capable of lifting large objects weighing up to 4 kg and a soft pinching gripper capable of holding a notebook weighing 1.85 kg by pinching it. The proposed actuator is capable of large forces and is versatile such that it is expected to be used in applications such as agriculture where many objects tend to be large and heavy yet require a delicate touch.

Highlights

Soft robotic grippers have attracted significant attention from industry for grasping objects in unstructured environments due to their compliance and ability to grasp objects without requiring precise alignment
Fluidic elastomer actuators (FEAs) generally consist of a polymeric matrix with cavities that expand upon pressurization and whose expansion causes an asymmetric deformation of the actuator which results in a bending motion
The bending force produced by the actuator using only positive pressure exceeds that predicted by the model, but the equilibrium angle of the model and the experimental results are in general agreement (Figure 3B)

Summary

Introduction

Soft robotic grippers have attracted significant attention from industry for grasping objects in unstructured environments due to their compliance and ability to grasp objects without requiring precise alignment. Soft pneumatic grippers have shown significant promise as they can conform themselves to the surface of the object and because the force produced by these actuators can be modulated through varying the applied pressure (Rus and Tolley, 2015; Mirvakili and Hunter, 2018; Shintake et al, 2018). Fluidic elastomer actuators (FEAs) generally consist of a polymeric matrix with cavities that expand upon pressurization and whose expansion causes an asymmetric deformation of the actuator which results in a bending motion. This is generally done by having a strain differential across the thickness of the actuator causing the longitudinal expansion of the actuator to produce a bending deformation.

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