Design and implementation of variable inclined air pillow soft pneumatic actuator suitable for bioimpedance applications

Abstract

The technological revolution has caused the modernization of human–machine relationship changing our approach in problem solving our society issues and deviated the science of robotic all together. An example for one of the most important pawn in this revolution is soft robotics, the soft robots are robots that are made of deformable materials that provide an alternative approach to rigid robots. The soft pneumatic actuator (SPA) is one of the most widely used and studied form of this type of robotics. In this study, a new geometrical parameter of the SPAs is introduced by studying the effect of the change of the air pillow Inclination angle on the SPA work envelope and tip reaction force against wide range of positive and vacuum pressure applied on SPAs inner surfaces. We are elaborating this effect by using nonlinear static Finite Element Analysis. (FEA) basing it on the hyper-elastic material model identified by testing a specimen from the SPA fabricated material. Three SPAs are fabricated using Fused Deposition Modeling (FDM) 3D printer for the experimental validation of two aspects the work envelope and the tipping force. The test was performed by the image processing of the work envelope comparing the FEA and the experimental work envelope results and the tipping force was validated by using the load force scales. Based on the FEA and the experimental results, two different grippers with two work envelopes and tips was created to observe the change in the effect of the gripper on the weight and surfaces of the grasped object. By the integration of the SPA gripper with bio-impedance measurements, the SPA gripper was enabled to be translated to an agricultural application for fruit picking. A device that is monitored by having soft gripper to have no detrimental effect on the collected fruit's tissues, hybrid with Electrochemical Impedance Spectroscopy (EIS) test for quality assurance. Finally, this work can be interrogated in the future to a gripper that have modifiable synchronized work envelope and tip force for each object.