Pneumatic Bending Soft Actuator Coupling With Revolute Joint With Different Boundary Constraints

Abstract

This article presents a study on pneumatic bending soft actuator (SA) coupling with revolute joint (RJ) with different boundary constraints (BCs), aimed to discover the bending performance of SA wearing on physical joint of human body as body joint actuators with different installation methods. First, a new pneumatic bidirectional bending SA is designed and fabricated, and its mechanical characteristic is obtained by experimental tests and fitting methods. Then, the mechanical characteristic is applied to the discrete bending model that approximates the continuous bending of the SA, and the kinetostatic analysis based on the principle of virtual work is conducted on the SA-RJ coupling system (SA-RJ CS) with fixing BC (FBC), hinging BC (HBC), and sliding BCs (SBCs). The kinetostatic equations are solved numerically, and thus the bending performance of the SA-RJ CS with different BCs is obtained. Results show the SA-RJ CS with SBCs performs better in bending angle and actuating torque than that with FBC or HBC. Therefore, it is suggested to install the SA of joint actuator on human body by SBCs. This study guides the application of pneumatic bending SA in rehabilitation exoskeleton. At present, we have used the axial SBC in rehabilitation exoskeleton.