Design and Modeling of an Expandable Bending Actuator With Multiple Pneumatic Sources

Abstract This article describes the design and modeling of an expandable and inflatable bending actuator with multiple pneumatic sources. The actuator includes independent pneumatic modules sewn onto a flexible, nonstretch fabric structure. The bladders of the actuator consist of the maintaining layer with constant pressure and the driving layer with adjustable pressure. The active state of the actuator can be altered by adjusting the pressure of the driving layer while varying the number of driving layers can lead to different operational modes. Compared to other soft actuators, the proposed pneumatic actuator can achieve a favorable balance between high unit mass output torque and better response performance. Based on the geometrical constraints, we propose a mathematical model for our design to forecast the output torque and confirm its validity through experimentation. Finally, we examine the impact of modifying the actuator air supply mode on both the functionality and operational state of the actuator and test its dynamic performance. Additionally, it should be mentioned that the output torque performance of the actuator remains stable, with no significant changes observed undergoing more than 500 inflation and deflation cycles.