Simulation analysis for optimal design of pneumatic bellow actuators for soft-robotic glove

Abstract

Soft actuators that have a bellows structure are favorable candidates for robots designed to interact with humans. However, a weak point in the actuator can occur as a result of deformation from the driving pressure. In this study, a simulation analysis of a soft bellows actuator composed of ethylene-vinyl acetate copolymer molding was conducted. The mechanical characteristics along different latitudes of the bellows in the soft actuator were evaluated using finite element modeling and analysis. Functional performance was studied during both compression and inflation using two driving methods (constant pumping rate-driven and constant displacement-driven). To validate the simulation, experimental tests were performed on a version of the soft bellows actuator that was constructed according to the same specifications as the model version; simulation and experimental displacements in relation to air pressure were compared. The results showed points near the trough were more likely to experience the largest stress during inflation and may suffer critical structural damage. During compression, points near the crest were more easily damaged. Stress variation showed good symmetry at points of interest on either side of the trough, during both inflation and compression. These findings provide a basis for precise control of and design improvements to soft bellows actuators for human-friendly usage.