Honeycomb-Inspired PPAMs Soft Actuators for the Modular Design of Versatile Robotic Systems

Biological organisms usually achieve multifunctionality and complex structures through modular combinations. Current pneumatic soft actuator research predominantly isolates linear and bending actuator designs, although there have been lots of pneumatic bending actuators, most of which are based on FEA (fluid elastomer actuation). Fewer studies focus on the PPAMs-based bending configurations, achieving bending actuation through the folding and unfolding of pleats. To address the challenge of achieving multifunctionality without compromising lightweight and flexible attributes, this study introduces two innovative PPAMs-based soft actuators, the honeycomb-inspired linear actuator (HLA) and bending actuator (HBA), drawing structural inspiration from honeycomb geometry. Both of the actuator units can be designed through a similar set of structural parameters. Furthermore, these actuators can be freely combined by modeling for the achievement of versatile structures. HLA demonstrates a deformation rate of 27.67%, while HBA achieves a 37° bending angle under negative pressure. By selecting suitable materials, modular-designed structures composed of several HBA or HLA units show excellent load-bearing performance (29.2 times their own weight) and bionic characteristics (mimicking the gestures of the human arm). Finally, we validate their integration into diverse soft robotic systems, including swimming, grasping, and crawling platforms, highlighting their multi-functionality and potential for advancing soft robotics.