Electro-pneumatic dielectric elastomer actuator incorporating tunable bending stiffness

The superior ability of soft robotic systems is their good adaptability to complicated external environments without damaging themselves and their surroundings. Dielectric elastomers (DEs) are known as artificial muscles for soft actuations; however, rigid frames are commonly required to sustain the prestretch, highly limiting flexibility designs. Moreover, under high actuation voltage, DEs are susceptible to electrical breakdowns. Furthermore, pure-soft actuators cannot sustain deformations under external loads. Therefore, based on the fiber-reinforced DE films, we develop a cylindrical freestanding electro-pneumatic DE actuator (EPDEA), which combines the advantages of pneumatic and electric actuators. The finite element model (FEM) simulation is also performed to study the combined deformations (a combination of elongation and bending) of EPDEAs. Due to fiber reinforcement, we introduce the mechanical anisotropies in DE films, and realize the large directional bending deformations (>180°) and output forces under the electro-pneumatic actuation. Fiber-jamming suits (FJSs) are simultaneously developed for the EPDEA to obtain the variable stiffness capability. The EPDEA with the FJS unit can hold the end position under a weight of 200 g (which is almost 4 times the weight of EPDEA). The effects of structural parameters and supporting pressure on the actuation and stiffness tuning the performance of EPDEA are also investigated.