Shape Optimization of Soft Pneumatic Bellows for High Energy Density

Pneumatic bellows can perform extending or contracting and output certain forces at the same time. However, after many years of development, there are few detailed shape design of soft bellows, which leads to relatively low energy density and hinders miniaturization of soft robotic systems. In this paper, to explore the design space, linear bellows are parameterized by variables concerning the cross section and lateral profile with sinusoid functions. Then, a fast finite element analysis script is developed to evaluate the mechanical behavior of bellows under different parameter sets. With the maximal radius ballooning strain constrained below 0.1, the optimal design is obtained with the axial strain up to 0.74, blocking force up to 228.7 N, and volumetric energy density up to 6549.7 J/m(3). Besides, we also adopt the idea of modular design which makes this soft bellow easy to be integrated. The developed soft pneumatic bellows are promising for use in scenarios where compact soft robots are expected.