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Force Measurement Toward the Instability Theory of Soft Pneumatic Actuators

Silicone-based bending soft pneumatic actuators (SPAs) have been very popular, since they provide solutions to many applications that require comfort and safety. However, their further utilization seems to be thwarted due to their limited force output. Force output can be the most important property for various SPAs, especially in assistive devices. Focusing on the SPA force application, this letter elaborates the yielding and buckling issues of the bending SPAs and introduces a novel perspective toward the understanding of these issues. Furthermore, we proposed a revised force measurement method and tested the force outputs of the newly designed bending SPAs of different materials and lengths. The results showed that the material and length are among the key factors that influence the instability occurrence. This letter, as our initial step toward the development of instability theory of different SPAs, can help the soft robot engineers to design force-robust soft actuators for different applications.