Fractional Order Modeling and Control of Hydrogel-Based Soft Pneumatic Bending Actuators

Soft pneumatic bending actuators (SPBAs) are commonly employed in soft robotics due to their unique charac- teristics, including safety, low weight, speed, and load capacity. However, the combination of pneumatics with soft materials causes SPBAs to exhibit nonlinearities and infinite degrees of freedom, complicating their dynamic modeling. In this work, we present how the dynamics of SPBAs can be adjusted to a fractional order model (FOM), showing an approach for their empirical identification. We also present a method for designing fractional order controllers (FOCs) for this type of actuators, based on the inversion of the empirical FOM. This modeling and control is applied to a modular SPBA made of a smart hydrogel, which endows the actuators with self-healing, self- adhesion, and self-sensing capabilities.