Morphological Control of Cilia-Inspired Asymmetric Movements Using Nonlinear Soft Inflatable Actuators

• Published in: Frontiers in robotics and AI Vol. 8; p. 788067
• Main Authors: Milana, Edoardo, Van Raemdonck, Bert, Casla, Andrea Serrano, De Volder, Michael, Reynaerts, Dominiek, Gorissen, Benjamin
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers Media S.A 03.01.2022
• Subjects: artificial cilia; bioinspiration; embodied intelligence; morphological control; nonlinear soft bending actuators; Robotics and AI; embodied intelligence; nonlinear soft bending actuators; bioinspiration; artificial cilia; morphological control
• ISSN: 2296-9144; 2296-9144
• DOI: 10.3389/frobt.2021.788067

Soft robotic systems typically follow conventional control schemes, where actuators are supplied with dedicated inputs that are regulated through software. However, in recent years an alternative trend is being explored, where the control architecture can be simplified by harnessing the passive mechanical characteristics of the soft robotic system. This approach is named "morphological control", and it can be used to decrease the number of components (tubing, valves and regulators) required by the controller. In this paper, we demonstrate morphological control of bio-inspired asymmetric motions for systems of soft bending actuators that are interconnected with passive flow restrictors. We introduce bending actuators consisting out of a cylindrical latex balloon in a flexible PVC shell. By tuning the radii of the tube and the shell, we obtain a nonlinear relation between internal pressure and volume in the actuator with a peak and valley in pressure. Because of the nonlinear characteristics of the actuators, they can be assembled in a system with a single pressure input where they bend in a discrete, preprogrammed sequence. We design and analyze two such systems inspired by the asymmetric movements of biological cilia. The first replicates the swept area of individual cilia, having a different forward and backward stroke, and the second generates a travelling wave across an array of cilia.