Nonlinear inflatable actuators for distributed control in soft robots.

As soft robotic systems grow in complexity and functionality, the size and stiffness of the needed control hardware severely limits their application potential. Alternatively, functionality can be embodied within actuator characteristics, drastically reducing the amount of peripherals. Functions such as memory, computation and energy storage then result from the intrinsic mechanical behavior of precisely designed structures. Here, we introduce actuators with tunable characteristics to generate complex actuation sequences from a single input. Intricate sequences are made possible by harnessing hysteron characteristics encoded in the buckling of a cone-shaped shell incorporated in the actuator design. A large variety of such characteristics are generated by varying the actuator geometry. We map this dependency and introduce a tool to determine the actuator geometry that yields a desired characteristic. Using this tool, we create a system with six actuators that plays the final movement of Beethoven's Ninth Symphony with a single pressure supply. This article is protected by copyright. All rights reserved.