Design, Fabrication, and Validation of a New Family of 3D-Printable Structurally-Programmable Actuators for Soft Robotics

Soft robots have shown great potential for manufacturing exoskeletons, prostheses, and surgical robots. In this paper, we propose the concept of programmable soft robotics and will experimentally evaluate the performance in the context of continuum mechanisms. The proposed novel concept is motivated by the mechanical shape of RNA molecules which has a single-stranded polymeric molecule with a sugar-phosphate backbone and nitrogenous bases. The shape of the RNA and the type, location, and characteristics of the bases define the coded information. Due to the complexity of RNA, the proposed robot cannot be considered a 'bio-inspired' design. Instead, we indirectly utilize the concept of encoding sequences and introduce a new family of soft continuum robots based on a novel design of 3D printable 'mechanical library' and 'embedded functions' to be implemented on the backbone structure for mechanical programming. Through structural coding of the bases, the paper proposed a wide range of continuum robots. The system has the potential to be scaled up for multiple degrees of freedom (DOF), while the dexterity and range can be structurally programmed. A set of three soft continuum systems are designed, simulated, manufactured. The performance is evaluated by comparing simulations and experiments. We observed that actuators have different hysteresis ranging from 7.50% to 38.36% (on average) with a standard deviation ranging from 5.56% to 40.72%. The results highlight the effect of inherent pneumatic delay causing the hysteresis loops, which should be considered for control.