Towards a Pump-Controlled, Propellant-Powered Pneumatic Source for Untethered Soft Robots: Modelling and Experiments.

Untethered soft robots have great potential in applications ranging from search-and-rescue to human-assistive robotics, and the light weight, impact resistance, and innate mechanical intelligence of soft robotics would provide untethered soft robots with unique capabilities compared to traditional robotics. Despite their great potential, most soft robots are still tethered to their power sources and the few existing untethered platforms suffer from either slow motions (for pump-based systems) or short lifetimes and a lack of controllability (for propellant-based systems). In this work, we introduce the concept of a pump-controlled propellant-powered (PCPP) system in which a pump moves fuel into a reaction chamber, where the produced gasses can pressurize a soft pneumatic system. We present a model to compare the performance of a pneumatic and PCPP system, demonstrating the PCCP system's favorable work savings and actuation speed. We then perform preliminary tests on a prototype system to validate the model, also demonstrating that the platform can inflate a soft actuator. In the future, the PCPP system has the potential to combine the best features of existing pneumatic and propellant systems, allowing for both controlled and fast-moving untethered soft robotic motion.