Development and Characterization of a Soft Valve for Automatic Fault Isolation in Inflatable Soft Robots

Abstract

Common causes of failure of inflatable soft robots are bursts due to wear, overpressurization or interactions with their surroundings. Resilience, the ability to survive such faults, is key for autonomous robotic systems, especially when human intervention is impossible or risky (e.g. robotic implants or space exploration). Although self-healing has been investigated as a possible solution, the approaches presented to date still have critical limitations. In this paper, we present a novel resilience mechanism based on soft valves. When used with soft actuators consisting of multiple inflatable segments connected in parallel, these are designed to readily isolate a burst section before the fault can propagate to the rest of the system. No additional sensing is required. The shut-off action of the valve is triggered by the pressure difference caused by the fault itself, as proved in the final application. The valve takes less than 30 ms to switch and can operate at various pressure levels: supply pressures up to 15 kPa were tested. This fault-isolating soft valve represents a new step towards soft robotic resilience, addressing soft robots vulnerabilities in difficult-to-access sites or in settings of high-risk for the system or its surroundings.