Design and Experimental Validation of a Three-Chamber Omni-Directional Soft Actuator

Soft actuators are moving from the world of research to real industrial applications. Specifically, soft pneumatic actuators (SPAs) are the most adopted because of their adaptability, cost-effectiveness, safety, and ease of use. These characteristics are required, for example, for locomotion of soft robots, and, under specific restrictions, for minimally invasive robotic surgery (MIRS), and for exploring environments that could be potentially hazardous. Generally, SPAs can only bend in one plane, managing the bending angle by feeding pressure. Different solutions have been proposed to make them omni-directional. The most common is using multiple actuation chambers or multiple actuators in parallel. However, high radial expansions often vary their dimensions, making them unusable for inspections in some confined environments. This paper presents the development and testing of an externally reinforced actuator with three independent chambers. The reinforcement limits its radial expansion, maximizing its bending angle. The three chambers, properly pressurized, provide for a hemispherical-shaped working volume. Experimental tests on the prototype demonstrated the omni-directionality of the actuator.