Last month, Michelle Rosen, assistant professor of mechanical engineering, presented research at the 2024 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS) in Abu Dhabi. The paper, “A Circular Soft Pneumatic Actuator with Bi-Directional Bending Behavior,” was co-authored with senior electrical engineering students, Isaiah Rivera and Ani Vardanyan, alumni Jeannette Circe ME’22 M.Eng’24 and Brandon Bunt BSE’22 M.Eng’24, and Electrical and Mechanical Engineering Lab Technician, Michael Giglia. 

Established in 1988, IROS provides a dynamic platform for the international robotics community to exchange knowledge and explore the latest advances in intelligent robots and smart machines. The conference is one of the largest and most prestigious robotics research conferences in the world, attracting researchers, academics, and industry professionals from across the globe. 

During the conference, Professor Rosen showcased their innovative actuator design, which offers advancements in soft robotics by enabling a wide range of bending angles with a simple, single-chamber mechanism and one positive pressure input. A video presentation of Professor Rosen's conference talk is available for viewing. 

Abstract 

Most existing soft robotic actuators require multiple chambers to achieve multi-directional bending. In this paper, we present the design, fabrication, and analysis of a novel circular actuator. The actuator is made from a single soft material and is capable of bi-directional bending using only positive pressure in a single chamber. To accurately predict the required pressure for all bending angles, we developed an analytical model for the full range of motion - both uncurling and curling. We tested and analyzed actuators fabricated out of four types of silicone and found that the softest actuators have a bending range from the initial bending angle, 210◦, to 0◦, and to 225◦ in the other direction in 112 kPa. When constraining the actuators, we found they can create up to 5.1 N of blocked force in 210 kPa. Additionally, we demonstrate that a single circular actuator can grasp objects of various weights up to 800 g from both the inside and outside.