The granular jamming integrated actuator

Soft robotics have opened a new field of flexible and dexterous manipulators. However, actuators to maximize a dexterous robot's workspace remain in their infancy. For a snake-like robot, actuation is emphasized on joint bending, which is the control of the bending angle and curvature. State of the art actuators can only independently control one of the two. This paper presents a granular jamming integrated actuator (JIA) which can control both the bending angle and curvature of joint independently. The JIA achieves this with its design, which consists of a granular-filled, bellowed walled membrane wrapped in a braided fiber sleeve. When inflated with positive pressure, the JIA expands and elongates in the axial direction. When the air flow is reversed and vacuum is achieved, the granules within the actuator stiffen it. By using granular jamming, JIAs in a bundle can restrict the movement of a neighboring elongating actuator. Our tests show that a bundle of this actuator type can vary its bending curvature, while maintaining a desired angle, by modulating the pressure differential between actuators within a bundle.