Discrete Layer Jamming for Safe Co-Robots

Abstract

High injury severity occurs when a stiff robot arm hits an operator. Introducing compliance into robot systems reduces the impact and enables safe interaction, but at the expense of positioning performance and payload capacity. This paper presents a tunable stiffness mechanism for safe human-robot interaction based on discrete layer jamming. The proposed design of a discrete layer jamming mechanism is a robot link made of multiple thin layers of ABS and multiple clamps. By applying high clamping pressure to the laminates, the link behaves like a rigid link; reducing the clamping pressure softens the link which yields safer human-robot interaction. Compared to conventional pneumatic layer jamming, discrete layer jamming allows for simplicity of installation with dynamic actuators, faster control, greater portability since no air supply is needed, and no sealing issues. To validate the concept, this paper investigates a discrete layer jamming beam made of ten ABS laminates and two aluminum clamps that cover 10% of the surface of the beam. Stiffness tests have been performed, showing that around 17 times bending stiffness change is achieved by increasing the clamping pressure of two clamps from 0 to 1 MPa.