Rollable-based layer jamming device with variable stiffness for soft wearable applications

Soft robotic layer jamming devices enable controlled movement restrictions through the application of vacuum pressure on jamming layers. Traditional vacuum-based layer jamming systems, however, have limitations such as a force that decreases throughout the deformation due to a decrease in the contact area of the jamming layers and are restricted to an increase in length equal to their initial length. This works proposes a rollable layer jamming device (RLJD) which offers a solution to these problems. This device leverages rolled and stacked films to overcome limitations in linear extension by storing the jamming layers compactly inside of a reel. Also, its tensile force increases throughout the deformation due to the frictional force between the polymer and the layers which increases as the radius decreases, effectively addressing the problem of force reduction encountered in conventional layer jamming systems. This paper details the device manufacturing process, introduces an analytical model that predicts the performance of the device and presents experimental results for various device parameters. The RLJD has been successfully incorporated as a wearable robot that provides support for both the upper limbs and the lower back when lifting and carrying objects.