Utilization of Magnetically Induced Jamming in a Novel Soft Robotic Gripper

Abstract

Today’s high-tech society creates a pressing need for advanced medical prosthetics and industrial grippers. However, as technological advancements continue to be incorporated, a gap is created by the quality–cost ratio associated with using technologically advanced solutions. For example, many open-source prosthetics provide relatively inexpensive devices, but they often sacrifice the ability to grip irregularly shaped or smooth objects. For instance, doorknobs are difficult to grip using the typical hard robotics approach but can be gripped using soft robotic techniques. Prior work with soft robotics successfully used compressed air and a small granular material (coffee grounds) to build a gripper that can hold various objects. However, the use of compressed air makes these devices relatively slow, and the need for an air compressor limits the applicability of this design. Our primary goal was to explore the feasibility of a soft robotic approach that utilizes ferromagnetic granular materials to grip an object via the granular jamming transition that is induced with an external magnetic field. The granular material is placed inside flexible membranes made of polyisoprene, wherein the granular materials can go from a more relaxed state to a more rigid state depending on the strength of the magnetic field. The flexible membrane also allows the object to be held and then return to its original state when released. A solenoid provides a magnetic field that is easily turned on and off to jam and unjam the magnetic granular material and thus allows us to hold an object in place without the use of compressed air. In searching for a magnetic granular material, we found that iron filings work well, as they easily conform to the shape of the object. We have observed success in holding and releasing several smooth knobs as well as more angular shapes. This work will further the development of a low-cost but high- functioning universal gripper with applications in prosthetics and pick-and-place devices, as well as a multitude of industrial applications.