Halbach array robot gripper for advanced handling of magnetic materials

Sustainability of permanent magnets is an increasingly important topic as technologies such as electric vehicles or advanced wind turbines are further developed. A potential alternative lies in extraterrestrial sources, such as the asteroid Psyche, which is rich in a tetrataenite that has high magnetocrystalline anisotropy and high saturation magnetization, making it a potential permanent magnet. Using a robot to extract and collect tetrataenite provides an avenue for replacing rare-earth element-free magnets where possible, but the state-of-the-art end effectors for grasping magnetic materials are inappropriate for these conditions. Operating in space introduces a significant constraint in the form of energy utilization, and most magnetic grippers are constructed with electromagnets, which are quite energy-intensive. We propose a design that instead uses an actuate set of parallel linear Halbach arrays to toggle between the strong and weak magnetic fields to grasp and drop objects, respectively. As part of the design process, field simulations were performed to ensure proper interaction between the arrays in the grasping and dropping configurations. To verify this data, the field of a single Halbach array was measured and compared to the simulations. A gripper prototype was fabricated and tested with a collaborative UR5e robot using several objects (4140 alloy steel) in varying orientations to determine the payload limits of the gripper, which was approximated to a maximum of 1.50 kg. This is correlated to magnetic field simulations in all grasping trials showing field strength and variance to provide a rough estimate for the gripper’s ability to grasp varied sizes of objects.