H-PME: Development of a Robot Skin Using Halbach Array Permanent Magnet Elastomer

Abstract

This article presents a novel 3-axis Halbach permanent magnet elastomer (H-PME) sensor for the robotic application, which effectively reduces crosstalk along when two sensors are used simultaneously in close proximity, for example, during grasping of thin and delicate objects, needle threading, etc. This sensor integrates a Halbach-array magnetic elastomer, a 3×3 Hall sensor matrix, and a silicone layer. The magnetic elastomer is produced by combining NdFeB powders with a diameter of 5 μm into silicone, following a weight ratio of 50%, and then magnetized using 2D Halbach-array magnets. Simulation results reveal the capability to adjust magnetic field strength and distribution by altering the magnet's orientation. The sensor's efficacy in 3-axis sensing is validated through calibration with a linear model, achieving a good root-mean-square error below 0.7 N in force measurement. The H-PME sensor, with a thickness of merely 4.5 mm, can detect forces up to 50 N. It's simple 3-layer design allows the thickness to be reduced to as low as 2 mm, while also offering ease of replacement. Crucially, crosstalk evaluation experiments show that the proposed H-PME sensor can dramatically mitigate crosstalk interference.