Tracking the Motion of an Intruder Particle in a Three-Dimensional Granular Bed On-board the Chinese Space Station

Three-dimensional (3D) particle tracking is a challenging task in dense granular systems. Magnetic particle tracking has been developed in recent years to reconstruct a tracer’s trajectory in granular systems. The method can be low-cost, compact, and flexible. In this work we applied a Hall sensor array method to track the trajectories of a magnetic intruder particle in a 3D granular bed in the centrifuge of the Chinese Space Station (CSS). We present a developed algorithm. By placing sensors in an array in a same plane, our algorithm can exclude the interference of varying external field. The method’s static accuracy can reach 0.02 cm, and the maximum deviation of our measurement from a known path is also checked to be 0.02 cm. On CSS, two independent sensor arrays are used to cross-check the accuracy of the method. The two measured trajectories are well overlapped. This confirms the method’s reliability and robustness of tracking an intruder in a dense granular bed.