Active Intruder Dynamics in Granular Beds

We will discuss the dynamics of magnetoelastic robots driven by an oscillating magnetic field in a granular bed as a function of the elasticity of the robot and the properties of granular medium. Our research draws inspiration from biomimetic soft robot designs that imitate how biological organisms respond to stimuli and their surroundings. The body changes shape from reciprocal rigid rod rotation to showing traveling wave as the applied field and the frequency is increased depending on the body elasticity. Depending on the lift generated due to the overburden pressure gradient, we find that the robot can rise through the bed and then crawl over the surface, or burrow through the bed. The rise time depends on many factors including the oscillating frequency and the body elasticity. While burrowing through the bed, we find that its speed is consistent with a model adapted from Lighthill’s elongated body theory of fish locomotion [1]. We will discuss the observed behavior as a function of experimental parameters, and compare and contrast behavior with intruder dynamics in vibrated granular beds.