A numerical study on a new bio-inspired micro-robot

The objective of this study is to model and simulate the equations of motion for a conceptual prototype of micro-robot powered by four propellers made of rigid helices and of a cargo head shaped as an ellipsoid. A finite element code has been developed, intended to simulate the Stokes flow in order to derive the hydrodynamic resistance coefficients by comparing them with those present in the literature. To achieve this as reliably as possible, benchmark cases are studied using a sphere and an ellipsoid whose coefficients can be obtained through analytical formulae. The solutions of these two cases allow to compare the streamlines, the velocity and pressure fields used to validate the code. Finally, the dynamics of the problem was solved using the coefficients calculated with the code to obtain the solutions that physically represent the translational and rotational velocities of the micro-robot. Assuming that the angular velocity and the chirality of the propellers are known and can be prescribed, an analysis was made to investigate how different combinations of these can affect the translational and rotational velocities of the micro-robot and therefore the trajectory. This was done with the perspective of being able, in the future, to have a greater control on these devices and to be capable to use them for different tasks.