Purcell type swimming robotsdesign alternatives and locomotion strategies

Abstract

Advances in micro- and nanotechnology have facilitated the fabrication of new miniature artificial devices for biomedical applications, posing a number of challenges, one of which is the understanding of microscale hydrodynamics. This means moving in a low Reynolds number (Re) regime where viscous forces dominate over inertial ones, and thus new modes of moon must be considered. Edward M. Purcell introduced three types of ‘animals’ capable of swimming at the microscale, the simplest of which is the Purcell’s swimmer, consisng of three segments connected by one-degree-of-freedom joints. This swimmer is able to move by rotating the lateral segments according to motion primitives. In this context, this thesis focuses on the above-mentioned swimmer. The swimmer motion has been modelled in low and medium Re environments, from which a detailed study of the motion primitives in the microscale environment has been carried out. In addition, two prototypes of the three-link Purcell’s swimmer, with different actuation technologies, have been developed to perform simulations and experiments in different environment conditions. Finally, a closed-loop control strategy for path following is proposed and experimentally implemented in one of the manufactured prototypes. This thesis is a step forward in the study of this swimmer by means of designing and fabricating prototypes on the macroscale, with the intention of downscaling in future works.