Section: Application Domains

Robotic swimmers

Some companies aim at building biomimetic toys robots that can swim in an aquarium for entertainment purposes (Robotswim) (The website http://www.robotic-fish.net/ presents a list of several robotic fishes that have been built in the last years.) and also for medical objectives. During the last three years, some members of the Inria Project-Team CORIDA (Most members of SPHINX where members of the former Inria project-team CORIDA) (Munnier, Scheid and Takahashi) together with members of the automatics laboratory of Nancy CRAN (Daafouz, Jungers) have initiated an active collaboration (CPER AOC) to construct a swimming ball in a very viscous fluid. This ball has a macroscopic size but since the fluid is highly viscous, its motion is similar to the motion of a nanorobot. Such nanorobots could be used for medical purposes to bring some medicine or perform small surgical operations. In order to get a better understanding of such robotic swimmers, we have obtained control results via shape changes and we have developed simulation tools (see [75] , [74] , [73] ). However, in practice the admissible deformations of the ball are limited since they are realized using piezo-electric actuators. In the next four years, we will take into account these constraints by developing two approaches :

1. Solve the control problem by limiting the set of admissible deformations.

2. Find the “best” location of the actuators, in the sense of being the closest to the exact optimal control.

The main tools for this investigation are the 3D codes that we have developed for simulation of fishes into a viscous incompressible fluid (SUSHI3D ) or into a inviscid incompressible fluid (SOLEIL ).