Section: Application Domains

Robotic swimmers

Some companies aim at building biomimetic robots that can swim in an aquarium, as toys (for instance robotswim) but also for medical objectives. The website http://www.robotic-fish.net/ presents a list of several robotic fish that have been built in the last years. Some members of our Inria Project-Team (Munnier, Scheid and Takahashi) developed a collaboration with members of the automatic control laboratory of Nancy CRAN (Daafouz, Jungers) in order 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 carry 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 ( [74], [85]). However, in practice the admissible deformations of the ball are limited since they are realized using piezo-electric actuators. In the future, we want to take these constraints into account 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 fish into a viscous incompressible fluid (SUSHI3D) or into an inviscid incompressible fluid (SOLEIL).