Development of an acoustico-vestibular system for head rolling stabilization : Aperception system to stabilize a bio-inspired swimming snake robot

Sammanfattning: Bioinspired robots are becoming more and more common and getting inspired by the solutions found in nature to tackle problems is often useful. Regarding the swimming robots Ąeld of research, we can get inspiration from swimming snakes. In the last twenty years several snake-like swimming robots have been conceived as their slender shape can allow more freedom in movements. It also may be less intrusive in an underwater environment. One problem encountered in swimming snake robots is to stabilize it on water surface and to control the head movement. Due to its shape it is very sensitive to rolling motion. A way to counter this is inspired by the swimming of the cottonmouth snake. By rotating its modules the robot can play on the buoyancy effect and gravity to stay stabilized and this would allow to stabilize the gaze of the robot. For that however we need to be able to locate the head, relatively to the water surface to have an absolute position of each module. The goal of this thesis is to conceive a perception module that would be able to reproduce the senses a cottonmouth snake uses to stabilize itself on the water surface. In order to achieve this an Inertial Measurement Unit is used to reproduce the information a snake gets from its inner ear. Distance sensors imitate the snakeŠs vision and provide an estimate of the distance of the head from the water surface. The perception module should be able to follow the movement of the snake robotŠs head relatively to the water surface. One of the challenges is that this module should be operational speciĄcally on water. To test the performances of the conceived perception module a hardware solution is presented in this thesis to simulate the movements of the robotŠs head above a water tank. This structure allows the perception module to do simple movements such as sinusoidal waves along the z axis or the movements the robot head would do when it is slightly disturbed, according to the simulation of that robot. The results show that the perception module has an accuracy similar to biological systems (the senses of the snake) so we believe that it will be usable to control the robotŠs stability.