Optimal Positioning of Snake Robots in Vortex Wakes using Extremum-Seeking Control.

In this paper we explore the optimal positioning of an underwater snake robot (USR) for energy harvesting in the wake of a bluff body. The USR and fluid are simulated jointly using a coupled vortex particle-mesh method and multi-body system solver. The power dissipated in the damped joints of the robot is used as a proxy for the harvested energy. Furthermore, the effect of different damper coefficients on power dissipation is explored. An extremum-seeking control (ESC) scheme for nonlinear systems with time-varying steady-state solutions is employed to optimize the horizontal placement of the robot. The results show that the dissipated power does have a clear optimum. Moreover, the horizontal position of the USR under the ESC scheme is demonstrated to converge to a vicinity of the optimal position.