This work explores the use of artificial whiskers as tactile sensors for enhancing the perception and navigation capabilities of mobile robots in challenging settings such as caves and underground mines. These environments exhibit inconsistent lighting conditions, locally self-similar textures, and general poor visibility conditions, that can cause the performance of state-of-the-art vision-based methods to decline. In order to evaluate the efficacy of tactile sensing in this context, three algorithms were developed and tested with simulated and physical experiments: a wall-follower, a navigation algorithm based on Theta*, and a hybrid approach that combines the two. The obtained results highlight the efficacy of tactile sensing for wall-following in intricate environments. When paired with an external method for pose estimation, it further aids in navigating unknown environments. Moreover, by integrating navigation with wall-following, the third, hybrid algorithm enhanced the map traversal speed by roughly 26−43% compared to standard navigation methods without wall-following.

Bio-inspired undulatory fin propulsion holds considerable potential for endowing robotic underwater vehicles with low-speed manoeuvrability and stable station-keeping. Robotic fins typically comprise a number of serially arranged and individually actuated “fin rays”, interconnected by a membrane-like flexible surface. Propulsive forces are generated by the propagation of a traveling wave along the mechanism, via appropriately timed ray oscillations. The present paper describes a dynamic model for an elementary two-ray fin system, analyzed as a standard robot mechanism with additional contributions arising from the elastic deformation of the flexible membrane and from the hydrodynamic forces. The model's main aspects, particularly with regard to the hydrodynamic effects, are explored via simulation studies, as well as via experiments with a robotic prototype. The developed model can serve a number of purposes towards optimizing the mechanical design, the control strategies, and the propulsive efficacy of robotic undulatory fins.