In this work we present the head assembly and the gaze shifting capabilities of the bipedal humanoid robot Romeo. The purpose of the head system is to provide a reliable hardware platform for Human-Robot Interaction (HRI) applications, stereo vision based navigation or gazing experiments, either as stand-alone version or in synergy with the body movements. Towards this purpose, the number of joints, the angular range, speed and acceleration of the eyes and neck rotations should be should be in agreement with human psychophysics, i.e. reproducing realistic kinematics. We present a mechatronic system of the head and neck; accompanied by experimental results of head-fixed eye movements, solely head rotations, as well as eye-head cooperative motion for large angles of gaze shifting. We compare the values achieved by the prototype, with those of an average adult human.

The locomotion of miniature medical robots in the interior of the human body, possibly in contact with the tissue of organs and vessels, is a challenging problem in robotics, which, if properly addressed, might favorably impact several significant applications. This paper investigates the potential of employing relatively low-frequency vibrations, generated by an on-board eccentric motor, to reduce friction for such robots, moving by some other primary mechanism over and in contact with liver tissue. This study focuses on the computational modeling and the experimental assessment of the interaction between vibratory-actuated miniature robots and compliant tissue. The computational model developed to analyze the effect of such vibrations, for a robot moving over a substrate with normal-wise viscoelasticity, is employing a modified Dahl model with viscous damping for the tangential friction. Experiments with a vibratory-actuated platform pulled over ex-vivo bovine liver tissue indicate that the friction reduces as the frequency of vibrations increases, in a manner consistent with the model's predictions, reaching a reduction of up to 40%.

Inspired by the octopus arm morphology and exploiting recordings of swimming octopus, we investigate the propulsive capabilities of an 8-arm robotic system under various swimming gaits, including arm sculling and arm undulations, for the generation of forward propulsion. A dynamical model of the robotic system, that considers fluid drag contributions accurately evaluated by CFD methods, was used to study the effects of various kinematic parameters on propulsion. Experiments inside a water tank with an 8-arm robotic prototype successfully demonstrated the sculling-only gaits, attaining a maximum speed of approximately 0.2 body lengths per second. Similar trends were observed, as in the simulation studies, with respect to the effect of the kinematic parameters on propulsion.

We consider robotic analogues of the arms of the octopus, a cephalopod exhibiting a wide variety of dexterous movements and complex shapes, moving in an aquatic environment. Although an invertebrate, the octopus can vary the stiffness of its long arms and generate large forces, while also performing rapid motions within its aquatic environment. Previous studies of elongated robotic systems, moving in fluid environments, have mostly oversimplified the effects of flow and the generated hydrodynamic forces, in their dynamical models. The present paper uses computational fluid dynamic (CFD) analysis to perform high-fidelity numerical simulations of robotic prototypes emulating the morphology of octopus arms. The direction of the flow stream and the arm geometry (e.g., the presence of suckers), were among the parameters that were shown to affect significantly the flow field structure and the resulting hydrodynamic forces, which have a non-uniform distribution along the arm. The CFD results are supported by vortex visualization experiments in a water tank. The results of this investigation are being exploited for the design of soft-bodied robotic systems and the development of related motion control strategies.

The multi-arm morphology of octopus-inspired robotic systems may allow their aquatic propulsion, in addition to providing manipulation functionalities, and enable the development of flexible robotic tools for underwater applications. In the present paper, we consider the multi-arm swimming behavior of the octopus, which is different than their, more usual, jetting behavior, and is often used to achieve higher propulsive speeds, e.g., for chasing prey. A dynamic model of a robot with a pair of articulated arms is employed to study the generation of this mode of propulsion. The model includes fluid drag contributions, which we support by detailed Computational Fluid Dynamic analysis. To capture the basic characteristics of octopus multi-arm swimming a sculling mode is proposed, involving arm oscillations with an asymmetric speed profile. Parametric simulations were used to identify the arm oscillation characteristics that optimize propulsion for sculling, as well as for undulatory arm motions. Tests with a robotic prototype in a water tank provide preliminary validation of our analysis.