Abstract
SENTINEL-Orb is an ongoing research and development initiative focused on creating a compact, fully autonomous flying robotic sphere. This sphere has been meticulously engineered to provide a comprehensive range of assistance to astronauts during both Extravehicular (EVA) and Intravehicular Activities (IVA). The system's design is intended to ensure operational effectiveness in microgravity and vacuum environments, thereby facilitating inspection, mapping, and navigation capabilities in areas that are either inaccessible or hazardous for human access. The development of the UX1-NEO system for flooded mine exploration was predicated on the advancement of underwater robotics technology pioneered at the Center for Robotics and Autonomous Systems (CRAS) of the Institute for Systems and Computer Engineering, Technology and Science (INESC TEC). This technology enabled the miniaturization, modular design, and integration of advanced perception and control algorithms for the SENTINEL-Orb. The current prototype incorporates a safe propulsion system designed to ensure the well-being of astronauts, a translation and attitude control mechanism, and a high-resolution camera that enhances the visual-inertial odometry module for object detection and anomaly identification. The propulsion and control subsystems were tested independently, while the six degrees of freedom (6-DoF) control performance has been validated through high-fidelity simulations, demonstrating precise maneuvering capabilities. The platform's modular architecture facilitates straightforward assembly and accommodates future enhancements. Preparations are underway for a parabolic flight campaign to evaluate the complete system's performance in a real microgravity environment. Preliminary findings suggest that the design meets rigorous safety standards and has significant potential for operational autonomy in space missions. A comparison of SENTINEL-Orb to the existing robotic solutions reveals that it addresses limitations related to atmospheric dependency and astronaut safety. This establishes SENTINEL-Orb as a promising tool for space maintenance, inspection, and exploration activities. © 2025 by INESC-TEC.