Development of a standard modular docking interface for On-Orbit assembly and servicing

The increasing role of satellites in communication, Earth observation, and security has made them indispensable infrastructures for modern society. However, the traditional “use and dispose” approach is no longer sustainable because it is economically inefficient and it accelerates the growth of orbital debris, which puts at risk the safety and viability of future missions. To overcome these issues, On-Orbit Servicing (OOS) and On-Orbit Assembly (OOA) have emerged as essential technologies for extending satellite life and for building spacecraft or structures directly in orbit. This dissertation, developed in collaboration with Thales Alenia Space Italy, provides a comprehensive examination of the design, development, and testing of a modular robotic interface designed for docking and berthing applications. An extensive state of the art analysis identified the strengths and weaknesses of existing robotic interfaces and defined the functional requirements and design drivers for the interface developed in this thesis. Based on this work, three concepts were proposed, with the Modular Androgynous Standard Interface (MASI) emerging as the most effective solution. In detail, MASI addresses the operational needs of the OOS and OOA mating phase by combining mechanical coupling with refuelling, data, electrical, and thermal power transfer capabilities. The androgynous design of MASI allows spacecraft to operate either as a servicer or as a client, thereby enhancing operational reliability and flexibility. Moreover, MASI also represents the first androgynous interface designed to be fully compatible with another existing system, the Mechanical Interface for Capture at End-of-Life (MICE). The detailed design phases of MASI focused mainly on the pose measurement subsystem and on the design of the capture module. The contactless pose measurement system was designed to ensure that the capturing mechanism is activated only if the target is in a position that allows it to be securely grasped. The system is based on infrared proximity sensors and it enables real-time relative position estimation without markers or additional hardware on the target interface. The capture module was optimised through kinematic modelling and structural analysis to tolerate misalignment during the capture phase, to withstand mechanical loads once mated, and to preserve the androgynous functionality of the system by incorporating a dedicated capture region. Both systems were tested in the laboratory, demonstrating their effectiveness and the satisfaction of the performance required by the functional requirements. Furthermore, the thesis expands the concept of interoperability between different systems by presenting the Common Passive Interface (CPI) developed within the Horizon Europe SPACE USB project. The CPI consolidates the requirements of several European standards (HOTDOCK, SIROM, and iSSI) into a unified solution that ensures cross-compatibility and supports the development of a cooperative orbital infrastructure.