Experimental Demonstration of Technologies for Autonomous On-Orbit Robotic Assembly

Abstract

The Modular Reconfigurable High Energy (MRHE) program aimed to develop technologies for the automated assembly and deployment of large-scale space structures and aggregate spacecraft. Part of the project involved creation of a terrestrial robotic testbed for validation and demonstration of these technologies and for the support of future development activities. This testbed was completed in 2005, and was thereafter used to demonstrate automated rendezvous, docking, and self-assembly tasks between a group of three modular robotic spacecraft emulators. This paper discusses the rationale for the MRHE project, describes the testbed capabilities, and presents the MRHE assembly demonstration sequence.I. E l Introduction urrent spacecraft design methodologies generally revolve about the concept of a solitary, monolithic spacecraft C bus. Such spacecraft are very capable, but also face significant limitations in view of future plans and visions for expanded human presence on-orbit, on the moon, and on Mars. Perhaps foremost is the spacecraft size limitation presented by current and next-generation launch vehicles, especially when considering the requirement to boost spacecraft beyond Earth orbit. Manned spacecraft clearly must carry additional resources and possess significant capabilities beyond those required for their unmanned counterparts, especially for extended-duration missions. This will likely require the assembly or construction of larger vehicles and/or structures in orbit, in order to concentrate these resources in locations where they are readily accessible and can be used effectively. This may take the form of large aggregate spacecraft that would then move out of low Earth orbit, or perhaps orbiting resource depots that would store consumables such as fuel, food, and water and provide large-scale power generation capabilities for future use. Besides merely allowing for the possibility of larger spacecraft, in-space assembly also offers potential benefits by allowing more-flexible use of launch vehicle types and launch dates.Although we have experience with on-orbit construction in the form of Mir and the International Space Station, such tasks are still difficult, time consuming, and expensive. Frequently requiring astronaut extravehicular assistance, they can be dangerous as well. Automation using robotic vehicles has the potential to reduce cost, time, and risk for such tasks, although it will also require additional development of numerous supporting technologies. These technologies include improved local sensing and relative navigation; more-efficient microthrusters and manipulators; robust fault-detection and correction software for automated rendezvous, docking, and assembly tasks; adaptive planning and scheduling; human-robotic interaction for complicated tasks that cannot be completely automated; and mechanical mechanisms such as deployable booms, tethers, docking interfaces, and other construction tools.Development of modular or standardized hardware and software components and interfaces will al...

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