International Space Station Design for Dexterous Robotics - Inboard Truss Segments

Over 200 International Space Station external high maintenance items have been designed for replacement by a dexterous robotics system in addition to space-suited astronauts. Planning for dexterous robotics maintenance increases flexibility for space station operations with a robot able to execute many tasks in place of a suited crew member, lowering the number of hours crew must spend on Extravehicular Activity (EVA). The five inboard truss segments of the station - S3, S1, S0, P1 and P3 - include 122 of these robot compatible maintenance items or On-orbit Replaceable Units (ORUs). This paper describes the impact robotic compatibility has had on the International Space Station (ISS) design, reviewing the inboard truss items as examples. Diverse challenges exist to verify each genre of ORU meets the dexterous robotics requirements. Each individual ORU is a unique task since the positioning of cameras and the orientation of both the dexterous and supporting robotic arms are unique for each worksite. This paper describes results of analysis and testing conducted to determine requirements compliance of the ORUs, and a discussion of the gaps between definitive requirements and realistically expected capabilities of a dexterous robotic system. The case in point is the Special Purpose Dexterous Manipulator (SPDM), which is currently planned to occupy the role of dexterous robot for the truss portion of the station. The purpose of compiling this experience is to suggest strategies for operation of the ISS, considerations for design of additional dexterous compatible hardware, and capabilities desirable in a follow-on dexterous robot for station operations.