Development of an Autonomous Umbilical Tending System for Rover-Supported Surface EVAs

For surface extravehicular activities, no parameter is more impactful on the design of spacesuits than the "weight on the back," or the weight of the suit system that must be supported by the astronaut under gravity. The portable life support system (PLSS) alone has nearly doubled the weight on the astronaut historically, significantly increasing the exertion required to conduct manned surface activities and drastically curtailing the range of motion of the astronaut due to the movement of the center of mass rearwards and upwards. Both of these negatively affect EVA performance of astronauts; as a result, the capability to offload an astronaut's PLSS would be of great benefit to future EVA operations. The University of Maryland Space Systems Laboratory has been investigating one potential solution to this via its "BioBot" concept, supported by the NASA NIAC program. The overall concept is of a rover carrying the life support system for the EVA crew and supplying consumables via umbilicals. This paper will focus on the critical technology to make this approach viable: the umbilical-handling robot and its associated rover-mounted life support hardware. The robotic manipulator must support both its own weight and that of the umbilical, while keeping close enough to the EVA crew to eliminate the need for additional slack which could snag the umbilical on surface features. This paper details the design of the umbilical-handling robot, which must function as an Earth analog system for human factors testing, and the designs of the umbilical, suit disconnect, and Earth analog life support system. Additionally, this paper describes the sensors and algorithms for smoothly blended motion between the manipulator and the rover, as well as the design implications for the astronaut-following rover itself. Test results to date are also presented and future design modifications discussed.