The future of EVA operations

EVA operations are currently the highest-risk task actually performed by humans in space and at the same time one of the most useful assets in human space missions. Despite the growing need for enhancement of EVA capabilities, the EVA technologies, such as spacesuits, stayed almost unaltered for more than 40 years, while new concepts are currently being developed (xEMU). MMEVR (Multi-Mission Extra Vehicular Robot) is a proposed design for a multipurpose EVA robot with high dexterity and mobility, which purpose is to collaborate with humans in Extra-Vehicular, in-space Operations and highly repetitive tasks.

MMEVR presents a new modular architecture that allows astronauts to configure the robot to follow specific mission requirements. The robot provides 2 to 4 additional robotic limbs and a navigation unit to perform autonomous tasks or collaborate with human crews during EVAs. The robot mobility is based on the joint use of RCSs (Reaction Control System) and CMGs (Control-Movement Gyroscope). MMVR can be operated in 3 different control modes: Autonomous, teleoperated or robotic augmentation for EVA suits. The design concept includes an ISPR (International Standard Payload Rack)-integrated control module for teleoperated scenarios and a standard docking interface with space assets such as orbital and deep space modules or spacecrafts. MMEVR incorporates the lessons learned from the MMU, Safer, Robonaut, DEXTRE, and other space robotic assets to achieve unprecedented flexibility for the future generation of In-Space operations.

MMEVR is a complex robotic platform for in-orbit servicing composed of three main elements: The service module, the control station, and the multi limb modular robot. The infrastructure is designed to be adapted for any modern and near-future spacecraft and its flexibility allows MMEVR to be implemented without massive changes in the target vehicle or the crew workflow. All the system components make substantial use of COTS, reducing the R&D time needed to reach the testing phase. The robot module is a modular, multi-component robotic platform that can be reconfigured to respond to different in-space servicing needs. The core unit, the MMEVR is a two limb free-flyer capable of high dexterity. The body, hosts 4 Li-ion Battery packs, a dual central processing unit, a Reaction wheel group, a stereovision camera-lidar system, and three small docking ports. It is also capable of hosting a multi-toolbox on the back. A robot module can work in a stand-alone configuration or join together with a navigation module or in a triple-module configuration with the navigation module and another robot module. Each limb is a 10 Dof high dexterity robotic arm capable of a 2.2m reach in any direction. The limb unit is designed to reach the workspace in front of the astronaut’s chest, without obstructing the helmet vision angle or the stereovision camera system. MMEVR provides from 2 to 4additional arms to the astronaut and vectorial navigation capabilities if the navigation module is mounted. The astronaut doesn’t control directly the arms, which can be teleoperated from the control station inside the spacecraft or controlled by the local robot AI. The limbs can be used both for enhancing the dexterity of the astronaut or climb and secure onto the spacecraft external shell, avoiding the need for additional retention systems. The camera-lidar stereovision system provides real-time images and distance-to-target to the crewmember using the control station inside the spacecraft. The four Li-ion battery packs are used in a two buses configuration for which two batteries (one main and one for backup)control one limb, one computer, and one camera-lidar system. Without an interfaced navigation system, the MMEVRrobot module can still crawl onto the spacecraft using the EVA handles on the external shell and using the Reaction wheels for precision orientation. The Reaction wheels are provided in a tetrahedral configuration, one for each ax and another one for redundancy. In order to dock with the service module of other MMEVR components, three docking elements. Each docking port includes a radial laser alignment system and autonomous docking/undocking capabilities.