Robotic Small Sat Servicing: A Next Generation Servicing Architecture Incorporating Advanced Robotics

Abstract

View Video Presentation: https://doi.org/10.2514/6.2021-0073.vid Maxar is working in partnership with the National Aeronautics and Space Administration (NASA) Space Technology Mission Directorate (STMD) to develop a new class of small scale robotics, called the Lunar Under-Actuated (LUnA) Robotic Arm. This robotic manipulator will be designed to minimize mass and manufacturing cost by implementing a new physical architecture that puts a single motor driven actuator at the robot base, which transmits torque to the joints via a cable drive system. This removes the need for actuators at each joint, as well as the associated avionics. This robot is being developed primarily for instrument position, sample collection, or geotechnical investigations, where it is already common to reduce power consumption by driving one joint at a time. Therefore, the inability of the LUnA arm to execute Cartesian space trajectories with simultaneous and coordinated motion of its joints is inconsequential. In this paper, we will present the results of a preliminary feasibility study, to demonstrate how the LUnA architecture can also be applied to orbital servicing use cases throughout the Earth orbit and cis-lunar sphere. For the purposes of this discussion, we will refer to the robotic system designed for such tasks as the UNder-Actuated Robotic Arm, or UNARA. These use cases may involve a variety of robotic tasks, such as refueling, payload swap, on orbit assembly, deployment, or manipulation. For this feasibility study, we will focus on the task of capturing a cooperatively equipped free flying payload. This task is chosen because it presents the most onerous requirements, thereby driving the need for system complexity. It is also chosen because it is an enabling capability for many on orbit servicing and logistics operations. Finally, it is important to note that using a robotic manipulator to capture a free flying client, instead of directly docking with it, creates huge advantages for the servicer system and client fleet. It allows us to take the “last meter” track and capture requirements and handle them with a large, mobile capture envelope instead of forcing high performance out of the servicer and client spacecraft control systems. It also allows for a much simplified failure management system (the robot reach creates a sort of buffer against catastrophic collision), which results in a simpler software system. These advantages can be particularly important when dealing with a fleet of client spacecraft, or even a variety of these provided by different suppliers.