Hardware-in-the-loop Proximity Operations in Cislunar Space

Space missions to Near Rectilinear Halo Orbits (NRHOs) in the Earth-Moon system are upcoming. A rendezvous technique in the cislunar space is proposed in this investigation, one that leverages coupled orbit and attitude dynamics in the Circular Restricted Three-body Problem (CR3BP). An autonomous Guidance, Navigation and Control (GNC) technique is demonstrated in which a chaser spacecraft approaches a target spacecraft in the southern 9:2 synodic-resonant L2 Near Rectilinear Halo Orbit (NRHO), one that currently serves as the baseline for NASA's Gateway. A two-layer control approach is contemplated. First, a nonlinear optimal controller identifies an appropriate baseline rendezvous path, both in position and orientation. As the spacecraft progresses along the pre-computed baseline path, optical sensors measure the relative pose of the chaser relative to the target. A Kalman filter processes these observations and offers precise state estimates. A linear controller compensates for any deviations identified from the predetermined rendezvous path. The efficacy of the GNC technique is tested by considering a complex scenario in which the rendezvous operation is conducted with a non-cooperative tumbling target. Hardware-in-the-loop laboratory experiments are conducted as proof-of-concept to validate the guidance algorithm, with observations supplemented by optical navigation techniques

Rendezvous in cislunar halo orbits: Hardware-in-the-loop simulation with coupled orbit and attitude dynamics

Space missions to Near Rectilinear Halo Orbits (NRHOs) in the Earth-Moon system are upcoming. A rendezvous technique in cislunar space is proposed in this investigation, one that leverages coupled orbit and attitude dynamics in the Circular Restricted Three-body Problem (CR3BP). An autonomous Guidance, Navigation, and Control (GNC) technique is demonstrated in which a chaser spacecraft approaches a target spacecraft in a sample southern 9:2 synodic-resonant L2 NRHO, one that currently serves as the baseline for NASA's Gateway. A two-layer guidance and control approach is contemplated. First, a nonlinear optimal controller identifies an appropriate baseline rendezvous path for guidance, both in position and orientation. As the spacecraft progresses along the pre-computed baseline path, navigation is performed through optical sensors that measure the relative pose of the chaser relative to the target. A Kalman filter processes these observations and offers state estimates. A linear controller compensates for any deviations identified from the predetermined rendezvous path. The efficacy of the GNC technique is tested by considering a complex scenario in which the rendezvous operation is conducted with an uncontrolled tumbling target. Hardware-in-the-loop laboratory experiments are conducted as a proof-of-concept to validate the guidance algorithm, with observations supplemented by optical navigation techniques

Towards incremental autonomy framework for on-orbit vision-based grasping

This work presents a software-oriented autonomy framework that enables the incremental development of high robotic autonomy. The autonomy infrastructure in space applications is often cost-driven and built for a narrow time/complexity domain. In domains like On-orbit Servicing Assembly and Manufacturing (OSAM), this prevents scalability and generalizability, motivating a more consistent approach for the incremental development of robotic autonomy. For this purpose, the problem of vision-based grasping is described as a building block for high autonomy of dexterous space robots. Subsequently, the need for a framework is highlighted to enable bottom-up development of general autonomy with vision-based grasping as the starting point. The preliminary framework presented here comprises three components. First, an autonomy level classification provides a clear description of the autonomous behavior of the system. The stack abstraction provides a general classification of the development layers. Finally, the generic execution architecture condenses the flow of translating a high-level task description into real-world sense-planact routines. Overall, this work lays down foundational elements towards development of general robotic autonomy for scalablity in space application domains like OSAM

Zero-G Lab: A multi-purpose facility for emulating space operations

peer reviewedDuring orbital rendezvous, the spacecraft typically approach in the same orbital plane, and the phase of the orbit eventually aligns. Potential rendezvous and docking missions need to be emulated and tested in an on-ground facility for micro-gravity research prior to meeting the harsh conditions of space environment. For orbital docking, the velocity profile of the two spacecraft must be matched. The chaser is placed in a slightly lower orbit than the target. Since all these tasks are quite complex and the realization of space missions are very expensive, any space-related hardware or software's performance must be tested in an on-ground facility providing zero gravity emulation before initiating its operation in space. This facility shall enable emulation conditions to mimic pseudo zero gravity. It is of critical importance to be equipped with all the necessary ”instruments and infrastructure” to test contact dynamics, guidance, navigation and control using robotic manipulators and/or floating platforms. The Zero-G Laboratory at the University of Luxembourg has been designed and built to emulate scenarios such as rendezvous, docking, capture and other interaction scenarios between separate spacecraft. It is equipped with relevant infrastructure including nearly space-representative lightning conditions, motion capture system, epoxy floor, mounted rails with robots, capability to integrate on-board computers and mount large mock-ups. These capabilities allow researchers to perform a wide variety of experiments for unique orbital scenarios. It gives a possibility to perform hybrid emulations with robots with integrated hardware adding pre-modeled software components. The entire facility can be commanded and operated in real-time and ensures the true nature of contact dynamics in space. The Zero-G Lab also brings great opportunities for companies/startups in the space industry to test their products before launching the space missions. The article provides a compilation of best practices, know-how and recommendations learned while constructing the facility. It is addressed to the research community to act as a guideline to construct a similar facility

Establishing a Multi-Functional Space Operations Emulation Facility: Insights from the Zero-G Lab

This methods paper outlines the development of the Zero-G Laboratory at the University of Luxembourg, a crucial resource for advancing research in space operations. The primary objective of this laboratory is to meticulously simulate operations in the micro-gravity conditions encountered in space, allowing for comprehensive testing of space-related hardware and software before their deployment in the demanding environment of outer space. The key methods employed in establishing this facility include replicating space-representative infrastructure elements such as realistic lighting conditions, epoxy flooring, and robotic systems mounted on rails. The laboratory integrates its hardware and software over a centralized Robot Operating System (ROS) network. Researchers can conduct hybrid emulations, combining robotic sys- tems with pre-modeled software components to simulate intricate orbital scenarios effectively. Furthermore, this paper serves as a practical guide for laboratory construction. The aim of this project is to assist the research community in establishing similar facilities and fostering advancements in space-related research and technology developmen