10-Year Anniversary of the European Proximity Operations Simulator 2.0—Looking Back at Test Campaigns, Rendezvous Research and Facility Improvements †
Abstract
:1. Introduction: A Look Back
2. Heritage: EPOS 1.0
3. New Challenges: EPOS 2.0
4. Early Rendezvous Research with EPOS 2.0
4.1. Spacecraft Rendezvous
4.2. First Scanning LiDAR Experiments
4.3. Contact Dynamics
4.4. Connection of External Dynamics Simulators
4.5. Multiobjective Optimization
5. Sunlight, Lasers and the VIBANASS Tests
5.1. A Sunlight Simulator
5.2. Preparing for Lasers
5.3. VIBANASS Test Campaigns
6. Teaching a Robot to Tumble: The DEOS Tests
- The numerous trajectories for the open-loop tests were mainly derived from actual dynamics simulations and provided by EADS Astrium. In many test cases, the target mock up was tumbling, in strong contrast to the attitude stabilized GEO scenarios up to this point. Mapping these trajectories to EPOS 2.0 was found to be difficult. Robot joint limits and particularly the so-called singularity—joint configurations that the robot could not reach due to mathematical reasons—required the development of an optimization algorithm that allowed mapping the trajectories in a semi-automated way on a trial and error basis. This was not a perfect solution but was the foundation for considerable improvements at a later time.
- The fact that robot 2 could rotate the mock up through only two revolutions about its symmetry axis at this time limited the duration of the tumbling trajectories considerably.
- As already mentioned, many trajectories included a tumbling target and active laser-based sensors. The shutters of all windows granting a glance into the laboratory had to be closed. It proved difficult for the EPOS operator to properly monitor the robots, especially at close range, with the two available surveillance cameras alone.
- In some cases, the laser curtain and the robot cell fence in the background of the target were too bright in the navigation camera images. Again, pieces of black cloth solved the problem.
7. The Moon in the EPOS Lab: The Fosternav Tests
8. Advanced Rendezvous Research in DLR’s OOS-E2E Project
8.1. OOS-E2E and EPOS 2.0
8.2. RICADOS
8.3. Making EPOS fit for E2E
- The dynamics simulation worked in Earth Center Inertial (ECI) coordinates, while, in the laboratory, only the relative pose can be realized reasonably.
- Robot joint singularities and work space limits set boundaries to the possible set of fixed transformations from ECI to laboratory coordinates. A trial-and-error approach for each trajectory, as used up to this point, was not practical nor feasible for a complex closed-loop simulation.
- The realization of the starting conditions in a distributed simulation was a real challenge. It was not possible to synchronize the whole setup, including another HIL simulator and the whole GSOC satellite operations infrastructure to EPOS 2.0 and then start everything exactly at the same time. The robots can not realize a specific state with non-zero velocity at once. Finally, in development work, a solution that required all subsystems to coordinate in such a way was not practical and would have been very fragile.
- Simply connecting the robots to an external simulator leaves the facility vulnerable to any software bugs or human error. In closed-loop simulations anything can happen. An unstable control loop may accelerate the robots smoothly and cause a collision.
8.4. On-Board Computer in the Loop
9. GEO Again: SpaceTug
10. Welcome Back Serial Number One: Testing RVS3000
11. Going Beyond Earth Orbit: Mars Sample Return
12. Conclusion: A Look Ahead
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Acknowledgments
Conflicts of Interest
References
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Rems, F.; Frei, H.; Risse, E.-A.; Burri, M. 10-Year Anniversary of the European Proximity Operations Simulator 2.0—Looking Back at Test Campaigns, Rendezvous Research and Facility Improvements. Aerospace 2021, 8, 235. https://doi.org/10.3390/aerospace8090235
Rems F, Frei H, Risse E-A, Burri M. 10-Year Anniversary of the European Proximity Operations Simulator 2.0—Looking Back at Test Campaigns, Rendezvous Research and Facility Improvements. Aerospace. 2021; 8(9):235. https://doi.org/10.3390/aerospace8090235
Chicago/Turabian StyleRems, Florian, Heike Frei, Eicke-Alexander Risse, and Matthias Burri. 2021. "10-Year Anniversary of the European Proximity Operations Simulator 2.0—Looking Back at Test Campaigns, Rendezvous Research and Facility Improvements" Aerospace 8, no. 9: 235. https://doi.org/10.3390/aerospace8090235
APA StyleRems, F., Frei, H., Risse, E. -A., & Burri, M. (2021). 10-Year Anniversary of the European Proximity Operations Simulator 2.0—Looking Back at Test Campaigns, Rendezvous Research and Facility Improvements. Aerospace, 8(9), 235. https://doi.org/10.3390/aerospace8090235