This thesis aimed to develop a rendezvous and proximity operation simulation to be tested with physical sensors and hardware, in order to assess the fidelity and performance of low-cost off-the-shelf systems for a hardware-in-the-loop testbed. With the push towards complex autonomous rendezvous missions, a low barrier to entry spacecraft simulator platform allows researchers to test and validate robotics systems, sensors, and algorithms for space applications, without investing in multimillion dollar equipment. This thesis conducted drone flights that followed a representative rendezvous trajectory while collecting lidar data of a target spacecraft model with a lidar sensor affixed to the drone. A relative orbital motion simulation tool was developed to create trajectories of varying orbits and initial conditions, and a representative trajectory was selected for use in drone flights. Two 3D tracking systems, OptiTrack and Vive, were assessed during these flights. OptiTrack is a high-cost state-of-the-art motion capture system that performs pose estimation by tracking reflective markers on a target in the tracking area. Vive is a lower-cost tracking system whose base stations emit lasers for its tracker to detect. Data collection by two lidar types was also assessed during these flights: real lidar data from a physical sensor, and virtual lidar data from a virtual sensor in a virtual environment. Drone flights were therefore performed in these four configurations of tracking system and lidar type, to directly compare the performance of higher-cost configurations with lower-cost configurations. The errors between the tracked drone position time history and the target position time history were analyzed, and the low-cost Vive and real lidar configuration was demonstrated to provide comparable error to the OptiTrack and real lidar configuration because of the dominance of the drone controller error over the tracking system error. In addition, lidar data of a target satellite model was collected by real and virtual lidar sensors during these flights, and point clouds were successfully generated. The resulting point clouds were compared by visualizing the data and noting the characteristics of real lidar data and its error, and how it compared to idealized virtual lidar data of a virtual target satellite model. The resulting real-world data characteristics were found to be modellable which can then be used for more robust simulation development within virtual reality. These results demonstrated that low-cost and open-source hardware and software provide satisfactory results for simulating this kind of spacecraft mission and capturing useful and usable data. / Master of Science / As space missions become more complex, there is a need for lower-cost, more accessible spacecraft simulation platforms that can test and validate hardware and software on the ground for a space-based mission. In this thesis, two position tracking systems and two lidar data collection types were assessed to see if the performance of a low-cost tracking system was comparable to a high-cost tracking system for a space-based simulation. The tracking systems tested were the high-cost state-of-the-art OptiTrack system and the low-cost Vive system. The two types of lidar data collected were real lidar from a physical sensor and virtual lidar from a virtual sensor. These assessments were performed in four configurations, to test each configuration of tracking system and lidar type. First, a simulation tool was developed to simulate the orbital dynamics of a spacecraft that operates in proximity to another spacecraft. After choosing an orbit and initial conditions that represent one such potential mission, the resulting trajectory was uploaded to a drone which acted as a surrogate for a spacecraft, and it flew the uploaded route around a model satellite, collecting lidar data in the process with a lidar sensor affixed to the drone. The tracking systems provided the drone with its position data, and the lidar sensor on the drone collected lidar data of a model satellite as it flew. The data revealed that the low-cost tracking system performance was comparable to the high-cost tracking system because the drone's controller error dominated over the tracking system errors. Additionally, the low-cost drone and physical lidar sensor generated high quality point cloud data that captured the geometry of the target satellite and illustrated the characteristics of real-world lidar data and its errors. These results demonstrated that low-cost and open-source hardware and software provide satisfactory results for simulating this kind of spacecraft mission and capturing useful and usable data.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/116171 |
| Date | 30 August 2023 |
| Creators | Meland, Tallak Edward |
| Contributors | Aerospace and Ocean Engineering, Schroeder, Kevin Kent, Kenyon, Samantha Parry, Black, Jonathan T. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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