Search

The pursuit of precision and flexibility in satellite missions has led to an increased number of formation flying missions being developed. These systems consist of multiple satellites flying at close distances (from a few kilometres to a few meters) to achieve common objectives. This master thesis delves into the domain of the Guidance, Navigation and Control (GNC) for formation flying satellite systems, aiming to propose a novel architecture of different sets of sensors capable of determining absolute and relative positioning of the formation, ensuring mission success. This research begins by providing an overall status of existing and tested in-space systems. It will be complemented with novel and other systems already tested and promising new technologies in development. The thesis then delves into the design of an absolute and a relative Extended Kalman Filter (EKF) for distributed Synthetic Aperture Radar (SAR) systems implemented as part of an in-house simulator. Concluding with the results when using simulated Global Navigation Satellite Systems (GNSS) data as the filter input. Finally, the thesis will be completed with a trade-off analysis of the sensor systems, which could be used in formation-flying satellite systems in the near future. The outcome of this thesis is a novel proposal of a set of sensors to be brought to space navigation, with a corresponding detailed trade-off analysis. Additionally, to validate some of the sensor systems, an EKF is proposed, implemented and tested with the results from an in-house formation flying simulator. This master thesis report is the outcome of the work done during an internship at the Microwave and Radar Institute of the Deutsche Zentrum für Luft- und Raumfahrt e.V. (DLR) – German Aerospace Center – in Oberpfaffenhofen, Bavaria, Germany.

There are different ways of providing free-fall conditions on Earth in order to test a component, perform an experiment or demonstrate equipment before it can be included in a space mission. One of these options is a parabolic flight: briefly, the aircraft flies on a parabolic trajectory with the on-board payload experiencing several seconds of weightlessness. These flights have been performed since the 1950s to simulate space conditions for experiments as well as astronaut training. The project objective is to develop a cubical platform to perform 3-axis attitude stabilisation for experiments during the microgravity phase of a parabolic flight. The goal is to stabilise the platform and thus reduce perturbations and vibrations that diminish the quality of the microgravity achieved. To do so the attitude control system, composed of three reaction wheels in orthogonal configuration, will counterbalance the disturbances measured by the attitude determination system, an inertial measurement unit. The platform will be tested using a small aircraft in a self-organised flight campaign. Comprising nine students, this project is currently in the preliminary design phase. However, the prototyping and testing of the platform structure has already been initiated using a small-scale design and several hardware components have been ordered. The platform will be printed using additive manufacturing due to the numerous benefits of this process. The component integration is expected to be completad in time in order to facilitate the laboratory testing of the various subsystems before the flight campaign in May 2022. After the flight campaign, the collected data will be analysed, processed and published to ensure that it is accessible to the scientific community.

This project wants to create a useful tool to analyse the behaviour of the mobile network by not only focusing on the traditional bidimensional plane but also with height, on a 3D globe environment. This tool is motivated by the increasing usage of drones in a day-to-day basis and the need of them to increase the coverage Beyond Visual Line-Of-Sight (BVLOS). Additionally, mobile networks can provide more features to the drone industry, to name a few: identification via unique IMEI number or definition of restricted NO-FLY Zones based on cell towers, etc. Because mobile network technology standards where not initially designed to cover above human heights there is a very big interest into analysing how, empirically, the coverage is with the height factor of the drones in mind. This project has successfully developed a web tool that can analyse and visualizes the coverages and parameters of different readings of drone data. The obtention of the raw mobile data have been possible using off the shelf DJI frame drones with custom made hardware and software solutions develop at MOCCA. The webpage has been developed, following the existing styles and rules at MOCCA, using the Ionic framework on top of the Angular and is based on the CesiumJS JavaScript library. MOCCA Mobile Network Analysis (http://mna-site.mocca-technologies.com/) is thought to be a user-based web application, where any user of MOCCA can log in and create, delete or request any analysis. These, can have a set of fully customizable parameters at the time of generation and can also be downloaded in a raw CSV format to be later analysed. It features some basic height and RAT filtering to increase the viewing angles on complex volumes and a great amount of colour palettes for increased visibility in any point on the earth globe. This options on top of the ones that MOCCA already has implemented gives the user a lot of flexibility with the analysis. Assisted by some external REST API -and after some extensive