Browsing by Author "Gerhards, Jan Patrick"

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Open Access
Cooperative radio navigation on the Moon
(2024) Gerhards, Jan Patrick
In recent years, interest in missions to the surface of the Moon has been going through a renaissance not seen since the Apollo era. An important consideration for such missions is how to accurately determine the position of objects on the Moon. In addition, mission components should have an understanding of a reference time in order to correlate measurements and plan actions. Currently, these capabilities are provided using different methods on a mission-by-mission basis. As this is inefficient compared to the use of a common approach, there are plans for a satellite constellation providing navigation and timing information, similar to satellite-based systems used for these purposes on Earth. However, a lunar equivalent is expected to have a smaller scale, which leads to a reduced accuracy and availability compared to terrestrial satellite navigation systems. In this context, suggestions have been made for combining a satellite navigation system with swarm navigation, in which entities of a swarm perform measurements between one another in order to estimate their position and clock parameters relative to one another. The goal of such a system is to complement the satellite navigation system with the higher availability and accuracy of the swarm navigation system. In this thesis, we propose and implement such a combined system, which we refer to as a hybrid navigation system. Based on a previous theoretical analysis, we implement a simulation to generate test data and use this data to evaluate our hybrid navigation system’s performance in various scenarios. As a swarm is a distributed system, we describe different algorithms which can be used by the hybrid navigation system in such an environment and evaluate their characteristics. Finally, we note practical considerations relevant for use of a hybrid navigation system and use cases in which such a system may provide benefits compared to satellite navigation only.
Open Access
Digital twin for fleet management of connected vehicles
(2021) Gerhards, Jan Patrick
Connected cars are capable of communicating with other devices (e.g., other vehicles, smartphones, road side units) in their environment. The domain in which they operate is a highly dynamic one. Reasons for this include changing demands of users and heterogeneity of technologies and interfaces. Due to this, developing a concept for a digital twin of a connected car that is capable of operating under these conditions is a challenging task. Especially handling of data and behavior of connected cars is an area of interest. In this thesis, we propose a digital twin architecture which can be used to implement connected car scenarios. We analyze challenges of the domain and assess in which ways and under what circumstances connected cars may interact. Based on these expectations, we introduce our concept for a digital twin. Our main goal is to provide interoperability between different car manufacturers, while still allowing developers to implement functionality in a way they deem appropriate. In order to verify our concept, a prototype of a digital twin is implemented. We explain this implementation and share experiences gained during this development. Finally, we draw conclusions on the concept as a whole and how it may be used in practice.