Spacecraft (S/C) docking is the last and most challenging phase in the contact closure of two separately flying S/C. The design and testing of S/C docking missions using software-multibody simulations need to be complemented by Hardware-In-The-Loop (HIL) simulation using the real docking hardware. The docking software multibody simulation is challenged by the proper modeling of contact forces, whereas the HIL docking simulation is challenged by proper inclusion of the real contact forces. Existing docking HIL simulators ignore back-reaction force modeling due to the large S/C sizes, or use compliance devices to reduce impact, which alters the actual contact force. This dissertation aims to design a docking HIL testbed to verify docking contact dynamics for small and rigid satellites by simulating the real contact forces without artificial compliance.
HIL simulations of docking contact dynamics are challenged mainly by:
I. HIL simulation quality: quality of realistic contact dynamics simulation relies fundamentally on the quality of HIL testbed actuation and sensing instrumentation (non-instantaneous, time delays, see Fig. 1)
II. HIL testbed design: HIL design optimization requires a justified HIL performance prediction, based on a representative HIL testbed simulation (Fig. 2), where appropriate simulation of contact dynamics is the most difficult and sophisticated task.
The goal of this dissertation is to carry out a systematic investigation of the technically possible HIL docking contact dynamics simulation performances, in order to define an appropriate approach for testing of docking contact dynamics of small and rigid satellites without compliance and using HIL simulation. In addition, based on the investigations, the software simulation results shall be validated using an experimental HIL setup.
To achieve that, multibody dynamics models of docking S/C were built, after carrying out an extensive contact dynamics research to select the most representative contact model. Furthermore, performance analysis models of the HIL testbed were built. In the dissertation, a detailed parametric analysis was carried out on the available models’ design-spaces (e.g., spacecraft, HIL testbed building-blocks and contact dynamics), to study their impacts on the HIL fidelity and errors (see Fig. 1). This was done using a generic HIL design-tool, which was developed within this work. The results were then used to identify the technical requirements of an experimental 1-Degree-of-Freedom (DOF) HIL testbed, which was conceived, designed, implemented and finally utilized to test and validate the selected docking contact dynamics model.
The results of this work showed that the generic multibody-dynamics spacecraft docking model is a practical tool to model, study and analyze docking missions, to identify the properties of successful and failed docking scenarios before it takes place in space.
Likewise, the 'Generic HIL Testbed Framework Analysis Tool' is an effective tool for carrying out performance analysis of HIL testbed design, which allows to estimate the testbed’s fidelity and predict HIL errors.
Moreover, the results showed that in order to build a 6DOF HIL docking testbed without compliance, it is important to study and analyze the errors’s sources in an impact and compensate for them. Otherwise, the required figure-of-merits of the instruments of the HIL testbed would be extremely challenging to be realized.
In addition, the results of the experimental HIL simulation (i.e., real impacts between various specimen) serve as a useful contribution to the advancement of contact dynamics modeling.
| Identifer | oai:union.ndltd.org:DRESDEN/oai:qucosa:de:qucosa:73251 |
| Date | 22 December 2020 |
| Creators | Bondoky, Karim |
| Contributors | Janschek, Klaus, Fasoulas, Stefanos, Technische Universität Dresden |
| Source Sets | Hochschulschriftenserver (HSSS) der SLUB Dresden |
| Language | English |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, doc-type:doctoralThesis, info:eu-repo/semantics/doctoralThesis, doc-type:Text |
| Rights | info:eu-repo/semantics/openAccess |
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