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PTB Smart-1 Simulator
Project Test Bed (PTB) Simulator
The goal of the Project Test Bed (PTB) Simulator study has been to systematically analyse the use of simulation to support the spacecraft design phase. A specific use case has been selected, being the Smart-1 mission to the Moon. For this use case, a simulator has been developed and has been used to analyse particular areas of the Smart-1 mission. The contract has been executed by SEA (UK) as prime contractor, with Terma (NL) and SSC (S) as sub-contractors. The study has been split into two phases, to allow for an incremental development of the simulation software.
Phase-1 Simulator
The objective of the phase-1 simulator is to support a spacecraft project during phase-B up to the PDR. Requirements have been derived for the generic case after a thorough review of reference material such as to analyse typical RIDs found during a spacecraft PDR. Then an instantiation of the generic requirements to specific Smart-1 requirements has been done. The implementation of the simulator has been based on the Generic Project Test bed (GPTB) as provided as input to this study. This simulation runs in the EuroSim simulation tool with C-code models based on the Software Model Portability (SMP) standard. For phase-1, the models have been mainly functional models of the spacecraft (sub-) systems, allowing analysing the spacecraft behaviour and various budgets such as mass, power consumption, memory usage, propellant consumption, etc. The simulation has been augmented with both 3D graphics displays and 2D mapping displays.  
PTB Simulator Controller
Phase-2 Simulator
The objective of the phase-2 simulator is to support a spacecraft project during phase-C up to the CDR. Also here requirements have been derived for the generic case by reviewing typical RIDs found during a spacecraft CDR. Specific Smart-1 simulator requirements and use cases have been defined. The implementation of the simulator has been based on the phase-1 simulator, with some sub-system models being refined. Realistic onboard software models have been included, by reusing the so-called flight cores (AOCS, Power) from the Matlab/Simulink design environment into C-code models integrated in the simulator. This required increased fidelity of any of the models providing inputs to these cores. The thermal and FDIR cores have been implemented as well, but here no direct reuse of the flight software has been done. In the phase-2 simulator, other high fidelity models have been included, such as a possibility to run the simulator together with a detailed thermal model simulation in ESATAN. For this, the ESATAN solver has been connected to the PTB simulator using an external interface to the ESATAN solver (DC-client). In this way, an unmodified version of the Smart-1 thermal model could be used in a simulation, providing detailed thermal data in combination with a realistic mission profile and interaction with other sub-systems.
Last update: 20 September 2006

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