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This paper focuses on verification of spacecraft SW for the electrical power subsystem (EPS) for a particular geostationary satellite. Choosing an appropriate topology is a key point in the process of electrical power subsystem design. Concepts of energy transfer. i.e. Direct Energy Transfer (DET) and Peak Power Tracker (PPT) are discussed. The EPS spacecraft SW verification is based on the functionality...
Spacecraft on-board autonomy is an important topic in currently developed and future space missions. In this study, we present a robust approach to the optimal policy of autonomous space systems modeled via Markov Decision Process (MDP) from the values assigned to its transition probability matrix. After addressing the curse of dimensionality in solving the formulated MDP problem via Approximate Dynamic...
Satellites are becoming increasingly software dependent. Due to the growth in computer hardware performance and the increasing complexity of space missions, On-Board Software (OBSW) plays nowadays a relevant role in implementing complex system-level requirements. In addition to this, stakeholders need to have preliminary OBSW versions to support satellite integration, testing, and validation activities...
Luminous flux tracking and junction temperature stress minimization are typical objectives in the regulation of high-brightness light-emitting diodes (LEDs). In this brief, a solution based on a model predictive controller approach is proposed. The state estimation is obtained using an LED photoelectrothermal dynamic model whose parameters are tuned through datasheets and dedicated experiments. By...
Functional and performance testing of critical space software is a very complex task since demanding quality requirements have to be fulfilled. In order to avoid any serious project delay and to preserve the product quality it is necessary to focus on test process definition, testing automation, testing tools, and standardization since the early phases of the project. This paper proposes a testing...
Formal verification techniques are necessary to demonstrate the completeness, the correctness, and the consistency in implementing spacecraft model-based autonomy requirements, where we have to explore the behavior of the system over a large input range. This paper introduces an approach based on probabilistic model checking to verify the specification of spacecraft autonomous reconfiguration functionality,...
The selection of an effective software development process is a crucial element in any space SW project. The waterfall software life cycle model as is can not provide an adequate solution to their relevant complexity and central role in the elicitation of spacecraft system-level requirements. Its main assumption of moving into a phase only when the preceding one is mature and complete is actually...
Software schedulability analysis is an important aspect for SW real-time verification. This paper proposes a concrete approach for analyzing the schedulability for the SW real-time application running on a spacecraft on-board computer. It is based on an extension of the response time analysis and takes into account many factors that could have a significant impact on the corresponding assessment....
Spacecraft autonomy is a crucial aspect of currently developed and future space projects. This paper presents a Markovian Decision Process (MDP) based framework as a way of modeling spacecraft on-board autonomy mechanisms. Its applicability to the three layered autonomous space systems architecture is shown. Special attention is given to its deliberative layer, where Approximate Dynamic Programming...
On-board autonomy is becoming a crucial aspect of currently developed and future space projects, especially for deep space exploration missions. In the near future, spacecrafts will be able to receive, process and achieve high-level goals even in an uncertain or dynamically varying context. This paper presents a Markovian based approach in order to model on-board autonomy mechanisms. This approach...
On-board Control Procedures (OBCPs) provide a useful mean to implement functional as well as operational flight procedures (e.g. payload switch-on/switch-off and spacecraft mode management) which can be modified, if necessary, even during the mission itself. This paper addresses the OBCP implementation in Meteosat Third Generation (MTG) satellite, where OBCPs are written in a specific language called...
Spacecraft health monitoring and management systems (also referred to as FDIR (Fault Detection, Isolation and Recovery) systems)) are addressed since the very beginning of any space mission design and play a relevant role in the definition of their reliability, availability and safety objectives. Their primary purposes are the safety of spacecraft/mission life and the improvement of its service availability...
Reliability of complex systems requires to take into account possible failures and strategies to detect and recover from system faults. This leads designers to consider models and algorithms capable of simulating and verifying fault detection, isolation and recovery (FDIR) strategies in different scenarios, characterized by uncertainty and partial information. Different solutions have been proposed...
FDIR functionalities are investigated since the very beginning of a space mission and play a relevant role in the definition of its autonomy, reliability and availability objectives. In this paper, an analytical methodology derived from the Timed Failure Propagation Graph (ETFPG) is proposed. TPFG is a causal model that captures the temporal aspects of failure propagation in a wide variety of engineering...
Light Emitting Diodes (LEDs) are one of the most promising technology for the future of lighting. The flexibility required by the dimming regulation introduces different and sometimes conflicting objectives which make challenging the control design. In this paper, a photoelectrothermal model of LED integrated with the dynamics of the power converter is presented. The model is used to design a model...
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