Evaluation of Verification Approaches Applied to a Nonlinear Control System

As the demand for increasingly complex and autonomous systems grows, designers may consider computational and artificial intelligence methods for more advanced, re- active control. While the performance gained by such increasingly intelligent systems may be superior to traditional control techniques, the lack of transparency in the systems and opportunity for emergent behavior limits their application in the field. New verification and validation methods must be developed to ensure the output of such controllers do not put the system or any people interacting with it in danger. This challenge was highlighted by the former Air Force Chief Scientist in his 2010 Technology Horizons Report, stating \It is possible to develop systems having high levels of autonomy, but it is the lack of suitable [verification and validation] (V&V) methods that prevents all but relatively low levels of autonomy from being certified for use

Pushing the Boundaries of Spacecraft Autonomy and Resilience with a Custom Software Framework and Onboard Digital Twin

This research addresses the high CubeSat mission failure rates caused by inadequate software and overreliance on ground control. By applying a reliable design methodology to flight software development and developing an onboard digital twin platform with fault prediction capabilities, this study provides a solution to increase satellite resilience and autonomy, thus reducing the risk of mission failure. These findings have implications for spacecraft of all sizes, paving the way for more resilient space missions

キューブサットバスシステムのための標準化・適応性インターフェース設計

Since the 2000s, small satellite launches have increased rapidly each year and the number of players in this field is strongly linked to the popularity of the CubeSat standard around the globe. Highlights of its achievements are often the compatibility of launches via a standardized deployer (i.e. POD), shorter development times and lower costs than conventional large satellites. CubeSats are not just popular instruments for educating students in space research and engineering, but also enable us to demonstrate challenging technologies in a cheaper and quicker way and carry out scientific research in the field. But the success of CubeSat\u27s mission often fails. Improvements in reliability and prevent poor workmanship are necessary. The CubeSat standard enabled the small satellite market to expand enormously. In fact, a modular spacecraft deployer which can be attached to many different launch vehicles as a secondary payload was the key technology for the CubeSat Standard. To date, only external CubeSat interfaces, especially the mechanical interface, have been standardized. CubeSat needs a standardized internal interface to take advantage of the modularity. It will contribute to cost reduction and development time. One key to cutting costs and delivery time is a standardized internal interface for different CubeSat missions. In three CubeSat projects at the Kyushu Institute of Technology in Kyutech, a backplane interface approach, proposed as UWE-3 by the University of Würzburg in Germany, has been implemented to reduce the time for development and assembly. The backplane approach also helped to reduce the risk of harnessing faults. In order to satisfy the mission requirements, however, modifications to the proposed standard interface board were necessary for each CubeSat project. The thesis proposes a new idea of a Software-Configurable Bus Interface (SoftCIB) with a backplane board to obtain more flexibility, particularly for data connections. Instead of hardware routing, a Complex Programmable Logical Device (CPLD) was used to reprogram the bus interface on the PCB. The following advantages will be offered by the standardized backplane interface board: (1) less harness, (2) ease of assembly and disassembly (3) compatible with different CubeSat projects and (4) flexible for routings. We can use the SoftCIB again to reduce the cost and development of the interface boards, rather than designing and making new interface boards for new CubeSat projects. Various projects have various payloads for missions and interface requirements. The high flexibility of SoftCIB\u27s interface allows one to select either the same or a different subsystem board such as an OBC or EPS. A functional test with a breadboard module validated the concept. A radiation test has shown that the selected CPLD is strong enough to maintain total ionization doses in low Earth orbit of more than 2 years. The system level verification has been carried out in the engineering model of the BIRDS-3 project at Kyutech.九州工業大学博士学位論文 学位記番号：工博甲第485号 学位授与年月日：令和元年9月20日1. Introduction|2. Background|3. Implementation of Backplane approach for CubeSats|4. Purposed interface – The SoftCIB|5. Testing campaign|6. On-orbit demonstration|7. Conclusions九州工業大学令和元年

Methods for dependability analysis of small satellite missions

The use of small-satellites as platforms for fast-access to space with relatively low cost has increased in the last years. In particular, many universities in the world have now permanent hands-on education programs based on CubeSats. These small and cheap platforms are becoming more and more attractive also for other-than-educational missions, such as for example technology demonstration, science application, and Earth observation. This new objectives require the development of adequate technology to increase CubeSat performances. Furthermore, it is necessary to improve mission reliability. The research aims at studying methods for dependability analysis conducted by small satellites. The attention is focused on the reliability, as main attribute of the dependability, of CubeSats and CubeSats missions. The work has been structured in three main blocks. The first part of the work has been dedicated to the general study of dependability from the theoretical point of view. It has been studied the dependability attributes, the threads that can affect the dependability of a system, the techniques that are used to mitigate the threads, parameters to measure dependability, and models and techniques for dependability modelling. The second part contains a study of failures occurred during CubeSats missions in the last ten years and their observed reliability evaluation have been conducted. In order to perform this analysis a database has been created. This database contents information of all CubeSats launched until December 2013. The information has been gathered from public sources (i.e. CubeSat projects webs, publications on international journals, etc.) and contains general information (e.g. launch date, objectives) and data regarding possible failures. All this information is then used to conduct a quantitative reliability analysis of these missions by means of non-parametric and parametric methods, demonstrating that these failures follow a Weibull distribution. In the third section different methods, based on the concept of fault prevention, removal and tolerance, have been proposed in order to evaluate and increase dependability, and concretely reliability, of CubeSats and their missions. Concretely, three different methods have been developed: 1) after an analysis of the activities conducted by CubeSat’s developers during whole CubeSat life-cycle, it has been proposed a wide range of activities to be conducted during all phases of satellite’s life-cycle to increase mission rate of success, 2) increase reliability through CubeSats verification, mainly tailoring international ECSS standards to be applied to a CubeSat project, 3) reliability rising at mission level by means of implementing distributed mission architectures instead of classical monolithic architectures. All these methods developed in the present PhD research have been applied to a real space projects under development at Politecnico di Torino within e-st@r program. The e-st@r program is being conducted by the CubeSat Team of the Mechanical and AeroSpace Engineering Department. Concretely, e-st@r-I, e-st@r-II, and 3STAR CubeSats have been used as test cases for the proposed methods. Moreover, part of the present research has been conducted within an internship at the European Space research and Technology Centre (ESTEC) of the European Space Agency (ESA) at Noordwijk (The Netherlands). In particular, the partially realisation of the CubeSats database, the analysis of activities conducted by CubeSat developers and statement of activities for mission rate of success increase have been conducted during the internship

Design of a flatsat for the AlbaSat mission

openThis thesis presents the design of a FlatSat for the AlbaSat mission. AlbaSat is a 2U CubeSat with four mission objectives: (1) to collect in-situ measurements of the sub-mm space debris environment in LEO, (2) to study the micro-vibration environment on the satellite throughout different mission phases, (3) to do orbit and attitude determination through laser ranging; (4) to investigate alternative systems for possible Satellite Quantum Communication applications on nanosatellites. Firstly, an overview of CubeSats state of art and of the AlbaSat mission is provided, illustrating the main mission objectives and the importance of testing and verifying the satellite performance before launch using, for instance, FlatSat. Subsequently, the objectives of the FlatSat in the AlbaSat mission are defined. These objectives include creating a test and verification platform to evaluate the satellite's functionalities, verifying the proper interaction between subsystems, and achieving performance and reliability requirements. The design of the FlatSat is described in detail, including component selection, functional architecture, subsystem arrangement, and interfaces between them. Aspects such as power supply, attitude control, data acquisition, and communication are considered. Special attention is given to subsystem integration to ensure proper connection and interaction. The tests programmed on the FlatSat are presented, including functional tests, integration tests, and communication tests. In addition, the Electro-magnetic Compatibility (EMC) of the satellite components is addressed. Aspects related to electromagnetic interference and protective measures are analyzed to ensure immunity to external electromagnetic disturbances and non-interference with other systems or devices. The thesis is developed in the framework of the Alba CubeSat project, which participate to the European Space Agency’s (ESA) Fly Your Satellite! – design booster program. The thesis provides the guidelines to assembly and integrate and test the FlatSat of AlbaSat, contributing to the development of the mission. The results and experiences gained from this research can be applied to future satellite development projects

Study of the Business Model of three Earth Observation (EO) companies already present in the Very Low Earth Orbit market (VLEO)

The emergence of a new private spaceflight industry has taken the Earth Observation (EO) sector by surprise. NewSpace companies are challenging the traditional satellite sector by addressing their services to mass market requirements of high-quality and low-cost EO. As part of the DISCOVERER project, this study aims to determine the Key Success Factors to consider by a new EO company at Low Earth Orbit (LEO). Hence, three businesses fitting the description were analyzed with the Case Study Methodology to establish their Business Model Canvas (BMC), associated Patterns, and Key Success Factors. The investigation consolidated the newly proposed Democratizing Business Model Pattern and added new characteristics. Successful EO NewSpace firms are getting divided between integrated operators, integrated manufacturers, and end-user specialists. A new EO company should consider the Democratizing Pattern success factors and the Vertically Integrated Strategies (VIS), depending on its disruptive idea and resource capabilities. Further research is needed to identify new factors, strengthen the validity of the Pattern, and VIS tendencies

Assembly, Integration, and Test Methods for Operationally Responsive Space Satellites

Current government and industry standards in spacecraft testing result in an Assembly, Integration, and Test (AIT) timeline greater than six months. These standards will not support the vision of Operationally Responsive Space (ORS) to deploy a satellite within six days to fill an urgent need. Using the Air Force Research Laboratory’s Plug-and-Play Satellite (PnPSat), multiple Rapid AIT trials were conducted. By exercising the AIT process with various spacecraft configurations and personnel, methods for reducing or modifying traditional testing regimen were investigated