Additive Manufacturing Applied to the Design of Small Satellite Structure for Space Debris Reduction

Space debris has become a major aspect in the last few years. The vast amount of artificial objects orbiting the Earth is increasing. These objects are a threat for active and future missions. Besides, the possibility of uncontrolled re-entry of some of them reaching the surface of the Earth exists. The aim of this work is to provide a view on how to use additive manufacturing technology to design the next generation of satellites in order to reduce the space debris. The components that can be manufactured with additive manufacturing are identified, together with the technologies that are enabled by additive manufacturing to reduce space debris. Finally, the results of these studies and analysis are incorporated into the design of the structure of a small satellite. This study is being part of the H2020 European Project ReDSHIFT (Project ID 687500)

Chapter Additive Manufacturing Applied to the Design of Small Satellite Structure for Space Debris Reduction

Space debris has become a major aspect in the last few years. The vast amount of artificial objects orbiting the Earth is increasing. These objects are a threat for active and future missions. Besides, the possibility of uncontrolled re-entry of some of them reaching the surface of the Earth exists. The aim of this work is to provide a view on how to use additive manufacturing technology to design the next generation of satellites in order to reduce the space debris. The components that can be manufactured with additive manufacturing are identified, together with the technologies that are enabled by additive manufacturing to reduce space debris. Finally, the results of these studies and analysis are incorporated into the design of the structure of a small satellite. This study is being part of the H2020 European Project ReDSHIFT (Project ID 687500)

Optimization of an Earth Observation Data Processing and Distribution System

Conventional Earth Observation Payload Data Ground Segments (PDGS) continuously receive variable requests for data processing and distribution. However, their architecture was conceived to be on the premises of satellite operators and, for instance, has intrinsic limitations to offer variable services. In the current chapter, we introduce cloud computing technology to be considered as an alternative to offer variable services. For that purpose, a cloud infrastructure based on OpenNebula and the PDGS used in the Deimos-2 mission was adapted with the objective of optimizing it using the ENTICE open source middleware. Preliminary results with a realistic satellite recording scenario are presented

Earth Observation Data Pilot in the ENTICE environment

The treatment of massive and large-sized data obtained from Earth Observation satellite recordings still presents a critical challenge. Remote sensing industries implement on-site conventional infrastructures to acquire, store, process and distribute the geo-information generated. However these solutions are not flexible neither easily scalable. The presented research focuses in the development of future internet technologies in order to improve Earth Observation (EO) services and to highly reduce the costs associated with on premises deployment. On the one hand, the EOD pilot case consists of the deployment in cloud of the gs4EO software, commercialized by Deimos. EOD pilot proposes several scenarios, all of them built with 4EO products: archive4EO collects data from different sources and triggers the processing of the raw data using process4EO; monitor4EO monitors all the process, and the resulting data is accessible using user4EO services (http://www.entice-project.eu/eodusecase). On the other hand, the ENTICE environment consists of a ubiquitous repository-based technology which provides optimised Virtual Machine image creation, assembly, migration and storage. The Earth Observation data processing and distribution pilot case (EOD) will be implemented in the ENTICE environment to test, validate and demonstrate that ENTICE can support and improve the performance of commercial Earth Observation platforms computed in cloud. Within the ENTICE project, the EOD pilot is implemented in a cloud computing infrastructure to provide satellite imagery to end users and carry out a pilot demonstration. The ENTICE environment, which is being developed to be an open source software (http://www.entice-project.eu/try-entice/), will be used to optimize the implementation and performance of the EOD pilot. It is expected that the optimization of the VMs highly contribute to provide autoscaling and flexibility to the ingestion of satellite imagery, its processing and distribution to end users with variable demands. The impact that ENTICE will have in the EOD pilot is the costs reduction (reduced storage of optimized VMIs, reduced reservation and deployment time and reduced runtime of the overall system), performance increase (reduced reservation and deployment time and reduced runtime of the overall system) and independence from a specific infrastructure provider (facilitation of the distribution of VMs in distributed infrastructures). Through the EOD pilot, ENTICE will be tested under a big data environment in which high size images and large amounts of data have to be processed in a market that is increasing: modernization of Earth Observation and space system by using future internet technologies. Not only the ENTICE partners will benefit, but also many European companies can strengthen their competitive position in the worldwide market due to the benefits expected by the ENTICE environment and its optimisation technology for VM images

Advanced Space Flight Mechanical Qualification Test of a 3D- Printed Satellite Structure Produced in Polyetherimide ULTEMTM

The aim of this work is to demonstrate the use of additive manufacturing with thermoplastic material in the whole functional structure of spacecraft and to mechanically qualify it for space flight. For such purpose, an 8 U CubeSat structure was manufactured in polyetherimide (PEI) ULTEM™ through 3D printing and passed several vibration tests. The results are compared with those obtained in the qualification of the same structure manufactured in aluminum alloy AA-6082 T651 through a conventional CNC method. The qualification consisted of passing the vibration requirements in quasi-static, sine, and random tests to fly in PSLV launcher. Finally, a robustness test for the 3D-printed structure is included, and all the results are analyzed. This study is being part of the H2020 European Project ReDSHIFT (Project ID 687500)

THE H2020 PROJECT REDSHIFT: OVERVIEW, FIRST RESULTS AND PERSPECTIVES

The ReDSHIFT (Revolutionary Design of Spacecraft through Holistic Integration of Future Technologies) project has been approved by the European Community in the framework of the H2020 Protec 2015 call, focused on passive means to reduce the impact of Space Debris by prevention, mitigation and protection. In ReDSHIFT these goals will be achieved through a holistic approach that considers, from the outset, opposing and challenging constraints for the space environment preservation, the spacecraft survivability in the harsh space environment and the safety of humans on ground. The main innovative aspects of the project concern a synergy between theoretical and experimental aspects, such as: long term simulations, astrodynamics, passive de-orbiting devices, 3D printing, design for demise, hypervelocity impact testing, legal and normative issues. The paper presents a quick overview of the first ReDSHIFT results in an effort to highlight the holistic approach of the project covering different aspects of the space debris mitigation field. De- tailed reports on the results of the single Work Packages can be found in other papers in this same volume

Earth Observation Technologies: Low-End-Market Disruptive Innovation

After decades of traditional space businesses, the space paradigm is changing. New approaches to more efficient missions in terms of costs, design, and manufacturing processes are fostered. For instance, placing big constellations of micro- and nano-satellites in Low Earth Orbit and Very Low Earth Orbit (LEO and VLEO) enables the space community to obtain a huge amount of data in near real-time with an unprecedented temporal resolution. Beyond technology innovations, other drivers promote innovation in the space sector like the increasing demand for Earth Observation (EO) data by the commercial sector. Perez et al. stated that the EO industry is the second market in terms of operative satellites (661 units), micro- and nano-satellites being the higher share of them (61%). Technological and market drivers encourage the emergence of new start-ups in the space environment like Skybox, OneWeb, Telesat, Planet, and OpenCosmos, among others, with novel business models that change the accessibility, affordability, ownership, and commercialization of space products and services. This chapter shows some results of the H2020 DISCOVERER (DISruptive teChnOlogies for VERy low Earth oRbit platforms) Project and focuses on understanding how micro- and nano-satellites have been disrupting the EO market in front of traditional platforms

A review of gas-surface interaction models for orbital aerodynamics applications

Renewed interest in Very Low Earth Orbits (VLEO) - i.e. altitudes below 450 km - has led to an increased demand for accurate environment characterisation and aerodynamic force prediction. While the former requires knowledge of the mechanisms that drive density variations in the thermosphere, the latter also depends on the interactions between the gas-particles in the residual atmosphere and the surfaces exposed to the flow. The determination of the aerodynamic coefficients is hindered by the numerous uncertainties that characterise the physical processes occurring at the exposed surfaces. Several models have been produced over the last 60 years with the intent of combining accuracy with relatively simple implementations. In this paper the most popular models have been selected and reviewed using as discriminating factors relevance with regards to orbital aerodynamics applications and theoretical agreement with gas-beam experimental data. More sophisticated models were neglected, since their increased accuracy is generally accompanied by a substantial increase in computation times which is likely to be unsuitable for most space engineering applications. For the sake of clarity, a distinction was introduced between physical and scattering kernel theory based gas-surface interaction models. The physical model category comprises the Hard Cube model, the Soft Cube model and the Washboard model, while the scattering kernel family consists of the Maxwell model, the Nocilla-Hurlbut-Sherman model and the Cercignani-Lampis-Lord model. Limits and assets of each model have been discussed with regards to the context of this paper. Wherever possible, comments have been provided to help the reader to identify possible future challenges for gas-surface interaction science with regards to orbital aerodynamic applications

Metodología de diseño de reguladores de posición y fuerza para robots flexibles de un grado de libertad basada en platitud.

En la década de los 70, surgen los robots flexibles en el campo de la ingeniería, y con ellos una nueva filosofía que da lugar a nuevas aplicaciones, la mayoría de ellas en la industria aeroespacial. Las características que originan el empleo de tales robots son la ligereza y la flexibilidad. Esto se traduce en menor peso y volumen en la estructura, y como consecuencia, en menor consumo de energía. El hecho de que se empleen materiales más ligeros origina una estructura más flexible, la cual puede presentar grandes vibraciones al ser sometida a pequeñas perturbaciones. Es por ello que resulta necesario emplear algoritmos de control específicos, capaces de cancelar las vibraciones. Pero, además, existen otras ventajas fundamentales que hacen que este tipo de robots puedan ser empleados, con mayor versatilidad y seguridad, que los robots rígidos. Tales son el aumento de la ligereza y la disminución de la inercia. Estas características permiten que los manipuladores puedan emplearse en tareas de contacto con cualquier tipo de objeto, especialmente, aquellos frágiles o fácilmente deformables, debido a que la gran flexibilidad de este tipo de robots permite absorber la energía del impacto. En esta tesis, se analiza el comportamiento dinámico de los robots flexibles de un grado de libertad y se estudian posibles soluciones para los problemas más relevantes que presentan estos sistemas en el ámbito científico-técnico. Se desarrollan algoritmos de control para la cancelación activa de las vibraciones de los robots flexibles de un grado de libertad y para controlar la fuerza que ejerce el robot cuando entra en contacto con una superficie. El tipo de controladores utilizados requieren el conocimiento de los parámetros físicos del sistema, por lo que se utilizan estimadores algebraicos para poder realizar una estimación de sus valores reales. Una vez conocidos los valores de los parámetros que rigen el comportamiento físico del sistema, pueden diseñarse los controladores. Son varios los algoritmos diseñados en esta tesis. Entre los controladores de posición destacan: el control de posición proporcional integral generalizado (gpi) #por sus siglas en ingles generalizad proporcional integral-, el control gpi adaptativo ante cambios de masa en el extremo y el control robusto al efecto que producen los modos superiores de vibración no tenidos en cuenta en el modelado dinámico del eslabón flexible, denominado spillover o deslizamiento (una estructura flexible está compuesta por infinitos modos de vibración; sin embargo, al aumentar la frecuencia de los mismos disminuye su amplitud, por lo que se pueden considerar los más significativos y despreciar el resto). Este efecto puede llegar a desestabilizar sistemas que son estables de forma teórica. Entre los controladores de fuerza (par) destacan dos: el control de fuerza en movimiento libre (cuando el robot se mueve libremente sin colisionar con ningún objeto ni someterse a ninguna restricción en su movimiento natural) y el control de fuerza en movimiento restringido (tras colisionar con una superficie). Todos estos controladores son desarrollados, simulados y experimentados, siendo, asimismo, combinados los de posición y de fuerza para dar lugar a un nuevo algoritmo de control combinado de posición-fuerza, capaz de controlar la posición de un robot flexible y aplicar una fuerza concreta tras impactar con una superficie

Robust Position Control of a DC Motor by Sliding Mode

Abstract. The position of the DC motor is controlled by using a continuous sliding mode control (SMC), which is highly robust to the Coulomb friction torque and to high unknown payload variations, which involve changes in the rotational inertia of the motor shaft. The main contribution of the work is the experimentation of a SMC control which does not requires the knowledge of the payload variation range, i.e., the system is quite robust to any unknown change in the payload mass value