| 1. |
- Elfvelin, Martin, et al.
(författare)
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A flexible ground segment for small satellite operations
- 2021
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Ingår i: IAC 2021 Congress Proceedings, 72<sup>nd</sup> International Astronautical Congress (IAC), Dubai, United Arab Emirates. - : International Astronautical Federation (IAF).
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Konferensbidrag (refereegranskat)abstract
- With the launch of the first CubeSat a trend of easy access to Low Earth Orbit was started. Today many educational institutes around the world design, build and operate CubeSats for educational as well as scientific purposes. This paper presents designs and development in hardware and software made to achieve a flexible ground segment at the Luleå University of Technology Space Campus in Kiruna, Sweden. The existing ground station is adapted to support more frequencies and modes of operation to enable future satellite projects at the university easy access to space communications. New equipment has been procured and integrated with existing equipment in a new location using a 19-inch server rack. The article presents a ground segment design using software-defined radio to promote flexibility and adaptability. A in-house developed sequence control board is presented that enables the ground station to quickly switch between full duplex and half-duplex modes.
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| 2. |
- Fernández Bravo, Elena, et al.
(författare)
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Solar panel and attitude control design for an Autonomous Table-Top Emulator (KNATTE)
- 2021
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Ingår i: IAC 2021 Congress Proceedings, 72<sup>nd</sup> International Astronautical Congress (IAC), Dubai, United Arab Emirates. - : International Astronautical Federation (IAF).
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Konferensbidrag (refereegranskat)abstract
- One of the challenges that satellites face is the interaction between control movement and vibration of flexible appendages such as solar arrays and antennas that can negatively affect the performance of the spacecraft. The aim of this work is to develop a numerical model of a solar panel structure for KNATTE (Kinesthetic Node and Autonomous Table-Top Emulator), a frictionless platform developed by the Space Systems group at LuleåUniversity of Technology, and develop a control law that reduces the flexible vibration of the solar arrays when attitude control manoeuvres are performed. A set of solar panel structures have been designed and tested, the mathematical model of the multibody system, which consists of KNATTE and two flexible solar panels, has been developed in MATLAB by applying the finite element method. A finite element analysis has been performed in MATLAB to extract the natural frequencies of the system. The model has been numerically verified using a commercial software, and experimentally verified by performing testing on the frictionless vehicle, KNATTE, equipped with the solar panel structures and a number of piezoelectric sensors. Once the model has been verified, a Linear Quadratic Gaussian (LQG) controller has been developed using the results from the finite element model in order to reduce the amplitude of the vibrations of the flexible solar panel structure. The behaviour of the system has been simulated when the spacecraft performs an attitude manoeuvre. The finite element model provides the modal behaviour of the multibody system, obtaining its natural frequencies with low relative error. The LQG controller reduces the amplitude of the vibrations of the flexible solar panel structure.
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| 3. |
- Golemis, Aris, et al.
(författare)
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KvarkenSat: mission concept and technical overview of a 2U Swedish - Finnish CubeSat
- 2021
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Ingår i: IAC 2021 Congress Proceedings, 72<sup>nd</sup> International Astronautical Congress (IAC), Dubai, United Arab Emirates. - : International Astronautical Federation (IAF).
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Konferensbidrag (refereegranskat)abstract
- Kvarken Space Centre is a project conducted by a consortium of Finnish and Swedish academic institutions aiming to enhance the economic activities of the Kvarken region shared by the two countries, by improving the regional competence in space technology. In this framework, the consortium is developing a first 2UCubeSat, namely KvarkenSat, with the goal of exhibiting the regional capabilities in satellite developmentvia performing science and in-orbit demonstration of Finnish payloads. Since the main areas of interestare forestry and sea transportation, the CubeSat will integrate a multispectral camera for forest health and seawater quality analysis and an automatic identification system (AIS) receiver for sea vessel tracking. In addition, the spacecraft will perform the in-orbit demonstration of a miniature water-based resistojet thruster system. KvarkenSat’s last payload will comprise a GNSS receiver that will extract raw data inorder to conduct precise point positioning (PPP) algorithm research. This work is meant to present the mission concept, objectives and technical overview of the current design. The launch of KvarkenSat is planned for Q4 2022 from northern Sweden.
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| 4. |
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| 5. |
- Johansson, Christoffer, et al.
(författare)
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Improving the Control Design of the KNATTE Platform with Flexible Panels
- 2022
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Ingår i: IAC 2022 Congress Proceedings, 73rd International Astronautical Congress (IAC), Paris, France. - : International Astronautical Federation.
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Konferensbidrag (refereegranskat)abstract
- The effect of flexible structures such as solar panels or long booms on the dynamics of a spacecraft of any size can become a problem for the stability of its control subsystem. That said, proper control algorithms can be designed to reduce the vibrations of such appendages. The Kinesthetic Node and Autonomous Table-Top Emulator (KNATTE), developed at Luleå University of Technology in collaboration with the University of Rome “La Sapienza”, is a frictionless vehicle that has been conceived as a multipurpose platform to perform hardware-in-the-loop simulation experiments with real and analogous small-satellite components. The platform can emulate spacecraft behavior in orbit for validating various guidance, navigation and control algorithms.The object of this study is the KNATTE platform carrying a pair of flexible mock-up solar panels. In such circumstances, the steering system of the vehicle is not able to maneuver by applying a conventional Proportional-Integral-Derivative control algorithm. However, a Linear-Quadratic-Gaussian (LQG) algorithm has been proven effective to control the vehicle with the appendages in former simulations. The purpose of this work is to validate the performance of the previously developed LQGalgorithm in a hardware-in-the-loop simulation experiment and compare its results to those of applying a Sliding Mode Control (SMC) algorithm to the same scenario.This article presents a comparative study of the LQG and SMCalgorithms. For that, both algorithms have been developed in Simulink and tested in equivalent modeled environments. Next, the algorithms have been adapted to the operation of KNATTE for their validation on hardware, includingadditional modifications to the experiment setup when necessary. The tracking data coming from a computer vision system has been filtered to improve the accuracy of the navigation block. The signal conditioning circuit has also been upgraded to improve the reliability of panel deflection measurements given by piezoelectric sensors.Both the LQG and SMC algorithms proved to be effective to reduce the destabilizing vibrations of the flexible panels and their suitability for controlling the KNATTE platform with such panels despite their dependency on an accurate model of the plant. The SMC algorithm showed less error than the LQG algorithm in the tested scenario. Additionally, the implementations in this work can be used for future educational and research experiments with frictionless platforms.
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| 6. |
- Lundström, Lars, et al.
(författare)
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A Multisensor Data Fusion Approach for Spacecraft Control Experiments with the KNATTE Platform
- 2022
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Ingår i: IAC 2022 Congress Proceedings, 73<sup>rd</sup> International Astronautical Congress (IAC), Paris, France. - : International Astronautical Federation.
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Konferensbidrag (refereegranskat)abstract
- The Kinesthetic Node and Autonomous Table-Top Emulator (KNATTE) is a three-degree-of-freedom frictionlessvehicle that serves as a multipurpose platform for real-time spacecraft hardware-in-the-loop experiments. The dataacquisition of the vehicle depends on a Computer Vision System (CVS) that yields position and attitude data, but alsosuffers from unpredictable blackout events. To complement such measurements, KNATTE incorporates an InertialMeasurement Unit (IMU) that yields accelerometer, gyroscope, and magnetometer data. This study describes amultisensor data fusion approach to obtain accurate attitude information by combining the measurements from theCVS and the IMU using nonlinear Kalman filter algorithms. To do this, we develop the data fusion algorithms andtest them in a MATLAB/Simulink environment. After that, we adapt the algorithms to the KNATTE platform andconfirm the performance in various conditions. Through this work, we can check the accuracy and efficiency of theapproach by numerical simulation and real-time experiments.
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| 7. |
- Nieto Peroy, Cristóbal, et al.
(författare)
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A Concurrent Testing Facility Approach to Validate Small Satellite Combined Operations
- 2021
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Ingår i: Aerospace. - : MDPI. - 2226-4310. ; 8:12
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Tidskriftsartikel (refereegranskat)abstract
- Federated remote laboratories allow for the execution of experiments ex situ. The coordination of several laboratories can be used to perform concurrent experiments of combined space operations. However, the latency of the communications between facilities is critical to performing adequate real-time experiments. This paper presents an approach for conducting coordinated experiments between floating platforms at two remote laboratories. Two independently designed platforms, one at Luleå University of Technology and the other at La Sapienza University of Rome, were established for this purpose. A synchronization method based on the Simple Network Time Protocol was created, allowing the offset and delay between the agents to be measured.Both platforms exchange data about their measured time and pose through a UDP/IP protocol over the internet. This approach was validated with the execution of simulated operations. A first demonstrative experiment was also performed showing the possibility to realize leader/follower coordinated operations. The results of the simulations and experiments showed communication delays on the order of tens of milliseconds with no significant impact on the control performance. Consequently, the suggested protocol was proven to be adequate for conducting coordinated experiments in real time between remote laboratories.
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| 8. |
- Nieto-Peroy, Cristóbal, et al.
(författare)
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A hardware-in-the-loop simulation testbed for validation of small satellite technologies
- 2021
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Konferensbidrag (refereegranskat)abstract
- This paper presents the research that is being conducted with the hardware-in-the-loop simulation testbed laying at the Nano Satellite Lab at the Kiruna Space Campus of Luleå University of Technology. Particularly, a brief introduction to the frictionless platform and both robot manipulators that comprise such a testbed is given. Additionally, this paper summarizes the simulations that are currently performed on the testbed. Finally, the paper also discusses some future activities that are planned to be conducted to improve the way systems and components of small satellites are currently validated.
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| 9. |
- Nieto Peroy, Cristóbal, et al.
(författare)
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Building a Center of Competence on Testing and Qualification Facilities at the Kiruna Space Campus in Northern Sweden
- 2023
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper presents the Kiruna Space Campus of Luleå University of Technology (LTU) and its associated integration, testing and qualification facilities for spacecraft systems, subsystems, and components. The availability of such facilities in close proximity to the Esrange Space Center makes it possible to address unexpected events that may affect the launch readiness of such systems. LTU's capabilities are further enhanced by the Swedish Institute of Space Physics' (IRF) SpaceLab and the planned orbital access from the new Esrange launch facility of the Swedish Space Corporation (SSC). Utilizing these resources, LTU is able to provide a comprehensive project lifecycle in-house, and is actively making the facilities accessible to external users to foster efficient utilization and support peers in getting their payloads ready for launch. Additionally, the paper discusses the rationale for developing these resources as part of wider academic-industry collaborations and regional economic cluster activities, such as the public-private “Space for Innovation and Growth” project and Aerospace Cluster Sweden.
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| 10. |
- Nieto-Peroy, Cristóbal
(författare)
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Concurrent Engineering of Small Satellites using Hardware-in-the-loop Simulations
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The miniaturization of spacecraft has brough the possibility of conducting space missions to a vast portion of private enterprises and scientific institutions. The inaccessibility of modest developers to the resources that governmental agencies and primary contractors utilize to develop conventional satellites has not been an obstacle for them to apply different, more agile and risk-seeking approaches. However, the failure rate of Small Satellite missions has increased to a higher degree than the total number of missions, particularly if only CubeSats are considered.The research conducted in this thesis proposes an improvement to the development of space systems by focusing on the verification and validation processes. For that, the thesis revolves around two main areas. First, the thesis deals with the engineering methodology. The notions of concurrent engineering are generalized and combined with the test-driven development and behavior-driven development methodologies to perform the parallel, yet integrated, development of the various spacecraft subsystems that can be at different maturity levels. For example, these processes have been applied in-house to the development of onboard computers and telecommunication systems. The proposed methodology allows for the automation of the engineering workflow and the early detection and correction of defects in the system by frequently testing it along the process.Secondly, the research also deals with the development and utilization of a simulation environment that fits the proposed methodology. The thesis provides advancements on hardware-in-the-loop simulation techniques with a particular focus on frictionless platforms. Such a platform can perform, but is not limited to, dynamic simulations. Additionally, the thesis also provides the characterization of the platform to use it as a reference for comparison with other similar ones.All in all, the simulation environment has demonstrated to provide the versatility needed by the methodology. Such environment has served as a platform to develop different subsystems from the simulation of physical models to the testing of actual hardware prototypes. Two studies are provided as examples of such accomplishments, i.e., a study with the remote simulation of cooperative maneuvers and a different one with the development of flexible appendages for a spacecraft.
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