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  • 1.
    Antoja Lleonart, Guillem
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    New Generation 4-Channel GNSS Receiver: Design, Production, and Testing2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Due to the current research needs and the lack of commercial multi-channel, multi-constellation GNSS receivers, a two-board solution has been developed so it can be mated with and take advantage of the processing power of the FPGA board branded as MicroZed.

    In order to achieve the proposed goals, an initial phase for assessing and updating the older design, building, and testing of SiGe modules (including both the electronics and casings) has been carried out. The results included demonstrate performances at logging GPS-L1 data with similar C/N0 and AGC values as the previous versions of the modules and offering navigation solutions with accuracies of a few meters. Secondly, a first iteration and design proposal for the new generation receiver has been proposed for GPS and GLONASS L1 and L2, which has been manufactured and tested. Partial tests have been performed due to the flaws of the current revision of the MicroZed Board in regards to its communication peripherals, and the results have validated the receiver’s design provided certain modifications are considered for future iterations. Furthermore, voltage and frequency tests have provided results with an error of less than 7%, and signal tests have provided C/N0 values similar to those of the SiGe modules of around 47[dB-Hz] which will be a useful baseline for future iterations. Finally, a design proposal for an Interface Board used between the older NT1065_PMOD Board and other FPGA boards carrying the standardized FMC connectors has been added to the report and negotiations with manufacturers have been engaged.

  • 2.
    Auenmüller, Christoph
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Automated Controller Design for a Missile Using Convex Optimization2016Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The focus of the present master thesis is the automation of an existing controllerdesign for a missile using two aerodynamic actuating systems. The motivation isto evaluate more missile concepts in a shorter period of time.The option used is trimming and linearization of a highly nonlinear missile at specic conditions. According to these conditions, either a two-dimensional operatingpoint grid dened by Mach number and height or three-dimensional operatingpoint grid dened by Mach number, height and angle of attack is generated forthe whole operating range of the missile. The controllers are designed at thesepoints using convex optimization. The convex set denes the pole placement areawhich is constrained by linear matrix inequalities according to the dynamic behaviorof the missile at the operating point conditions. These controllers describea validity area where the missile can be stabilized. This area consists all neighboringoperating points and denes therefore the grid density which can dier atspecic regions of the operating range. Controlling the missile to the target makesit necessary to apply gain-scheduling in order to get the manipulated variable byinterpolation of adjacent operating points. During this blending of the controllersa problem called windup can occur when an actuator is saturated. This mightlead to instability in worst case but can be counteracted by a model-recovery antiwindupnetwork which guarantees stability in the presence of saturation. Thisanti-windup design is automated by an ane linear parameter dependency of thegrid parameters and has the same validity area like the controllers.The whole design was successfully developed and tested in MATLAB/Simulink onmissiles using one or two aerodynamic actuating systems. The controllers have agood performance at small and high acceleration steps and the anti-windup keepsthe missile stable even though the actuators are saturated. Stability and robustnessof the controllers and anti-windup networks was veried as well as an airdefense maneuver where the missile starts at the ground and intercepts a targetat high altitude was successfully simulated for dierent grids and missiles.

  • 3.
    Avasak, Kalyani
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik. Institute of Space Systems, University of Stuttgart.
    Mission Analysis and Trajectory optimisation for project CAPE2016Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Atmospheric reentry is a challenging part of human space ight and planetary entry missions.At the Institute of Space Systems in University of Stuttgart the idea of projectCAPE was conceived in 2012. Project Cubesat Atmospheric Probe for Education aimsto demonstrate the capability of miniaturised technologies of the micro electric plasmathruster, reentry vehicle design and ablative shielding material developed in this institute.The mission scenario is such that the CAPE is being deployed from the InternationalSpace Station and needs to complete the de-orbit of the Service and deorbit module andre-entry of the Atmospheric entry module in less than 1 year. The Cube satellite weighs3.0 kg consisting of a 2+1 unit service design module with solar panels, pulsed plasmapropulsion system of the university of Stuttgart (PETRUS) and a micro atmosphericreentry module (MIRKA-2). This reentry vehicle is unique in its size and weighs 0.5kg. During its reentry phase, it will be subjected to the intense aero-thermal loads at theThermal Protection System front which are absorbed by its ablative heat shield. But thecharacteristics of the re-entry trajectory like the ight path angle, entry velocity and entrypoint greatly determine the survivability against the integral heat load for this ballisticreentry vehicle. Although the success of the mission is considerably higher when having acontrolled reentry, in case of ballistic vehicles it is solely determined by the mission design.The main task is to investigate and develop the optimal re-entry trajectories in thedesign-time phase of mission development for MIRKA-2 vehicle that satises the objectiveof minimizing heat loads and adhering to operational constraints. Thus, the aimof this thesis is to provide a novel solution and optimum trajectory of the de-orbit andre-entry ight to maximize the survivability of the reentry module. The con icting parametersin this mission would be the operational limit of the pulsed plasma thruster andminimum heat loads during reentry ight. The simulation of these trajectories is carriedout in MATLAB using the REENT software developed in the Institute of Space Systems,University of Stuttgart. Its source code is composed in Fortran 77 which is integratedinto MATLAB. A careful mission analysis with the constraints of the capacity of pulsedplasma thruster, impulse provided by the separation mechanism and survivability of thereentry vehicle is carried out to prove the feasibility of this mission. In order to accomplishthe survivability during re-entry the aspects that have been modelled are the ight dynamicsof the satellite, aerodynamic and aero-thermal loads, spacecraft behaviour underthe external loads and local heating process.

  • 4.
    Baker, Mark
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Optimization of CHIMS2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The CHopper (Comet Hopper) was a proposal for a NASA mission to visit comet 46P/Wirtanen. A time of flight ion and neutral mass spectrometer (CHIMS) was developed especially for the proposed mission and was to be mounted on the Chopper spacecraft. CHIMS was to establish the composition and isotopic ratios of the comet's volatile components. Since NASA selected the InSight mission, CHIMS had been proposed for other missions: LIFE, Life Investigation For Enceladus, a low-cost sample return mission to Enceladus and Castalia, an ESA medium-sized mission to explore the Main Comet Belt. CHIMS was in need of fine tuning; the scientific demand of having accurate detection efficiency, combined with high performance make it necessary to rigorously test and calibrate instruments to operate at their optimum level. The goal of this work is to improve the performance of the ion source by applying simulation and optimization techniques to the CHIMS lab prototype. The results show a positive outcome, and propose a number of future modifications that should help obtain the desired results for any future missions.

  • 5.
    Baker, Niklas
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Feasibility and design of miniaturized Control Moment Gyroscope for a 3-axis stabilized Micro Satellite2016Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    In this thesis, a feasibility study will be conducted in order to determine if the usage of acontrol moment gyroscope is a possibility for a micro satellite as its attitude control. Thegoal is to conclude if gyroscopes are suitable replacements for the current reaction wheelswhich are acting as the attitude control for the satellite. In the first part of the thesis thegeneral function of the control moment gyroscope and three different types of arrangementsare displayed with all their respective advantages and disadvantages. Then one ofthem will be designed to fit within the restrictions of 1U. The full design of the pyramidconfiguration was chosen due to its compact size and spherical angular momentum envelope.The full design contains all the components such as motors, flywheels, mounts,frame, screws etc. which provide a cost estimate which is a huge input in determiningthe feasibility of this thesis. In the future the manufacture of the pyramid configurablecontrol moment gyroscopes shall be tested in the future with a more advanced steeringlaw in order to determine the full potential of the attitude control system.

  • 6.
    Bergmann, Matthias
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Topography of the Chittagong (Bangladesh)shoreline: a combined approach withremote sensing and in situ observations2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    In this thesis I present the algorithms and methods used to extract a shoreline from remote sensing data (i.e. satellite imagery) and the determination of the water level at the time of the data recording, which are both used to generate a DEM (Digital Elevation Model) of the intertidal area. The generation of the DEM is done in multiple steps, with the first one being the shoreline extraction. To find the shoreline, satellite imagery from the PROBA-V satellite is used. The image data consists of four channels (Red, Blue, NIR, SWIR), which are then combined to generate an artificial RGB image. This RGB image is then converted into the HSV colour space. To finally determine the threshold, the hue and value channel are selected, and a simple thresholding is applied to separate water masses from land masses. The final binary image is then cleaned from noise, and reduced to only a pixel-wide line representing the detected shoreline. This process is applied on several images taken at different water levels (i.e. different parts of the tidal cycle). To estimate the altitude level of the waterline, tidal data from tide gauges at Chittagong and Coxs Bazar are used. First, both tidal records are compared to determine the phase and amplitude scaling with respect to the distance of the two gauges. Afterwards, these values are used to inter- and extrapolate the water level along the shoreline. This allows to generate a synthetic tide measurement for every point at any time based on only the tidal records at Chittagong. The synthetic tide measurements are then combined with the shorelines to generate the final DEM. In the end, the generated DEM is compared with nautical charts of the area, as well as a different remotely-sensed DEM of Chittagong to estimate its accuracy. This whole process allows for a simple generation of inter tidal areas without having to make in-situ measurements of the area, and especially without repeating the measurements due to fast changes in the shoreline.

  • 7.
    Berčič, Laura
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik. Swedish Institute of Space Physics.
    Instrumental and environmental effects on RPC-ICA measurements of the cometary ion dynamics at comet 67P/CG2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Observations provided from RPC-ICA in combination with the data from RPC-MAG and ROSINA-COPS show that many aspects of the time variability of the detected ions is correlated with the magnetic field or -- to a smaller extent -- with neutral atmosphere density. We also show that not all changes in the cometary ion data reflect the nature of the plasma dynamics, but are a consequence of the instrumental limitations. The main outcome of the article in Appendix 1 is that the cometary ions can be divided into two populations with distinct characteristics. One population we termed the convecting population, is accelerated to higher energies through the interaction with the solar wind. The other population we termed the expanding population is moving radially away from the nucleus in the terminator plane. Both populations exhibit a significant anti-sunward component.In addition we present in this thesis a case with observations day-side of the terminator plane. There we show how the expanding population has a sunward component, consistent with initial radial expansion of the ions from the nucleus which gradually turn into an anti-sunward flow which is then observed in the terminator plane.

  • 8.
    Bethge, Matthias
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Situation and Threat Comprehensionand Conduit of Action with particular reference to aFuture Technology Data Fusion System2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
  • 9.
    Bhattacharya, Shaondip
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Multi-agent System Distributed Sensor Fusion Algorithms2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The concept of consensus filters for sensor fusion is not an entirely new proposition but one with an internally implemented Bayesian fusion is. This work documents a novel state update algorithm for sensor fusion which works using the principle of Bayesian fusion of data with variance implemented on a single integrator consensus algorithm. Comparative demonstrations of how consensus over a pinning network is reached are presented along with a weighted Bayesian Luenberger type observer and a ’Consensus on estimates’ algorithm. This type of a filter is something that is novel and has not been encountered in previous literature related to this topic to the best of our knowledge. In this work, we also extend the proof for a distributed Luenberger type observer design to include the case where the network being considered is a strongly connected digraph.

  • 10.
    Bilal, Mohd
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    A Heuristic Search Algorithm for Asteroid Tour Missions2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Since the discovery of Ceres, asteroids have been of immense scientific interest and intrigue. They hold answers to many of the fundamental questionsabout the formation and evolution of the Solar System. Therefore, a missionsurveying the asteroid belt with close encounter of carefully chosen asteroidswould be of immense scientific benefit. The trajectory of such an asteroidtour mission needs to be designed such that asteroids of a wide range ofcompositions and sizes are encountered; all with an extremely limited ∆Vbudget.This thesis presents a novel heuristic algorithm to optimize trajectoriesfor an asteroid tour mission with close range flybys (≤ 1000 km). The coresearch algorithm efficiently decouples combinatorial (i.e. choosing the asteroids to flyby)and continuous optimization (i.e. optimizing critical maneuversand events) of what is essentially a mixed integer programming problem.Additionally, different methods to generate a healthy initial population forthe combinatorial optimization are presented.The algorithm is used to generate a set of 1800 feasible trajectories withina 2029+ launch frame. A statistical analysis of these set of trajectories isperformed and important metrics for the search are set based on the statistics.Trajectories allowing flybys to prominent families of asteroids like Flora andNysa with ∆V as low as 4.99 km/s are obtained.Two modified implementations of the algorithm are presented. In a firstiteration, a large sample of trajectories is generated with a limited numberof encounters to the most scientifically interesting targets. While, a posteriori, trajectories are filled in with as many small targets as possible. Thisis achieved in two different ways, namely single step extension and multiplestep extension. The former fills in the trajectories with small targets in onestep, while the latter optimizes the trajectory by filling in with one asteroid per step. The thesis also presents detection of asteroids for successfullyperforming flybys. A photometric filter is developed which prunes out badlyilluminated asteroids. The best trajectory is found to perform well againstthis filter such that nine out of the ten planned flybys are feasible.

  • 11.
    Blanco, Enrique
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    DESIGN OF A SCALABLE, ADAPTABLE AND RELIABLE DEORBITING MECHANISM2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
  • 12.
    Brett, Christopher
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Control System Design for an Orbital Inspection Vehicle and Servicing Satellite Using Thrust-Vectoring Cold-Gas Propulsion2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This Thesis presents the work leading to the design of a closed loop control system for a prototype six-degree-of-freedom orbital inspection vehicle named Cerberus. Each of Cerberus' three compressed Nitrogen gas thrusters can be rotated about their elevation and azimuth axes, providing a thrust-vectored control capability. In order to test this capability in a simulated space environment Cerberus is mounted on the DAWN six-degree-of-freedom air-bearing vehicle. The control schemes presented in this thesis allow joystick control, station-keeping at a set distance from a moving target and inspection fly-around manoeuvres to be conducted before a docking procedure is initiated with a non-cooperative client vehicle. The following Thesis describes the decision-making process used to select the appropriate control scheme for each control mode, with the purpose of providing accurate position control for the module.

  • 13.
    Dikmen, Serkan
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Development of Star Tracker Attitude and Position Determination System for Spacecraft Maneuvering and Docking Facility2016Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Attitude and position determination systems in satellites are absolutely necessary to keep the desired trajectory. A very accurate, reliable and most used sensor for attitude determination is the star tracker, which orient itself in space by observing and comparing star constellations with known star patterns. For on earth tests of movements and docking maneuvers of spacecrafts, the new Spacecraft Maneuvering and Docking (SMD) facility at the chair of Aerospace Information Technology at the University of Würzburg has been built. Air bearing systems on the space ve- hicles help to create micro gravity environment on a smooth surface and simulate an artificial space-like surrounding. A new star tracker based optical sensor for indoor application need to be developed in order to get the attitude and position of the vehicles. The main objective of this thesis is to research on feasible star tracking algorithms for the SMD facility first and later to implement a star detection software framework with new developed voting methods to give the star tracker system its fully autonomous function of attitude determination and position tracking. Furthermore, together with image processing techniques, the software framework is embedded into a controller board. This thesis proposes also a wireless network system for the facility, where all the devices on the vehicles can uniquely communicate within the same network and a devel- opment of a ground station to monitor the star tracker process has also been introduced. Multiple test results with different scenarios on position tracking and attitude determination, discussions and suggestions on improvements complete the entire thesis work. 

  • 14.
    Dillibabu, Surender
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Design,Analysis, and prototype of underwater glider2016Independent thesis Advanced level (degree of Master (Two Years)), 80 poäng / 120 hpOppgave
  • 15.
    Dundar, Ismail Ugur
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Improvement of a Space Surveillance Tracking Analysis Tool2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Since the beginning of space exploration, the amount of space debris has increased with thedevelopment of new space technologies. In fact, when a collision happens, new space debris aregenerated. Hence, collision risk between space debris and operational satellites rises. The purpose ofa surveillance network system consists of the detection of space objects, their classification and theirtracking. To avoid collisions, space debris objects’ orbit must be computed with sufficient accuracy.

    The goal of this thesis is the improvement of a pre-existing Space Surveillance and Tracking AnalysisTool. The tool is able to simulate different observation scenarios for radar or optical observer,which can be space-based or ground-based. To enhance the orbit determination, an ExtendedSquare Root Information Filter is implemented and incremented with a Smoother. Smoothers havebeen implemented for the existing filters as well, such as the Extended Kalman Filter and theUnscented Kalman Filter. A bias estimation method was added as part of the OD for all filter types.Additionally, different outlier detection methods were implemented for the automatic detection ofoutliers within the measurement data. To find the optimum orbit determination interval, differentscenarios were considered in LEO, MEO and GEO orbits. The methods were implemented anddifferent scenarios for validation will be discussed. A wide discussion on the methods implementationand their validation on different scenarios is presented, together with a comparison of the orbitdetermination results with the other filters.

    All the recently implemented features increase the efficiency of the tool to simulate the differentscenarios and enhance the tracking of space debris objects.

  • 16.
    Ekelund, Jonah
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Calibration and evaluation of the secondary sensors for the Mini-EUSO space instrument2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The Mini-EUSO (Mini - Extreme Universe Space Observatory) is an instrument for observation of ultra-high energy cosmic rays (UHECR) from space. It is designed to observe Earth from the international space station (ISS) in the ultra-violet (UV), visible (VIS) and near-infrared (NIR) light ranges. The UV sensor is the main sensor, designed and built by the EUSO collaboration. The visible and near-infrared sensors are secondary sensors. These are two cameras, FMVU-13S2C-CS and CMLN-13S2M-CV, from Point Grey Research Inc. The near-infrared light camera has a phosphor coating on the sensor to convert from near-infrared light to visible light, which is detectable by the camera's CCD.

    This thesis deals with the calibration and evaluation of the secondary sensors. This is done by first evaluating the bias and dark current for both cameras. After which a calibration is done using the light measurement sphere, located at the National Instituteof Polar Research (NIPR) in Midori-cho, Tachikawa-shi, Japan. Due to the low sensitivity of the near-infrared light camera, an evaluation of its ability to see celestialobjects are also performed.

    It is found that the visible light camera has a high bias with values around 5 ADU (Analog-to-Digital unit), but almost non-existing dark current, with mean values below 1 ADU. The visible light camera has good sensitivity for all the colors: red, green and blue. However, it is most sensitive to green. Due to this, it is easy to saturate the pixels with too much light. Therefore, saturation intensity was also examined for the shutter times of the visible light camera. This is found to be between 900μWm-2sr-1 and 1·107μWm-2sr-1, depending on color and shutter time.

    The near-infrared light camera is the opposite; it has a low bias with values below 1 ADU and a high dark current. The values of the dark current for the near-infrared light camera are highly dependent on the temperature of the camera. Mean values are below 1 ADU for temperatures around 310K, but mean values of almost 2 ADU at temperatures around 338K. The sensitivity of the near-infrared light camera is very low, therefore, the only way to detect a difference between the light levels of the light measurement sphere was to use a high ADC amplication gain. With this it was found that there is a power-law behavior, values between 1.33 and 1.50, of the relationship between pixel values and light intensity. This is likely due to the phosphor coating used to convert to visible light. When trying to detect celestial objects, the faintest object detected was Venus with a magnitude of less than -4.

  • 17.
    Fahlgren, Jessica
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Satellite observations of temporal changes in the high latitude glaciers due to the changing climate2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
  • 18.
    Flores Garcia, Erick
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Simulation of attitude and orbital disturbances acting on ASPECT satellite in the vicinity of the binary asteroid Didymos2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Asteroid missions are gaining interest from the scientific community and many new missions are planned. The Didymos binary asteroid is a Near-Earth Object and the target of the Asteroid Impact and Deflection Assessment (AIDA). This joint mission, developed by NASA and ESA, brings the possibility to build one of the first CubeSats for deep space missions: the ASPECT satellite. Navigation systems of a deep space satellite di er greatly from the common planetary missions. Orbital environment close to an asteroid requires a case-by-case analysis. In order to develop the Attitude Determination Control System (ADCS) for the mission, one needs detailed information about orbital disturbances in the vicinity of the asteroid.

    This work focuses on the development of a simulator that characterises the orbital disturbances a ecting the ASPECT satellite in the space environment near the Didymos asteroid. In this work, a model of orbital conditions and disturbances near the Didymos system was defined. The model integrates several classical and modern models of spacecraft motion and disturbance. An existing Low Earth Orbit (LEO) simulator was modified and updated accordingly to the ASPECT mission scenario. The developed simulator can be used to analyse the disturbances to be counteracted by the ADCS of the ASPECT satellite. The objective of the study was to quantify the e ect of both non-gravitational and gravitational disturbances. The simulator was used to analyse di erent orbit scenarios related to the period of the mission and to the relative distance between the spacecraft and the asteroid system. In every scenario, the solar radiation pressure was found to be the strongest of the disturbance forces. With the developed simulator, suitable spacecraft configurations and control systems can be chosen to mitigate the e ect of the disturbances on the attitude and orbit of the ASPECT satellite. 

  • 19.
    Forsberg, Fredrik
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Providing Air Traffic Control Services for Small Unmanned Aircraft Through LTE2016Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
  • 20.
    Garcia Hernandez, Juan Camilo
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Development of a Class D motor amplifier for a next-generation mechanism control electronics2016Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This thesis was written at Airbus DS GmbH in Friedrichshafen, Germany, as part of a project which aims to develop a new generation of class-D power amplification circuits for sinusoidal commutating motors controlling the movement of different mechanisms in satellites. Currently used topologies have disadvantages such as high power loss, analog controlling and high degree of signal distortion.

    This work first simulates available topologies which were previously developed by the company in order to compare them and build a trade-off list so the most suitable circuit is selected. Then, by further simulating and analysis several improvements to the circuit are suggested and a final schematic is developed including an analogue-to-digital converter and a total of three phases to power a motor. After a demonstrator circuit was designed and built, it was tested by using an external real time target machine to generate the corresponding PWM signals in correspondence to a controlling signal generated via Simulink.

    The final product of this thesis confirmed the simulation results such as an improved signal quality at higher frequencies in comparison to an available measurement from a previous generation circuit. The flexibility of the topology as well as the possibility of implementing a digital control was also confirmed during this phase of the project. Upon further work, the dimensioning of the output low pass filter should be improved and a digital PID controller should be implemented in the controlling FPGA.

    NOTE: This version of the Master Thesis deviates from the formal original  submitted for examination in order not to disclose confidential information of Airbus DS GmbH. All positions in the document, where additional information was removed are properly identified. This document can be published according to the general rules of the Julius-Maximilians-Universität Würzburg and the Lulea University of Technology.

  • 21.
    Garcia, Laura
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    UKF-SLAM Implementation for the Optical Navigation System of a Lunar Lander2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
  • 22.
    Georgieva, Iskra
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Searching for Exoplanets in K2 Data2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The field of extrasolar planets is undoubtedly one of the most exciting and fast-moving in astronomy. Thanks to the Kepler Space Telescope, which has given us the Kepler and K2 missions, we now have thousands of planets to study and thousands more candidates waiting to be confirmed.For this thesis work, I used K2 data in the form of stellar light curves for Campaign 15 – the 15th observation field of this mission – to search for transiting exoplanets. I present one way to produce a viable list of planetary candidates, which is the first step to exoplanet discovery. I do this by first applying a package of subroutines called EXOTRANS to the light curves. EXOTRANS uses two wavelet-based filter routines: VARLET and PHALET. VARLET is used to remove stellar variability and abrupt discontinuities in the light curve. Since a transit appears box-like, EXOTRANS utilises a box-fitting least-squares algorithm to extract the transit event by fitting a square box. PHALET removes disturbances of known frequencies (and their harmonics) and is used to search the light curve for additional planets. Once EXOTRANS finishes its run, I examine the resulting plots and flag the ones, which contain a transit feature that does not appear to be a false positive. I then perform calculations on the shortlisted candidates to further refine their quality. This resulted in a list of 30 exoplanet candidates. Finally, for eight of them, I used a light curve detrending routine (Exotrending) and another software package, Pyaneti, for transit data fitting. Pyaneti uses MCMC sampling with a Bayesian approach to derive the most accurate orbital and candidate parameters. Based on these estimates and combined with stellar parameters from the Ecliptic Plane Input Catalogue, I comment on the eight candidates and their host stars.However, these comments are only preliminary and speculative until follow-up investigation has been conducted. The most widely used method to do this is the radial velocity method, through which more detailed information is obtained about the host star and in turn, about the candidate. This information, specifically the planetary mass, allows for the bulk density to be estimated, which can give indication about a planet’s composition.Although the Kepler Space Telescope is at the end of its life, new missions with at least a partial focus on exoplanets, are either ongoing (Transiting Exoplanets Survey Satellite – TESS) or upcoming (Characterising Exoplanets Satellite – CHEOPS, James Webb Space Telescope – JWST, Planetary Transits and Oscillations – PLATO). They will add thousands of new planets, providing unprecedented accuracy on the transit parameters and will make significant advances in the field of exoplanet characterisation. The methods used in this work are as applicable to these missions as they have been for the now retired Convection, Rotation et Transits planétaires (CoRoT) – the first space mission dedicated to exoplanet research, and Kepler.

  • 23.
    Grigat, Felix
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik. ONERA.
    Optimizing the architecture of the Salammbô-EnKF data assimilation tool for radiation belt modeling2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
  • 24.
    Grosse, Christian
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Development of a Star Camera Algorithm for Calculating thePosition on Earth and Mars (VaMEx DLR)2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Within the scope of the Valles Marineris Explorer mission of the German Aerospace Center(DLR), the position of a ground vehicle on Mars needs to be determined. Due to the fact thatMars has no global magnetic field and no positioning system like Earth, a facility independentsystem is necessary. In this context, a star camera based positioning system shall be developed.The subject of this thesis is the development, implementation and verification of a star camerabased transformation algorithm for calculating the latitudinal and longitudinal position on Mars.In addition, an Earth based transformation algorithm is developed, implemented and evaluated fortesting purposes, that is for testing the hardware for the mission under real conditions on Earth.The thesis gives an insight into the fundamental theory of transformation algorithms commonlyused for the transformation between celestial and planet coordinate systems. A self-developedtransformation algorithm is presented which is able to transform a tilted star vector in TopocentricHorizon Coordinate System into observer longitude and latitude position. Moreover, themodular implementation in MATrix LABoratory (MATLAB) and Realtime Onboard DependableOperating System (RODOS) is described in detail. In the further course of the thesis the results ofdifferent test scenarios are outlined and evaluated. The overall results are eventually discussed regardingtheir implications for the mission and subsequently, suggestions for further improvementof the algorithm are made.

  • 25.
    Guha, Yash
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Investigation of progressive damage mechanisms in aerospace grade composites2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
  • 26.
    Guldevall, Peter
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Development of an FPGA based Trigger for Slow Moving Events for the EUSO-TA Telescope2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
  • 27.
    Gúrpide Lasheras, Andrés
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik. Galaxies, High Energy Astrophysics and Cosmology at Institut de Recherche en Astrophysique et Planétologie.
    Investigating super-Eddington accretion flows in Ultraluminous X-ray sources2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    It is now widely known that most of the large galaxies we observe (e.g. the Milky Way) host in their center a supermassive black hole ($10^{6}-10^{9}$ $M_\odot$). Several relationships between the central black hole mass and the properties of the stars in the central part of the galaxy have been established in the past 3 decades indicating that the central black hole is able to efficiently structure the matter around it due to episodes of accretion of matter onto the black hole. Recent infrared and optical sky surveys have detected supermassive black holes with masses around $10^{8-9}$ $M_\odot$ when the universe was less than a tenth of its current age and current theories have difficulties explaining how such massive objects could have formed over such short timescales. The goal of the present work is to shed light on the properties of a still largely unknown extreme accretion regime, the so called super-Eddington accretion regime. If such accretion regime could be sustained over sufficient timescales, it could play an important role in both the rapid growth of supermassive black holes as well as its co-evolution with its host galaxy. The aim of this work is therefore to apply high resolution spectroscopy to Ultraluminous X-ray sources in order to identify narrow spectral features to derive constrains on the outflows expected from super-Eddington accreting sources using data from the XMM-Newton observatory. For this purpose I developed a framework to analyse low count background dominated spectra that uses a Monte Carlo approach to detect these narrow features. After analysis of the source Holmberg II X-1, I identify 7 unresolved discrete features with a 3$\sigma$ confidence level that can be tentatively identified with ionic species. Furthermore, the instrumental resolution allows us to put upper limits on the broadening of the lines. This findings will allow us to probe the properties of the outflows of the super-Eddington regime and by extending the analysis to other sources we will able to characterize the observational properties of this accretion regime.

  • 28.
    Güttler, Johannes
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Field-Site Prototype for HABIT (FSP-HABIT): Characterizing Martian Salts Prior to the ExoMars 2020 Mission2016Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    One of the major remaining question about Mars is its habitability - if the requirements necessary to allow for life are presently fulfilled. One of the most relevant ingredients for life, as we know it, is water. Indirect evidence of transient liquid water on Mars has been retrieved from both rover [Martín-Torres et al., 2015] and orbiter [Ojha et al., 2015].

    [Martín-Torres et al., 2015] inferred the existence of an active water cycle, driven by chlorate and perchlorate salts, which are commonly found on the Martian surface, and absorb atmospheric water to form stable hydrated compounds and liquid solutions. This happens through a process called deliquescence (absorption of moisture from the atmosphere by the salts and dissolving into a liquid solution). One of the goals of HABIT is to confirm the hypothesis about the water cycle on Mars. HABIT will record the behavior of a selection of salts on Mars, and will also record Martian environmental conditions (UVdose, air and ground temperatures).

    The Field-Site Prototype for HABIT (FSP-HABIT) was the first prototype of HABIT deployed during field-site campaigns. Three campaigns took place during summer 2016: First, a short preparatory campaign in Abisko, Sweden, was carried out. The second campaign took place in Iceland, within the EU COST Action TD1308 ORIGINS (Origins and evolution of life on Earth and in the Universe), and the third campaign was conducted within the NASA Spaceward Bound India Program in Ladakh. After providing the corresponding background on the mission framework and the scientific background, this document covers the mechanical, electrical, and software design of the instrument. Afterwards, the steps taken to test the instrument and their results are covered, followed by a rating of the instrument and ideas for future improvements. Instruments like FSP-HABIT will enable the characterization of hygroscopic salts by their conductivity as liquid brines are good conductors, hydrated salts are poor conductors, and dehydrated salts are insulators. During the field-site campaigns, the measurements of FSP-HABIT were used to characterize the near surface environment by its temperature, pressure and relative humidity. Now, these measurements are available for comparison with microbiological studies of the water, ice and soils to characterize the habitability of the explored site. The lessons learned while designing and building FSP-HABIT can be used to inform the development of further prototypes for space missions such as HABIT.

  • 29.
    Hagen, Christoph
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    A Bluetooth based intra-satellite communication system2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This thesis presents a wireless communication system for intra-satellite communication based on Bluetooth Low Energy technology, which can have many benefits regarding the design and operation of satellites. The proposed design based on the nRF53832 chip from Nordic Semiconductor is described, followed by the results of several tests regarding the most important design criteria for its application in small satellites. The tested aspects include the power consumption of the wireless module in different operation modes, which is sufficiently low for the application even in small satellites. Signal strength measurements for various output power settings and obstacles show that reliable communication is possible in a satellite mockup. No packet error was detected, and latencies of less than 30 ms combined with achievable data rates between 200 and 700 kbps should be sufficient for most CubeSat satellites. Additionally, details are given to successfully integrate the chip with existing satellite subsystems. A code library is provided to simplify the communication between the modules, and a concept of a redundant system is established to increase the reliability for critical satellite subsystems. The overall assessment of the technology suggests that the presented system is suitable for in-orbit deployment with the Aalto-3 satellite (currently being developed at Aalto University), which will provide further validation of the technology. 

  • 30.
    Hagos, Tesfamichael Marikos
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik. Aalto University .
    Estimation of phases for compliant motion: Auto-regressive HMM, multi-class logistic regression, Learning from Demonstration (LfD), Gradient descent optimization,2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
  • 31.
    Hammarsten, Michael
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    A statistical study of incoherent scatter plasma line enhancements during the International Polar Year ’07-’08 in Svalbard2016Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    There was a large radar campaign during 2007 and 2008, the International Polar Year (IPY),and at that time the EISCAT Svalbard Radar was operated and measured the ionosphere continuouslyat most times. This report presents statistical results from an electron enhancementpoint of view. Until now there has been some research into the field and results based on theions in the ionosphere, and the enhancements we refer to as Naturally enhanced ion acousticlines (NEIALs). Plasma line data from May 2007 to February 2008 has been analysed inorder to find and classify enhancements as NEIALs have been classified but with respect tothe electron distribution instead of the ion distribution. A method of detection was developedin order to differentiate the enhancements from the background with a relation between theminimum and maximum power of each measured dump. Results show that there is a largedifference between the downshifted plasma lines and the upshifted plasma lines, both has arange distribution peak at 180 km and the upshifted plasma line has another peak at 230 kmwhich the downshifted plasma line does not. The occurrence rate of the enhancements was1.64 % for the downshifted plasma line and 4.69 % for the upshifted plasma line. Threedifferent types of enhancements are classified using the variance distribution for the peakfrequency of that detected dump, Single, Profile, and Diffuse. The Single enhancements havea bit different spectral, range, and time of day distributions than of the Profile and Diffusedistributions. The Diffuse classifications are mostly wrong classifications and aliasing and itis very similar to Profile enhancements as seen by its distribution.

  • 32.
    Hirschmüller, Korbinian
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Development and Evaluation of a 3D Point Cloud Based Attitude Determination System2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
  • 33.
    Hladký, Maroš
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik. Julius-Maximilians-University Würzburg, Informatics VII : Robotics and Telematics .
    Vision Based Attitude Control2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The problematics of precise pointing and more specifically an attitude control is present sincethe first days of flight and Aerospace engineering. The precise attitude control is a matter ofnecessity for a great variety of applications. In the air, planes or unmanned aerial vehicles needto be able to orient precisely. In Space, a telescope or a satellite relies on the attitude control toreach the stars or survey the Earth. The attitude control can be based on various principles, pre-calculated variables, and measurements. It is common to use the gyroscope, Sun/Star/horizonsensors for attitude determination. While those technologies are well established in the indus-try, the rise in a computational power and efficiency in recent years enabled processing of aninfinitely more rich source of information - the vision. In this Thesis, a visual system is used forthe attitude determination and is blended together with a control algorithm to form a VisionBased Attitude Control system.A demonstrator is designed, build and programmed for the purpose of Vision Based AttitudeControl. It is based on the principle of Visual servoing, a method that links image measure-ments to the attitude control, in a form of a set of joint velocities. The intermittent steps arethe image acquisition and processing, feature detection, feature tracking and the computationof joint velocities in a closed loop control scheme. The system is then evaluated in a barrage ofpartial experiments.The results show, that the used detection algorithms, Shi&Tomasi and Harris, performequally well in feature detection and are able to provide a high amount of features for tracking.The pyramidal implementation of the Lucas&Kanade tracking algorithm proves to be a capablemethod for a reliable feature tracking, invariant to rotation and scale change. To further evaluatethe Visual servoing a complete demonstrator is tested. The demonstrator shows the capabilityof Visual Servoing for the purpose of Vision Based Attitude Control. An improvement in thehardware and implementation is recommended and planned to push the system beyond thedemonstrator stage into an applicable system.

  • 34.
    Håkansson, Marcus
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Back-tracing of water ions at comet 67P/Churyumov–Gerasimenko2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This paper examines the neutral coma of comet 67P/Churyumov–Gerasimenko by using measurements of charged particles (water ions) and tracing them back to their place of ionisation. The measurements were taken from Rosetta’s Ion Composition Analyser. The simulations made use of an existing program which traces particles forward, which was changed to trace particles backwards, with new conditions for terminating the simulation.

    Two types of simulations were made. The first type is referred to as ”one-day simulations”. In these, simulations are made using data from a single occasion, with nine occasions studied per selected day. The days were selected so that the spacecraft was in different positions in relation to the comet. The second is referred to as the ”full-hemisphere” simulation. In this simulation, data from all usable days are used to produce an image of the hemisphere facing the Sun.

    The full-hemisphere simulation suffers from lack of simultaneous measurements, and indeed it is impossible to obtain in-situ measurements at all positions at once. Both simulations could be improved using more precise models, which could not be done within the allotted time of this work.

  • 35.
    Ishtiaq, Shehryar
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Optimization of a Laser Coarse Pointing Assembly for Low Earth Orbit Satellite Missions2016Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    A laser communications terminal was developed by the Deutsches Zentrum für Luft- und Raumfahrt and is already being flown over the BIROS satellite, however it is desired to improvepointing performance with the utilization of a coarse pointing assembly. This study presents theseries of optimizations towards space applicability performed on an existing coarse pointingassembly for such a laser communications terminal. This module was initially built for airborneapplications and tested upon the tornado aircraft. The idea was to use this existing flight performanceproven system and with the help of commercial off the shelf components providebetter structural stability and tolerance to the Low Earth Orbit space environment. Criticalpoints were highlighted and the scope of the study was defined to provide reliable modal andthermal analysis results for its performance under the specified mission design parameters. Acircular low earth orbit of 450 km altitude with an inclination similar to that of the BIROS satellitewas chosen to simulate the space environmental effects for this analysis. A preliminary designreview highlighted the need to increase the link budget, which brought down the beamdivergence to 50 μrad from a previous 100 μrad. This made the entire system sensitive andmore susceptible to environmental factors requiring a more rigid and deformation tolerantstructure. In this study the effect of thermal loadings in worst-case scenarios were analysed.Aside from the optimization changes, the results of the analysis pointed out the need to utilizethermal control measures for optimum performance. Therefore, some passive thermal controlmeasures are also presented in this study, which are necessary to meet the requirements.

  • 36.
    Jegatheesan, Anjana
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Development of Rear Entry HUT/PLSS Design for Aouda.X Spacesuit Simulator2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The Aouda.X Space suit simulator, developed by The Austrian Space Forum( OeWF) currently consists of a system that weighs 48 kg of which nearly 57% is comprised of the Suit's HUT (Hard Upper Torso), PLSS (Portable Life Support System) and OBDH (On- board data handling). In addition to this, the current conguration requires 3 hours of assisted donning/doffing. To improve the ergonomics of the design, a relatively lighter HUT/PLSS design prototype with efficient donning capabilities, preferably self -donning, must be developed. This issue can be addressed by proposing a Rear - Entry Design that when implemented on the Aouda.X, can potentially ease these impediments.This study aims at identifying a suitable Rear entry closure design for the current conguration of Aouda.X based on planetary suit performance indicators and operational requirements. The Aouda.X rear entry design is also targeted to be compatible with the NDX -Suitport developed by the University of North Dakota's Human Space Flight Laboratory. The thesis work comprises of the development of a suitable methodology to distinguish a rear entry design for the HUT and PLSS of the spacesuit simulator with the identication of a self-sealing/locking mechanism based on these requirements. A full scale CAD model of the HUT and PLSS with optimal dimensions of compatibility for the Spacesuit with the suitport is designed as a result of this study. Static load bearing analysis is performed to validate the feasibility of the structure and make suitabe recommendations for choice of materials. Methods for further improvement for rear entry suit development are outlined.

  • 37.
    Jensen, Filip
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Topology Optimization of Turbine Manifold in the Rocket Engine Demonstrator Prometheus2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The advantages of Topology Optimization (TO) are realized to a large extent due to the manufacturing freedom that Additive Manufacturing (AM) offer, compared to more conventional manufacturing methods. AM has the advantage of manufacturing shallow and complex structures previously not possible, and consequently opens up a whole new design spectrum. This thesis investigates the possibilities of using Topology Optimization as a tool to find stronger and lighter designs for the inlet turbine manifold in the rocket engine demonstrator Prometheus. The manifold is optimized by giving it more mass, subjecting it to load cases and pushing the topology optimization to make the manifold meet the weight requirement without exceeding the yield strength. Result validation indicates that the pressure and thermal loadings are the most prominent. The current topology optimization tools in ANSYS do not support optimization due to thermal features and thus optimization in the presented work has only been able to consider static structural loads. Nevertheless, it is possible to optimize the manifold due to static structural loads and achieve a manifold which satisfies the weight requirement. However, optimization tools due to thermal loading would be a desirable feature in the future.

  • 38.
    Jerker, Bergström
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Path Planning with Weighted Wall Regions using OctoMap2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    In the work of the Control Engineering research group of the Department of Computer Science, Electrical and Space Engineering, Signals and systems at Luleå University of Technology a need had arisen for a path planning algorithm. The ongoing research with Unmanned Aerial Vehicles(UAVs) had so far been done with any complicated paths being created manually with waypoints set by the uses. To remove this labourious part of the experimental process a path should be generated automatically by simply providing a program with the position of the UAV, the goal to which the user wants it to move, as well as information about the UAV's surroundings in the form of a 3D map.In addition to simply finding an available path through a  3D environment the path should also be adapted to the risks that the physical environment poses to a flying robot. This was achieved by adapting a previously developed algorithm, which did the simple path planning task well, by adding a penalty weight to areas near obstacles, pushing the generated path away from them.The planner was developed working with the OctoMap map system which represents the physical world by segmenting it into cubes of either open or occupied space. The open segments of these maps could then be used as vertices of a graph that the planning algorithm could traverse.The algorithm itself was written in C++ as a node of the Robot Operating System(ROS) software framework to allow it to smoothly interact with previously developed software used by the Control Engineering Robotics Group.The program was tested by simulations where the path planner ROS node was sent maps as well as UAV position and intended goal. These simulations provided valid paths, with the performance of the algorithm as well as the quality of the paths being evaluated for varying configurations of the planners parameters.The planner works well in simulation and is deemed ready for use in practical experiments.

  • 39.
    Johansson, Mattias
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Evaluation of Sensor Solutions & Motor Speed Control Methods for BLDCM/PMSM in Aerospace Applications2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The goal of this thesis was to evaluate sensors and motor speed control methods for BLDC/PMSM motors in Aerospace applications. The sensors and methods were evaluated by considering accuracy, robustness, cost, development gain and parameter sensitivity. The sensors and methods chosen to simulate were digital Hall sensors and sensorless control of BLDC motors. Using Matlab Simulink/Simscape some motor speed control methods and motor speed estimation methods were simulated using the Hall sensors and sensorless control as a basis. It was found that the sensorless control methods for BLDC motors couldn't estimate the speed accurately during dynamic loads and that the most robust and accurate solution based on the simulations was using the digital Hall sensors for both speed estimation and commutation and this was tested on a hardware setup.

  • 40.
    Joshi, Archana Ananta
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Heat Flux Measurements in Radiation and Arcjet Furnaces and In-situ Ablation Experiments with X-ray Tomography2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    A spacecraft entering an atmosphere experiences high heat fluxes giving rise to the need ofthermal protection systems. Materials necessary for thermal protection are investigatedin various ground facilities and one of the important parameters that has to be computedis the heat flux at the stagnation region. The heat flux envelope of the mini-radiation andarc-jet facilities using a copper cylinder probe is investigated in this thesis. The heat fluxprobe used in the investigation was calibrated against a null point calorimeter; tests wereconducted by permuting different parameters and the effect of the varied parameter was studied. The variation in static chamber pressure was found to be the major contributorin the fluctuation of heat flux in both the facilities.

    The radiative heat flux investigation tests allowed to conduct in-situ ablation tests. Thein-situ ablative tests with X-ray tomography were done for DLR-cork and ZURAM materials.The tests further showed the degradation of material inside the chamber on areal-time basis leading to better understanding of the structural changes in materials dueto high directional heat loads. In-situ tests with the arc-jet facility and comparative studiesusing the same testing conditions with different material models will provide a goodfollow-up to this research.

  • 41.
    Kettig, Peter
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Benchmarking of C++ image processing libraries within the Euclid project2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    In this report, the issue of selecting a C++ image processing library for the Euclid science ground segment (SGS) is tackled. A new benchmark is proposed to objectively compare libraries according to both static, development-related, and dynamic, execution-related criteria.

    Instead of comparing isolated functions, a much more realistic scenario is implemented: a complete processing pipeline based on a use-case algorithm, called L.A. cosmic. Already existing in the SGS and used multiple times for the flagging of galactic cosmic rays (GCRs), this algorithm is the optimal choice for setting up the benchmark. This makes the results much more usable than with classical single- function benchmarks.

    First, the used tools as well as both categories are explained with their respective criteria listed, all tailored to the needs of the SGS. This also introduces the statistical profiling used throughout the project. Additionally, a scientific validation is introduced that monitors the accuracy of the implementations created.

    Afterwards, the benchmark is conducted and the results are presented and discussed. Indeed, including static criteria helps taking into account development and debugging time – key elements of the project life. Moreover, most library contenders are lacking important functions required for the implementation of the reference algorithm and are therefore excluded from further measurements. Documenting the missing or unclear functions gives then an overview about how user-friendly a library is to develop with.

    The scientific validation depicts that a missing function in one of the contenders and the resulting deviation from the reference results in a lower accuracy. Leaving out the problematic part of the pipeline improves the results, yet only with a higher amount of stars being misinterpreted as GCRs.

    The dynamic criteria report that all contenders perform better than a python reference version as well as a consistent linear dependency to the input image size, while also offering an approach to multi-core processing. Yet, the latter exhibits problems of some libraries to scale appropriately with more resources, leaving the results divided between the single- and multi-core setups for this benchmark.

    When taking this parameter of cores into account, the benchmark allows to recommend the most appropriate library to the SGS. 

  • 42.
    Kiewiet, Luca
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik. Université Toulouse III Paul Sabatier.
    Design of the Hold-Down and Release System for the Concur™ Solar Array Wing2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Fulltekst tilgjengelig fra 2018-12-31 08:00
  • 43.
    Kindberg, Peter
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Development of a miniature Gridded ion thruster2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
  • 44.
    Kohlbacher, Anton
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Development of a Novel Relative Localization Sensor2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    By enabling coordinated task execution and movement, robotic swarms can achieve efficient exploration or disaster site management. When utilizing Ultra-wideband (UWB) radio technology for ranging, the proposed relative localization sensor can be made lightweight and relatively indifferent to the ambient environment. Infrastructure dependency is eliminated by making the whole sensor fit on a swarm agent, while allowing for a certain amount of positional error. In this thesis, a novel algorithm is implemented in to constrained hardware and compared to a more traditional trilateration approach. Both algorithms utilize Particle Swarm Optimization (PSO) to be more robust towards noise and achieves similar accuracy, but the proposed algorithm can run up to ten times faster. The antenna array which forms the localization sensor weighs only 56g, and achieves around 0.5m RMSE with a 10Hz update rate. Experiments show that the accuracy can be further improved if the rotational bias observed in the UWB devices are compensated for.

  • 45.
    Kudaravalli, Venkata Narayana Chowdary
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Design and fabrication of test-bed for testing attitude determination of spin stablilized spacecraft.2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

     Attitude determination for a spin stabilized satellite is calibrated. A mock spacecraft and a spin simulation test bed are designed and developed. Spin simulation testbed which provides position data is used to acquire true position data. The data from the simulator test bed is used as reference for the sensor data to estimate the error in position of sensor data. Two vector method attitude solutions are used here for attaining the estimated position. Two vectors used for attitude determination are magnetic field vector and sun sensor vector. Calibration of accuracy for sensors is main goal, which is attained by calculating error by comparing the estimated position with true position.

  • 46.
    Kunicka, Beata Iwona
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Spacecraft dynamic analysis and correlation with test results: Shock environment analysis of LISA Pathfinder at VESTA test bed2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The particular study case in this thesis is the shock test performed on the LISA Pathfinder satellite conducted in a laboratory environment on a dedicated test bed: Vega Shock Test Apparatus (VESTA). This test is considered fully representative to study shock levels produced by fairing jettisoning event at Vega Launcher Vehicle, which induces high shock loads towards the satellite.

    In the frame of this thesis, some transient response analyses have been conducted in MSC Nastran, and a shock simulation tool for the VESTA test configuration has been developed. The simulation tool is based on Nastran Direct Transient Response Analysis solver (SOL 109), and is representative of the upper composite of Vega with the LISA Pathfinder coupled to it. Post-processing routines of transient response signals were conducted in Dynaworks which served to calculate Shock Response Spectra (SRS).

    The simulation tool is a model of forcing function parameters for transient analysis which adequately correlates with the shock real test data, in order to understand how the effect of shock generated by the launcher is seen in the satellite and its sub-systems. Since available computation resources are limited the parameters for analysis were optimised for computation time, file size, memory capacity,  and model complexity. The forcing function represents a release of the HSS clamp band which is responsible for fairing jettisoning, thus the parameters which were studied are mostly concerning the modelling of this event. Among many investigated, those which visibly improved SRS correlation are radial forcing function shape, implementation of axial impulse, clamp band loading geometry and refined loading scheme. Integration time step duration and analysis duration were also studied and found to improve correlation.  From each analysis, the qualifying shock environment was then derived by linear scaling in proportion of the applied preload, and considering a qualification margin of 3dB.

    Consecutive tracking of structural responses along shock propagation path exposed gradual changes in responses pattern and revealed an important property that a breathing mode (n = 0) at the base of a conical Adapter translates into an axial input to the spacecraft. The parametrisation itself was based on responses registered at interfaces located in near-field (where the clamp band is located and forcing function is applied) and medium-field with respect to the shock event location. Following shock propagation path, the final step was the analysis of shock responses inside the satellite located in a far-field region, which still revealed a very good correlation of results. Thus, it can be said that parametrisation process was adequate, and the developed shock simulation tool can be qualified. However, due to the nature of shock, the tool cannot fully replace VESTA laboratory test, but can support shock assessment process and preparation to such test.

    In the last part of the thesis, the implementation of some finite element model improvements is investigated. Majority of the panels in spacecraft interior exhibited shock over-prediction due to finite element model limitation. Equipment units modelled as lump masses rigidly attached with RBE2 elements to the panel surface are a source of such local over-predictions. Thus, some of the units were remodelled and transient responses were reinvestigated. It was found that remodelling with either solid elements, or lump mass connected to RBE3 element and reinforced by RBE2 element, can significantly improve local transient responses. This conclusion is in line with conclusions found in ECSS Shock Handbook.

  • 47.
    Leblebici, Robin
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Development of an automated adjusting process for robotic end-effectors to handle dry textiles for preforming of carbon fiber reinforced plastics2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    In order to fulfill increasing production rates, new automated production technologies are required for manufacturing carbon fiber reinforced plastic components for the aerospace industry. Currently, large, double curved composite components have to be manufactured manually, which leads to high process times and poor scalability. As a consequence, a team of cooperating robots with passively adjustable end-effectors was developed, that is capable of handling dry carbon textiles and can be used for layups in double curved molds. This thesis deals with the implementation of a robot program, that performs an automated adjustment of each end-effector to the surface geometry of the manufactured part. The functional principle and the accuracy of the process are evaluated. Further, the automatically adjusted end-effectors are utilized to cooperatively layup carbon plies. The results show, that the accuracy of the automated adjusting process is sufficient to drape carbon fabrics during pick-up and automated layup is possible with this approach. In conclusion, the developed process can be integrated into a fully automated process for future experiments, but hardware inaccuracies should be improved, in order to further enhance the accuracy of the system.

  • 48.
    Lidström, Viktor
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Mass Loading of Space Plasmas2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The solar wind interaction with an icy comet is studied through a model problem. A hybrid simulation is done of a box with evenly distributed water ions and protons, where initially the water ions are stationary, and protons move with the speed of the solar wind. The purpose of the thesis is to investigate the interaction between the two species through the convective electric field, and focus is on early acceleration of pick-up ions, and deflection of the solar wind. It is relevant to the cometary case, because it enables study of the physics of this interaction, without involving other mechanisms, such as bow shock, magnetic field pile-up and draping. The species are found to exchange kinetic energy similar to a damped oscillator, where the dampening is caused by kinetic energy being transferred to the magnetic field. At early times, i.e. times smaller than the gyration time for the water ions, the solar wind does not lose much speed when it is deflected. For comparable number densities, the solar wind can be deflected more than 90° at early times, and loses more speed, and water ions are picked up faster. The total kinetic energy of the system decreases when energy builds up in the magnetic field. The nature of the energy exchange is strongly dependent on the number density ratio between water ions and protons. A density instability with behaviour similar to a plasma beam instability forms as energy in the magnetic field increases, and limits the amount of time the simulation preserves total energy, for the particular hybrid solver used. There is a discussion on the structure of the density instability, and it is compared to cometary simulations.

  • 49.
    Lukanovic, Matej
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Evaluation Analysis of the UV-detector on the Mini-EUSO Space Telescope2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Extragalactic charged particles, each with energies rising up to and beyond 1 Joule, have been studied for almost a century. Yet, no precise evidence have proven to show where they might originate from as their energy levels rise above the current familiar acceleration sources in outer space. The highly energetic particles have been given the name Ultra-High Energy Cosmic Rays (UHECR) and investigations of particle properties such as primary energy, mass composition and direction can be made through indirect measurements of the interaction between the UHECR and Earth's atmosphere. The considered interaction induces an Extensive Air Shower (EAS) which emits fluorescent light in the Ultraviolet (UV) range. The probability of detecting such events is, however, as low as a few particles per km2 per century. Making observations more sufficient therefore requires larger detection volumes.

    By introducing the Mini-EUSO instrument, a telescope of which the main purpose is to measure the UV-light radiated from the Earth in the wavelength range of 300-400 nm, allows just for this. To be accommodating the International Space Station and targeting Earth in the nadir direction, the Mini-EUSO instrument will allow for a higher exposure to the interactions than what is currently available. The use of two Fresnel lenses provides the instrument with a large field of view (±22o) and the detections are made through multiple photomultiplier tubes.

    The scope of this thesis is to evaluate the main detector of the Mini-EUSO instrument (i.e. the UV-detector) through ground-based tests. The procedures involved in the evaluation have consisted of; validating the statistical distributions of the signals, implementing dark field and flat field calibrations, and radiations measurements with three kinds of radiation sources. The data from the tests were provided during two periods and the visualization was made by adapting an already existing piece of code, using Python and ROOT Cern, to perform step by step procedures such that all operations are overlooked properly.

    The analysis showed that the implementation of the dark field and flat field procedures improved the original image significantly. It also showed that both the lower and higher photon count values in a pixel indeed gave the expected statistical behaviours, with a Poissonian distribution for low values and a Gaussian distribution for higher values. The flat fielding screen did however show unknown fluctuations in the emitted light and further tests have to be implemented to assure its functionality. Under proper covering, almost no dark current was found, however, observation tests showed that the borders of the Multi-Anode Photomultiplier Tubes (MAPMTs) gave higher photon count values than the center part even when they were emitted with Lambertian light.

  • 50.
    Mannes, Quentin
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    ICE Cubes Mission: Design, Development and Documentation of the Cube-Zero System2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The International Space Station provides a high-quality of microgravity and extended exposure time which makes it a platform of choice for microgravity research. In order to increase accessibility of onboard experimentation, Space Applications Services will soon launch the ICE Cubes facility as part of its ICE Cubes Service. The facility is foreseen to host standardized plug-and-play payload cubes to reduce overall cost and procedure time required to install payloads on the station. To remotely support the facility it is decided to develop a utility cube named Cube-Zero that will be launched and installed with the facility on the station. This thesis work included the complete design, development and documentation of the cube.

    The thesis started by conducting a preliminary needs and market study from which two specific purposes were defined for the cube. In addition to its original function of support-utility, the cube is tasked to be a technical commercial demonstrator for the service. This led to the conceptual design of the cube as a multidisciplinary framework able to host two user-defined experiment modules. The preliminary concept was further refined in this paper and with support of prototypes, simulations and analyses led to a final functional design for the Cube-Zero.

    The work is concluded with the manufacturing of an engineering model of the cube. The model is fully operational, can support the test of the facility before launch and can demonstrate to users its versatility and ease of use in operating any kind of experiment module.

    Eventually, the information gathered in this thesis report will support future users into developing their own Cube-Zero payload module and guide Space Applications Services into manufacturing, testing and operating the Cube-Zero protoflight model.

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