Robotics and Computer Engineering - Master's theses

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Browsing Robotics and Computer Engineering - Master's theses by Author "Allik, Viljo"

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    Autonomous motion planning for spacecrafts near small solar system bodies: simultaneously refining the gravitational field model and re-planning gravity dependant maneuvers
    (Tartu Ülikool, 2020) Paul, Aditya Savio; Otte, MichaelW.; Allik, Viljo; Tartu Ülikool. Loodus- ja täppisteaduste valdkond; Tartu Ülikool. Tehnoloogiainstituut
    Small solar system bodies can be better studied while orbiting in their vicinity. However, orbital motion around such bodies is challenging due to their irregular and weaker gravity as compared to larger bodies. Moreover, a-priori paths developed by earth-based measurements tend to generate monolithic trajectories. Dynamic path planning in space has the potential to improve the study of small solar system bodies. Fine-grained motion plans require detailed knowledge of the gravitational forces, that can be measured in the sphere of influence. The gravity models can be analysed for mass and material distribution across the body. We propose a method for autonomous motion planning around small solar system bodies that simultaneously measures and refines the gravitational model. The trajectories are replanned considering the updated model to perform stable orbital maneuvers eventually providing a high fidelity gravity model. The research shall enable the spacecraft to perform autonomous maneuvers, design landing strategies and scout for in-situ resources.
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    Software Development for the Mechanical Shock Testing System at Tartu Observatory
    (Tartu Ülikool, 2016) Allik, Mari; Allik, Viljo; Tilk, Teet; Vendt, Riho; Tartu Ülikool. Loodus- ja täppisteaduste valdkond; Tartu Ülikool. Tehnoloogiainstituut
    Components used in space are subject to high frequency and high amplitude mechanical shocks that occur during the launch and separation phases of the space vehicles. Shock testing is done to ensure that components can withstand the shock events. A shock can be described by an acceleration and time history, but in shock testing it is difficult to manage and quantify shocks by only looking at the acceleration and time history of a shock. Instead, a shock response spectrum is used, which plots the peak accelerations of multiple single degree of freedom systems with their own unique frequencies over a range of frequencies, usually from 100 Hz to 10 000 Hz. The shocks that occur in space can reach up to acceleration levels of 10 000 g’s. The main objective of this work was to develop a software application for the mechanical shock testing system at Tartu Observatory. The shock testing system at Tartu Observatory consists of a resonant plate, pendulum hammer, guiding rod, weights and a data acquisition module with acceleration sensors. The software was developed in Microsoft Visual Studio .NET 2003 using the C++ programming language and external libraries. The software is required to acquire the data from the sensors connected to the data acquisition module and process and plot it. The shock response spectrum and acceleration-time histories can be plotted. An important aspect of shock testing is to be able to recreate shocks of various levels. If the shock testing system manages to do this, the system is considered reliable. To test the reliability of the system, the developed software was tested by performing shock testing on test objects and plotting the results.