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Displacement Analysis of a Geodetic Network : A case study of the Vasa warship

By measuring coordinates repeatedly in time we can detect movements of an area or an object by establishing and monitoring a geodetic network. Since it is known that the Vasa warship is suffering from decomposition, a geodetic network has been established around the ship to monitor its deformation. This is an important task for preserving and supporting the ship in its place. In this thesis, time series of coordinates are considered over 22 epochs of the ship measurements, a quadratic line is fitted to them and acceleration and velocity for each point on the ship’s hull are obtained. The x-axis is across the ship, the y-axis is along and the zaxis is the vertical one in the local coordinate system of the ship. A method is developed for monitoring displacement and its error at different parts on the ship in two successive epochs, considering the covariances between the point coordinates. The covariances influence the result of the displacement. Significant displacements, calculated with a variance-covariance matrix were compared with the displacements calculated without variance-covariance matrix. Considering the covariances gave 108 more insignificant three dimensional displacements, which means that they are in the order of random errors. The largest acceleration and velocity are found in the upper part of the ship stern in the Zcoordinates, where all points have significant acceleration and velocity. The ship bow has the second highest acceleration and velocity, while the midsection of the ship seems to be more stabile. In the X- and Y-coordinates the acceleration and velocity are smaller, in Ycoordinates almost all points have significant acceleration and velocity. In the Xcoordinates there are several points of data with insignificant acceleration and velocity, most of them located at the midsection of the vessel. The results show that the ship is moving and accelerating at various speeds on different sides of the ship, which indicates that there are parts that suffer from more crucial decomposing. The stern is the part of the vessel that has the highest velocity, acceleration and displacement. The ship is moving downwards with respect to the museum building at the same time as it tilting towards the port. The down pulling force can explain the movements downwards, the strength of the oak can also be one reason. The tilting could depend on the support structure since points in various part of the ship seems to have the same amount of movement in the direction towards the port.
Date January 2017
CreatorsJohansson, Filippa, Karlsson, Lenita
PublisherHögskolan Väst, Avdelningen för data-, elektro- och lantmäteriteknik, Högskolan Väst, Avdelningen för data-, elektro- och lantmäteriteknik
Source SetsDiVA Archive at Upsalla University
Detected LanguageEnglish
TypeStudent thesis, info:eu-repo/semantics/bachelorThesis, text

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