Discrete Basis Function Methods for the Solution of Inverse Problems in Mechanical Measurements

Sabrina Pretzler

Research output: ThesisDiploma Thesis

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Abstract

This thesis presents a new approach to curve reconstruction from over constrained gradients. This type of problem arises when measuring deformation of structures using inclinometers. The new methods investigated are based on discrete orthonormal polynomials and a method of synthesizing constrained basis functions, whereby the constrained basis functions span the complete space of all possible solutions. Furthermore, they are ordered in increasing mode number, which supports a simple solution for spectral regularization. Two new methods are derived for the reconstruction of curves from gradients. The first reconstruction method uses admissible functions for regularization, the second method is of variational nature. Monte Carlo simulations are presented which verify the principle of the numerical approach. Additionally a real inclinometer measurement system for the measurement of a deflected beam was implemented and an independent optical system was constructed for measurement validation. The real measurements confirmed the correctness of the new approach. Furthermore, they revealed issues which are relevant for future research, i.e., placing constraints on the interpolating functions and not on the reconstructed points.
Translated title of the contributionDiskrete Basisfunktionen Methoden zur Lösung von inversen Randwertproblemen von mechanischen Messsystemen
Original languageEnglish
QualificationDipl.-Ing.
Supervisors/Advisors
  • Harker, Matthew, Co-Supervisor (internal)
  • O'Leary, Paul, Supervisor (internal)
Award date28 Jun 2013
Publication statusPublished - 2013

Bibliographical note

embargoed until 03-06-2018

Keywords

  • curve reconstruction from gradients
  • discrete orthonormal polynomials
  • admissible functions
  • inclinometers
  • inverse boundary value problem

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