Modelling and optimization of a SG type seismometer proportional to the elongation

Abstract

In this thesis, a new SG type seismometer is modelled and its counterforce constant is optimized to have an increased period length large enough to make seismic measurements. In the first part of the thesis a “Kinematic Model of the Seismometer” is built in simulink. It consists of three subsequent submodels which are an “Idealized Pendulum Angle Model”, a “Magnetic Counterforce Effect on Period Model” and a “Drag Force Model”. The problem of period increase with magnetic counterforce is defined in the second part of the thesis. The simulink models, which are built in the first part, are used to study and to solve this optimization problem. The binary search is used to find the best magnetic counterforce constant value and the golden section search is used to find the highest possible period value which grants harmonic oscillation and lowest error output. As a result; a magnetic counterforce constant value is reached for every desired period length, which is possible to reach due to the mechanical restrictions of the pendulum. It is proven that with an optimized magnetic counterforce constant, a SG type seismometer will have an increased period value, which grants the seismometer to become as effective as a high cost seismometer.