Modal fitting

Circle fitting

class cued_datalogger.analysis.circle_fit.CircleFitWidget(parent: QWidget = None, flags: Union[Qt.WindowFlags, Qt.WindowType] = Qt.WindowFlags())

Bases: PyQt5.QtWidgets.QWidget

Methods

error_function(parameters)

The error function for least squares fitting.

refresh_nyquist_plot()

Clear the nyquist plot and add the items back in.

refresh_transfer_function_plot()

Clear the transfer function plot and add the items back in.

sdof_get_parameters()

Fit a SDOF peak to the data with a least squares fit, using values from the current peak as a first guess.

sdof_peak_with_offset(w, wn, zn, an, phi)

An SDOF modal peak fitted to the data using the geometric circle.

set_selected_channels(selected_channels)

Update which channels are plotted.

class cued_datalogger.analysis.circle_fit.CircleFitToolbox(parent=None)

Bases: cued_datalogger.api.toolbox.Toolbox

The Toolbox for the CircleFitWidget.

This Toolbox contains the tools for controlling the circle fit. It has two tabs: ‘Transfer Function’, for tools relating to the construction of a transfer function, and ‘Autofit Controls’, which contains tools for controlling how the circle is fit to the data.

Attributes

sig_construct_transfer_fn	(pyqtSignal) The signal emitted when a new transfer function is to be constructed.
sig_show_transfer_fn	(pyqtSignal(bool)) The signal emitted when the visibility of the transfer function is changed. Format (visible).

Methods

cued_datalogger.analysis.circle_fit.fit_circle_to_data(x, y)

Fit a geometric circle to the data given in x, y.

Parameters:

x : ndarray

y : ndarray

Returns:

x0 : float

The x-coordinate of the centre of the circle.

y0 : float

The y-coordinate of the centre of the circle.

R0 : float

The radius of the circle.

Notes

This function solves a standard eigenvector formulation of the circle fit problem. See [R11] for the derivation.

References

[R11]

(1, 2) Maia, N.M.M., Silva, J.M.M. et al, Theoretical and Experimental Modal Analysis, p221, Research Studies Press, 1997.