Input File Formats#

All pyOMA configuration files are plain-text, line-by-line key–value files. Every key appears on one line and its value on the next line. Lines starting with # are comments.

Note

These files are only needed when using the init_from_config helper methods. If you prefer to configure everything in Python code (recommended for Jupyter notebooks) you can pass parameters directly — see Getting Started.

Geometry files#

grid.txt#

Node coordinates. One header line, then one node per line. Columns are separated by whitespace (spaces or tabs).

node_name    x             y             z
1    1.8100000e+01  -1.8100000e+01   0.0000000e+00
2    1.8100000e+01   1.8100000e+01   0.0000000e+00
3   -1.8100000e+01   1.8100000e+01   0.0000000e+00
4   -1.8100000e+01  -1.8100000e+01   0.0000000e+00
5    1.8100000e+01  -1.8100000e+01   1.9200000e+01

  • node_name — a string label (any alphanumeric identifier)

  • x, y, z — coordinates in any consistent unit (metres, cm, etc.)

lines.txt#

Structural connectivity. One header line, then one edge per line.

node_start   node_end
1            2
2            3
3            4
4            1

Node names must match exactly those in grid.txt.

parent_child_assignments.txt (optional)#

Defines sensor-to-node rigid-body offsets for sensors that are not located exactly on a structural node. One header line, then one assignment per line.

node_parent  x_m  y_m  z_m  node_child  x_sl  y_sl  z_sl
24           0.0  0.0  1.0  5           1.0   0.0  0.0

Each entry defines a parent node with its local-frame axis directions and a child node. Displacements are interpolated from parent to child during mode-shape animation.

Measurement configuration#

setup_info.txt#

Describes one measurement setup: sampling rate, channel classification, and optional channel deletion.

Setup Name:
my_setup
Sampling Rate [Hz]:
256
Reference Channels:
2 3
Delete Channels:
5
Accel. Channels:
2 3 4
Velo. Channels:
0 1
Disp. Channels:

####
Note:
Channel numbering starts with 0.
Numbers are space-separated; leave a line blank for "none".

  • Setup Name — arbitrary string; used to label saved results.

  • Sampling Rate — in Hz (float or integer).

  • Reference Channels — column indices of the permanently installed sensors used as references for cross-spectrum / cross-correlation estimation.

  • Delete Channels — column indices to discard at load time. Remaining channels are renumbered consecutively starting from 0.

  • Accel. / Velo. / Disp. Channels — every remaining channel must appear in exactly one of these three lists. Used for unit conversion when computing mode shapes in displacement.

channel_dofs.txt#

Maps channel numbers to structural degrees of freedom for mode-shape plotting.

Channel-Nr.   Node   Azimuth   Elevation   Channel Name
0             5       28.87     -8.70       vib_l
1             5       80.98     -7.31       vib_r
2             5       55.88     29.35       vib_t
3             24       0.00    180.00       ref_x
4             24     -90.00      0.00       ref_y

  • Channel-Nr. — 0-based channel index (after deletions from setup_info.txt).

  • Node — node name matching an entry in grid.txt.

  • Azimuth, Elevation — sensor orientation in degrees. Azimuth is measured counter-clockwise from the x-axis in the x-y plane; elevation is measured up from the x-y plane.

  • Channel Name — arbitrary label used in plots.

Method configuration files#

ssi_config.txt (BRSSICovRef / SSIData / SSIDataMC)#

Number of Block-Columns:
200
Maximum Model Order:
40
Use Multiprocessing:
yes

  • Number of Block-Columns — number of block columns in the Toeplitz / Hankel matrix. Must satisfy block_columns + block_rows < m_lags where block_rows defaults to block_columns and m_lags is the lag length used in corr_blackman_tukey / corr_welch.

  • Maximum Model Order — model orders 1 … max_order are evaluated.

  • Use Multiprocessing — yes / no (currently not used by all methods).

plscf_config.txt (PLSCF)#

Begin Frequency:
0
End Frequency:
20
Samples per time segment:
4096
Maximum Model Order:
50

  • Begin / End Frequency — restrict the identified frequency band (Hz). Set Begin Frequency: 0 and End Frequency to the Nyquist frequency to include everything.

  • Samples per time segment — length of the correlation sequence used to build the half-spectra (equivalent to m_lags for SSI-cov).

varssi_config.txt (VarSSIRef)#

Number of Block-Columns:
200
Maximum Model Order:
100
Use Multiprocessing:
yes
Number of Blocks:
30
Subspace Method (projection/covariance):
covariance
LSQ Method for A (pinv/qr):
pinv
Variance Algorithm (fast/slow):
fast

Additional parameters compared to ssi_config.txt:

  • Number of Blocks — the record is split into this many non-overlapping blocks for Monte-Carlo variance estimation.

  • Subspace Method — covariance uses block-Toeplitz covariance matrices (recommended); projection uses a direct subspace projection.

  • LSQ Method for A — least-squares solver for the state matrix: pinv (Moore–Penrose pseudo-inverse) or qr (QR decomposition).

  • Variance Algorithm — fast uses a linearisation approximation (recommended); slow uses the full sensitivity computation.

Configuring without files#

All parameters that can be set via configuration files can also be set directly in Python, which is the recommended approach in Jupyter notebooks. See Getting Started for the equivalent Python-only workflow.