.. _auto_curve_disp_to_ait:

*DISP TO ENERGY DENSITY VS TIME*
================================

Converts a displacement–time curve into an Acceleration Injury Threshold (AIT) energy-density-vs-time curve by differentiating twice to obtain acceleration, optionally scaling axes, and applying a selectable low-pass filter. Use this worker when you need to derive AIT injury metrics directly from raw displacement time-history data.

When to use
-----------

Classification: **process**.

Tagged: ``AIT``, ``CFC``, ``SAE``, ``acceleration``, ``crash``, ``curve_transform``, ``disp_to_ait``, ``displacement``.

Inputs
------

.. list-table::
   :header-rows: 1
   :widths: 20 20 20 20 20 20

   * - Label
     - ID
     - Type
     - Default
     - Required
     - Description
   * - Base Curve
     - base_curve
     - vector
     - —
     - 
     - Input displacement–time curve (vector of [time, displacement] pairs) to be transformed into an AIT energy-density curve; leave empty only if the curve is supplied upstream in the workflow.
   * - X Sf
     - x_sf
     - scalar
     - —
     - 
     - Multiplicative scale factor applied to the time axis (x-values) before processing; defaults to 1.0 (no scaling) if left blank.
   * - Y Sf
     - y_sf
     - scalar
     - —
     - 
     - Multiplicative scale factor applied to the displacement axis (y-values) before processing; defaults to 1.0 (no scaling) if left blank.
   * - FilterType
     - filter_type
     - scalar
     - lsprepost_sae
     - 
     - Low-pass filter algorithm applied to the differentiated acceleration signal; choose from lsprepost_sae (default), lsprepost_bw, lsprepost_cos, lsprepost_fir, cfc, or sae — match the filter convention used in your post-processing tool.
   * - Frequency
     - frequency
     - integer
     - 300
     - 
     - Cut-off frequency (Hz) for the selected filter; standard crash-channel values are 30, 60, 120, 180, 300 (default), 600, or 1000 Hz — select per the applicable injury-channel class (e.g., SAE 300 for head/chest).

Outputs
-------

.. list-table::
   :header-rows: 1
   :widths: 20 20 20 20

   * - Label
     - ID
     - Type
     - Description
   * - curve_disp_to_ait_output_1
     - curve_disp_to_ait_output_1
     - vector
     - Resulting AIT energy-density–vs–time curve (vector of [time, energy-density] pairs) derived from the scaled, filtered, and twice-differentiated input displacement signal.

Disciplines
-----------

- data.curve.transform
- data.signal_processing
- engineering.crash.occupant_safety

Runnable example
----------------

A runnable example is registered for this worker. Open the example workflow on the d3VIEW canvas: `/api/workflow/example?id=curve_disp_to_ait <https://www.d3view.com/api/workflow/example?id=curve_disp_to_ait>`_

.. raw:: html

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   Auto-generated from <code>transformation</code> schema. Worker id: <code>curve_disp_to_ait</code>. Schema hash: <code>36c692d90137</code>. Hand-curated docs in <code>workerexamples/</code> override this page when present.
   </p>