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Table of Contents
Metric Time of Global Minimum from Event
Overview
The Metric Time of Global Minimum from Event command can be used to record the time or value of a global min in relation to a defined event. For example, one could record the time to minimum knee flexion in a jump in relation to to their takeoff/landing. The command can be found in the Pipeline Workshop under Metric.
Pipeline Command
The command syntax is as follows:
Metric_Time_Of_Global_Minimum_From_Event ! /RESULT_METRIC_TIME= ! /RESULT_METRIC_VALUE= ! /RESULT_FOLDER=PROCESSED ! /RESULT_COMPONENTS=ALL ! /SIGNAL_TYPES= ! /SIGNAL_FOLDER=ORIGINAL ! /SIGNAL_NAMES= ! /SIGNAL_COMPONENTS= ! /FRAME_OFFSET=0 ! /TIME_OFFSET= ! /EVENT_SEQUENCE= ! /EXCLUDE_EVENTS= ! /EVENT_SEQUENCE_INSTANCE=0 ! /EVENT_SUBSEQUENCE= ! /SUBSEQUENCE_EXCLUDE_EVENTS= ! /EVENT_SUBSEQUENCE_INSTANCE=0 ! /EVENT_INSTANCE=0 ! /THRESHOLD= ;
Command Parameters
The following table shows the command parameters seen above and their descriptions:
| /RESULT_METRIC_TIME= | Time of minimum from event. |
| /RESULT_METRIC_VALUE= | Value of minimum after event. |
| /RESULT_FOLDER= | Name of folder designated for results. |
| /RESULT_COMPONENTS= | Components to be included in results. |
| /SIGNAL_TYPES= | The type of signal to be processed |
| /SIGNAL_NAMES= | The name of the signal to be processed |
| /SIGNAL_FOLDER | The folder of the signal to be processed |
| /SIGNAL_COMPONENTS= | The component of the signal to be processed |
| /FRAME_OFFSET= | The offset (in frames) to apply to the event. |
| /TIME_OFFSET= | The time offset (in seconds) to apply to the event. |
| /EVENT_SEQUENCE= | A list of events (separated by “+” signs). |
| /EXCLUDE_EVENTS= | This Event_Sequence must not be during the sequence requested. |
| /EVENT_SEQUENCE_INSTANCE= | Index of the sequence instance to evaluate (0 = all, 1 = first, etc.). |
| /EVENT_SUBSEQUENCE= | Optional inner event window within a broader sequence. |
| /SUBSEQUENCE_EXCLUDE_EVENTS= | This Event subsequence must not be during the sequence requested. |
| /EVENT_SUBSEQUENCE_INSTANCE= | Index of the subsequence instance to evaluate (0 = all, 1 = first, etc.). |
| /EVENT_INSTANCE= | Defines how many event occurrences to consider. |
| THRESHOLD | Threshold value to trigger event detection. |
Dialog
The command can be edited in a text editor or in a dialog form. To edit in the dialog pop up form either click on the Edit button in the pipeline workshop or double-click on the pipeline command. The dialog is shown below.
The dialog box allows you to assign values to the command parameters outlined above.
Notes
Event_Labels are defined by the c3d format. Event_Labels exist only at Motion Capture frames (e.g. at Point Rate). For model based kinematic and kinetic calculations this is fine, because these signals only exist at Motion Capture frames.
For measures of timing that involve signals that are at ANALOG rate (e.g. Force Platform data) the motion capture rate isn't sufficient.
In Version 5 a series of metric commands were introduced to identify the time of a threshold crossing or maximum at the analog rate.
Example:
Example: Finding Trail leg minimum GRF in Baseball Swing
Here we look at how to create key events at global maximums in the baseball swing and determine the time between those events and other maximums.
First, define a new event for maximum bat speed in the z direction:
Event_Global_Maximum /RESULT_EVENT_NAME=MAX_BAT_SPEED /SIGNAL_TYPES=LINK_MODEL_BASED /SIGNAL_FOLDER=ORIGINAL /SIGNAL_NAMES=BAT_ANGULAR_VELOCITY /SIGNAL_COMPONENTS=Z ! /FRAME_OFFSET=0 ! /TIME_OFFSET= ! /EVENT_SEQUENCE= ! /EXCLUDE_EVENTS= ! /EVENT_SEQUENCE_INSTANCE=0 ! /EVENT_SUBSEQUENCE= ! /SUBSEQUENCE_EXCLUDE_EVENTS= ! /EVENT_SUBSEQUENCE_INSTANCE=0 ! /THRESHOLD= ;
Now that this event has been defined we can use the Metric Time of Global Minimum command to determine the difference in time between the maximum bat speed (which should occur around impact) and the minimum vertical reaction force in the trail leg.
Metric_Time_Of_Global_Minimum_From_Event /RESULT_METRIC_TIME=MIN_TRAIL_GRF_TIME /RESULT_METRIC_VALUE=MIN_TRAIL_GRF_VALUE /RESULT_FOLDER=PROCESSED /RESULT_COMPONENTS=Z /SIGNAL_TYPES=FORCE /SIGNAL_FOLDER=ORIGINAL /SIGNAL_NAMES=FP4 /SIGNAL_COMPONENTS=Z ! /FRAME_OFFSET=0 ! /TIME_OFFSET= /EVENT_SEQUENCE=MAX_BAT_SPEED ! /EXCLUDE_EVENTS= ! /EVENT_SEQUENCE_INSTANCE=0 ! /EVENT_SUBSEQUENCE= ! /SUBSEQUENCE_EXCLUDE_EVENTS= ! /EVENT_SUBSEQUENCE_INSTANCE=0 ! /EVENT_INSTANCE=0 ! /THRESHOLD= ;
The new metric MIN_TRAIL_GRF_TIME tells us that for this trial the lowest vertical reaction force at the trail foot came just 0.031 seconds after max bat speed.
