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visual3d:tutorials:emg:typical_emg_processing [2024/06/18 13:35] – sgrangervisual3d:tutorials:emg:typical_emg_processing [2024/11/15 18:04] (current) – [Open Files and Tag] wikisysop
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-====== Introduction ======+====== Typical EMG Processing ======
  
-**EMG** stands for **electromyography**, which is the study of electrical signals from active muscles that are receiving input from the central nervous system. More information on EMG can be found in most good biomechanics and motor control textbooks, and on [[http://en.wikipedia.org/wiki/Electromyography|Wikipedia]]. Additional information on EMG processing requirements for the [[http://www.isek-online.org/standards.html|International Society of Electrophysiology and Kinesiology]]. You will also find other useful information on EMG signal processing posted by [[[http://noraxon.com/downloads/educational.php3|Noraxon]]]+**EMG** stands for **electromyography**, which is the study of electrical signals from active muscles that are receiving input from the central nervous system. This wiki includes an overview of [[visual3d:documentation:emg:emg_overview|how to process EMG data in Visual3D]]. More information on EMG can be found in most good biomechanics and motor control textbooks, and on [[http://en.wikipedia.org/wiki/Electromyography|Wikipedia]]. Additional information on EMG processing requirements for the [[http://www.isek-online.org/standards.html|International Society of Electrophysiology and Kinesiology]]. You will also find other useful information on EMG signal processing posted by [[http://noraxon.com/downloads/educational.php3|Noraxon]].
  
-This tutorial will show the basic steps for processing EMG data into Visual3D. Files used in this tutorial can be found here: [[[https://www.has-motion.com/download/examples/EMG_Tutorial.zip|EMG Tutorial]]]+===== Overview ===== 
 +This tutorial will show the basic steps for processing EMG data into Visual3D. Files used in this tutorial can be found here: [[https://www.has-motion.com/download/examples/EMG_Tutorial.zip|EMG Tutorial]]
  
-The tutorial will go through a step by step process using Visual 3D pipeline commands to process the example EMG data. It will do the following:+===== Visual 3D Implementation ===== 
 + 
 +Visual3D expects the EMG signals to be stored in the C3D file as ANALOG data, not unlike force platform data. One point of importance is that EMG typically has very high frequency content, which means that it must be sampled at high data sampling rates. As of Visual3D Version 5.0, EMG signals are stored as integer multiples of the motion capture sampling rate (e.g. consistent with the common use of the C3D file format). One of the nuisances caused by this requirement is that force platform data must be sampled at a very high rate in order to match the EMG sampling rate. 
 + 
 +All of Visual3D's [[visual3d:documentation:pipeline:signal_commands:signal_commands_overview|pipeline commands for signal processing]] can be used with EMG data. 
 + 
 +===== Processing EMG Signals with the Visual3D Pipeline ===== 
 + 
 +The tutorial will go through a step by step process using [[visual3d:documentation:pipeline:general_information:pipeline_commands_reference|Visual3D pipeline commands]] to process the example EMG data. It will do the following:
  
   - Open Files and Tags   - Open Files and Tags
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   - Normalize based off of 4 different methods   - Normalize based off of 4 different methods
  
-====== Visual 3D Implementation ====== +==== Open Files and Tag ====
- +
-Visual3D expects the EMG signals to be stored in the C3D file as ANALOG data, not unlike force platform data. One point of importance is that EMG typically has very high frequency content, which means that it must be sampled at high data sampling rates. +
- +
-As of Visual3D Version 5.0 EMG signals are stored as integer multiples of the Motion Capture sampling rate (e.g. consistent with the common use of the C3D file format). One of the nuisances caused by this requirement is that force platform data must be sampled at a very high rate in order to match the EMG sampling rate. +
- +
-All signal processing commands in the pipeline can be used with EMG data. +
- +
-====== EMG Processing using Visual 3D Pipeline commands ====== +
- +
-The tutorial will go through a step by step process using Visual 3D pipeline commands to process the example EMG data. +
- +
-===== Open Files and Tag =====+
  
 This section will walk you through pipeline commands that will open files and automatically assign tags to motion files for **Movement** and **MVIC** trials. This section will walk you through pipeline commands that will open files and automatically assign tags to motion files for **Movement** and **MVIC** trials.
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 ! /QUERY= ! /QUERY=
 /TAGS=MVC_C /TAGS=MVC_C
-';+;
  
 !Assign Tags to walking files !Assign Tags to walking files
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 </code> </code>
  
-===== Create Pipeline Parameter "EMG Signals" =====+==== Create Pipeline Parameter "EMG Signals" ====
  
 Use the command **Set_Pipeline_Parameter**, to set up a pipeline parameter to contain the EMG signal names. Use the command **Set_Pipeline_Parameter**, to set up a pipeline parameter to contain the EMG signal names.
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 </code> </code>
  
-===== Apply a Band Pass Filter =====+==== Apply a Band Pass Filter ====
  
 Apply a band pass filter to the EMG data with the commands **Highpass_Filter** and **Lowpass_Filter**. Surface EMG signals have a frequency content between 20 and 500 Hz. Apply a band pass filter to the EMG data with the commands **Highpass_Filter** and **Lowpass_Filter**. Surface EMG signals have a frequency content between 20 and 500 Hz.
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 </code> </code>
  
-===== Compute an Envelope =====+==== Compute an Envelope ====
  
 Compute the linear envelope of the EMG signal by calculating the RMS value using the command **Moving_RMS** for short successive time periods (the time period is described as a moving window). More information on calculating the RMS can be found at the [[Visual3D:Documentation:Pipeline:Signal_Commands:Moving_RMS|Moving RMS]] page. Compute the linear envelope of the EMG signal by calculating the RMS value using the command **Moving_RMS** for short successive time periods (the time period is described as a moving window). More information on calculating the RMS can be found at the [[Visual3D:Documentation:Pipeline:Signal_Commands:Moving_RMS|Moving RMS]] page.
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 </code> </code>
  
-===== Create Normalization Factor and Scale =====+==== Create Normalization Factor and Scale ====
  
 There are four alternative normalization methods describes in this tutorial. There are four alternative normalization methods describes in this tutorial.
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 </code> </code>
  
-==== Normalize EMG to MVC ====+==== Approach 1: Normalize EMG to MVC ====
  
 This pipeline normalizes the EMG signal by dividing the EMG signal by the maximum value of the EMG signal from a separate trial (e.g. a trial that elicits a maximum voluntary contraction (MVC) from the muscle). This pipeline normalizes the EMG signal by dividing the EMG signal by the maximum value of the EMG signal from a separate trial (e.g. a trial that elicits a maximum voluntary contraction (MVC) from the muscle).
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 </code> </code>
  
-==== Normalize EMG to Generic Global Variable ====+==== Approach 2: Normalize EMG to Generic Global Variable ====
  
 Typically the scaling factors for EMG signals are the result of other data trials (such as MVIC trials). Individual files in Visual3D cannot access the data from other files, so the only way signals can be shared is through the Global Workspace. This pipeline normalizes the EMG signal to a global variable. Typically the scaling factors for EMG signals are the result of other data trials (such as MVIC trials). Individual files in Visual3D cannot access the data from other files, so the only way signals can be shared is through the Global Workspace. This pipeline normalizes the EMG signal to a global variable.
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 </code> </code>
  
-==== Normalize to Maximum 30 second interval ====+==== Approach 3: Normalize to Maximum 30 second interval ====
  
 This pipeline normalizes to the greatest ½ second activity during a 5 second trial. A window of twenty-five .02 second intervals of integrated EMG is moved one interval at a time across the 5 seconds of data to find the greatest EMG. The average integrated EMG during the ½ second is used to compute the normalization factor. It does the following: This pipeline normalizes to the greatest ½ second activity during a 5 second trial. A window of twenty-five .02 second intervals of integrated EMG is moved one interval at a time across the 5 seconds of data to find the greatest EMG. The average integrated EMG during the ½ second is used to compute the normalization factor. It does the following:
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 </code> </code>
  
-==== Normalize to the Maximum within Each Gait Cycle ====+==== Approach 4: Normalize to the Maximum within Each Gait Cycle ====
  
 For this example, the goal is as follows: For this example, the goal is as follows:
visual3d/tutorials/emg/typical_emg_processing.1718717716.txt.gz · Last modified: 2024/06/18 13:35 by sgranger