Table of Contents
Removing DC Bias
Background
Normalize to greatest ½ second activity during 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.
This is just an example, so the user should modify the meta-command to suit their own needs.
The task is as follows:
- Compute a normalization factor
- Normalize to greatest ½ second during 5 second trial.
This is accomplished by using an average filter (see the bottom of the page)
- 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.
Examples
The following are examples of how to do the above task. The maximum value is calculated is a little different in the following examples. You should choose the method which makes the most sense to you.
Example 1: Single MVC Trial
- Process EMG
- High pass filter (remove DC offset)
- Calculate RMS of predetermined time intervals (example: 0.02 seconds)
- Normalize
- Calculate the average of the processed signal over 30 second intervals
- Get the maximum of the 30 second interval
- Normalize by dividing the average by the maximum
Download
You can download the sample files here.
The download contains:
- MVC_Example.cmz with -
- 3 MVC trial
- 2 Dynamic Trials
- EMG_Norm_MVC_Max_Mean_Example_1.v3s (Example Pipeline Script)
- EMG_Norm_MVC_Max_Mean_Example_1.v3m (Example Meta-Command)
- Call_EMG_Norm_MVC_Max_Mean_Example_1_Meta.v3s (Example Pipeline Script calling Meta-Command)
Example 2: Multiple MVC Trials
- Process EMG
- High pass filter (remove DC offset)
- Calculate RMS of predetermined time intervals (example: 0.02 seconds)
- Normalize
- Calculate the average of the processed signal over some time interval (in this example: 0.5 seconds)
- Get the maximum of the processed signal
- Calculate the maximum of the average signal
- Normalize by dividing the processed signal by the maximum average over the interval
Download
You can download the sample files here.
The download contains:
- MVC_Example.cmz with -
- 3 MVC trial
- 2 Dynamic Trials
- EMG_Norm_MVC_Max_Mean_Example_1.v3s (Example Pipeline Script)
- EMG_Norm_MVC_Max_Mean_Example_1.v3m (Example Meta-Command)
- Call_EMG_Norm_MVC_Max_Mean_Example_1_Meta.v3s (Example Pipeline Script calling Meta-Command)