EMG Filters

Overview

This library provides the following filters for processing OYMotion's sEMG signals:

1. an anti-hum notch filter to filter out 50HZ or 60HZ power line noise.
2. a lowpass filter to filter out noises above 150HZ.
3. a highpass filter to filter out noises below 20HZ.

You can turn on or off these filters by the init function.

Note:

Only input frequencies of 500HZ and 1000HZ are supported!

As you might have known, there has been some existing DSP libraries which provide rich set of functions you may need (e.g. https://github.com/vinniefalco/DSPFilters). Rather than re-inventing the wheel, what we're going to provide is a set of simplified functions that allows developers to focus on sEMG signal processing with common configurations.

How to Use It

The library is written in standard C++ without dependency of external libraries, so it should be easy to embed it into any C++ project.

A simple sample code for using on Arduino in the example folder is provided for your reference.

The sample program prints envelope, which is squared sEMG signal data, to serial line. The user can plot it using Arduino SerialPlotter.

This sample program also helps the user calibrate the baseline value with the maximal value of input sEMG signal while relaxing muscles for a while.

Note:

It is recommended that you do calibration every time you wear the sEMG sensor before using the data. After calibration, any squared value of sEMG signal below the baseline will be treated as zero.