EEG Controlled Robot

For collecting the EEG signals we had used the OpenBCI's kit and we had used gopigo robot based on raspberrypi 3 for our experiments.

Data Collection

The OpenBCI EEG kit can be connected to Laptop via bluetooth dongle. The OpenBCI GUI can be used to write the raw EEG values received from kit to a file which can be used for further processing.

Data transmission between Laptop and Robot

Client-Server architecture has been used to exchange data between Laptop and robot. A server code is run on gopigo robot which is based on Linux. A client code which runs on Laptop which is based on Linux, captures data written to file from GUI and tranfer it to server running on gopigo robot. The codes specific to client and server can found under main directory and are named as read_data_file_client.py, robot_server.py respectively.

Controlling Robot with blink of an Eye

The goal of this experiment is to detect blink of an eye from EEG signal collected from FP1 area in real time and move the robot forward (f) on blink, stop (s) the robot on next blink, again forward (f) on next blink, again stop(s) on next blink and so on.

The blink is detected from EEG signal as follow.

1. The absolute current sample value is subtracted from the mean of previous 8 absolute sample values.
2. If the absolute deviation of the absolute current sample value is subtracted from the mean of previous 8 absolute sample values is greater than 100 we detect it as blink

Detection and Capture of new Samples written to a file by OpenBCI GUI

The OpenBCI GUI writes data of different EEG channels to a file. Inorder to get a new sample written to file we had used watchdog module in python to capture file system change events, when a change is observed an observer calls a function which reads new samples of different channels and transmits data of required channel namely FP1 using bash commands tail, cut and data is transmitted over socket to server running on gopigo robot.

class my_handler(FileSystemEventHandler):
    def on_modified(self,event):
        os.system('tail -1 '+ sys.argv[2] + ' | cut -d "," -f2 > tmp')
        data=open('tmp', 'r').read()
        print(data)
        global s
        s.send(str.encode(data))

event_handler = my_handler()
observer = Observer()
observer.schedule(event_handler, path, recursive=False)
observer.start()

References:

[1] Automated eye blink detection online by Irene Vigué Guix
[2] Execute shell commands in Python
[3] Socket Programming in Python (Guide) by Nathan Jennings
[4] python watchdog monitoring file for changes