SSVEP-Based BCI Wheelchair Control System
Ce Zhou
A brain-computer interface (BCI) is a system that allows a person to
communicate or control the surroundings without depending on the brain's normal
output pathways of peripheral nerves and muscles. A lot of successful
applications have arisen utilizing the advantages of BCI to assist disabled
people with so-called assistive technology. Considering using BCI has fewer
limitations and huge potential, this project has been proposed to control the
movement of an electronic wheelchair via brain signals. The goal of this
project is to help disabled people, especially paralyzed people suffering from
motor disabilities, improve their life qualities. In order to realize the
project stated above, Steady-State Visual Evoked Potential (SSVEP) is involved.
It can be easily elicited in the visual cortical with the same frequency as the
one is being focused by the subject. There are two important parts in this
project. One is to process the EEG signals and another one is to make a visual
stimulator using hardware. The EEG signals are processed in Matlab using the
algorithm of Butterworth Infinite Impulse Response (IIR) bandpass filter (for
preprocessing) and Fast Fourier Transform (FFT) (for feature extraction).
Besides, a harmonics-based classification method is proposed and applied in the
classification part. Moreover, the design of the visual stimulator combines
LEDs as flickers and LCDs as information displayers on one panel.
Microcontrollers are employed to control the SSVEP visual stimuli panel. This
project is evaluated by subjects with different races and ages. Experimental
results show the system is easy to be operated and it can achieve approximately
a minimum 1-second time delay. So it demonstrates that this SSVEP-based
BCI-controlled wheelchair has a huge potential to be applied to disabled people
in the future.