Abstract
Amyotrophic lateral sclerosis (ALS) patients whose voluntary muscles are paralyzed commonly communicate with the outside world using eye movement. There have been many efforts to support this method of communication by tracking or detecting eye movement. An electrooculogram (EOG), an electro-physiological signal, is generated by eye movements and can be measured with electrodes placed around the eye. In this study, we proposed a new practical electrode position on the forehead to measure EOG signals, and we developed a wearable forehead EOG measurement system for use in Human Computer/Machine interfaces (HCIs/HMIs). Four electrodes, including the ground electrode, were placed on the forehead. The two channels were arranged vertically and horizontally, sharing a positive electrode. Additionally, a real-time eye movement classification algorithm was developed based on the characteristics of the forehead EOG. Three applications were employed to evaluate the proposed system: a virtual keyboard using a modified Bremen BCI speller and an automatic sequential row-column scanner, and a drivable power wheelchair. The mean typing speeds of the modified Bremen brain–computer interface (BCI) speller and automatic row-column scanner were 10.81 and 7.74 letters per minute, and the mean classification accuracies were 91.25% and 95.12%, respectively. In the power wheelchair demonstration, the user drove the wheelchair through an 8-shape course without collision with obstacles.
Highlights
Human computer/machine interface (HCI/HMI) is an interfacing technology between the user and a computer/machine
Amyotrophic lateral sclerosis (ALS), well known as Lou Gehrig’s disease, is a disease that causes the death of motor neurons [4]
In addition to the virtual keyboards, we evaluated the usability of forehead EOG for driving a power wheelchair
Summary
Human computer/machine interface (HCI/HMI) is an interfacing technology between the user and a computer/machine. HCIs using bio-signals that are voluntarily controlled, such as electromyograms (EMGs), electroencephalograms (EEGs), and electro-oculograms (EOGs), have been studied for people with disabilities. Artificial prosthesis and communication systems, including virtual keyboards, are typical HCI applications [1,2,3]. HCIs are very important technologies for people with disabilities because they are not just support tools, but they could improve a disabled person’s quality of life. The symptoms get worse until voluntary breathing becomes difficult in the end stage. Eye movements are usually spared until the final stage, the limbs and tongue are paralyzed. Many patients with ALS use communication supporting tools based on eye movement [5]
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