Design of a Novel Efficient Human–ComputerInterface: An Electrooculoagram Based Virtual

Keyboard

出處 :IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT,

VOL. 59, NO. 8, AUGUST 2010作者 :Ali Bulent Usakli and Serkan

Gurkan報告者 : 洪家楠

1.INTRODUCTION 2.HCIs 3.NEW EOG-BASED SYSTEM 4.RESULTS AND DISCUSSION 5.CONCLUSION

Outline

It is assumed that the population of people aged 60 and beyond will range from one to three in 2030

Considering life span extension and the handicapped, the need for a human–computer interface (HCI) has been increasing

1.INTRODUCTION

Cognitive functions are generally normal, patients with amyotrophic lateral sclerosis

Other tetraplegic clinical conditions (e.g., the locked-in syndrome) have severe disabilities in moving their whole bodies.

INTRODUCTION(2)

Some of these patients can only move their eyeballs. Establishing a new channel without overt speaking and hand/arm motions makes life easier for patients and therefore improves their life quality.

INTRODUCTION(3)

Paralyzed stroke patients are unable to normally communicate with their environment.

their body that is under their control, in terms of muscular movement, is their eyeballs.

INTRODUCTION(4)

As a review of the state of the art of electrooculogram (EOG) systems, there are several EOG-based HCI applications for different purposes in the literature.

Our motivation is to increase the quality of life of these patients using an HCI that provides an efficient communication channel.

INTRODUCTION(5)

The interface that provides control of machines for disabled people is called manmachine interface (MMI) in general.

If control can be made by using a computer-based (or microcomputer-based) system, it is called HCI, instead of MMI, which has the same meaning.

2.HCIs(human-computer interface)

The electrical signals generated by the human brain that are related to body functions are called an electroencephalogram (EEG).

If the assistive system is based on EEG, it is called the brain computer interface (BCI), and its applications for severely disabled people are increasing.

HCI(2)

A. EEG-Based HCI Systems B. EOG-Based HCI Systems C. EOG Measurement

HCI(3)

EEG-based systems are the most commonly used in HCI applications because of the possibility of noninvasive measurement on the scalp.

BCI systems are generally EEG-based systems and can translate brain activity into electrical signals that control external devices.

EEG-Based HCI Systems

BCI systems can provide a communication and control channel

That bypasses conventional neuromuscular pathways involved in speaking or making movements to manipulate objects.

EEG-Based HCI Systems(2)

Electroculography is a technique for measuring the resting potential of the eye, and the resulting signal is called EOG.

These signals show certain patterns for each kind of eye movement (left, right, up, down, and blink).

EOG-Based HCI Systems

An EOG-based virtual keyboard provides a means for paralyzed patients to type letters onto a monitor with eye movements without using the normal keyboard.

Most of the research in this research field focused on translating four eye movements (left, right, up, and down) and eye blink to select characters from the monitor for typing onto the screen (i.e., speller).

EOG-Based HCI Systems(2)

Considering EOG signal properties, EOG-based HCI systems are more efficient than EEG-based systems in some cases.

When light comes to this layer, the nervous system transmits the signal to the visual cortex in the brain. The eyes are rotated by six muscles, and the eyeballs make these movements.

EOG-Based HCI Systems(3)

1) Saccadic 2) Vergence 3) Pursuit 4) Vestibular occular reflex (VOR): 5) Optokinetic response (OKR):

EOG-Based HCI Systems(4)

EOG-Based HCI Systems(5)

Recordings in EOG signal measurement electrodes

EOG Measurement

EOG signals are roughly in the band of about 0–100 Hz and 50–3500 μV.

Measurement and processing of the EOG signal are easier than those of EEG (< 100 μV) signals.

Compared with EEG signals, EOG signals have greater amplitude.

EOG Measurement(2)

In the design of EOG amplifiers, removing dc drift and providing signal linearity are the main research areas.

In the design of biopotential amplifiers, saturation due to dc level, dc drift, 50-Hz (or 60-Hz) power line noise, and other noises .

3.NEW EOG-BASED SYSTEM

1) Subject/patient safety must be provided.

2) Electronic noise, particularly power line noise, is reduced as much as possible.

3) Biological signal originality must be kept.

4) Electronic noise and electromagnetic interferences should be considered.

NEW EOG-BASED SYSTEM(2)

NEW EOG-BASED SYSTEM(3)

1) Two channels for horizontal and vertical eye movements.

2) Use of Ag/AgCl electrodes. 3) By using differentiating approaches, the dc level and power line noise are removed.

4) 10-bit digital resolution. 5) μC-based system. 6) Communication through serial ports. 7) Event marker ability. 8) Battery-powered operation. 9) NN algorithm for classification. 10) The system is realized with available and economical components.

NEW EOG-BASED SYSTEM(4)

NEW EOG-BASED SYSTEM(5)

Electronic Circuitry

Electronic Circuitry(2)

輸入放大器電路 濾掉直流電頻

Electronic Circuitry(3)

NEW EOG-BASED SYSTEM(6)

NEW EOG-BASED SYSTEM(7)

NEW EOG-BASED SYSTEM(8)

NEW EOG-BASED SYSTEM(9)

EOG signal measurements are easier than EEG signal measurements. Because EOG signals are caused by muscle motions

In the design of biopotential measurement systems, to reject the common-mode signal

4.RESULTS AND DISCUSSION

Although EEG-based HCI systems are common, they are expensive, inefficient, and impractical, compared with EOG based systems for patients who are able to move their eyeballs.

RESULTS AND DISCUSSION(2)

1) Horizontal and vertical EOG signals are successfully measured.

2) The EOG signals for different eye movements are classified in real time.

3) The realized virtual keyboard .

RESULTS AND DISCUSSION(3)

Crucial factors in the design of an EOG-based system include subject/patient safety.

Power line noise reduction, and keeping signal originality.

V. CONCLUSION

These properties are speech ability, wheelchair control, and robot arm control.

Speech and device motion control with eye movement facility is important in making the life of a severely disabled patient easier.

Then, the realized system will be tested by several patients to improve the quality of the graphic interface for better and quick selections of the menu options.

CONCLUSION(2)