Alternative communication systems for people with severe motor disabilities: a survey <s> EOG applications <s> User-computer dialogues are typically one-sided, with the bandwidth from computer to user far greater than that from user to computer. The movement of a user’s eyes can provide a convenient, natural, and high-bandwidth source of additional user input, to help redress this imbalance. We therefore investigate the introduction of eye movements as a computer input medium. Our emphasis is on the study of interaction techniques that incorporate eye movements into the user-computer dialogue in a convenient and natural way. This chapter describes research at NRL on developing such interaction techniques and the broader issues raised by non-command-based interaction styles. It discusses some of the human factors and technical considerations that arise in trying to use eye movements as an input medium, describes our approach and the first eye movement-based interaction techniques that we have devised and implemented in our laboratory, reports our experiences and observations on them, and considers eye movement-based interaction as an exemplar of a new, more general class of non-command-based user-computer interaction. <s> BIB001 </s> Alternative communication systems for people with severe motor disabilities: a survey <s> EOG applications <s> Present the development of a human-mobile robot communication system using electrooculogram (EOG) signals. An ideal velocity shape signal processing algorithm is proposed to extract position data where the eyes are focusing on from the noise and drift included in EOG signals. Additionally, an efficient algorithm for the detection of various eye-lip movements such as blink and wink is suggested. Two experiments were performed for the validation of the human-mobile communication system. One is point stabilization of a mobile robot, using extracted eye focusing position data. The other is a moving target following experiment using various eye-lip movements as mobile robot commands. <s> BIB002 </s> Alternative communication systems for people with severe motor disabilities: a survey <s> EOG applications <s> This paper describes an eye-control method, based on electrooculography (EOG), for guiding and controlling a wheelchair for disabled people; the control is actually effected by eye movements within the socket. An eye model based on an electrooculographic signal is proposed and its validity is studied. Different techniques and guidance strategies are then shown with comments on the advantages and disadvantages of each one. The system consists of a standard electric wheelchair with an on-board computer, sensors and a graphic user interface run by the computer. This control technique could be useful in multiple applications, such as mobility and communication aid for handicapped persons. <s> BIB003 </s> Alternative communication systems for people with severe motor disabilities: a survey <s> EOG applications <s> This paper describes an eye-control method based on electrooculography (EOG) to develop a system for assisted mobility. One of its most important features is its modularity, making it adaptable to the particular needs of each user according to the type and degree of handicap involved. An eye model based on electroculographic signal is proposed and its validity is studied. Several human-machine interfaces (HMI) based on EOG are commented, focusing our study on guiding and controlling a wheelchair for disabled people, where the control is actually effected by eye movements within the socket. Different techniques and guidance strategies are then shown with comments on the advantages and disadvantages of each one. The system consists of a standard electric wheelchair with an on-board computer, sensors and a graphic user interface run by the computer. On the other hand, this eye-control method can be applied to handle graphical interfaces, where the eye is used as a mouse computer. Results obtained show that this control technique could be useful in multiple applications, such as mobility and communication aid for handicapped persons. <s> BIB004 </s> Alternative communication systems for people with severe motor disabilities: a survey <s> EOG applications <s> A communication support interface controlled by eye movements and voluntary eye blink has been developed for disabled individuals with motor paralysis who cannot speak. Horizontal and vertical electro-oculograms were measured using two surface electrodes attached above and beside the dominant eye and referring to an earlobe electrode and amplified with AC-coupling in order to reduce the unnecessary drift. Four directional cursor movements ---up, down, right, and left--- and one selected operation were realized by logically combining the two detected channel signals based on threshold settings specific to the individual. Letter input experiments were conducted on a virtual screen keyboard. The method's usability was enhanced by minimizing the number of electrodes and applying training to both the subject and the device. As a result, an accuracy of 90.1 ± 3.6% and a processing speed of 7.7 ± 1.9 letters/min. were obtained using our method. <s> BIB005 </s> Alternative communication systems for people with severe motor disabilities: a survey <s> EOG applications <s> An alternative human interface enabling the handicapped with severe motor disabilities to control an assistive system is presented. Since this interface relies on the biosignals originating from the contraction of muscles on the face during particular movements, even individuals with a paralyzed limb can use it with ease. For real-world application, a dedicated hardware module employing a general-purpose DSP was implemented and its validity tested on an electrically powered wheelchair. Furthermore, an additional attempt to reduce error rates to a minimum for stable operation was also made based on the entropy information inherent in the signals during the classification phase. In the experiments in which 11 subjects participated, it was found most of them could control the target system at their own will, and thus the proposed interface could be considered a potential alternative for the interaction of the severely handicapped with electronic systems. <s> BIB006 </s> Alternative communication systems for people with severe motor disabilities: a survey <s> EOG applications <s> This paper describes an eye-gaze interface using a biological signal, electro-oculorgram (EOG). This interface enables a user to move a computer cursor on a graphical user interface using eye gaze movement alone. It will be useful as a communication aid for individuals with mobility handicaps. Although EOG is easily recordable, drifting and blinking problems must be solved to produce a reliable eye-gaze interface. Here we introduced a calibration method and a feedback control to overcome these problems. <s> BIB007 </s> Alternative communication systems for people with severe motor disabilities: a survey <s> EOG applications <s> A communication support interface controlled by eye movements and voluntary eye blink has been developed for disabled individuals with motor paralysis who cannot speak. Horizontal and vertical electro-oculograms were measured using two electrodes attached above and beside the dominant eye and referring to an earlobe electrode and amplified with AC-coupling in order to reduce the unnecessary drift. Eight directional cursor movements and one selected operation were realized by logically combining the two detected channel signals based on threshold setting specific to the individuals. As experimental results using a projected screen keyboard, processing speed was improved to 12.1 letters/min. while the accuracy was 90.4%. <s> BIB008 </s> Alternative communication systems for people with severe motor disabilities: a survey <s> EOG applications <s> Human-computer interactions (HCI) have become an important area of research and development in computer science and psychology. Appropriate use of computers could be of primary importance for communication and education of those subjects which could not move, speak, see or hear properly. The aim of our study was to develop a reliable, low-cost and easy-to-use HCI based on electrooculography signal analysis, to allow physically impaired patients to control a computer as assisted communication. Twenty healthy subjects served as volunteers: eye movements were captured by means of four electrodes and a two-channel amplifier. The output signal was then transmitted to an ''Analog to Digital'' (AD) converter, which digitized the signal of the amplifier at a rate of 500Hz, before being sent to a laptop. We designed and coded a specific software, which analyzed the input signal to give an interpretation of eye movements. By means of a single ocular movement (up, down, left and right) the subjects were then able to move a cursor over a screen keyboard, passing from one letter to another; a double eye blink was then necessary to select and write the active letter. After a brief training session, all the subjects were able to confidently control the cursor and write words using only ocular movements and blinking. For each subject we presented three series of randomized words: mean time required to enter a single character was about 8.5s, while input errors were very limited (less than 1 per 250 characters). Our results confirm those obtained in previous studies: eye-movement interface can be used to properly control computer functions and to assist communication of movement-impaired patients. <s> BIB009 </s> Alternative communication systems for people with severe motor disabilities: a survey <s> EOG applications <s> Bio-based human computer interface(HCI) has attracted more and more attention of researches all over the world in recent years. In this paper, an EOG-based HCI system is introduced. It is composed of three parts: EOG amplifying and acquisition, EOG pattern recognition and control command output. Three plane electrodes are employed to detects the EOG signals, which contains the information related to the eye blinking and vertical( or horizontal ) eye movements referred to pre-designed command table. An online signal processing algorithm is designated to get the command information contained in EOG signals, and these commands could be used to control the computer or other instruments. Based on this HCI system, the remote control experiments driven by EOG are realized. <s> BIB010 </s> Alternative communication systems for people with severe motor disabilities: a survey <s> EOG applications <s> This paper discusses a brain-computer interface through electrooculogram (EOG) and electromyogram (EMG) signals. In situations of disease or trauma, there may be inability to communicate with others through means such as speech or typing. Eye movement tends to be one of the last remaining active muscle capabilities for people with neurodegenerative disorders, such as amyotrophic lateral sclerosis (ALS) also known as Lou Gehrig's disease. Thus, there is a need for eye movement based systems to enable communication. To meet this need, we proposed a system to accept eye-gaze controlled navigation of a particular letter and EMG based click to enter the letter. Eye -gaze direction (angle) is obtained from EOG signals and EMG signal is recorded from eyebrow muscle activity. A virtual screen keyboard may be used to examine the usability of the proposed system. <s> BIB011
Compared with the EEG, EOG signals have the characteristics as follows: the amplitude is relatively high, the relationship between EOG and eye movements is linear, and the waveform is easy to detect BIB010 . Considering the simplicity of EOG is also easier to classify it when compared to EMG. For these reasons, EOG-based HCI systems have become a very interesting field of research in recent years. In addition, the majority of the patients with severe motor disabilities remain able to control their eye movements. In this sense, recent studies have shown the viability of the EOG application in assistive communication systems. Borghetti et al BIB009 developed a system for writing in an alphanumeric matrix based on two EOG channels (vertical and horizontal). The cursor movement in the orthogonal directions was carried out by EOG classification based on elementary parameters like polarity, amplitude and slope, and the letter selection was made by double blinking detection from EOG. The study appealed to the low cost, around € 100. As a preliminary research, there were no bindings with voice synthesizer or other software of any kind. The interface was very simple as even the backspacing function was missing. Usakli et al  proposed a similar system where both cursor movement and letter selection were supported by an EOG classification algorithm based on the nearest neighbourhood (NN) relation. The performance of the designed system was compared with that of a P300-based BCI speller. Results showed the EOG system more efficient than P300-based BCI system in terms of accuracy, speed, applicability, and cost efficiency. Dhillon et al BIB011 proposed a virtual keyboard writer system based on two EOG channels and one EMG channel. The cursor movement was associated to the gaze angular displacement in the vertical and horizontal directions, and the letter selection was carried out by an "EMG click" obtained from eyebrow. The authors reported as advantages the lower cost and complexity of their system compared to more sophisticated methods to detect eye movements like videooculography (VOG) and infraredoculography (IROG). Other studies prove the possibility of using eye movements as a control source, such as in BIB010 to control a mini-car. The signal was transformed into trains of rectangular pulses and moving the eyes twice in the same direction indicated the command the mini-car should execute. A feedback was offered to the user, allowing the command confirmation, also through the eyes. Other applications demonstrating the potential of the EOG signal for control are to handle wheelchairs through eyes movements BIB003 BIB004 BIB006 or to control a robot BIB002 . Cursor control was showed in BIB004 where a simulator on the screen was used to train the patient to control a powered wheelchair and in BIB002 to control a robot. Being a manifestation of eye movements, EOG signals are processed to identify gaze BIB003 BIB004 BIB007 BIB001 , usually for cursor control on the screen. However, the most popular method for gaze estimation is using infrared cameras BIB001 , through the reflection in the eye structures and their geometric relations. In fact, gaze based devices may be best suitable for users with severe motor impairment that cannot move the head, as one of the technical problems presented by gaze based devices that is the lost of reference once the user moves it. Cursor control may be offered with absolute coordinates (gaze) BIB007 BIB001 or through direction of movement BIB008 BIB005 . With a simpler application, EOG signal may be used to encode Morse code messages  with looking left and right as 'dash' and 'dot', respectively. Another way of communication is to associate eyes movements sequences with symbols  that in turn, could be characters or even high level commands.