Eye tracking has a long history in medical and psychological research as a tool for recording and studying human visual behavior. Real-time gaze-based text entry can also be a powerful means of communication and control for people with physical disabilities. Following recent technological advances and the advent of affordable eye trackers, there is a growing interest in pervasive attention-aware systems and interfaces that have the potential to revolutionize mainstream human-technology interaction. In this chapter, we provide an introduction to the state-of-the art in eye tracking technology and gaze estimation. We discuss challenges involved in using a perceptual organ, the eye, as an input modality. Examples of real life applications are reviewed, together with design solutions derived from research results. We also discuss how to match the user requirements and key features of different eye tracking systems to find the best system for each task and application.

Eye Tracking and Eye-Based Human–Computer Interaction

The electroencephalogram (EEG), the blood pressure wave, and the electrocardiogram (ECG), produce patterns that the eye of the physician has empirically correlated with important aspects of health. Digital computer techniques for the recognition of these patterns are made particularly difficult by the realities of pattern context sensitivity, frequent signal artifact, real-time operation, finite storage limitations, and reasonable cost. Evaluations of these techniques are handicapped by the absence of absolute standards, the wide signal variability associated with pathologic states, and the sheer mechanics of comparison with human analysis. Computer analysis of the EEG has been directed toward monitoring sleep and certain pathologic states, leaving the more difficult problem of diagnosis to the trained neurologist. Automatic pattern recognition of the blood pressure wave has been implemented with straightforward techniques for diagnostic use in the cardiac catheterization laboratory and for monitoring in the intensive care unit. Computer analysis of the ECG has been directed toward morphological and rhythm diagnosis, having great potential utility in clinical heart stations, and toward rhythm monitoring, a most practical application arising in coronary intensive care units. Promising systems are emerging, but years of evaluation and adjustment will be necessary to meet the need for both accuracy and economy.

Digital analysis of the electroencephalogram, the blood pressure wave, and the electrocardiogram

EEG sleep stage scoring by an automatic hybrid system.

The placement of fully available prime movers having a DC output at a location inside or adjacent to an inverter-based intermittently available renewable energy site is disclosed. The fully available prime movers add reliability to an unreliable energy asset that is reaching its maximum penetration within the grid due to its unpredictability and the requirement for additional spinning reserves in other parts of the grid. The present invention can provide a portion or all of the power to an intermittently available renewable power generating facility so that the power output to the power grid is dispatchable power. In particular, a method and means are disclosed to utilize high-efficiency engines operated on various fuels some of which may be non-fossil fuels to maintain a constant power output from an otherwise intermittent power generating facility.

Dispatchable power from a renewable energy facility

Principles of Automatic Analysis of Sleep Records with a Hybrid System

A voltage and current monitoring system for use in detecting pulse and continuous voltages and currents on a rotating shaft. The system includes contacts for electrically grounding a shaft and means for monitoring current flow through a grounding contact and to provide an alarm if excessive current is present. Voltage monitoring circuits are also provided to ascertain whether the grounding contacts are operative and to provide an alarm is excessive voltage is present between the shaft and ground.

Voltage and current monitoring system

A multichannel hybrid system for rapid eye movement detection (REM detection)

A control system for a marine turbine power plant is disclosed wherein the input signal to an electrohydraulic valve positioning circuit for ahead and astern turbines may be directly related to a desired valve position signal input set at a throttle lever. Hence, primary control is by a desired valve position signal. A speed feedback circuit is included and selectively applied to the desired valve position signal as a valve position trimming signal. Another input into the primary control or desired valve position is a malfunction proportional control signal which tracks boiler operation, shaft vibration and overspeed. The valve position signal is applied to the valve positioning circuit through a rate limiter which may be set at a fast, normal, or slow rate depending upon an input from a system interface board.

Marine turbine control

An automatic rollover circuit is included in a marine turbine control system, the automatic rollover circuit capable of detecting zero-shaft speed and directing an output signal to the valve position control for opening either ahead and astern valves. If rollover is detected, then the automatic rollover circuit is reset to await the next zero-speed condition. If rollover does not occur, the automatic rollover circuit is reset to attempt a rollover in the opposite direction and a shaftstopped alarm is activated. A rollover trip circuit is also included as a protective device when the automatic rollover circuit is in use.

Automatic rollover marine turbine control

A valve actuating system is comprised of a pair of valves spring-biased to their closed positions, a pair of hydraulic actuators, each controlling one of the valves, and means for introducing pressurized fluid into the actuators. The actuators are so arranged that when pressurized fluid is introduced into the actuators, the valves are sequentially moved in opposite directions, thus closing one valve and then opening the other. The means for introducing pressurized fluid includes two pressure sources for actuation of the valves, a pair of solenoid valves and hydraulic circuitry, all interconnected, so that fluid can be introduced from either pressure source. Emergency and fail-safe closure of the valves is also provided by biasing the valves to their closed positions.

Michael J. Cronin

Papers

Voltage and current monitoring system

A multichannel hybrid system for rapid eye movement detection (REM detection)

Marine turbine control

Automatic rollover marine turbine control

Valve actuating system