Part 4: The Eye-Com PERCLOS Validation Study

Eye-Com Corporation uses the EC-6 to Further Validate PERCLOS as a Metric for Drowsiness and Fatigue Detection

With the EC-6 prototype completed, a study—sponsored by the US Department of Defense (DOD) and the US Department of Transportation—was performed by Eye-Com Corporation to further validate the use of the PERCLOS alertness metric and to extend it to include those with clinical causes of drowsiness and inattention. The Eye-Com study measured PERCLOS on sleep-deprived healthy subjects as well as subjects with sleep and attention disorders using the Eye-Com Drive Simulator facility in the Washoe Sleep Disorders Center (WSDC) of Reno, Nevada.

The study consisted of thirty-one subjects divided into four groups: eight subjects with diagnosed narcolepsy, seven subjects with diagnosed obstructive sleep apnea, seven adolescent subjects of driving age diagnosed with Attention Deficit Disorder with or without Hyperactivity (ADD/ADHD), and nine control subjects with no demonstrable or significant sleep or attention disorders. In order to best replicate driver fatigue, all subjects were required to stay awake and submit to six test sessions over the course of a thirty-four-hour period. The six sessions were approximately six hours apart, and each session was divided into four tests.

The first test was performed in the WSDC/Eye-Com Drive Simulator facility. The simulator consists of a Dodge Ram truck cab facing an eighteen-foot curved screen onto which a realistic driving scenario is projected. The test duration is based on distance, not time, although the average length is forty minutes. During this session the subject was fitted with EEG electrodes and an EC-6 unit. The driving scenario was relatively simple, with no dramatic changes or obstacles.

After the subject completed the drive simulation, they then stayed in the truck cab to perform a Test of Variables of Attention (TOVA), and it is typically used in the evaluation of ADD. The test is twenty-one minutes long and is a simple and objective neurophysiological measure of attention.

Upon completing the TOVA test, subjects were then moved out of the simulator and required to complete the Maintenance of Wakefulness Test (MWT). This test simply requires the subject to sit quietly and stay awake for up to forty minutes. The test ended when the forty-minute time elapsed or when the subject fell asleep, as indicated by their ECG recording.

The final test was for the subject to respond to the SSS, or Stanford Sleepiness Scale. This test is used to quickly and subjectively assess how alert or sleepy the subject is. It consists of the subject ranking themselves on a seven-point scale, with “Feeling wide awake and alert” on one end and “Sleep onset soon” at the other.

During the simulator tests, oculometric data recorded using the EC-6 system was synchronized with data from the drive simulator, which included speed, lane position, and the time and distance across the center line, as well as the number of off-road accidents, collisions, and road-edge excursions. This made it possible to measure the eye’s behavior prior to and during various driving deviations. Analysis of the data revealed that PERCLOS is indeed an accurate measure of relative long-term sleep deprivation, although eye-blink duration (EBD), eye-gaze, and pupil area are more effective real-time indicators of an impending accident.

Read about the study’s Conclusions in Part 5…

Part 3: The Eye-Com Biosensor, Communicator and Controller (EC6)

The EC6 Measures PERCLOS to Detect Driver Drowsiness

The EC6 device is worn as an eyeglass-style, wrap-around frame. Micro-cameras embedded in the bottom, horizontal portion of the eye-frame provide video of the wearer’s eyes. LED illuminators embedded in the vertical portions of the eye-frame provide the necessary illumination upon the eye without obscuring the wearer’s vision. Data are transferred by wires running through the ear supports through a power box and to a computer running the operating software (the Eye-Com Eye-See® software).

This device can be worn as an ambulatory biosensor in any environment or domain, stationary or moving, and in any vehicle. The EC6 moves with one’s head, maintaining its same orientation to the eyes, regardless of the direction the wearer is looking or to what direction the wearer’s head is turned.

The Eye-See® program can identify the disappearance of a pupil as it is covered by a closing lid, thereby allowing for the determination of eye-blink duration (EBD) and eye-blink frequency (EBF) as well as PERCLOS. The software can also identify and track the diameter and area of the pupil, and it can track eye gaze and the movement of an eyeball over time. The EC6 system can detect and respond to driver impairment, including the gradual loss of awareness of one’s own state of sleepiness, which occurs in association with lapses in attention or sudden two- to three-second-long micro-sleeps. The EC6 can record and distinguish, in real-time, human-factor error from machine failure.

Continued in Part 4: The Eye-Com PERCLOS Validation Study

Part 2: The PERCLOS MEASURE

The PERCLOS Measure is a Reliable Indicator of Driver Drowsiness and Fatigue

PERCLOS stands for the percentage of eyelid closure over the pupil over time. A PERCLOS-monitoring device provides video taken of the eyes of the operator in order to score the percentage of a specified time that the eyelid is at least 80% closed over the pupil. First studied in 1994, PERCLOS soon proved to be more effective at drowsiness detection than all other available technology at the time. Later PERCLOS studies prompted the National Highway Traffic Association Safety Administration (NHTSA) and the US Department of Transportation (DOT) to declare PERCLOS “the most reliable and valid bio-physiological determinant of a driver’s alertness level.” The NHTSA Drowsy Driver Technology program has since produced many validation studies of the PERCLOS metric in laboratory, simulator, and applied settings.

After a review of these studies, it was determined that the ideal drowsiness-detection system would conform to NHTSA’s standard that an in-vehicle monitoring system should be unobtrusive to the vision or activity of the operator. The challenges to developing such a technology included designing a system that operates under all lighting conditions and environmental domains, especially where the driver’s head or face is constantly moving or where the driver’s eyes are obscured by sunglasses, lenses and other eye-ware, glare, or oncoming headlights. Keeping this in mind, Eye-Com Corporation developed the ambulatory and wearable Eye-Com Biosensor, Communicator and Controller System, also known as the EC-6.

Continued in Part 3: Detecting Drowsiness with the Eye-Com Eye-Com Biosensor, Communicator and Controller

Part 1: Background

Startling Statistics Present a Need For Driver Drowsiness Detection Technology

Of the many public safety issues plaguing our roadways today, drowsy-driving is of major concern. Those who drive while sleep-deprived, whether it’s a result of lifestyle choices or because of clinical sleep disorders, are shown to perform as poorly behind the wheel as legally intoxicated drivers.

According to the National Sleep Foundation (NSF), more than one-half of adults have admitted to driving while drowsy at least once in the past year. These numbers are unlikely to improve; NSF polls report that more and more Americans are getting inadequate sleep. Chronic sleep deprivation is especially common amongst shift workers, who account for 20% of the US work force and have twice the number of highway accidents as day workers. Thirty one percent of fatal commercial accidents are drowsiness related, causing the 1995 US Truck and Bus Summit to identify driver fatigue as its number-one safety issue. Driver fatigue is estimated to result in 1500 fatalities, 70,000 injuries, and over $54 billion in economic loss, health care costs, and loss of productivity each year.

Due to these alarming statistics, many studies have been conducted over the past fifteen years to identify what technology is the most effective at detecting and predicting driver fatigue. In 2000, Krueger Ergonomics Consultants conducted a comprehensive review of the available technologies in an effort to determine which had the most potential for future development. Krueger concluded that the ideal technology would, amongst other criteria, be able to perform in real time, be non-obtrusive to the driving process, be operational under all lighting conditions, be reliable and sensitive enough to detect even slight loss of attention or fatigue, and be able to predict the operator’s future state.

Possible technologies that met these criteria included head-movement detectors, EEG or EKG algorithms, and various eye-related technologies. Of the eye-related technologies, those that measure PERCLOS are considered to be one of the most reliable in determining a driver’s alertness levels.

To be continued in Part 2: The PERCLOS Measure….

1) Development of the Eye-Com™ 9 Biosensor, Communicator, Controller (EC9) prototype. This wireless, wearable eye- and head-tracking device will have a more streamlined design and improved capabilities than the current EC7 model. It will have an integrated head mounted display and eventually capabilities to capture EEG and other physiological measures.

2) Use of the EC9 system in different simulated operational scenarios to include unmanned aerial vehicles (UAVs), underwater, and driving scenarios. The overall objective is to determine operator states associated with performance degradation (e.g. drowsiness related to both sleep deprivation and/or time-on-task, hypoxia, general fatigue, and distraction and inattention).

3) Improve the current Assistive Communications and Controller capabilities of Eye-Mouse® Software. These developments will be used in conjunction with the EC9 to assist disabled soldiers and civilians with communication and control of electronics or electromechanical devices (i.e. TV, robotic devices, wheel chair, etc.) by means of eye movement and Eye-Mouse® control.

4) Formulation of a field-ready system to detect and measure unique oculometric characteristics in subjects with Post Traumatic Stress Disorder and other neuro-ophthomological and traumatic brain and eye injuries. A method for distinguishing normal from abnormal oculometrics will be determined to aid in the development of diagnostic and predictive algorithms which can be used to assess the efficacy of treatment in these medical conditions.

Beyond the immediate purposes for the Department of Defense, these technological advances will lay the foundation for many exciting commercial applications in the medical, transportation, and field operation arenas.

The conference took place on September 28 & 29, 2009, and was organized by the Vehicle and Traffic Safety Centre at Chalmers University of Technology (SAFER) and the French National Institute for Transportation and Safety Research (INRETS). ECC representatives met with several European car companies and universities about the capabilities of the EC7 and its potential for improving safety on the road.

Eye-Com is headquartered in Reno, NV and was founded by Dr. Torch in 1998. Since then, the company has become a leader in the newly emerging industries of eye-tracking and head-tracking. The wireless, wearable eye-tracking device developed by Eye-Com has multiple applications, such as using eye movement to control a wheelchair, detecting fatigue, and video gaming. The company is also involved in several extensive research projects for the U.S. Department of Defense and the medical field. For more information, visitwww.eyecomcorp.com.