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Collision Avoidance Through Vision Enhancement         Printer-friendly version

• Introduction
• Technological Solutions 
• Systems in Development 
• Project Evaluation
• References

INTRODUCTION

The National Highway Traffic and Safety Administration (NHTSA) has estimated that approximately 44% of all crashes, including 60% of fatal crashes, occurred during times of degraded visibility conditions. Adverse weather such as fog, rain, heavy mist, sleet, or snow also help to reduce activity and range of vision. Driver sensory impairments brought on by glare and loss of peripheral-vision further degrade night vision and recognition.

Vision Enhancement Systems provide augmented information to improve the driver's perceptual ability when visibility is reduced. In line with NHTSA's program for improved Collision Avoidance Systems, a range of technological solutions to aid driver perception during times of unfavorable travel conditions are being tested.

TECHNOLOGICAL SOLUTIONS

Allowing the driver to accurately recognize the environment constitutes the basis of preventative safety. Current technologies used to improve driver perception include polarized headlights and windshields, and rear-view monitoring systems. Other classes of technologies are also being tested, such as infrared imaging systems, radar-based detection, and ultra-violet light technology.

Infrared Imaging
Infrared cameras define the scene by detecting radiation from or emitted by various objects within the field of view. Roadway environments are dominated by traces of this visible and thermal radiation. Many types of imaging systems are currently in development, and these systems are generally defined by the varying transmission bands in which they operate and the optimal distance that it can detect radiation (Near Infrared, Medium-Range Infrared, and Long-Range Infrared). The simplest form of imagers are the Visible/Near infrared systems. Fortunately, these systems are commercially available and easily adaptable to many applications related to ITS and vision enhancement. The imagers detect the inherent thermal signature of radiating objects. These images can then be presented on a head-up display (HUD) inside the vehicle. These images can easily prompt drivers as to possible dangers or collisions in the roadway ahead. The most well known version of this system is the Cadillac Night Vision option.

Radar Detection
Radar detection is also being studied in hopes of possible application toward vision enhancement systems. The benefit of such a system is that it is an all-weather technique, unlike infrared detection, which can be degraded by weather. Active radar imaging systems use their own source of illumination by transmitting millimeter-wave energy, which can travel through rain, snow, fog, etc. The reflected energy is detected by the radar, and images are reconstructed by means of a signal processor. A HUD may then be used to show the driver the locations of obstacles by projecting a symbol overlay onto the windshield.

UV Light
Another technology being applied toward vision enhancement systems are ultraviolet headlights. Although quite simple, the system has shown itself to be successful in improving sight distance and detecting obstacles and other hazards, and does so at a minimal cost. UV high-beam headlights are paired with normal low-beam headlights and can increase visibility range at night up to 200m. Since UV radiation is virtually invisible to the human eye, the UV headlights do not cause blinding glare to oncoming traffic. The lighting system augments the brightness of fluorescent pigments embedded in many objects in the road environment, making them more visible to the driver.

SYSTEMS IN DEVELOPMENT

There are currently many projects underway to develop Vision Enhancement Systems. Three projects that typify the direction of Vision Enhancement research include work done by Toyota, Ford and Volvo.

Toyota
Toyota is developing a Rear-View Monitoring System to assist drivers in recognizing obstacles behind the vehicle. A compact camera is installed at the top of the trunk lid, and shows the rear-view on a display that the driver can readily access. The system is designed to show objects in the vehicle's blind spots. However, improvements are needed in the following areas: (1) the distortion of images due to the wider lens angle, and (2) the visibility of objects at night.

Included in the Rear-View Monitoring System is the Backing and Clearance Sonar. This component is aimed at detecting the distance to each obstacle by means of ultrasonic sensors installed at the rear-end and corners of the vehicle. The driver is then informed of the distance to an obstacle by the changing tone of the alarm. Such devices are equipped on many vehicles in Japan and have proven to be highly effective in real-world situations and most useful during parallel parking maneuvers.

Ford
Researchers at Ford Automotive have been developing a Vision Enhancement system based on millimeter-wave radar technology. Although information on the system is limited, Ford plans installation of the system in the near future. As previously discussed, a millimeter-wave radar system identifies obstacles in the roadway by locating reflected radar particles and projecting them onto an in-vehicle display.

Ford's system employs a 4.5" diameter antenna, and the company asserts that the system can differentiate between 2 cars travelling 1m apart at a distance of 400m. This is remarkable resolution for such a small antenna. Such accuracy has not yet been reported in current research circles.

Volvo
Volvo is currently developing a headlamp that uses ultraviolet headlights as a vision enhancement tool. These special high-beam headlights are capable of illuminating objects at a distance of 100 to 150m, compared with the normal 40 to 50m of ordinary headlights. Their method for producing UV light uses gas discharge lamps, though alternate methods are being considered.

The lamps are projected in front of the vehicle and highlight the fluorescent elements in pedestrian clothing, road signs, lane markings, vehicles and other objects in the field of vision. Preliminary tests have shown drastic improvements in sight distance and clarity. Volvo is planing on introducing the technology to its vehicle within the next few years.

Veridean Operations
Veridian Operations is developing an on-vehicle threat detection system for intersection collision avoidance using a combination of GPS/GIS technology and radar instrumentation. Through the Global Positioning System (GPS) and the Geographical Information System (GIS), on-board computers can identify the roadway on which a vehicle is travelling and the approach of an intersection. Using a GIS map datafile, the configuration of the intersection and the angles of the adjoining roadways can be obtained. This feature allows the threat detection system, which is radar based, to scan the intersection's highest risk areas during the test vehicle's approach of the intersection.

Knowing each intersection's "threat regions", a radar based system can optimally scan the intersection for possible conflicts. This system consists of a three-radar assembly that will monitor traffic in the same fashion as the tracking radar systems previously mentioned. But, the intersection area provided by the GIS will then be used to develop the appropriate gap time, which utilizes the time predicted by the tracking radar for vehicles to enter and exit the intersection. A collision-warning algorithm would then obtain the gap time metric and issue warnings to the test vehicle if the gap time is insufficient for a safe crossing, or if it and any other vehicle are predicted to occupy an intersection simultaneously.

This project is a good example of a combination of technologies used to enhance current intersection collision avoidance capabilities. The joining of GPS/GIS information with radar detection is still being evaluated, but results thus far are quite promising. Future endeavors include testing in real-world conditions and use of a multi-beam radar assembly.

PROJECT EVALUATION

The technologies being applied in these projects show marked advances in vehicular safety, and emphasize the importance of Vision Enhancement in the NHTSA's program for Collision Avoidance. Vision Enhancement is a very wide-ranging topic, and improvements can be made in many areas (behind the vehicle, as well as in front), as we have seen in the list of representative projects. By making more information available to the driver, it allows him/her to make better judgements, resulting in a safer trip.

These projects used in coordination with other Collision Avoidance Systems, such as Lateral and Longitudinal CAS, have the ability to greatly improve safety on the roadway. And as the tools for Vision Enhancement progress, their combination with CAS systems will serve to enhance the entire driving environment.

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Denes, Louis J., Richard Grace, David A. Purta, Alberto M. Guzman "Assessment of Driver Vision Enhancement Technologies" Collision Avoidance and Automated Traffic Management Sensors 1995 Pages 17-29

Najm, Wassim G. "A Review of IVHS Crash Avoidance Technologies" Collision Avoidance Systems: Issues and Opportunities Proceedings March 21-22, 1994 Notes from the Collision Avoidance Workshop

Kawai, Mitsuo "Collision Avoidance Technologies" Leading Change: The Transportation Electronics Revolution 1994 Proceedings

Gish, Kenneth W., Loren Staplin, Michael Perel "Vision Enhancement Systems" Transportation Research Record No. 1694 1999

Author: Bryon Li. Date: 06/26/2000