WO2003019494A1

WO2003019494A1 - System and method for notification of hazardous road conditions

Info

Publication number: WO2003019494A1
Application number: PCT/CA2002/001300
Authority: WO
Inventors: Donald Rafol; Sarath Gunapala; John Liu; Riad Chehayeb
Original assignee: Qwip Technologies, Inc.
Priority date: 2001-08-23
Filing date: 2002-08-23
Publication date: 2003-03-06

Abstract

A system for detecting hazardous road condition on a portion of road that utilizes an infrared detector mounted with a field of view covering the road. The system further includes a signal processing unit electrically coupled to the infrared detector that identifies thermal signatures representative of certain hazardous conditions such as iced roads, rain, snow, animals, and stopped vehicles. The signal processing unit is further coupled to a notification device that alerts vehicular drivers of the hazardous conditions. In some embodiments the notification device is a sign with a flashing light, in other embodiments, the notification device is a digital sign or an internet web site.

Description

SYSTEM AND METHOD FOR NOTIFICATION OF HAZARDOUS ROAD

CONDITIONS

BACKGROUND OF THE INVENTION The present invention relates to the electronic arts. More specifically, the present invention relates to a system and method for notifying vehicular operators of hazardous road conditions.

Annually, vehicular accidents due to hazardous road conditions cost millions of dollars for medical treatment, vehicular repair, and to lost productivity due to congestion that often accompanies accidents. Such accidents are often caused by weather conditions {i.e., snow, sleet, rain, ice), animals traversing the road, and to collisions resulting from stopped vehicles. Furthermore, in addition to the immediate impact felt by such accidents, a multiplier effect results in similar economic detriment to the local region, which when such accidents accumulate over large areas, can greatly harm the economy of a state or province.

Currently, there are a few mechanisms by which a driver can be notified of a hazardous road condition such as roadside signs and traffic reports. While warning signs can identify certain areas that are prone to environmental conditions {i.e. "bridge may freeze") or to animal traffic {i.e., "deer crossing"), such signs are limited in that they only identify roadway areas of potential increased risk, not areas of actual risk. Furthermore, in urban areas, digital roadside signs can provide updates on traffic conditions, but rarely are used as a preventive measure to as alert to hazardous conditions. Furthermore, such Traffic conditions, in cities such as Los Angeles, are also linked and available via the Internet.

It should therefore be appreciated that there remains a need for a reliable and durable system and method for notifying vehicular users of hazardous road conditions.

SUMMARY OF THE INVENTION

The present invention is embodied in a system for detecting roadside hazards comprising a road, an infrared detector mounted adjacent to said road with a field of view at least partially covering the road, a signal processing unit in communication with said infrared detector for detecting the presence of a roadside obstruction or a potential roadside obstruction, and a notification device electronically coupled to the signal processing unit for displaying a predetermined alert when a roadside obstruction is detected. In some embodiments, the infrared detector is a quantum well infrared detector, while in other embodiments, the infrared detector is chosen from the group of HgCdTe based detectors, SiBiB based detectors, InSb based detectors, HgCdTe based dectors, and PtSi based detectors. Preferably, the infrared

detector detects infrared radiation in the 8-12 μm wavelength range, and most preferably, in the

8-9 μm wavelength range. In other embodiments, the infrared detector detects infrared

radiation in the 3-5 μm wavelength range.

In some embodiments, the signal processing unit is capable of identifying water, ice, and the presence of animals on the road. In other embodiments, the signal processing unit can identify stopped vehicles on the road. Such identifications may be enhanced through the utilization of pattern recognition software.

In yet other embodiments of the current system, a temperature sensor in electrical communication with the detector and in the field of view of the detector is utilized to determine the absolute temperature of items within the field of view of the infrared detector.

The present invention is also embodied in a method for notifying vehicular users of hazards for a length of roadway comprising the steps of, providing an infrared detector adjacent to the roadway with a field of view that covers the roadway, coupling the infrared detector to a signal processing unit that can identify roadway hazards and communicate a signal corresponding to such hazards to a notification device, and displaying an alert when the signal is received by the notification device. In such a method, the notification device may be a roadway sign with a light that may be strobed, it may be a digital roadway sign, or it may be a computer available through the Internet that displays the existence of the hazardous condition via the Internet.

Finally, the present invention is also embodied in a system for identifying and notifying vehicular users of a hazardous condition over a portion of road comprising, detection means for detecting infrared radiation on or near the road corresponding to a hazardous condition, notification means for notifying the vehicular user of the hazardous condition, and communication means for communicating the hazardous condition detected by the detection means to the notification means. Though the current system is described in connection with a Quantum Well Infrared Photodetector (QWIP) , it will be appreciated that the current system and method can employ other types of infrared detectors.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating the current invention as employed adjacent to a roadway; and

FIG. 2 is a block diagram illustrating the major components of the system of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to the figures, preferred and exemplary embodiments of the invention will now be described. The invention is described primarily with respect to an exemplary roadway hazard detection system and method that utilize an infrared detector positioned to monitor a roadway where the detector is coupled to a notification system. Several other exemplary systems are also described.

FIG. 1 illustrates an infrared detector that is positioned to monitor a length of roadway. The detector is enclosed within a weather resistant casing and is mounted on a stand so that the detector has within its field of view, a significant portion of the road. Preferably, the current system is used at a relatively straight portion of road so that the distance monitored is increased. When a straight flat portion of road is monitored, the system in clear environmental and weather conditions may monitor up to a 2 km stretch of road. The infrared detector, depending on the particular technology utilized, may need to be cooled. In the preferred embodiment, a cryogenic cooler containing liquid nitrogen is used so that it may cool the infrared detector to 60-70 K for a period ranging from 4,000 hours to 12,000 hours of operation.

As seen in FIG. 2, a signal processing unit is electrically coupled to the infrared detector and is able to determine when a hazardous condition exists. The signal processing unit may incorporate pattern recognition software which may be programmed to recognize and associate certain thermal signatures that enter into the field of view of the infrared detector with hazardous conditions. For example, as animals such as moose, deer, and elk, travel at certain rates and emit certain levels of heat, when such patterns are recognized as series of pixels by the signal processing unit, the signal processing unit may send a predetermined signal to a notification device.

In its simplest form, the notification device may comprise of a roadside sign with a message such as "HAZARDOUS CONDITION AHEAD WHEN FLASHING" and a warning light. When a predetermined signal is received from the signal processing unit, the warning light may flash to notify vehicular drivers that a hazardous condition may be on the roadway and that they may wish to reduce their speed. In other embodiments, the notification device may be a digital sign that identifies the particular road hazard {i.e., animal obstructions, stopped vehicles, ice, snow, rain). Furthermore, the notification device may also be coupled to the Internet so that travelers may be notified of hazardous conditions on a web site. In addition, vehicles with interactive radio systems or traffic notification systems may be notified of the hazardous road condition.

In the preferred embodiment, the detector is a Quantum Well Infrared Photodetector (QWIP) such as those described in U.S. Pat. Apps. Ser. Nos. 09/198,059, 09/173,965,

08/708,076, 08/785,350, 09/198,059, 08/928,292, 09/305,121, 60/147,375, 08/785,350,

09/443,177, 60/147,513, 60/147,514, and 09/443,925, all of which are hereby incorporated by reference.

Visible light spanning the wavelength range from blue (~ 0.4 μm) to red (~ 0.7 μm) is a tiny slice of the electromagnetic spectrum. Objects that are invisible to the human eye may be visible at other wavelengths. For instance, an object at room temperature (~ 300 K) and in complete darkness, may be perfectly invisible to the human eye; but its temperature will make it glow in the infrared (at wavelengths longer than the 0.7 μm wavelength of red light), shining brightest at an infrared (IR) wavelength of around 8.5 μm. The preferred infrared detector can detect 8.5 μm light and convert such light to a visible pixellated black-and-white image on a standard TV monitor or such data may be used for the signal processing unit. Temperature and emissivity variations in the dark scene translate to contrast in the gray scale of the black-and- white image, rendering objects and their motion visible. Detectors that are highly sensitive to light at these wavelengths are ideal. At the heart of the IR detector (in its focal plane) is its eye: a 2-dimensional array of detector pixels, each pixel converting some of the IR photons hitting it to an electric signal. In front of the eye is a lens system to zoom and focus a scene onto the array. The eye can be made sharper by cooling, through a variety of commercially available cryogenic coolers (the eye is glued to the cold head and stares out through a sealed window in the surrounding vacuum jacket). Additional electronics process output signals of the array that may be used to produce a composite video signal that can be fed to a standard TV monitor if remote viewing of the roadway conditions is desired.

The idea of using a quantum well to detect light can be understood by the basic principles of quantum mechanics. An electron in a square quantum well is the classic particle-in-a-box of basic quantum mechanics. The electron cannot have just any energy inside the well; rather, it is constrained to reside in certain discrete energy levels, i.e., its energy is quantized. These allowed energy levels, which depend on the electron mass and the size and shape of the quantum well, can be calculated by solving the time-independent Schrδdinger wave equation. For a square quantum well the energy levels depend in a straightforward way on the well dimensions (width and potential depth). At low temperatures, an electron will reside in the lowest energy level (called the ground state) of the well. When a photon strikes the well, it can impart its energy to the ground state electron and excite it to the next allowed energy level (called the first excited state), a process called intersubband absorption. In order for this to happen, the photon energy must equal the energy separation between the ground state and the first excited state. A photon with a different energy (i.e., light of a different wavelength) is not absorbed because there is no allowed energy- state available for the photon to excite the ground state electron. The simplest QWIP design uses a simple square quantum well designed to hold just two states: a ground state deep inside the well, and the first excited state near the well top. A voltage bias can now be applied to sweep out the photoelectron; under constant illumination a steady-state photocurrent (a measure of the incident photon flux) thus flows through the detector. The spectral response of the QWIP is therefore quite narrow, its sharpness determined by the sharpness of the two energy states involved. Making a QWIP to detect light of a different wavelength is then simply accomplished by changing the width and potential depth of the well in such a way that the two energy states are separated by the corresponding photon energy.

The QWIP detector incorporates a focal plane array (FPA) that detects long wavelength infrared radiation (LWIR) in the 8-12 μm spectral region. The FPA consists of a bound-to- quasibound QWIP containing multiple quantum wells (MQW) of Gallium Arsenide (GaAs) sandwiched between barriers of Aluminum Gallium Arsenide (AlGaAs). Ground state electrons are provided in the detector by doping the GaAs well layers with Silicon. This photosensitive MQW structure is then encased between 0.5 μm heavily doped GaAs top and bottom contact layers , grown on a semi-insulating GaAs substrate by Molecular Beam Epitaxy (MBE).

Some embodiments also employ a temperature sensor that is placed within the field of view of the infrared detector. The temperature sensor is preferably placed in a location where it can be electrically coupled to the signal processing unit and where it is unlikely to be obscured by vehicular and animal traffic, as well as environmental conditions. The pixels in the detector as detected by the signal processing unit that correspond to the location of the temperature sensor represent a known temperature. Such an arrangement allows absolute temperatures to be detected by the color gradations received at each pixel location in the infrared detector. Such information, while not necessary for the implementation of the current invention, can provide for more accurate hazard detections. In the alternative, a dual band QWIP infrared detector such as those described in Application Ser. No. 08/928,292 which examines spectra radiation at two different wavelengths may also be employed in order to determine temperature.

During clear weather conditions, vehicular drivers may not need the assistance of the current system to identify upcoming hazards on the roadway. Accordingly, several devices may be employed that either limit or cease the operation of the infrared detector when there is adequate visibility of the upcoming road. For example, a visibility meter, such as those made by Qualimetrics Inc., may be employed on a top surface of the system to measure the amount of light scattered by atmospheric particles of fog, dust, snow or rain in the air. Furthermore, a Precipitation Detector, such as those also produced by Qualimetrics Inc., that detect the occurrence of precipitation and signal a relay closure in response. The signal can then be used to activate the detection system.. Such an arrangement reduces power consumption of the system and increases the operation lifetime of the detector.

It will, of course, be understood that modifications to the preferred embodiments will be apparent to those skilled in the art. For example, different IR systems that operate in the 8-12 μm wavelength range and are more expensive to manufacture and to operate such as cooled HgCdTe based detectors, and SiBiB detectors may be used. In addition, systems that operate in the 3-5 μm wavelength range such as InSB, HgCdTe, and PtSi may also be used despite the higher level of scattering associated with these shorter wavelengths. Consequently, the scope of the present invention should not be limited by the particular embodiments discussed above, but should be defined only by the claims set forth below and equivalents thereof.

Claims

What is claimed is:

1. A system for detecting roadside hazards comprising: a road; an infrared detector mounted adjacent to said road with a field of view at least partially covering said road; a signal processing unit in communication with said infrared detector for detecting the presence of a roadside obstruction; and a notification device electronically coupled to said signal processing unit for displaying a predetermined alert when the roadside obstruction is detected.

2. The system of claim 1 wherein said infrared detector is a quantum well infrared photodetector.

3. The system of claim 2 wherein said quantum well infrared photodetector detects

infrared radiation in the 8-12 μm wavelength range.

4. The system of claim 3 wherein said quantum well infrared photodetector detects

infrared radiation in the 8-9 μm wavelength range.

5. The system of claim 1 wherein said signal processing unit is capable of identifying water on said road.

6. The system of claim 1 wherein said signal processing unit is capable of identifying animals on said road.

7. The system of claim 1 wherein said signal processing unit is capable of identifying ice on said road.

8. The system of claim 1 wherein said signal processing unit is capable of identifying stopped vehicles on said road.

9. The system of claim 1 wherein said signal processing unit includes pattern recognition software for identifying specific hazardous conditions.

10. The system of claim 1 further comprising a temperature sensor in electrical communication with said detector and in the field of view of said detector.

11. A method for notifying vehicular users of hazards for a length of roadway comprising the steps of: providing an infrared detector adjacent to the roadway with a field of view that covers the roadway; coupling the infrared detector to a signal processing unit that can identify roadway hazards and communicate a signal corresponding to such hazards to a notification device; and displaying an alert when the signal is received by the notification device.

12. The method of claim 11 wherein the notification device is a roadway sign with a light that may be strobed.

13. The method of claim 11 wherein the notification device is a digital roadway sign.

14. The method of claim 11 wherein the notification device displays the hazardous condition via the Internet.

15. A system for identifying and notifying vehicular users of a hazardous condition over a portion of road comprising: detection means for detecting infrared radiation on or near the road corresponding to a hazardous condition; notification means for notifying the vehicular user of the hazardous condition; and communication means for communicating the hazardous condition detected by said detection means to said notification means.