DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the figures, wherein like numerals refer to like elements, FIG. 1 shows a schematic diagram of the system 10 for providing traffic information to a plurality of user stations 52 connected to a network 50. A plurality of traffic monitors 20 are arranged at spaced apart locations along a road 12. The traffic monitors 20 measure traffic information by detecting the speed (velocity) or frequency of vehicles traveling along the road (freeway or highway) 12. For example, in one embodiment, the traffic monitors 20 may detect. the speed of individual vehicles 14 traveling along the road 12. Alternatively, the traffic monitors 20 may measure the frequency with which the individual vehicles 14 pass specified points along the road 12.
FIG. 2 shows a front elevational view of an exemplary embodiment of a traffic monitor 20. The traffic monitor 20 has a detector 22 for measuring or otherwise sensing traffic. FIG. 2 shows two different embodiments 22A and 22B of a detector 22. The detector 22 may be any type of measuring device which is capable of measuring or otherwise sensing traffic and generating a signal representative of or capable of being used to determine the traffic conditions. For example, the detector 22 could measure the average speed of the vehicles (cars or trucks) 14 at locations along the road 12, or it could measure the individual speed (velocities) of each vehicle 14. The detector 22 may detect vehicle frequency, that is, the frequency at which vehicles pass a certain point, or may measure traffic flow, consisting of the number of vehicles passing a certain point for a unit of time (e.g., vehicles per second). The detector 22 may use any suitable technique to measure traffic conditions (data). For example, in one embodiment, the detector 22A could employ radio waves, light waves (optical or infrared), microwaves, sound waves, analog signals, digital signals, doppler shifts, or any other type of system to measure traffic conditions (data). In one embodiment, the detector 22A uses a transmitted beam to measure the velocity of the vehicles 14 passing along the road 12, such as with a commercial radar gun or speed detector commonly used by police. Alternatively, the detector 22A may detect when cars having magnetic tags or markers pass. The detector 22A may either detect signals reflected from the vehicle or signals transmitted by the vehicles.
The traffic monitor 20 is shown with an alternative embodiment 22B consisting of one or more pressure sensitive detectors which extends across the road 12. Preferably two spaced apart detectors are positioned at a predetermined spacing to make the velocity determination readily available. The pressure sensitive detector 22B detects when a vehicle passes over the detector 22B. Such a pressure sensitive detector may be used alone or in combination with detector 22A to measure the frequency or speed (velocity) of the traffic passing along the road 12. Likewise, the detector 22A may be used alone or in combination with the detector 22B to measure the frequency or speed (velocity) of the traffic passing along the road 12. Alternatively, detector 22B could be a wire loop buried in the road to measure changing magnetic fields as vehicles pass over the loop.
The detector 22 may measure traffic conditions in a single lane of a freeway or road, or may measure average traffic information across several lanes. The detector 22 could also be embedded in each lane of a road or freeway, such as with a pressure sensitive detector 22B. Alternatively, individual detectors could be embedded in a roadway which would sense signals or conditions generated by passing vehicles. For example, each vehicle could include a magnet or could include a signaling device which would be detected by the detector, which could be an electromagnetic sensor or a signal receiver.
Referring to FIG. 5, the traffic monitors 20 may also include a processor and a memory for collecting, processing, and storing traffic information provided by the detector 22.
The traffic monitor 20 preferably further includes a transmitter 26 for transmitting the traffic information collected by the detector 22. The transmitter 26 may be any type of device capable of transmitting or otherwise providing data in either digital or analog form, either through the air or through a conductor. For example, the transmitter could be a digital or analog cellular transmitter, a radio transmitter, a microwave transmitter, or a transmitter connected to a wire, such as a coaxial cable or a telephone line. The transmitter 26 is shown as transmitting the signals through the air to a receiver 30. Alternatively, the transmitter 26 could transmit the data to an intermediate receiver before being transmitted to the receiver 30. For example, several traffic monitors 20 could transmit traffic information in a daisy chain manner from one end of a road 12 to the last traffic monitor 20 at the other end of the road before being transmitted to receiver 30. To facilitate this type of transmission most traffic monitors 20 would require a receiver. Alternatively, one or more traffic monitors 20 could transmit data to other traffic monitors 20, which in turn transmit the data to the receiver 30.
In order to conserve power, the transmitter 26 and the detectors 22 preferably transmit and sense information periodically rather than continuously. Further, the traffic information generated by the detector 22 is preferably averaged, or otherwise statistically modified, over a period of time so as to limit the amount of data that needs to be transmitted and increase its accuracy.
In one embodiment, the traffic monitoring unit 20 may further include a video camera 29. The video camera 29 is also connected to the transmitter 26, so that the transmitter 26 may transmit signals corresponding to the image sensed by the video camera 29. Alternatively, the traffic monitors 20 may be replaced by video cameras 29. Multiple images may be obtained by a video camera and the speed of the vehicles 14 determined based on image analysis of multiple frames from the video camera(s).
One preferred type of monitor 20 utilizes signals from a digital video camera to provide the traffic information. Traffic-related information may be obtained by analyzing the video sequences from the monitoring video cameras 29. The information may include how fast the traffic moves and how congested the road is. The speed of the traffic may be derived by measuring the speed of vehicles in the video. The degree of congestion may be estimated by counting the number of vehicles in the video. This invention provides two algorithms for estimating traffic speed and road congestion based on video input.
The first algorithm is based on optical flow and its flow diagram is shown in FIG. 9. First, the algorithm performs camera calibration based on the input video of the road and the physical measurements of certain markings on the road. Then the algorithm (1) takes a number of frames from the input video; (2) computes optical flow; (3) estimates camera motion which may be caused by wind, etc., (4) estimates independent vehicle motion after compensating the camera motion; (5) estimates traffic speed based on the averaged vehicle motion and the camera parameters obtained from the camera calibration step; estimates road congestion by counting the number of independent motion components; and (6) outputs the estimated speed and congestion results.
The second algorithm is based on motion blob tracking and its bock diagram is shown in FIG. 10. First, the algorithm performs camera calibration based on the input video of the road and the physical measurements of certain markings on the road. The algorithm (1) takes a number of frames from the input video; (2) estimates camera motion; (3) detects independent motion blobs after compensating the camera motion; (4) tracks motion blobs; (5) estimates traffic speed based on the averaged blob motion and the camera parameters obtained from the camera calibration step; estimates road congestion by counting the number of independent motion blobs; and (6) outputs the estimated speed and congestion results.
Traffic monitor 20 further includes a power supply 24. The power supply 24 is preferably a battery, or may alternatively be a power line, such as a 12 or 120 volt power line. The traffic monitor 20 is shown with an optional solar power supply 28. The power supply 24 or 28 provides the power necessary for the detectors 22A and/or 22B, the transmitter 26, and any other electronics, such as a computer system and/or video camera.
The receiver 30 receives the signals from the traffic monitors 20 and/or video cameras 29. The receiver 30 may be any device capable of receiving information (data) such as in either an analog or a digital form. For example, the receiver 30 may be a digital or analog cellular receiver, a standard phone, a radio receiver, an antenna, or a data port capable of receiving analog or digital information, such as that transmitted pursuant to a data protocol.
The receiver 30 receives the information from the traffic monitors 20 and/or video cameras 29 and passes that information to a computer system 40. The computer system 40 preferably includes a processor (such as a general purpose processor, ASIC, DSP, etc.), a clock, a power supply, and a memory. The computer system 40 preferably has a port 42, or any type of interconnection, to interconnect the computer system 40 with the network 50. Preferably, the computer system 40 includes information representative of the road 12 along which the traffic monitors 20 are located, such as a map database. The computer system 40 receives the traffic information transmitted by the respective traffic monitors 20. The information transmitted by the traffic monitors 20 includes the location or identification of each particular traffic monitor 20 together with the data representative of the traffic data provided by the detector 22 and/or video camera 29 at each traffic monitor 20. The computer system 40 may manipulate the traffic information in some manner, as necessary, so as to provide average speeds or other statistical data. In the event of video, the computer system 40 may process the images to determine the speed of vehicles. Also, the video may be provided. Alternatively, the user stations may process the traffic information.
In one embodiment, both the receiver 26 of the traffic monitors and the transmitter 30 of computer system are each capable of receiving and transmitting data. This allows for two way communication between the monitor 20 and the computer system 40. Thus, the computer system 40 could remotely operate the traffic monitor 20 to change settings, diagnose problems, and otherwise provide input to traffic monitor 20 to facilitate collection of traffic data. For example, the video camera 29 could be remotely positioned to view a traffic lane of interest.
Traffic information may be provided to users in any suitable manner, such as the examples that follow. A user station 52 is connected to the network 50. Preferably, the user station 52 includes a graphic display unit 54 (see FIG. 3). For example, the user station 52 may be a standard personal computer with a display monitor 54. The network 50 is preferably the Internet. However, the network 50 could also be a local area network or any other type of closed or open network, or could also be the telephone network. The user station 52 sends a signal over the network 50 to the computer system 40 requesting traffic information. In response to receiving a request from the user station 52, the computer system 40 transmits traffic information representative of the traffic information collected by the various traffic monitors 20 to the requesting user station 52. The computer system 40 may transmit average speeds detected by each of the traffic monitors 20 at each of their respective locations. The traffic information may be presented to the user as a web page. The computer system may send traffic information corresponding to only some of the traffic monitors. The user may select which portions of the road 12 are of interest, and the computer system 40 may transmit traffic information corresponding to that portion of the road 12.
FIG. 3 shows an exemplary display 54 displaying the traffic information provided by the computer system 40. The computer system 40 provides data from its memory which is representative of the road 12, such as data from a map database, which is displayed as a road 112 on the display 54. The computer system 40 also provides traffic information collected by each, or a selected set, of the respective traffic monitors 20 which is displayed in portions 114a-114d and/or the traffic information derived from individual mobile user stations having a global positioning system locator as described in detail below. In the exemplary display shown in FIG. 3, the portions 114a-114d display different colors or patterns representative of average vehicle speeds (for example, in miles per hour) along different portions of the road 112. Of course, the display may display other types of information, such as traffic flow (vehicles per second) or vehicle frequency. The display 54 may include information in either graphical or text format to indicate the portion of the road displayed, such as location of milepost markers or place names 116.
While the display 54 shows one format for displaying the information, other formats for presenting the information may likewise be used, as desired. It is not necessary to provide a graphical representation of the road 12. Instead, information could be provided in a textual manner, such as, for example, mile post locations for each of the traffic monitors 20 and presenting textual traffic information for each location.
Thus, the system may operate as follows. The traffic monitors 20 detect or otherwise sense traffic to provide traffic information. The traffic monitors 20 may detect or otherwise calculate vehicle speed, average vehicle speed, traffic flow, vehicle frequency, or other data representative of the traffic. The traffic monitors 20 may sample either continuously, or may sample at intervals to conserve power. The transmitter 26 transmits the signals provided by the traffic monitors 20 to the receiver 30 either continuously or at intervals. Such signals may be either transmitted directly to the receiver 30, or may be transmitted through other traffic monitors 20. The receiver 30 receives the signals received by the various traffic monitors 20 and passes these signals to the computer system 40. The computer system 40 receives the data from the traffic monitors 20. The computer system may calculate or process the traffic information for the users, as necessary. It is not necessary for the traffic monitors 20 to calculate traffic data, if desired. In response to a request from a user station 52, the computer system 40 provides the traffic information over the network 50 to the user station 52.
The system 10 has many advantages. It allows a user to receive contemporaneous traffic information from a plurality of locations. It allows the user to obtain immediate information rather than waiting for the broadcast of information at specified times. Further, the amount of information provided by the system is far superior to that provided by any other traffic reporting system. A user can obtain immediate and contemporaneous traffic conditions, such as average vehicular speed, traffic flow, or vehicle frequency, for a plurality of locations along a road. Where traffic monitors are provided along several different roads, a commuter may then select among the various alternative routes, depending on the traffic conditions for each road. The system also does not rely on the manual input of information, and thus provides information more accurately and more quickly. It also eliminates subjective descriptions of traffic information by providing measured data representative of traffic conditions.
In one embodiment, the computer system 40 also receives the signals generated by the video cameras 29 at the respective traffic monitors 20. FIG. 3 shows an exemplary display 54 in which a video image 129 is provided. In this embodiment, the user may select from which traffic monitoring unit 20 the video image 129 is to be received from. For example, a user could initially select to view the image generated by the video camera at a first location, and then later view the image transmitted by another video camera 29, preferably at another traffic monitor 20, at a different location.
The system 10 preferably further includes the ability to send messages about road conditions. FIG. 3 shows such an exemplary message 130 in text format. The computer system 40 is capable of storing data messages and transmitting the data messages with the traffic information. The data messages would indicate items of particular interest to the commuter. For example, the text message 130 could indicate that there was an accident at a particular location or milepost, that construction was occurring at another location or milepost, or that highway conditions were particularly severe and that alternative routes should be selected. The system 10 could provide multiple messages through which the user could scroll so as to receive different messages in addition to the traffic information received from the various traffic monitors 20. In another embodiment, the user station 52 includes a voice synthesizer capable of reading the messages to the user.
In yet another embodiment, the system 10 may also provide additional graphical information relating to traffic conditions. For example, the computer system 40 could transmit the location of an accident or construction site along the road 12. The information would be displayed on display 54 as an icon or other symbol at the location indicating the presence of an accident or highway construction. Such an icon is shown at 140 in FIG. 3. Alternatively, the computer system could also display an icon representative of a restaurant, gas station, hospital, rest area, or roadside attraction. In such a system, the computer system would contain or be linked to a database containing such information. The information could be displayed automatically, or in response to a request for such information from a user.
In another exemplary embodiment, the computer system 40 automatically generates traffic reports to be sent to the user station 52 at predetermined times. For example, a user may indicate that it wishes to receive a traffic report every morning at 7:30 a.m. The computer system 40 automatically sends to the user station 52 at the predetermined time (7:30 a.m., for example) the traffic information collected from the traffic monitoring units 20. The information could be sent to be displayed, such as in FIG. 3, or could be sent alternatively in a text or graphical format via e-mail. The traffic report may also be provided in a format specific to the user's geographic region and/or user's driving habits, such as anticipated (potential) route to be traveled. The computer system 40 may also automatically send the traffic information to a display in the user's vehicle in response to some event, such as turning on the vehicle, time, key press, etc.
In another embodiment, the computer system 40 allows a user to calculate the amount of time necessary to travel from one location to another location along the road 12. The user sends a request to the computer system 40 indicating the two locations along the road along which travel is desired. The user may, for example, indicate on the display by highlighting the two locations on the road 112 using a computer mouse. Alternatively, the two locations may include the user's current location, as determined by a vehicle based GPS system, so that only the destination needs to be entered. The computer system 40 then calculates the anticipated amount of time it will take to travel from one point to the other point based upon the traffic data collected by the various traffic monitors 20 between the two locations. In addition, the system may calculate alternative routes in order to determine the fastest route in view of the traffic information. The computer system 40 then sends a signal back to the user station 52 to indicate the amount of time that the travel from the first to the second location will take. The route determined as the best may be overlaid on a map to assist the user in travel.
In yet another embodiment of the invention, FIG. 7 shows a divided freeway with vehicle traffic flowing in opposite directions in each of the divided sections. Each section of the freeway 12 has multiple lanes 12A-12C. The traffic monitors 20 measure traffic in each of the lanes 12A-12C of each section 12 of the divided freeway. The monitors 20 may measure traffic on only one portion of the divided freeway, or may measure traffic conditions in each of the lanes of each of the sections of the divided freeway. The monitor used to measure traffic in multiple lanes may be a digital video camera.
FIG. 8 shows yet another embodiment of a display 54, which displays traffic information for each individual lane of the divided freeway shown in FIG. 7. For example, in display 54, the traffic conditions in each individual lane 112A-112C is displayed for the road section 112. By displaying conditions for each particular lane, the system has the advantage of allowing the user to anticipate particular lane problems which may occur ahead, such as a wreck 140 in lane 112C. In addition, in an alternative embodiment, the display 54 is capable of displaying the individual location of each individual vehicle on the road 112.
FIG. 4 shows an alternative embodiment of a user station 52. User station 52 is a mobile unit in a car 60. User station 52 has transmitting and/or receiving units 64 for communicating with the network 50. Such transmitting and receiving units 64 may be any devices capable of transmitting digital or analog data, such as, for example, a digital or analog cellular phone.
The user station 52 may also be contained within a car 60 that further includes an associated global positioning system (GPS) receiver 62. The GPS receiver 62 receives signals from GPS satellites 70 which enable the GPS receiver to determine its location. When a commuter requests traffic information using the mobile user station 52, the request for traffic information may include the location of the user as determined by the GPS receiver 62. When the computer system 40 receives this request, it provides traffic information back to the mobile user station 52 based on the location of the car 60 as provided by the GPS receiver 62. Alternatively, the computer system 40 may provide traffic information to the user station 52 which in combination with the position determined by the GPS receiver 62 displays suitable data to the user on a display or audibly. The user station may also be a cellular phone with an integrated or associated GPS.
FIG. 6 shows a representative display of the traffic information provided by the computer system 40. The information provided is essentially the same as that shown in FIG. 3, except that the display 54 contains at 161 the position of the car 60. The mobile user station 52 provides a significant advantage in that it allows the commuter to immediately determine traffic information in the commuter's immediate vicinity based on the commuter's present location. The commuter does not have to wait for a periodic traffic report. Further, traffic conditions are provided at a plurality of locations, and the information is contemporaneous. Based on the receipt of such information, the commuter may decide to use an alternate route rather than continue on the current freeway.
Thus, in the embodiment shown in FIG. 4, the system provides the relevant traffic information to the commuter or user on a timely basis. The display may be tailored to provide the information for the current location of the commuter, together with the upcoming traffic that lies ahead.
In a preferred embodiment, the system obtains traffic information from users that have a GPS receiver 62. In this system, whenever a user station 52 requests traffic information from the computer system 40, the computer system 40 associates a velocity (speed) of that particular user with its current location. The velocity may be determined through a variety of methods. In one system, when the user requests traffic information, the user station 52 supplies not only its location but also its current velocity. The user station 52 may obtain its current velocity in any fashion. For example, the user station 52 may track its location over time using the GPS receiver 62, and also keep track of the time associated with each location by using an internal clock. The velocity could then be calculated by simply dividing the difference between respective locations by respective times. Alternatively, the user station 52 may be connected to the vehicle's speedometer or odometer, and measure velocity using information provided by the vehicle 60 itself. Alternatively, the computer system 40 itself could calculate the velocity of each user. In such a system, each user station 52 would provide the computer system 40 with a unique identification code together with its location. The computer system 40 then associates a time using an internal clock with each location reported by each user. Preferably, the GPS location is sent together with the current time at the user station so that delays incurred in transmission do not change the result. The velocity of each user could then be calculated by calculating the difference in location for a particular user (identified by its unique identification code) by the respective times associated with each of these locations.
Thus, the computer system 40 develops a database consisting of the location of a plurality of users together with the respective velocities of each of the users. The computer system 40 thus has traffic information consisting at least of the velocity of the traffic for a plurality of locations corresponding to the locations for each of the reporting users. It is preferred in such a system that each user station 52 would contribute to the database, but the computer system could use data from fewer than all of the user stations