Moving vehicle specification system including an auxiliary specification function

A moving vehicle specification system having an auxiliary specification function. If a vehicle could not be specified by a local controller, the license plate number is decoded from a license plate image in a method where a number database is referenced according to grouped information and number information is retrieved. Auxiliary specification of the vehicle is performed through a comparison between the searched result and the decoded result. This prevents any impairment in the real-time performance of the processing based on local controller and permits more accurate vehicle specification.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a moving vehicle specification system for 
specifying in general vehicles in free lane travel on a road having 
multiple lanes. 
2. Description of the Prior Art 
Heretofore, various systems have been proposed for debiting tolls against 
vehicles traveling on toll roads. For example, Japanese Patent Laid-Open 
Publication No. Hei 4-34684 discloses a system having functions to 
optically detect vehicles entering a tollgate, as well as their lengths 
and types, and to separate and detect multiple cars entering the tollgate 
consecutively. According to the related system, tolls can be debited 
against vehicles moving, for example, on toll roads. Furthermore, 
according to this system, the license plate numbers or the portraits of 
drivers of the vehicles forcibly passing through the toll bars at the 
tollgate exit can be photographed. However, a major problem of this system 
is the requirement of a tollgate to let vehicles pass through one at a 
time. Since providing a tollgate generally necessitates providing an 
interchange or similar large facility, tollgate installation, maintenance, 
and management will result in considerable labor and cost. Furthermore, 
tollgates obstruct vehicular traffic so the possibility of causing traffic 
jams is high. 
SUMMARY OF THE INVENTION 
The idea for this invention is a partial functional improvement of an 
automatic debiting system (referred to as a "previously proposed system" 
hereinafter) as proposed in Japanese Patent Application No. Hei 7-82523. 
In the previously proposed system, first and second gantries are arranged 
so as to span a predetermined number (generally a multiple number) of 
lanes along the direction of traffic, under which vehicles are permitted 
free lane travel. Debiting and debiting confirmation against moving 
vehicles are performed by radio communication between communication means 
arranged on these gantries and the moving vehicles. Furthermore, the 
passage of vehicles under these gantries, their passage points, timing, 
and so forth, are detected by loop coils, line scanners, optical distance 
sensors, and so forth. Moving vehicles are specified by a correlation 
process of the detection results and the results of communications 
relating to debiting or debiting confirmation. The results of specifying 
vehicles, or the results of photographing vehicles, for which confirmation 
that toll has been properly imposed was not obtained, and their drivers 
are transmitted to a host controller. According to the previously proposed 
system, tollgates can be obviated since debiting can be individually 
performed against multiple vehicles in free lane travel on multiple lanes. 
Therefore, the previously proposed system is able to solve all the 
aforementioned problems of prior art systems. Furthermore, the particular 
arrangement of vehicle detection means and the design of a process based 
on its output enable multiple vehicles traveling side by side or in tandem 
to be separated and detected with high accuracy, without any omissions, 
and at high speeds, and to be accurately determined for vehicle type. 
However, the previously proposed system poses a trade off between real-time 
performance and accuracy of specifying moving vehicles. In other words, 
when specifying moving vehicles from the correlation of the communication 
data obtained during debiting and debiting confirmation and the detection 
data obtained from vehicle detection, the real-time performance suffers if 
accurate and exact specifying is to be executed since it is necessary to 
wait for a pair of data items required for the correlation process. 
Conversely, if the specifying results are to be output in real time, 
accurate and exact specifying cannot be executed, and a probability 
judgment yielding a certain degree of inaccuracy becomes unavoidable. 
A first object of the present invention is to improve the specifying 
accuracy while maintaining the real-time performance and in turn prevent, 
for example, the occurrence of vehicles regarded as illegal even though 
they were properly debited, by adding an after-the-fact auxiliary 
specifying processing function to the previously proposed vehicle traffic 
control, management or debiting system or its various modifications. A 
second object of the present invention is to achieve a system having high 
confidentiality on treating or processing the information that allows 
vehicles to be specified, and requiring comparatively simple maintenance 
by the operator by centralizing the database provided to achieve the first 
object. 
One aspect of the present invention is a moving vehicle specification 
system having communication means, vehicle detection means, specification 
means, a number database, and auxiliary specifying means. The 
communication means performs radio reception of identification information 
unique to individual vehicles moving on roads having multiple lanes. The 
vehicle detection means generates vehicle detection information by 
detecting the passage of corresponding vehicles at predetermined 
positions. The specifying means specifies moving vehicles by correlating 
the generated vehicle detection information and the received 
identification information. 
Moving vehicles are, for the most part, already specified at the specifying 
means. However, because of the trade off between real-time performance and 
specification accuracy, a certain degree of specification failures must be 
expected if the demands of real-time performance are to be met. One 
characteristic of the present invention lies in providing auxiliary 
specification means for specifying moving vehicles that the primary 
specification means failed to specify. The auxiliary specification means 
specifically references the number database with the identification 
information, and compares the result with license number images obtained 
from photographs of the vehicle passage positions or their vicinity, 
thereby the vehicle detection information and/or identification 
information and the number information are correlated. The number database 
mentioned here stores a correlation of number information inscribed on the 
license plates of the vehicles with the corresponding identification 
information for vehicles having identification information. 
According to the present invention, after most of moving vehicles are 
specified based on the correlation of vehicle detection information and 
identification information, auxiliary specification of at least those 
moving vehicles for which the specification was not successful is 
executed, by comparing the number information obtained from a search of 
the number database with the license number images obtained from 
photographs. Therefore, according to the present invention, the trade off 
between the real-time performance and the specifying accuracy can be 
resolved or improved since a design or functional assignment is possible, 
for example, where processing based on the specifying means is executed 
with priority on the real-time performance, and the auxiliary specifying 
means compensates for the inaccuracy of the specifying means. For example, 
when the present invention is applied to the previously proposed system, 
the occurrence of vehicles regarded as illegal even though they have been 
properly debited is reduced, while at the same time the real-time 
processing performance is maintained. Effects that are identical or 
similar to the related effects are also produced when this configuration 
is applied to other types of vehicle moving control or management systems. 
The arrangement of the various functions comprising the present invention 
can be designed in various ways. As an example, an embodiment can be 
presented wherein multiple local controllers arranged along a road are 
each provided with a communication means, a vehicle detection means, and a 
specification means, while on the other hand, the host controller, which 
inputs the specification results, vehicle detection information and 
identification information for which the corresponding specification means 
failed at correlation, and the above-mentioned license number images, from 
the specification means in these local controllers is provided with the 
number database and the above-mentioned auxiliary specification means. 
Since the number database is centrally arranged in the host controller and 
the auxiliary specifying is executed by the host controller in the present 
embodiment, the operator, during license number data maintenance (for 
example, registering new license numbers for vehicles assigned with 
identification information), need only perform maintenance on the number 
database in the host controller, and not for the local controllers that 
are usually provided in multiple numbers. Thus, maintenance becomes 
comparatively easy. Furthermore, the information stored in the number 
database includes information that can specify a vehicle or individual, 
such as the license numbers and identification information of vehicles, 
and represents the type of information for which high security must be 
maintained. Achieving a centralized number database in this configuration, 
namely, avoiding a distributed database, can improve the protection of 
confidentiality of these types of information.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Preferred embodiments of the present invention will be described with 
reference to the accompanying drawings in which the configuration and 
functions of the local controller, and the means for debiting, debiting 
confirmation, vehicle detection, vehicle photography, and so forth, will 
for simplicity be partially omitted from the description that follows. For 
their details and modifications, the reader should refer to the series of 
systems previously proposed by the applicant such as Japanese Patent 
Application No. Hei 7-82523 and the corresponding US Patent Application. 
FIG. 1 shows a general configuration of an automatic debiting system 
related to the embodiment of the present invention. In the system shown in 
this figure, a local controller (LC) 10 is arranged at each required 
(generally multiple) position along an expressway, for example. LC 10 
executes the procedure disclosed in Japanese Patent Application No. Hei 
7-82523, yielding results such as the specifying of moving vehicles which 
are gathered at a host controller (HC) 14 via communication lines 12. HC 
14 is arranged at a Land Transport Office, which is a section of the 
Ministry of Transportation of Japan or a similar administrative facility. 
FIG. 2 and FIG. 3 show a general arrangement of LC 10 and various types of 
associated equipment. The arrangement shown in these drawings represent 
only one example and various modifications as shown in Japanese Patent 
Application No. Hei 7-82523, for example, are possible. In FIG. 2, a first 
gantry 16 and a second gantry 18, each spanning multiple lanes (6 lanes 
are shown in the figure), are provided in sequence from the upstream side 
in the direction of traffic, and vehicles 20 are in free lane travel from 
the upper left of the drawing to the lower right. This system is designed 
so that, while vehicles 20 traveling within the maximum legal speed limit 
pass between first 16 and second 18 gantries, LC 10 can execute processes 
for debiting, debiting confirmation, illegal vehicle identification, and 
so forth. 
On the spanning portions of the first 16 and second 18 gantries are 
arranged debiting antennas 22, enforcement cameras 24, debiting 
confirmation antennas 26, line scanners 28, lighting units 30, and so 
forth. Debiting antennas 22 and debiting confirmation antennas 26 perform 
debiting communications and debiting confirmation communications, 
respectively, with vehicles 20 traveling on the road, or more specifically 
with their in-vehicle units (IU) 32. IU's 32 are affixed to vehicles 20, 
such as to their windshields (below the rearview mirror, for example), 
where each comprises, as shown in FIG. 4, an antenna 34 for radio 
communications with debiting antennas 22 and debiting confirmation 
antennas 26, a transceiver 36 for performing radio communications with LC 
10 using antenna 34, a reader/writer 38 for writing information (such as 
debiting information) onto an IC card 42 or reading information (such as 
identification information) from IC card 42, and a controller 40 for 
controlling the operation of IU 32. Enforcement cameras 24 photograph the 
license plates of moving vehicles 20 in capture zones 100 (FIG. 3). 
Lighting units 30 illuminate at least their respective camera capture 
zones 100. A zone 102 in FIG. 3 represents the communication coverage of 
debiting confirmation antenna 26. 
On the other hand, loop coils 44 are embedded in the road and arranged 
transversely across the lanes, namely, at the positions indicated by the 
rectangular frames in FIG. 2 and FIG. 5. Since the inductances of loop 
coils 44 vary with the passage of vehicles 20, the passage of vehicles 20 
and their positions and timing can be known by monitoring the amplitude, 
phase, and so forth of the output signals from loop coils 44. The road 
surface is further provided with a line 46 having a black-and-white 
pattern. While using the black-and-white pattern to perform calibrations, 
line scanners 28 photograph line 46 to detect the passage of vehicles 20 
and their positions and timing. Instead of these means, optical detectors 
based on triangulation principles, for example, may be used. 
LC 10 has a configuration shown in FIG. 6, for example, in the case of a 
3-lane road. In the figure, an antenna controller (ANTC) 48 and an ANTC 50 
execute transmit and receive control and other control operations, under 
the control of a central controller 52, for respective debiting antennas 
22 and debiting confirmation antennas 26. As a result, central controller 
52 gathers identification information of vehicles 20 for which debiting 
and debiting confirmation have been completed, namely, unique codes stored 
in IC cards 42 or assigned to IUs 32. A loop type vehicle detector 54 
performs processes relating to vehicle detection using loop coils 44, and 
supplies a vehicle detection signal indicating, for example, the passage 
of vehicles 20, to central controller 52. Central controller 52 performs, 
for example, vehicle type identification based on a combination of high 
sensitivity outputs and low sensitivity outputs of loop coils 44. A line 
type vehicle detector 56 performs processes relating to vehicle detection 
using line 46 and line scanners 28, and supplies a vehicle detection 
signal indicating, for example, the passage of vehicles 20, to the central 
controller 52. As the passage of vehicles 20 is detected by loop type 
vehicle detector 54 and/or line type vehicle detector 56, a capture 
controller 58 photographs license plates using any of the enforcement 
cameras 24 according to command from the central controller 52. Capture 
controller 58 extracts license plate images from among the images obtained 
from the photography and an image compressor 60 performs data compression 
on the images. The central controller 52 transmits the compressed images, 
together with specifying results, and so forth, described later, to HC 14. 
A light controller 62 activates lighting units 30 when the road is dark, 
and an environmental controller 64 supplies detected values for ambient 
temperature and humidity to central controller 52 to normalize the various 
operations of LC 10. 
Based on the communication results (communication data) by debiting 
antennas 22 and/or debiting confirmation antennas 26 and the results of 
the passage detection of vehicles 20 (detection data) by loop coils 44 
and/or line scanners 28, LC 10 executes processes which should reliably 
verify the specification of illegal vehicles to correlate the passage of 
vehicles with the communication results, namely, to execute the vehicle 
specifying process according to the procedure shown in FIG. 7. 
As shown in the figure, LC 10 first executes a predetermined initialization 
process (200). When, after the initialization process is executed, signals 
(communication data) are received (202) by debiting antennas 22 or 
debiting confirmation antennas 26 from IUs 32, LC 10 stores the received 
communication data to the database within central controller 52. LC 10 
repeatedly calculates the degree-of-coincidence between the newly obtained 
and the previously obtained communication data (204) in proportion to the 
number of received communication data items. LC 10 further stores the 
detection data when it is obtained (206) from loop coils 44 and line 
scanners 28 to the database within central controller 52, and repeatedly 
executes degree-of-coincidence calculations regarding the detection data 
(208) in proportion to the quantity of the obtained detection data. 
LC 10 initiates, when the conditions for initiating the vehicle specifying 
process have been satisfied, for example, after the elapse of a 
predetermined time (210), the vehicle specifying process (correlation 
mapping) while using the degree-of-coincidences calculated according to a 
predetermined algorithm in step 204 or 208 as indexes. At this time, LC 10 
selects (212) the detection data to be supplied to the vehicle specifying 
process from among the detection data stored in the database acquired so 
far, and supplies the selected detection data one item at a time to the 
processes relating to steps 214 through 220. In other words, the processes 
relating to steps 214 through 220 are repeatedly executed for a number of 
times equal to the number of selected detection data items. 
Based on the degree-of-coincidences calculated in steps 204 and 208, the 
communication data is selected in step 214 for which the correlation to 
the detection data supplied to the current vehicle specifying process is 
seen as valid. If the number of communication data items selected in this 
manner is one or less (216), LC 10 judges (218) that the vehicle 20 
relating to the selected one or no communication data is the same as the 
vehicle 20 relating to the detection data supplied to the current vehicle 
specifying process. On the other hand, if a multiple number of 
communication data items is selected (216), LC 10 groups these 
communication data items and correlates them with the detection data 
supplied to the current vehicle specifying process (grouping process 220). 
After the processes in steps 214 through 220 are executed for all detection 
data items selected in step 212, LC 10 generalizes the results of the 
processes based on steps 218 and 220 so that the detection data supplied 
to the vehicle specifying process is correlated as much as possible to the 
communication data relating to a single vehicle (confirmation of 
specifying result 222). LC 10 operates so that a pair of communication 
data and detection data items (called a "specifying result (normal)" 
hereinafter) specified as data relating to a single vehicle is transmitted 
to HC 14 when the correlation is successful, and deleted (224) from the 
database within central controller 52. For illegal vehicles (for example, 
vehicles 20 for which debiting was not properly performed due to the 
shortage of remainder in IC card 42) compressed images of the license 
plates are also transmitted with the specifying result (normal). The 
detection data (called a "specifying result (without IU)" hereinafter), 
which clearly does not have the corresponding communication data, is 
transmitted together with the license plate images and so forth. 
Furthermore, the group of communication data and detection data (called 
"specifying information (unable to specify)" hereinafter), which has been 
subjected to the grouping in step 220 and for which the specifying of a 
single vehicle was unsuccessful, is also transmitted together with the 
license plate images and so forth. After this, the flow of the vehicle 
specifying process by LC 10 returns to step 202 to enter a standby state 
for the acquisition of communication data and detection data. 
By executing this sort of process, multiple vehicles 20 traveling side by 
side or multiple vehicles 20 traveling in tandem can be distinguished and 
accurately correlated with the communication results and/or the license 
plate images even if the communication coverage for debiting antennas 22 
and debiting confirmation antennas 26 is set to a wide area. Furthermore, 
by executing the processes shown in FIG. 8 and FIG. 9 at HC 14, vehicle 
specification (auxiliary specification) is possible in this embodiment, 
even with regard to specifying information (unable to specify) that is 
transmitted from LC 10. 
Viewed functionally, HC 14 includes a result registration/illegal vehicle 
processor 66 and a vehicle auxiliary specifying section 68. The result 
registration/illegal vehicle processor 66 generally gathers specifying 
results (normal) and specifying results (without IU) from multiple LCs 10, 
registers the results to the internal database, and executes a 
predetermined process such as formal notice or black list registration 
regarding illegal vehicles based on the specifying results (without IU) 
and so forth. Result registration/illegal processor 66 also executes the 
same processes regarding the auxiliary specifying results (normal) and the 
auxiliary specifying results (without IU), which are supplied from vehicle 
auxiliary specifying section 68 and described later, as those regarding 
the specifying results (normal) and the specifying results (without IU) 
from LC 10, respectively. 
Vehicle auxiliary specifying section 68 comprises a number decoder 70, a 
registered vehicle searcher 72, a number database (NDB) 74, and an 
auxiliary specifying section 76. As shown in FIG. 9, when vehicle 
auxiliary specifying section 68 inputs (300) information that LC 10 has 
grouped in step 220, namely, specifying information (unable to specify), 
the license number images that are the results of photography by 
enforcement cameras 24 and the detection data representing information 
obtained by processing the outputs of loop coils 44 and/or line scanners 
28 is supplied to number decoder 70, and the communication data obtained 
by processing the results of communications with debiting antennas 22 and 
debiting confirmation antennas 26 is supplied to registered vehicle 
searcher 72. These are registered (302) in an internal auxiliary 
specifying standby database by number decoder 70 and registered vehicle 
searcher 72. 
After all the specifying information (unable to specify) belonging to a 
single group is received (304), vehicle auxiliary specification section 68 
automatically decodes (306) license numbers from the license number images 
by number decoder 70. This decoding process is executed for all vehicles 
belonging to that group. The automatic decoding may be replaced with 
human-based visual confirmation, with results supplied to auxiliary 
specifying section 76 to be described later. On the other hand, registered 
vehicle searcher 72 searches (308) NDB 74 with the identification 
information included in the communication data, namely, the unique 
identification code in IU 32. NDB 74 is a database storing the correlation 
of the identification codes of IU's 32 with the license numbers of 
vehicles 20 carrying IU's 32. Therefore, as a result of this search, the 
license number of the vehicle 20 carrying the IU 32 relating to the 
corresponding communication data is identified. Repeating this sort of 
search will, in general, yield a license number (310) identical to the 
license number decoded by number decoder 70. When a license number 
obtained from the search is the same as the decoded license number, 
registered vehicle searcher 72 informs auxiliary specifying section 76 of 
the result so that auxiliary specifying section 76 combines and stores 
(312) the corresponding license number with the corresponding detection 
and communication data. 
After number decoding and searching are collectively executed by number 
decoder 70 and registered vehicle searcher 72, auxiliary specifying 
section 76 checks that there are no discrepancies in the stored 
combinations (314). In other words, although the combination of 
communication data, detection data, and license number must show a 1:1:1 
relationship, there are instances, such as due to number decoding errors, 
where this relationship does not hold. Accordingly, when auxiliary 
specifying section 76 discovers such a combination (314), this combination 
is deleted (316) from storage. Regarding vehicles 20 for which the 
auxiliary specifying was successful, auxiliary specifying section 76 
separates (318) corresponding vehicles 20 from specifying information 
(unable to specify) and informs result registration/illegal vehicle 
processor 66. 
Since the auxiliary specifying of vehicles 20 is executed in this manner in 
this embodiment at HC 14 based on specifying information (unable to 
specify), vehicles 20 can be accurately and precisely specified compared 
to the system proposed previously by the applicant when the specifying 
results and auxiliary specifying results that are obtained in the end are 
generalized. Furthermore, since vehicle auxiliary specification is 
performed at HC 14, it is not necessary for each LC 10 to possess its own 
NDB 74. Therefore, the protection of confidentiality of the data in NDB 74 
can be improved and the maintenance of NDB 74 becomes easy in this 
embodiment. Furthermore, all the vehicle specifying processes executed in 
LC 10 (refer to FIG. 7) may be performed at HC 14. In this case, however, 
it becomes necessary to transmit all license number images regarding 
vehicles, against which proper debiting and debiting confirmation are 
being performed, to HC 14, thus causing communication lines 12 to be 
congested. According to the present embodiment, the specifying of vehicles 
20 is performed in LC 10, and as a result, only the information for which 
specifying was not successful, namely, only specifying information (unable 
to specify), or only the license number images of vehicles 20 for which 
specification was successful and were thereby recognized as illegal 
vehicles need be transmitted from LC 10 to HC 14 so as to alleviate the 
congestion of communication lines 12. 
This invention is not limited to the above-mentioned type of processes. For 
example, if specifying is performed by vehicle auxiliary specifying 
section 68 for the data regarding illegal vehicles in the specifying 
results (normal) that are transmitted from LC 10, the probability of 
treating vehicles 20, which should be treated as having been properly 
debited and confirmed, as illegal vehicles becomes small. 
While there have been described what are at present considered to be 
preferred embodiments of the invention, it will be understood that various 
modifications may be made thereto, and it is intended that the appended 
claims cover all such modifications as fall within the true spirit and 
scope of the invention.