- CA 02480134 2004-09-O1
Probe-Car ~ystera Using seaeon and Apparatus Therefore
Background of the Tnvention
Field of the Tnvention
s The present invention relates to a probe-car system
which collects measurement data measured while a car is
moving and utilizes it fow traffic information and an
apparatus therefore, and particularly to a probe-car system
which enables measurement data to be efficiently collected
to through a beacon and an apparatus therefore.
Description of the Related Art
In recent years, an investigation has been made on
the introduction of a probe-car system (also called a
is floating car data (FCD) system) using a running vehicle as
a s@nsor (probe) for collecting traffic information. In
this system, an FCD on-vehicle apparatus installed in a
vehicle records the speed of the vehicle and the swept path
thereof, and transmits them to a center. In the center,
za . measurement data transmitted from respective vehicles are
analyzed to create road traffic information relating to
traffic flow and the like.
Qatent document 1 (gyp-A-2002-269659) discloses a
probe-car system in which a center specifies a collection
zs area of FCD, an FCD on-vehicle apparatus of a vehicle
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CA 02480134 2004-09-O1
running zn this area measures and stores a running
position, a running speed az~d the like at every unit time,
and the stored measurement data is transmitted to the
center by usincr a cellular phone at e~rexy regular time
S period.
However, in the probe-car system using the cellular
phone, it becomes a serious problem who bears the
communication cost. In the case where the center bears the
communication cost, the cooperation of the FCD on~vehicle
so apparatus side is easily obtained, and it is expected that
a large amount of measurement data are collected. However,
the burden of the center becomes severe. On the other
hand, when the FGb on-vehicle apparatus side is forced to
bear the communication cost, it becomes difficult to
i5 collect a large amount of data.
Summary of the Invent.~.on
The invention solves the conventional problem as
stated above, and an object thereof zs to provide a probe~-
2o car system in which beacons used for providing traffic
information are utilized to efficiently collect measurement
data from an FCD on~vehi.c~.e apparatus, and an apparatus for
constructing the system.
A probe--car system of the invention includes an on-
~s board unit of a probe-car which selects one of second
z
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information of measurement information measured during
running and road section xefererce data ~,ndicating a
measurement section of the measurement informat~.on and
first xn~ormation of the measurement information, and
s uploads it to a beacon, and a center apparatus which
collects the measurement information from the on-board unit
of a probe-car through the beacon.
Besides, an on-board unit of a probe-car of the
invention includes a communication unit for communicating
~.o with a beacon, an own vehicle position judgment unit for
detecting own vehicle position, a sensor information
collection unit fox collecting measurement information of a
sensor, a storage unit for stor~.ng the measurement
Information collected by the sensor information collection
is unit and a swept path made of a sGt of the own vehicle
position detected by the own position judgment unit, a
coding process~.ng unit for transforming the measurement
information and the swept path stored in the storage unit
into coded data, an informat~.on transmission. unit for
2o transmitting the coded data of the one of ,the second
information ~.~acluding the measurement ~.n,~ormation and the
swept path arid the first information the rneasurernent
information, to the beacon, when passing through the
beacon, and an instructir~n informat~.on reception unit for
as receiving instruction information including izzstructions of
a measurement method of the measurement inforrna~tion and a
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coding method of the coded data from the beacon.
In this system, when the probe-car runs along an
installation route of beacons and passes through under a
downstream side beacon, only the measurement. information is
s uploaded, so that the data amount of the measurement
information can be increased, and the detazled measurement
information can be transmitted. When the probe-car runs
along a bypass and passes through under a downstreaza sl.de
beacon, the swept path of the bypass and the measurement
~o information are uploaded. so that the center apparatus can
utilize it as the measurement information of the bypass.
Brief Description of the Dxavafngs
is Fig. 1 is a view showing a data structure of
transm.itted/received data in a probe-car system according
to a first embodiment of the invention;
Fig. 2 is a block diagram showing a structure of
the probe~car system according to the first embodiment of
2o the invent~.ox~,;
Fig. 3 is a flow chart showing an operation of the
probe-car system according to the first embodiment of the
invention;
Fig. 4 is a view showing a relation between
z5 ox~.g~.nal data and a first order scaling coefficient;
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Fig. 5 is a view Showing a relation among first
order, second order and third order scal.ang coefficients;
Fig. 6 ~.s a view showing gez~exal expressions of
wavelet transform;
Flgs. 7A and '7B are views showing filter circuits
for realizing AWE;
Fig. 8A is a view show~.ng separation of a signal in
DWT and Fig. 8~ zs a view showing reconstruction of signals
in IDW'F;
to Figs. 9A and ~B are views showing filter circu~.ts
realizing the DWT and the IDWT in the first embodiment of
the invention;
Figs. 10A to lOC are explanatory views of road
section reference data;
is Fig. 11 zs a view showing a data structure of
transmitted/xeceived data in a probe-car system according
to a second embodiment of the ~.nvention:
Fig. 12 is a block diagram, showing a structure of
the probe--car system according to the second embodiment of
20 the invent~o~l;
Fig. 13 is a flow chart showing an operation of 'the
probe-car system according to the second embodiment of the
invention;
Fig. 14 is a view showing a data structure of
2s transmitted/received data in a probe-car system according
to a third embodiment of the invention; and
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Fig. 15 is a flow chart showing an operat~.oh of the
probe-car system according to the third embodiment of the
invention.
s In the drawings, a reference numeral 80 refers to a
center apparatus; 81 to a swept path measurement
information utilization part; 82 to a coded data decodi.n.g
part; 83 to a fCD ~.nfoxznat~.on reception part; 84 to a
measurement coding instruction transmission part; 8S to a
to measurement coding instruction selection part; 86 to a
measurement coding ar~stxuct~.on data; 87 to a beacorx
communication part; 90 to an on-board unit of ~. probe-car;
91 to a FCD information transmission part: 92 to a FCD
informati.ox~ selection part; 93 to a coda-ng processing part:
is 94 to a measurement coding xnstxuct~.on reception part; 95
to a measuremEnt coding instruction data: 96 to a default
measurement coding instruction data; 9'7 to an own vehicle
position judgment part; 98 to a swept path measurement
information storage part; 99 to a sensor information
20 COlleCtl.On part; 100 to an on-vehicle apparatus
communication part; 101 to a GPS antenna;102 to a gyro; 106
to a sensor A; 107 to a sensor B; 108 to a sensor C; 121 to
a probe-car; 122 to an u~astream side beacon; 123 to a
downstream side beacon; 183 to a low-pass filter; 1,82 to a
2s high-pass filter; 18~ to a thznn~.ng circuit; 184 to a low-
pass filter; 3.85 to a high-pass filter; 185 to a thinning
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circuit: Z87 to an adder circuit; 191 to a filter circuit:
192 to a filter circuat: and 193 to a filter circuit.
Detailed Descrzpgion o~ the preferred Embodiments
xn a probe-car system of an embodiment of the
invention, measurement information measured by a probe-car
is collected through a beacon.
At present, beacons are installed an a road in
order to provide VICS road traffic information to a passing
vehicle at a pinpoint. The beacons have two Types, that
io is, an optical beacon for a general road and a radio beacon
for ar. expressway. For example, in the case of the optical
beacon, two-way communication with an on-vehicle apparatus
can be performed at a data transfer speed of 1 Mbps.
Although a distance between beaGOns varies according ~o an
is installation state or the like, it is about several hundred
m to several Km.
(First Embodiment)
Tn a probe-car system of a first embodiment of the
2o invention, a swept path and measurement information of
speed, fuel consumption and the like are measured by a
probe-car, and when the probe-car first passes through
under a beacon, or passes through under a next beacon after
a specified time has passed since the probe-car passed
z~ through under the last beacon for after running a specified
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.,
distance or more), the measurement information and the
swept Bath data are uploaded as FCD information from an on-
board un~.t of a probe-car through the beacon. The scaept
path data has a meaning as road section refex-ence data
s indicating an object road section of the measurement
infoxmat~.on.
A center apparatus haring received the FCD
information specifies the object road section of the
measurement information from the swept path data, and
utilizes the measurement information for the creation of
traffic in:~ormation of the object road section.
When the probe-car passes through under the next
bt~acon within the specified time since it passed through
under the last beacon (or before it runs the specified'
distance?, the travel distance and the number of the last
passed beacon, togefi,her with the measurement information,
are up~.oaded as the road section reference data from the
on-board unit of a probe-car.
T'he center apparatus having received the FCD
2o inforinat~.on regards the probe-car as having run along the
installation route of the beacons in a case where the
travel distance and the installation distance between the
beacons are substantially coincident with each other, and
utilizes the measurement information for the creation of
2s the traffic information of the route. On the other hand,
in the case where the travel distance and the installation
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distance between the beacons are much different from each
other, the center apparatus rEgards the probe-car as having
run slang a bypass, and stops the use of the measurement
information.
s Respective processings will be described ~.n deta~.J..
<Cxeation of Running Locus Data>
position data at every regular distance L (for
example, 20o m) is sampled from t~Ze posit~.on data measured
so by the probe-car during running, the position data at the
respective sampling points (.nodes) are arranged in
seq~:ez~ce, and the node row is made the swept path data. and
is transmitted to the center apparatus. At this time, in
order to decrease the data amount of the swept path data, a
is . following processing is performed.
First, 'the position data of a sampling point (node)
is expressed by an argument 8 from an adjacent node. When
a measurement start point or an end point is made a
reference point, and the position of the reference point is
zv specified by latitude and longitude, and when L is made
canstant, the position of each node can be specified by
only the argument 8. Next, the positian data is
transformed into data haring a bias statistically. For
tk~at purpose, when an argument from an adjacent node oz a
z5 noticed node is made 8;, the position. data of the node is
expressed by a difference between an argument predicted
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value of the node predicted by using arguments 8~_~, and 6y_~
of preceding nodes (stat~.stical predicted value: for
example, (8~_1 + 0~_2) !2) and the argument 8~ . l~ext, the data
Qf the node row expressed by the argument predicted
s difference value is subjected to variable length cod~.ng on
the basis of a code tab3.e, and the coded data is
transmitted to the center apparatus through the beacon.
when receiving the swept path data, the center
apparatus decodes the coded data by using the same code
so table, and decodes the arrangement of the position data of
the nodes. Map matching of the arrangement of the nodes
and the own map data is performed, and the swept path data
of the probe-car i,s specified can the own map data.
is <Cx~eat~.on of Measurement Tnformation~
,Ia~.so with respect to the measurement information of
speed, fuel cons~unptioz~ and the lilze, coding is made in
order to reduce the data amount. l~ex~e, a descript~.on will
be given. to a case where sampling data of the measurement
zo information is supjected to discrete wavelet transform
(DWT) to code the measurement information.
hig. 6 s~aows general expressions of the wavelet
transform. The waveiet is a set of functions such as
(mathematical expression 3) which is formed by performing
z5 an operation (scale transform) of magnifying a function
'Y (t) , which is called a basic wavelet arid exists only in a
3. 0
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limited range in time and frequency, by a factor of a on a
time axis, or an operation {shift transform) of sh~,ft~.ng it
by b in time. The firequenoy and time components of a
signal corresponding to the parameters "a" and "b°' can be
s extracted by using this function, and this operation is
call the wavelet transform.
The waveJ.et transform zz~c7.udes a continuous wavelet
transform and a discrete wavelet transform (DWT). The
forward transform of the continuous wavelet transform is
o expressed by (mathematical expression 1), and the inverse
transform thereof is expressed by (mathematical expression
2), when the real numbers a and b are made a = 2j and b =
2jk ( j > 0) , the forward txaz~sform of the discrete wavelet
transform is expressed by (mathematical expression 5), and
u5 the inverse transform (IDWT) is expressed by {mathematical
expression 6).
The DWT can be realized by a filter circuit for
recursively d:.vidi.ng a J.ow frequency, and the wIDWT is
realized by a filter circuit repeating synthesis inverse to
zo the time of division. Fig. 7A shows the filter circuit of
the DwT. The DWT circuit is constructed of plural caseade--
connected circuits 19J., 192 and 193 each including a low
pass filter 181, a high-pass filter 182, and a thinning
circuit 183 fax thinning out signa~.s to J./2. The high
zs frequency component of a signal inputted to the circuit 191
passes through the high-pass filter 182, is thi.nz~ed out by
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the thinning circuit to 1/2, and is outputted. The low
frequency component thereof passes through the low--pass
filter 181, is th~,nz~ed out by the thinning circuit to 1/2,
and is inputted to the next cixcuit 192. Similarly, a~.sa
s in the circuit 192, the high frequency component is thinned
out and is outputted, and the low frequency component is
thinned out, is inputted to the next circuit 193, and is
similarly divided into a high frequency componer_t anal a low
frequency component.
to Fig. 8A shows signals decomposEd by the respective
circuits 191, 192 and 193 of the DWT circuit. An input
signal f(t) (--- Ski°a; a superscript denotes the order) is
divided in the circuit 193 into a signal. Wk;1? having passed
through the high~pass filter 7.82 anci a signal Sk~l~ having
is passed through the low-pass filter 1~~1. The signal. Sk~2~ is
divided in the next circuit 92 into a signal wk~2? having
passed through the high-pass filter 182 and a signal Sk{'~
having passed through the low pass filter 18v. The Sk~2~ is
divided in the next circuit 193 zntc> a signal Wkt~~ having
2o passed through the high.-pass filter 182 and a signal Sk°3a
having passed through the low-pass filter 187.. The S(t) is
called a scaling coefficient (or low-pass filter), and W(t)
is called a wave7.et coefficient (or high--pass filter) .
Next (mathematical expression B) and (mathematical. I
2s expression 9) indicate transform expressions of the DWT
usEd in the embodiment of the invention.
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step 1: wt (t) - f (at~i) ~ C { f (2t) + f (2t~z) ~/2)
(mathezn~atzca7. expression 8)
step 2: s (t) - f (2t) + j (w(t) + w(t-1) + 2}/9]
(mathematical expression 8)
s Tn the first order forward transform, sampling data
of the measurement ~.nfoxmatian is made the discrete vaJ.ue
f(t), and is transformed by the (mathematical expression 8)
and the (mathematical expression 9) into the first order
wavelet coefficient and the first order scaling
so coefficient. zn a subsequent nth order forward transform,
an (n-1)th order scaling coefficient is made f(t), and
transform into an nth order waveiet coeff~.cient and nth
order scaling coefficient is performed by the (mathematical
expression 8) and the (mathematical expression 9). Fig, 9A
is shows a structure of each of the circuits 191, 192 and ?.93
of the DWT circuit reaiizing this transform. zn the
drawing, "Round" indicates a rounding processing. The
sampling data (state amount) of a traffic w state is
transformed into the scaling coefficient and the wavelet
zo coefficient by the (mathematical expression 8) and the
(mathematical expression 9) and is p~.~ovided.
Fig. 7B shows a filter circuit of the IDWT. The
TDWT circuit is con.stxucted of plural cascade-connected
circu~.ts 194. 195 and 196 each including an interpolafiion
zs circuit 186 for interpolating a signal by a factor of 2, a
low-pass filter 184, a high-pass filter 185, and an adder
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187 for adding outputs of the low-pass filter 184 and the
high-pass filter 185. Signals having a high frequency
component and a low frequency component inputted to the
circuit Z94 are interpolated by a factor of 2, are added to
s each other, are inputted to the next circuit 295, are added
with a high frequency component in this circuit 195, are
further added with a high frequency component in the next
circuit 195, and are autputted.
Fig. 8~ shows signals reconstructed by the circuits
l0 194, 7.95 and 196 of the TDWx c~.rcuit:. In the circuit 194,
the scaling coefficient Sk~3~ and the wavelet coefficient
Wk~3~ are added to each other, so that the scal,~.ng
coefficient Sk~Zf is created. In the next circuit 195, the
sca7.ing coefficient Sk~2r and the wavelefi coefficient Wk~z~
xs are added to each other; so that the scaling coefficient
Sksl~ is created. In the next circuit 196, the scaling
coefficient Sk{1~ and the wavelet coefficient Wk«~ are
added to each other, so that the Ski°' (= f(t)) is created.
Next (mathematical expression 10) and (mathematical
2o expression 11) indicate transform expressions of the TDWT
used in the embodiment of the inrrenti.on.
step ~.: f(~t) - s(t) + [~w(t) * w(t-1) ~- 2}/4~
(mathematical expression 10)
step 2: f (2t*1y ~ w(t) - [~f(2t) * f(Zt+2) }/2a
25 (mathematical expression 11)
Tn the nth order inverse transform, the signal f(t)
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transformed by (nø1)th order IDWT is made the scaling
coefficient, and the transform with the stEps of the
(raathEmatical expression 10) a~zd the (mathematical
expression 11) is performed. Fig. 9~ shows a structure of
each of the circuits 194, 195 and lg5 of the IDWT circuit
for realizing this transform.
A.s stated above, from the sampling data of the
measurement informat~.on, the scal.~.rag coefficient and the
wavelet coefficient can be ca~.culated by the (mathematical
so expressian $) and the (mathematical expression 9).
Besides, from the scaling coeffzc:ient and the wavelet
coei~ficient, the sampling data of the measurement
information. can be restored by the (mathematical expression
10) anal the (mathematical expression 17.) .
The first order scaling coefficient smoothes and
indicates the shape expressed by the sampling data
(original data), and the nth order scaling coeffic~.ent
smoothes and indicates the shape expressed by the (n-~1~) th
order scaling coefficient. In Fig. 4, the ~rertical axis
2o indicates speed, the horizontal axis indicates distance
from a reference point, the sampling data of speed measured
by the probe-car is indicated by a solid line, and the
first scaling coefficient obtained when the original data
is subjected the DWT once is indicated by a dotted line.
zs Fig. ~ shows the first scaling coeff~.cient (dotted line), a
second scal~.ng coefficient (dashed line) obtained when the
7. 5
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DWT is further repeated, and a third scaling coefficient
tdotted line with long ling portions). The distance
interval between the first order scaling coefficients is
twice the distance interval of the original data, and the
s value of the scaliing coefficient is an average of the
values of the original data included in the distance
interval. ?'he distance interval between. the nth order
scalzng coefficients is twice the distance interval between
the (n-1)th order scaling coefficients, and the value of
to the nth order scaling coefficient i$ an average ofi the
vaJ.ues of the (n-1)th order scaling coefficient included in
the distance interval.
Accordingly, even in the case 'where the amount of
data uploaded from the on-board unit of a probe--car is
15 limited, when data capable of restoring the nth (n ~ 1, 2,
scaling coefficient as transz~itted, the center
apparatus can grasp the rough state (coarse measurement
information) of the measurement inf~~rmation,. ~As the order
of the scaling coeffac~.ent becomes high, the amount of data
ao transmitted from the on-board unit of a probe-car is
decreased, and the measurement information which can be
grasped by the center apparatus becomes coarse.
~cTransmitted/Reeeived Data Structuxe>
z5 Fig. 1 exemplifies a data structure of data
transmitted and received between the on-board unit of a
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probe-car and the beacon.
When a probe-car i21 first passes through under a
beacon 122, or passes through under the beacon 122 after a
specified time has passed since it passed through under the
s last beacon (or after it travels a specified distance), FCD
information ("swept path * measurement information'P)
indicated by (1) is transmitted from the on-board unit of a
probe-car to the beacon 122. The information includes the
identification number of a code table used for encoding of
;o swept path, sampling distance interval of position
information indicating the swept path, distance interval of
the measurement information, coded data indicating the
swept path, and coded data of the measurement information
subjected to the DWT transform.
15 Since the position Information of the beacon 122 as
the reference paint (end point) of the swept path is
already known in the center apparatus, it is not necessary
w that the position information of the reference point is w
included in the data indicating the swept path.
zo Nevertheless, since the data amount of the coded data
indicating the swept path is large, it is necessary to
lessen the data amount of the coded data of the measurement
information in the FCD Information c>f (1}. Thus, measures
are taken such that only data necessary fox restoring the
zs nth prdex scaling coefficient is made to be includEd, the
sampling distance Interval of the measurement information
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is expanded to roughen the accuracy o~ the measurement
information, or the distance of the sectzon as the object
of the measurement information is narrowed.
~On the other hand, the beacon 7.22 downloads
s ~.nstruction information indicated by (2) to the on-board
unit of a probe-car passing through under the beacon 122.
The information includes the beacon number of the beacon
122, instruction information of the measurement method and
coding method of the measurement information (information
xo of the number of the measurement method and coding method
previously transmitted to the on--board unit of a probe-car,
and a code table used for coding), sampling distance
znterval of the measurement information, and 'the like_
when the probe-car ~.2~. passes through under a
~s downstream side beacon 123 within the specifa.ed time since
it passed through under the upstream side beaGOn 122 (or
before it runs the specified distance), FCD information
("travel distance + measurement information") indicated by
(3) is transmitted from the on-board unit of a probe--car to
zo the beacon 123. This information inc3.udes the number of
the last passed beacon 7.22, the travel distance from the
~.ast passed beacon x.22, the instruction number of the
measurement method and cod~.ng method recei~red from th.e 'last
passed beacon 122, the sampling distance interval of the
2s measurement information, and the coded data of the
measurement information subjected to the DWT transform.
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5i.nce the FCD information does not include the data
o~ the swept path, the data amount c~f the coded data of the
measurement information can be increased, and the
infoxznation accuracy of the measurement information can be
s raised.
.System Structure>
Fig. 2 shows a structure of this probe-car system.
This system includes an on-board unit 90 of a probe-car,
~o for measuring and providing data at the time of running,
and a center apparatus 80 for collecting the data through a
beacon. The beacon itself may have the structure of the
center apparatus 80.
The onboard unit 90 ir.~cludes an on-~rehicle
is apparatus com.~nunacatidn part 100 :Eor performing two-way
communication with the beacon, a measurement coding
instruction reception part 94 fox receiv~.ng ir_stxuction
information. from the beacon, a~ sensor information
cc~lleGti.on part 99 for collecting measurement ~.nformat~.on
zo of a sensor A 10~ for detecting speed, a sensor H 107 for
detecting power output, a sensor C 108 for detecting fuel
consumption, and the like, an own vehicle position judgment
part 9? for detecting own vehicle position by using GPS
information received by a GPS antenna 10~. and information
zs of a gyro 102, a swept path measurement information storage
part 98 for storing the swept path of the own vehicle and
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the measurement information of the sensors A, H and C, a
coding processing part 93 for coding the measurement
~.nformation and sampling data of the swept path on the
basis of instruction data 95 of the measurement method arid
s coding method rece~.ved from the beacon and instruction data
96 of the default measurement method, and coding method
pre~riously held by the on-board unit ~0, an FCD information
selection part 92 for selecting whether the FCD information
(1) of Fig. 1 is to be transmitted tc> the beacon or the FCD
to informata.on of (3) is to be transmitted, and an FCD
~.nformation transmission part 91 for. transmitting the FCb
information selected by the FCD information selection part
92 to the beacar_ when passing through, under the beaGan.
pn the other hand, the center apparatus 80 includes
15 a beacon communication part 87 for perfarmin,g two-way
communication with the on-board unit 90, an fD information
reception part 83 for receiving the FC1~ information from
the on-board unit 90, a coded data decoding part 82 for
decoding the coded data included in the F'CD information, a
2o swept path measurement information utilizing part 81 for
utilizing the data of the decoded measurement information
and swept path, a measurement coding instruction selection
part 85 for selecting measurement coding instruction data
86 to be gi~rer. to the on-board unit 90, and a measurement
25 COdl~I7g ~.nstruction transmission part 84 fior transmitting
the selected measurement coding s.nstruct~.an data 86 to the
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on-board unit 90.
zn the center apparatus 80, there are prepared the
plural measurement coding instruction data 86 made to
correspond to traffic states and each including the
s measurement method and coding method of the measurement
information, the information of the code table, and the
like. When the beacon communication part 87 starts the
two-way communication with the on-board unit 90, the
measurement coding instruction selection part 85 selects
io the measurement coding instruction data 86 Corresponding to
the present traffic state, arid the selected measurement
coding instruction data 86 is transmitted to the on~bard
unit 98.
is <Processing Flow>
dig. 3 shows a processing flow of the probe-car
system. The on-board unit 90 measures present position and
speed (measurement information) in a unit of, for example,
one second, and stores the measurement data in the swept
zo path measurement information storage part 98 (step 1). The
coding processing part 93 creates sampling data of sampling
distance interval of position information and creates
coding data expressing the swept path from the stored swept
path data in accordance with the measurement coding
z5 instruction data 95 when the instruction data has been
received from the beacon, or in accordance with the default
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measurement coding instruction data 96 if not so. Besides,
the coding processing pant creates, from the stored speed
information, the sampling data of sampling distance
interval of the measurement infozmation, and creates coded
data of speed information subjected to the CWT transform
(step 2) .
text, the coding process~,nc~ part 93 creates th.e
data of travel distance from the last passed beacon, and
creates tk~e coded data o~ speed information subjected to
so the DWT tr ansform ( step 3) .
The FCD information se~.ection part 92 counts up an
accumulation counter for counting the accumulated value of
distance (or time) froze the last passed beacon, and when
the count value of the accumuJ.ation counter exceeds a
is specified value, the "swept path ~ measurement information"
((1) of Fig. 1) created at step 2 is determined to be the
transmission data. When the count value of the
accumulat~.on counter is the specif~,ed value or less, the
~~travel distance + measurement information" ((3) of Fig. 1)
2o created at step 3 is determined to be the trans~uisszon data
(step 9) .
In the case where the on-vehicle apparatus
communication paxt 100 starts the communication w~.th the
beacon coz~.munication. part 87, the FCD information
z5 transmission part 9J. judges that the timing of transmission
occurs (step 5), and transmits the FCA information selected
22
CA 02480134 2004-09-O1
by the FCD information selection part 92 to the beacon
(step 6) . When the tiz~,ing of transmission does not occur,
the procedure from step ~. is repeated.
After transmitting the FCD information to the
s beacon, the on-board unit 90 resets the accumulation
.counter, and resets the data stored in the swept path
measurement information storage part 98 (step 7).
When receiving the FCD a.nformation (step 20), the
cex~tex apparatus 80 transmits the new measurement and
io coding instruction data 86 selected by the mEasurernent
coding instruction selection part 85 to the on-board unit
90 (step 21). The on,-board unit 90 receives the new
measurement coding instruction data (step 8), and repeats
the procedurE from step 1.
is In the case where "swept path a~ trie~.sur ement
information" ((1) of Fig. I) is received, the center
apparatus 80 refers to the pertinent measurement and coding
instruction data, decodes the coded data, and reproduces
the measurement information on the swept path. In the case
zo where "travel distance + measurement information" ((3) of
Fig. 2) is received, the center apparatus refers to the
travel distance and the beacon number included in the FCD
information. When the installation interval between the
upstream side beacon and the downstream side beacon is
2s substantially coincident with the travel. distance, the
center apparatus refers to the pertinent measurement and
23
CA 02480134 2004-09-O1
coding instruction data, decodes the coded speed data, and
reproduces the speed information whi3e the installation
route of beacons is made the swept path (step 22).
The center apparatus 80 utilizes the reproduced
s speed information for creation of the traffic information
and the like (step 23).
As stated above, in the probe-car system, the FCD
information can be efficiently collected from the on-board
unit by using the beacon.
io
Modified Example>
Although the description has been given to the case
where the variable 2ength coding system of an argument
predicted difference value is applied to the coding of the
is swept path data, and the coding system by DWT is applied to
the coding of the measurement information, the invention is
not limited to this. The measurement information can be
coded by the variable length coding system of the argument
predicted difference value, and the swept path data can be
zo coded by the DWT. Besides, it is also possible to use
orthogonal transform such as DFT (discrete Fouriex
transform), DGT idiscrete cosine transform), DHT (discrete
Hadamard transform), or DWT (discrete wavelet transform).
Besides, although the description has been given to
2s the case where the measurement and coding instruction data
is downloaded from the beacon to the on-board unit, this is
24
CA 02480134 2004-09-O1
not inevitabJ.e,
Besides, a~.though the description has beer. given to
the case where the swept path data is transmitted as the
road section reference data ind~.ca,ting the object z~oad
s section of the measurement information, the road section
reference data may be othexs» For example, as shown in
Fig. 10A, un~.formly determined road section identifiers
(link number) and intersection identifiers (node number)
may be used.
to zz~ the case where both the on-board unit and the
center apparatus refer to the same map, the on-board unit
transmits the latztude and longitude data of the
measurement start ~aoint on the map to the center apparatus,
and the center apparatus can specify the road section based
on this data.
Besides, as shown in fig< IO:B, the abject road may
be transmitted by transmi.tt~.ng latitude and longitude data
(including the attribute information of name, kind of road
and the 7.zke as well) for position reference of
zg interm~.ttent nodes P1, P2, 1~3 and P~~, which are extracted
from intersection parts and roads at midpoints in the link,
to the centex apparatus. Here, the nodes are as follows:
P1 - link center point, P2 = zr~tersection part, p3 = 1. ink
center point, and P4 = link center point. Zn this case, as
zs Shawn i.n Fig. IOC, the oenter apparatus specifies the
respective positions of Pl, P2, P3 and P4, and next,
CA 02480134 2004-09-O1
COhneCt9 the respective sections by a route search to
specify the cbject road section.
Besides, as the road section reference data fox
specifying the object raad, a road map is divided into
s tile-~li.ke parts, and identifiers attached to the respective
ones, kilo posts provided on the road, road name, address,
zip code and the ZiJ~e may be used.
Movement distance, movez~ent time, exhaust gas
information, wiper operation state, parking brake operation
la state and the like in addition to the speed, the power
output, and the fuel consumption can be included in the
measurement informatian.
(Second ~mbodzment)
xs In a probe-car system of a second embodiment of the
invention, when a an--board unit of a probe-car having
passed through under an upstream side beacon passes along a
previous3y determined xoad and reaches a~ downstream side
beacon, only measurement information is uploaded to the
za downstream side beacon, and when passing along another road
and reaching the downstream s~.de beacon, swept path data
and the measurement information are uploaded to the
downstream side beacon. In order to enable the on-board
unit itself to discrim~.nate whether it has passed along the
z5 previously determined road, the upstxeam side beacon
transmits the number of the downstream side beacon and the
26
CA 02480134 2004-09-O1
distance to the downstream side beacon to the on-board
unit. When the on-board unit reaches the downstream side
beacon, in the case where the travel distance is
substantially coincident with the distance to the
s downstream .side beacon transmitted from the upstream side
beacon, the on-board unit discrimina°tes that it has passed
along the previously determined road, and when the travel
distance is much different from the dzstance to the
downstream side beacon transmitted from upstream side
so beacon, the on-board unit discriminates that it has not
passed along the prev~.ous3y deterrnine:d road.
Fig. 17. exemplifies the data structure of data
transmitted and received between the on-board unit and the
beacon.
Data (1) "swept path * measurement z,nformation~~ is
FCD information uploaded from the on-board unit to the
downstream side beacon ~.2~ when the probe~car 121 reaches
the downstxeaxn side beacon 123 without passing along the
prev~.ously determined road. This is the same as the FCD
zo information transmitted from the on-board unit fid the
beacon 122 in the fzrst embodiment (~'ig. ~.) when the probe-
car ~.2~, first passes through under the beacon I,22, or
passes through u_~nder the beacon 122 after the specified
time has passed since it passed thxough under the last
2s beacon (or after it runs the specified distance or more).
Data (2) "instruction informat~.oz~ to probe-car" is
27
- CA 02480134 2004-09-O1 - . , ,."
~.nstruction information transmitted from the downstream
side beacon 122 to the on-board unit. 'this informati.an
includes information of the number of the downstream side
beacon 123, and the distance to the beacon 123 in additior_
s to the beacon number of the beacon 122, instruction
information of x~.easurement method and cading method, and
saz~pli,ng distance interval of measurement informatian.
Data (3) "only measurement information" is FC1~
informati.an upJ.oaded from the on-board unit to the
to downstream side beacon 123 when the pxobe-car 121 passes
along the pre~riously determined road and reaches the
downstream side beacon 123. This is the same as the FCD
iz~foxzn.ation. transmitted to the downstream side beacon 123
in the first embodiment (Fig. 1) when the probe~car 121
1$ passes through under the downstream side beacon 123 within
the specified time since it passed through under the
upstream side beacan 122. Incidentally, in the case of
"only measurement information", the information of "travel
distance from last passed beacon" may not be ancludcd.
2o Fig. 12 shows a structure of thus probe~car system.
In this system, an FCD information selection part 92 of an
on-board un~.t 90 selects FCD information to be uploaded on
the basis of the information of distance to the downstream
side beacon included in measurement coding instructzox~ data
z5 95. The other structure is identical to that of the first
embodiment (Fig. 2).
28
_ _.. ."", CA 02480134 2004-09-O1
Fig. 13 shows a processing flow of this system.
The processings of step 1 to step :3 are the same as the
processings,af the same steps of the processing flow (~'ig.
3) of the f~.xst embodiment.
s When the probe-car reaches the beacon, and an onw
vehicle communication part 100 starts two-way commun.,zcation
with a beacon communication part 87 (step 5), the FCD
information selection part 92 acquires information of the
beacon number of the beacon 'through the on--vehicle
to communication. part 100, refers to the measurement coding
instruction data 95, reads information of distance to the
beacon having the pext~.nent number, and compares this
distance with th.e travel distance from the last passed
beacon obtained at step 3 (step 51). Tn the case where
~.5 both. axe coincident with each other (Yes at step 52); it is
determined that "only measurement in:Eormaf.ion" ( (3) of Fig.
11 ) is the FCD information, to be transmitted, and the FCD
information transmiss~.or part 91 transmits the d@termined
"only measurement information" to the beacon (step 53). In,
zo tk~e case where both are much different from each other (No
at step 52), it is determined that "swept path +
measurement information" ((1) of Fig, 7.i) is the FCD
information to be transmitted, and the FCD information
transmission part 91 transmits the determined "swept pafih +
z5 measurement information" to the bea con (step 59). After
transmitting the FCD irzfox~mataon to the beacon, the on'
29
CA 02480134 2004-09-O1
board unit 90 resets the data stored ~.n a swept path
measurement storage part 98 (step 55).
When receiving the ~'C~ anformation (step 20), the
center apparatus 80 transmits new measurement and coding
s instruction data 86 selected by a measurement coding
instruction selection part 85 to the on-board unit 90. As
shown by (2) of Fig. 11, the measurement and coding
instruction data 8s includes the information of the number
of the next beacon and the distance to the beacon (step
~.0 211). The on-board unit 90 reGe~.ves the new measurement
and coding instruction data (step 56), and repeats the
procedure from step J..
In the case where "swept path -~ measurement
information" ((1) of Fig. 11) is received, the center
is apparatus 80 refers to the pertxz~ent measurement and coding
instruction data, decodes the coded data, and reproduces
the measurement inforznataon on the swept path. In the case
where "only measurement information°' ((3) of Fig. 11) is
received, the center apparatus refers to the pertinent
zo measurement and coding instruction data, decodes the ceded
speed data, and reproduces the speed infox-mat~.on in which
the installation route of the beacon is the swept path
(step 22). The reproduced speed information is utilized
for creation of traffic information .and the J.~.ke (step 23).
2s As stated above, in this system, even in the case
where the probe-car runs while bypassing the installation
CA 02480134 2004-09-O1
route of beacons, it becomes possible for the center
apparatus to utilize the measurement information measured
by the an-board unit and the swept path information.
Although the judgment as to whether the probe-car
s bypasses the installation route of the beacons is made by
the on-board unit itseJ.fr in the case where the information
of "travel distance from last passed beacon" is made to be
included ix~ (J.l "on3.y measurement information", the center
apparatus can check the propriety of the judgment of the
zo on-board unit.
(Third Embodiment)
In a probe-car systerct of a Lhird embodiment of the
invention, similarly to the second embodiment, when an on
ls boaxd unit of a probe-car having passed through under an
upstream side beacon passes along a previously determined
road and reaches a downstream side beacon, only measurement
information is uploaded to the downstream side beacon, and
when the on~-board unit passes along another xoad and
za reaches the downstream side beacon, swept path data and
measurement information axe uploaded to the downstream side
beacon.
zn the system of the th~.xd embodiment, the upstream
side beacon transmits a road network (road shape), which
25 leads to the downstream side beacon, to the on-board unit,
so that the on-board unit itself can discriminate whether
31
CA 02480134 2004-09-O1
it has passed along the previously determine road. The on-
board unit compares the road shape with the swept path, and
fudges whether the route to the dawnstream side beacon is
the previously determ~.n.ed road.
Fig. ~.4 exemplifies a data structure of data
transmitted and received between the on-board unit and the
beacon.
Data (1) "swept path + measurement information" is
FCD information uploaded from the on-board una.t to the
ao downstream side beacon when the probe-car 121 reaches the
downstream side beacon without passing along the prev~.ously
determined road, and is the same as the FCD information
((1) "swept path + measurement information") of the second
embodiment (Fig. 11).
2s Data (2} "instruction informal ion to probe~car" is
instruction information transmitted from the downstream
s~.de beacon 122 to the on-board unit. This information
includes the number of a downstream side beacon, and a data
row composed of variab~.e length coded data of argument
2o predicted difference values expressing the road shape to
the beacon, in addition to the beacon number of the beacon
122, instruction information of measurement method and
coding method, and sampling distance interval of
measurement zx~formation. The coded data of the road shape
2s is created by the method described in the forego~.ng
<Creation of Running Locus Data>.
32
CA 02480134 2004-09-O1
Data (3) "only measurement information" is FCD
information uploaded from the ors--board unit to the
downstream side beacon when the probe-car 121 passes a7.ong
the previously determined road and reaches the downstream
s side beacon 123, and is tY~e same as the FCD information
((3) "only measurement information") of the second
embodiment (Fig. 11).
The structure of the probe-car sxstem is the same
as the second embodiment (~'ig. 12) .
~o Fig. 15 shows a processing flow of this system.
Processings of step 1 to step 3 are the same as the
process~.ngs of the same steps zn the processing flow (Fig.
3) of the first embodiment.
The FCD information selection part 92 of the on-
is board unit 90 refers to the measurement Coding instruct~.oz~
data 95, and compares the road shape to the downstream side
beacon included therein with the swept path by map matching
or the like. When they are coincident with each other, it
is determined that (3) "only measurement information"
zo created at step 3 is to be transmitted as the FCD
information, and when they are n.ot coincident with each
other, i t is detern~ir_ed that ( 1 ) "swept path t measurement
information" created at step 2 is to be transmitted as t~:e
FCD information (step 41)_ This operation is repeated
z5 until the transmission timing occurs.
When the probe-car reaches i~he beacon and the on-
33
CA 02480134 2004-09-O1
vehicle apparatus communication part 100 starts the two-way
communication with the beacon communication part 87 (step
5), the FCD information transmission part 9~. transmits the
FCD information determined by the FCD information se7.ection
s part 92 to the beacon (step 6). After transmitting the fC~7
information to the beacon, the on--board unit 90 resets the
data stored in the swept path measurement information
storage part 98 (step 61).
When receiving the FCD information (step 20), the
to center apparatus 80 transmits the new measurement and
coding instruction data 86 selected by th,e measurement
coding instruction selection part 85 to the on-board unzt
90. As indicated by (2) of Fig. 1~~, the measurement and
coding instructz.on. data 86 includes the numlaer of a next
x5 beacon and the information indicating the road shape to the
beacon (step 212). The on-board unit 90 receives the new
measurement and coding instruction data (step 62), and
repeats the procedure from step 1.
The center apparatus 80 reproduces the swept path
zo and measurement information and utilizes it. This
processing is the same as steps 22 and 23 in the processing
flow (Fig. 13y of the secozad embodiment.
As stated above, the on-board unit of this system
travels while judging whether the swept path is coincident
z5 w~.th the previous7.y determined passage to the beacon. In
the case where the on-board unit passes along the
34
CA 02480134 2004-09-O1
previously determined passage and reaches the beacon, it
uploads only the measurement information to the beacon. rn
the case where the on-board unit reaches the beacon without
passing along the previously determined passage, it uploads
the measurement infox~ation and the swept path to the
beacon.
In this system. 3t is possible to accurately
discriminate whether the probe-car passes along the
previously determined passage, and accordingly, even in the
io case where the probe~car passes along any route, the
measurement information measured by the an~board unit can
be effectively utilized.
As zs apparent from the above description, in the
~s probe-car system of the invention, the measurement
information is effectively collected from the onboard unit
by using the beacons, and can be effectively utilized.
Besides, the on-board unit of the invention can
realize the probe-car system.
35
