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JP,09-237399,A(1997)
PATENT ABSTRACTS OF JAPAN
(11)Publication number : 09-237399
(43)Date of publication of
application :
09.09.1997
(51)Int.Cl. G08G 1/042
B60R 21/00
G01R 33/02
G01V 3/08
G01V 3/10
// G01C 21/00
(21)Application
number :
08-
043933
(71)Applicant
:
CANON ELECTRON
INC
(22)Date of filing : 01.03.19
96
(72)Inventor : KAWASE
MASAHIRO
TAZAKI SHINICHI
(54) METHOD, DEVICE AND SYSTEM FOR VEHICLE DETECTION
(57)Abstract:
PROBLEM TO BE SOLVED: To improve
reliability by making the magnetic
detection of an vehicle highly precise
through the use of a magnetic sensor
consisting of plural small magnetic
detection elements.
SOLUTION: The magnetic sensor 12
plurally arranging along the
longitudinal direction of the vehicle
the magnetic detection elements 1A
to 11N with magnetic field detecting
sensitivity in a direction vertical to the
ground is installed on or in the ground
within the passing width of the
vehicle. Through the use of a selector 21, a timer counter 20 and RAM
26 storing the early value of external magnetic intensity, a control
part 19 measures each change of external magnetic field intensity
basing on the state of no vehicle with respect to each magnetic
detection element as a reference based on the intensity of external
magnetic field detected by each magnetic detection element. Then
the part 19 judges vehicle detection depending on whether the total
sum of the respective absolute values of the measured values
exceeds a prescribed combined threshold values.
CLAIMS
[Claim(s)]
[Claim 1]In a vehicle detecting method which detects a magnetic field
generated from vehicles with a magnetic sensor, and detects vehicles
magnetically, A magnetic sensor which put in order two or more
magnetism detecting elements which have magnetic field detection
sensitivity in the direction vertical to a ground surface along with a
vehicles longitudinal direction is installed in a ground surface in a
band pass of vehicles, or underground, A vehicle detecting method
detecting vehicles by the judgment of whether external magnetic
field intensity change as on the basis of the state where each of two
or more of said magnetism detecting elements detects external
magnetic field intensity, and there are no vehicles is measured, and
total of an absolute value of two or more measurement values of this
measuring result exceeds predetermined joint threshold S.
[Claim 2]The vehicle detecting method according to claim 1 setting
said joint threshold S as a value of a product which hung threshold s
in the case of one magnetism detecting element, and a square root of
the addition numbers n of said measurement value added in order to
ask for said total.
[Claim 3]An absolute value of two or more measurement values of a
measuring result of the aforementioned external magnetic field
intensity change is arranged in descending, it is considered as |
deltaH(k) | (k= 1, 2, ordinal number of --), and they are the following
expression about this value, threshold s in the case of one magnetism
detecting element, and a square root of said addition numbers n.
[Mathematical formula 1]
The vehicle detecting method according to claim 2 judging with
having detected vehicles when it compared whether it is alike, it
would set, would substitute one by one from k= 1, and the above-
mentioned expression would be satisfied and the above-mentioned
expression was satisfied.
[Claim 4]The vehicle detecting method according to claim 2 or 3
setting threshold s in the case of said one magnetism detecting
element as the range of 0.05-0.1 gauss.
[Claim 5]It is a vehicle detecting device which detects a magnetic
field generated from vehicles with a magnetic sensor, and detects
vehicles magnetically, A magnetic sensor which consists of two or
more magnetism detecting elements arranged so that it may have
magnetic field detection sensitivity in the direction vertical to a
ground surface and may rank with a ground surface in a band pass of
vehicles, or underground along with a vehicles longitudinal direction,
A measurement means which measures each of external magnetic
field intensity change as on the basis of the state where there are no
vehicles to each magnetism detecting element, based on external
magnetic field intensity detected by each of two or more of said
magnetism detecting elements, A vehicle detecting device having a
judging means which judges vehicle detection by whether total of
each absolute value of a measurement value of external magnetic
field intensity change measured by this measurement means exceeds
predetermined joint threshold S.
[Claim 6]It has a memory measure which memorizes a value of
external magnetic field intensity detected by said two or more
magnetism detecting elements in the state where said measurement
means does not have vehicles as an initial value used as a standard,
The vehicle detecting device according to claim 5 measuring the
aforementioned external magnetic field intensity change on the basis
of an initial value memorized to this memory measure.
[Claim 7]A Colpitts oscillator in which said magnetism detecting
element incorporated a magnetic impedance component which
attached a coil, It comprises a comparator [ predetermined
comparison voltage / output / of a detector circuit which detects an
output of this oscillator and this detector circuit ], By detecting
external magnetic field intensity, applying an AC bias magnetic field
to said magnetic impedance component with said coil, A Pulse-
Density-Modulation output in which a pulse which is two kinds from
which pulse width differs according to external magnetic field
intensity in an output of said comparator appears by turns is
obtained, The vehicle detecting device according to claim 5 or 6,
wherein said measurement means measures external magnetic field
intensity change as on the basis of the state where ask for data of a
difference of pulse width of two kinds of said pulses as external
magnetic field strength data, and said vehicles cannot be found based
on this data.
[Claim 8]It is a vehicle detection system which carries out vehicle
detection to any 1 clause from Claim 5 to 7 using a vehicle detecting
device of a description, A judging means which judges whether
whether vehicles advanced on a magnetic sensor, whether it stopped
on a magnetic sensor based on a decided result of vehicle detection
by a judging means of said vehicle detecting device, and on a
magnetic sensor were left, Car presence information on a purport that
vehicles have stopped on a magnetic sensor based on a decided
result of this judging means, And a vehicle detection system
characterized by having an output means to which vehicles output
**** information on a purport that on a magnetic sensor was left, and
enabling it to manage parking vehicles with the output of said car
presence information and **** information.
DETAILED DESCRIPTION
[Detailed Description of the Invention]
[0001]
[Field of the Invention]This invention detects the magnetic field
generated from vehicles, such as a car, with a magnetic sensor, and
detects vehicles magnetically, namely, relates to the vehicle
detecting method which detects the existence of vehicles thru/or
passage, a vehicle detecting device, and a vehicle detection system.
[0002]
[Description of the Prior Art]Conventionally, the sensor which detects
vehicles, such as a car, is used in the use of measuring the distinction
of the existence of parking in the managerial system of a motor pool,
and the traffic of the vehicles in a traffic control system.
[0003]Usually, since vehicles, such as a car, are tinged with
magnetism using the metallic material which is easy to be tinged with
magnetism, such as a steel plate, it is detecting the magnetic field
generated from vehicles with a magnetic sensor, and it is possible to
recognize existence of vehicles or passage.
[0004]Conventionally, in the motor pool, the loop coil type magnetic
sensor was buried in the earth, and it has been used for vehicle
detection in it. A loop coil type magnetic sensor is that generate a
magnetic field by an eddy current in the metal part of the body of
vehicles to the alternating current sent through a coil, or the
magnetic field from the body's own magnetization interlinks with a
loop coil, A coil's own inductance changes, it is changed as change of
oscillating frequency or amplitude in a circuit, and vehicle detection is
performed by the existence of the change.
[0005]However, although the loop coil type magnetic sensor is
spreading by detection of vehicles, it has the following problems.
[0006]- Since a loop coil opens an interval a little with vehicles and is
installed, in order to detect the inductance variation in vehicles
existence, there is the necessity of enlarging size of a sensitivity
secured upper coil (about 1mx1m).
[0007]- If metal bodies, such as a steel rod, are in the neighborhood,
S/N cannot be taken enough.
[0008]- Since a loop coil is large and power consumption is large, it is
not fit for continuous energization use.
[0009]- A coil is a size which is about 1mx1m, and the burden of
construction expense is heavy in subterranean installation.
[0010]Then, although the small magnetic sensor was used and the
substitution was considered, When the magnetic field generated from
a vehicles pars basilaris ossis occipitalis was measured, near the zero
crossing point which remarkable unevenness is made to distribution
of magnetic field strength, and magnetic field polarity reverses by the
local magnetization of Body Manufacturing Division article each which
it has, it turned out that the dead point which does not exceed a
threshold required for the judgment of vehicle detection arises.
[0011]
[Problem to be solved by the invention]Then, a reliable vehicle
detecting method in which SUBJECT of this invention can perform
magnetic detection of vehicles with high precision using the magnetic
sensor which consists of two or more small magnetism detecting
elements, And it is in providing the vehicle detection system which is
a vehicle detecting device which performs vehicle detection by the
method, can attain a miniaturization and can be used effective in
management of parking vehicles using the vehicle detecting device of
low power consumption, and this vehicle detecting device.
[0012]
[Means for solving problem]In the vehicle detecting method which
according to this invention detects the magnetic field generated from
vehicles with a magnetic sensor, and detects vehicles magnetically in
order to solve above-mentioned SUBJECT, The magnetic sensor which
put in order two or more magnetism detecting elements which have
magnetic field detection sensitivity in the direction vertical to a
ground surface along with the vehicles longitudinal direction is
installed in the ground surface in the band pass of vehicles, or
underground, The external magnetic field intensity change as on the
basis of the state where each of two or more of said magnetism
detecting elements detects external magnetic field intensity, and
there are no vehicles was measured, and the method of detecting
vehicles by the judgment of whether total of the absolute value of two
or more measurement values of this measuring result exceeds
predetermined joint threshold S was adopted.
[0013]According to such a vehicle detecting method, the influence of
the zero crossing point which the magnetic field polarity looked at by
distribution of the magnetic field strength in the case of measuring
the magnetic field generated from a vehicles pars basilaris ossis
occipitalis reverses can be avoided, and highly precise and reliable
vehicle detection can be performed.
[0014]According to this invention, it is a vehicle detecting device
which detects the magnetic field generated from vehicles with a
magnetic sensor, and detects vehicles magnetically, The magnetic
sensor which consists of two or more magnetism detecting elements
arranged so that it may have magnetic field detection sensitivity in
the direction vertical to a ground surface and may rank with the
ground surface in the band pass of vehicles, or underground along
with a vehicles longitudinal direction, The measurement means which
measures each of external magnetic field intensity change as on the
basis of the state where there are no vehicles to each magnetism
detecting element, based on the external magnetic field intensity
detected by each of two or more of said magnetism detecting
elements, Total of each absolute value of the measurement value of
external magnetic field intensity change measured by this
measurement means adopted the composition of the vehicle
detecting device which has a judging means which judges vehicle
detection by whether predetermined joint threshold S is exceeded.
[0015]While being able to perform reliable vehicle detection with high
degree of accuracy with the vehicle detecting method of this
invention according to such composition, the magnetic sensor can
consist of small size which consists of plurality of the small
magnetism detecting element constituted, for example using the
magnetic impedance component as a magnetic sensor of low power
consumption.
[0016]It is a vehicle detection system which performs vehicle
detection using the vehicle detecting device by above-mentioned this
invention according to this invention, The judging means which
judges whether whether vehicles advanced on the magnetic sensor,
whether it stopped on the magnetic sensor based on the decided
result of the vehicle detection by the judging means of said vehicle
detecting device, and on the magnetic sensor were left, The car
presence information on the purport that vehicles have stopped on a
magnetic sensor based on the decided result of this judging means,
And it has an output means to which vehicles output the ****
information on the purport that on the magnetic sensor was left, and
the composition of the vehicle detection system which enabled it to
manage parking vehicles with the output of said car presence
information and **** information was adopted.
[0017]According to such composition, the advantage of the vehicle
detecting device of this invention can be enjoyed, exact car presence
information and **** information can be outputted based on highly
precise and reliable vehicle detection, and it can use effective in
management of parking vehicles.
[0018]
[Mode for carrying out the invention]Hereafter, an embodiment of the
invention is described with reference to figures.
[0019][Embodiment of a vehicle detecting method] Drawing 1 - 3
explain the embodiment of the vehicle detecting method by this
invention first.
[0020]In this embodiment, as shown in drawing 1, to the ground
surface 14 in the width which the vehicles (car) 10 pass, or
underground. The magnetic sensor 12 which has arranged two or
more magnetism detecting elements 11A, 11B, and 11C which have
magnetic field detection sensitivity in the direction (Z direction)
vertical to a ground surface so that it may stand in a line along with
the longitudinal direction of the vehicles 10 is installed, and vehicle
detection is performed.
[0021]The external magnetic field intensity change as on the basis of
the state where each magnetism detecting element of the magnetic
sensor 12 detects external magnetic field intensity, and there are no
vehicles 10 is measured, and total of the absolute value of two or
more measured magnetic-field-strength change detects vehicles by
the judgment of whether to exceed a predetermined joint threshold.
[0022]This method was drawn from the following examining results.
[0023]First, on the ground surface 14 in the width which the vehicles
10 pass as shown in drawing 2, The magnetic sensor 12 which
comprised one magnetism detecting element which has magnetic
field detection sensitivity in the Z direction which is a vertical
direction to the ground surface 14 is arranged, the vehicles 10 were
moved on the sensor 12, the magnetic sensor 12 detected external
magnetic field intensity, external magnetic field intensity change was
measured, and the situation of the change was investigated. The
variation of external magnetic field intensity made the measurement
value in the state where there are no vehicles 10 the initial value
used as a standard, and displayed a changed part from it. The
element using the magnetic impedance component mentioned later
as a magnetic sensing device was used for the magnetism detecting
element. Two or more vehicles performed the sampling. Four data
measuring of a characteristic example is shown in drawing 2 (a) - (d)
in it.
[0024]Generally, magnetic field distribution of the cross direction of a
bar magnet has a peak of reverse polarity at both ends of the bar
magnet 16 like drawing 3, and has a tendency which carries out a
zero cross in the center section. On the other hand, it can guess that
the body of a car constitutes a roughly big bar magnet from a
vehicles longitudinal direction from it being in agreement with how of
data measuring of drawing 2 to lengthen the skirt near the both-ends
peak of magnetic field distribution of drawing 3 by (c) and (d),
especially, if it observes near the both ends of a magnetic field
change. However, attitude of a peak has dispersion considerably by
overall magnetic-field-strength distribution, and it does not become a
beautiful form like a bar magnet because local magnetization exists
by part each of a body pars basilaris ossis occipitalis.
[0025]Since detection of vehicles will detect a magnetic field of a
body center section if detection of parking vehicles is taken into
consideration, for example, it observes a magnetic field of a center of
the body by width of the length of a half of the body shown in the
range of H seal in a figure of each data measuring of drawing 2. It is
because movement speed of a difference in the length of each body
and the body at the time of Measurement Division had dispersion that
the length of H seal differs.
[0026]Also when unevenness is looked at by magnetic-field-strength
change within the limits of H seal of data of four examples and a zero
cross exists, an absolute value of a measurement value may go into a
DETTO point on which it is less than threshold s, and one magnetism
detecting element is not enough as it for vehicle detection at a
certain thing.
[0027]When threshold s of one magnetism detecting element
considers resolution of a magnetism detecting element, and S/N of a
circuit, 0.05 gauss of a minimum is a limit, and considering that a
maximum has about 0.1 gauss vehicles like drawing 2 (c) in the
maximum of a magnetic field change by vehicles, it is difficult to set
up exceeding 0.1 gauss.
[0028]Then, two or more magnetism detecting elements are arranged
along with a vehicles longitudinal direction, and if vehicle detection is
carried out by whether either exceeds threshold s, detection
probability will increase.
[0029]However, in a case of vehicles of drawing 2 (d), when four
magnetism detecting elements have been arranged to each of a
position corresponding to four points, a in a figure, b, c, and d, a
measurement value by which element will also be less than 0.05
gauss. If such a case is taken into consideration, a device which raises
detection probability further is required.
[0030]Then, an absolute value of a measurement value of two or
more magnetic-field-strength change which detected external
magnetic field intensity by each of two or more magnetism detecting
elements, and was measured is added, A value of a product which, on
the other hand, hung said number (addition numbers of a
measurement value) n of a magnetism detecting element of added
square roots on threshold s at the time of detection by an
independent magnetism detecting element is set up as joint threshold
S, If vehicle detection is judged by whether total of an added result of
said absolute value exceeds joint threshold S, it is detectable by high
probabilities.
[0031]A noise component serves as a mean square to addition of an
output of each magnetism detecting element, and if it is considered
as a noise component of the respectively same size, this will use that
a product of a noise for one element and a square root of the addition
numbers n serves as a noise at the time of combination, and will try
to earn the whole S/N.
[0032]For example, magnetic-field-strength change, a of the data
measuring of the vehicles of drawing 2 (d), b, c, and d, of four points,
It will be 0.03G-0.04G-0.02G-0.03G, and if threshold s of independent
detection is set to 0.05G, when these are added, it will be 0.12G, and
0.05xroot4=0.1 gauss is set to joint threshold S, total of the added
result of an output will exceed joint threshold S, and detection of it
will be attained.
[0033]Therefore, when the magnetic field component of a direction
vertical to the ground surface of the magnetic field generated from
vehicles is detected by two or more Magnetism detecting elementn
and the magnetic-field-strength change by vehicles existence is
measured, It turned out that it is suitable that the total adding each of
the absolute value of magnetic-field-strength change measured based
on the detection result of n magnetism detecting elements of a result
performs vehicle detection by whether joint threshold S as
independent threshold sxrootn is exceeded.
[0034]By the way, since a magnetic-field-detection output may
become near a zero cross with a certain element and total of the
above-mentioned added result may become low when detecting as
mentioned above by two or more magnetism detecting elements, the
method explained below can also be chosen as a method of raising
vehicle detection efficiency further.
[0035]Arrange in descending each absolute value of the
measurement value of the external magnetic field intensity change
from the initial value which detected external magnetic field intensity
by two or more magnetism detecting elements of the magnetic
sensor mentioned above, and was measured, consider it as |deltaH(k)
| (k= 1, 2, ordinal number of --), and Namely, this value, They are
[ threshold s in the case of one magnetism detecting element, and ]
the following expression about said addition numbers n.[0036]
[Mathematical formula 2]
[0037]It compares whether it is alike, it sets, substitutes one by one
from k= 1, and the above-mentioned expression is satisfied, and
when the above-mentioned expression is satisfied, it judges with
having detected vehicles.
[0038]According to this method, vehicle detection efficiency can be
raised by adding the measurement value of two or more external
magnetic field intensity change to descending one by one, and using
for the judgment of vehicle detection.
[0039]In above-mentioned explanation, the "ground surface of
"underground" meaning the inside of those fields including all the
fields that vehicles, such as a floor line in the building of not only the
ground surface of the ground, and the road surface of a road and the
ground surface of an outdoor parking lot but a multi-level car parking
tower, run fields thru/or park" of 14 is natural.
[0040][Embodiment of a vehicle detecting device] Next, the
embodiment of a vehicle detecting device which enforces concretely
the vehicle detecting method mentioned above, and performs vehicle
detection is described.
[0041]First, the magnetism detecting element of the magnetic sensor
used for a vehicle detecting device is explained. Being required of this
magnetism detecting element should be 10 or more milligauss in (1)
magnetic field detection sensitivity.
[0042](2) There is two or more dispersion [ little ] of the performance
of an element for use.
[0043](3) Considering ground surface installation, the height of an
element should be several millimeters.
[0044](4) The detector circuit of an element is excellent in a noise-
proof and temperature characteristics, and be low power
consumption.
[0045]Although there is a flux gate type magnetism detecting
element as what satisfies the conditions of (1), if it is going to raise
detection sensitivity with this element, several 10 mm of the length of
an element will be needed, and it will not be satisfied with it of the
conditions of (3).
[0046]Since it is easy to come out of dispersion in performance, a
problem produces a flux gate type magnetism detecting element also
on condition of (2).
[0047]Then, the magnetism detecting element constituted using a
magnetic impedance component is seemed that it is the optimal by it.
[0048]The magnetic impedance component is indicated by JP,H7-
181239,A and the element body as a magnetic body is constituted
from an amorphous wire or these days by the magnetic thin film etc.
If the high frequency current of an MHz band is impressed to this
element body, according to a magnetic impedance effect, according
to an external magnetic field, the impedance of an element body
changes several 10%, and can detect an external magnetic field using
this.
[0049]Sensitivity of a magnetic impedance component has the
sensitivity of a 10-5 gauss stand, and number milligauss is securable
and it is satisfied also with practical resolution in a case where it
connects with a circuit of a magnetism detecting element of
conditions of (1).
[0050]From there being little influence of a demagnetizing field, it is
easy for the length of an element to be 5 mm or less, and conditions
of (3) are also cleared.
[0051]About dispersion in performance, when supplied with an
amorphous wire, since it is easy to control thickness, dispersion in
performance resulting from an outside dimension of a magnetic body
of an element body is pressed down, and is satisfied with that there is
little dispersion in a path of a wire, and a magnetic film of conditions
of (2).
[0052]Although application was considered according to contents
reported at a society etc. about magnetic field detection which uses
the Colpitts oscillating circuit about conditions of (4), there is a
problem practically.
[0053]For example, an application of a magnetic field sensor as an
azimuth sensor is shown by an "amorphous wire MI Colpitts oscillation
type micro magnetic sensor" announced at the 18th Maganetics
Society of Japan academic lecture meeting (14pB-7).
[0054]In composition of this azimuth sensor, an amorphous wire is
included in a Colpitts type oscillator, and since change of an external
magnetic field turns into change of oscillation amplitude and it
appears, an output is obtained through a detector circuit. While
sending a direct current through a coil directly twisted around a wire
of an element, applying a DC bias magnetic field and making it
operate in a field where sensitivity is high, he is trying to know the
polarity of the direction of north and south.
[0055]However, in minute magnetic field detection, such as
geomagnetism (about 0.3 gauss) by this method. Change of an output
after a detector circuit is as small as several percent, and in order to
treat absolute value change of oscillation amplitude as an output as it
is, sufficient S/N is not obtained from it being easy to be influenced by
change of power supply voltage, the temperature characteristics of
an element, etc. by amplitude fluctuation, and it is unreliable.
[0056]So, in this embodiment, circuitry of a magnetism detecting
element shown in drawing 4 was adopted.
[0057]Circuitry of a magnetism detecting element shown in drawing 4
consists of a Colpitts oscillator, a detector circuit, and a comparator,
the magnetic impedance component 1 mentioned above is included
in a Colpitts oscillator, it direct-winds, or the magnetic impedance
component 1 is approached, and the coil 2 for bias is formed.
[0058]In this composition, AC bias current Ib is sent through the coil
2, and an about **1-**2 gauss AC bias magnetic field is impressed to
the magnetic impedance component 1. As shown in (a), amplitude
modulation of the oscillation output which appears like the after-
mentioned by this at an A point in a figure of a Colpitts oscillator
according to intensity of the external magnetic field Hex for [ which is
impressed to the magnetic impedance component 1 ] detection is
carried out, A ripple waveform corresponding to a bias magnetic field
which has the difference of elevation of an adjacent peak
corresponding to intensity of the external magnetic field Hex by
detecting this in a detector circuit at a B point as shown in (b) is
acquired, By carrying out a party rate with the comparison voltage
Vref which crosses a voltage waveform of said ripple with a
comparator, a Pulse-Density-Modulation output corresponding to
intensity of the external magnetic field Hex can be obtained at C
point.
[0059]A signal of AC bias current Ib carries out dividing of the clock
from a microcomputer judgment part mentioned later, with a low pass
filter, it may be made into a sine wave or the shape of a triangular
wave, and it may throw it in, or may provide and throw in an oscillator
individually.
[0060]Next, details of operation of circuitry of a magnetism detecting
element of drawing 4 mentioned above are explained.
[0061]the characteristic of a magnetic impedance component is
symmetrical with the direction of +- in several gauss to the external
magnetic field Hex, as shown in drawing 5 -- a V character-like
impedance change is shown in general. As shown in drawing 5 (a) as
a principle of operation of the magnetic impedance component 1 of
drawing 4, when there is no external magnetic field, an AC bias
magnetic field is +. - It touches symmetrically, In change of
impedance to it, an impedance change which the difference of
elevation does not have in peaks on a ripple breaks out by a magnetic
field twice the frequency of AC bias.
[0062]Since an AC bias magnetic field and an unsymmetrical
magnetic field which an external magnetic field superimposed will
start the magnetic impedance component 1 like drawing 5 (b) there if
an external magnetic field is impressed to a longitudinal direction of
the magnetic impedance component 1, An impedance change (ripple
waveform) from which height of a peak differs by turns on an
impedance change arises.
[0063]The ripple waveform in an impedance change as showed the
output after detection of drawing 4 (b) which appeared as amplitude
modulation in the oscillation amplitude characteristic of the Colpitts
oscillator as change of this impedance was shown in drawing 4 (a),
and detected that oscillation output in the detector circuit by drawing
5 (b), and a similar signal are acquired. The size of an external
magnetic field is changed into the output of a digital signal by which
Pulse Density Modulation was carried out by carrying out a party rate
with the comparison voltage Vref which crosses a ripple waveform as
the signal is shown in drawing 6 in a comparator. That is, the Pulse-
Density-Modulation output in which the pulse which is two kinds from
which pulse width differs according to external magnetic field
intensity appears by turns is obtained.
[0064]Thus, pulse width [ of two kinds of pulses ] A which appears by
turns, and B can be measured and evaluated using the timer counter
of a microcomputer, and the digital data in which external magnetic
field intensity is shown can be obtained by asking for the digital data
of difference A-B of pulse width by an operation after that. Although
the measurement data of pulse width to a actual external magnetic
field is shown in drawing 7, in **0.5 gauss shows an almost linear
change. The numerical input value of joint threshold S mentioned
above can be decided by transposing the magnetic field strength of
magnetism detecting element independent threshold s to the math-
processing value of pulse width based on this data, and hanging the
several n square root of a magnetism detecting element on it.
[0065]And the digital data of difference A-B of the pulse width
measured in the state where there are no vehicles, in detection of
vehicles is memorized as data of the initial value of the external
magnetic field intensity used as a standard, Then, the absolute value
of the difference of difference A-B of pulse width and the initial value
according to the measured external magnetic field intensity is
calculated as data corresponding to the absolute value of intensity
change of an external magnetic field, It can ask for total of the data of
said absolute value called for by further two or more magnetism
detecting elements, and the existence of vehicles can be judged by
whether the figure exceeded the numerical value of joint threshold S.
[0066]Next, drawing 8 explains the composition of the vehicle
detecting device using the magnetism detecting element of drawing
4.
[0067]Colpitts oscillator 3 incorporating the magnetic impedance
component 1 which wound the coil 2 for bias which 12 is a magnetic
sensor and was mentioned above in the composition of the vehicle
detecting device shown in drawing 8, They are the marks 11A and
11B about the magnetism detecting element of drawing 4 which
consists of the detector circuit 4 and the comparator 5. -- As shown in
11N, N pieces are provided and it is constituted. Magnetism detecting
elements 11A and 11B -- 11N is arranged so that it may rank with the
ground surface in the band pass of vehicles, or underground along
with the longitudinal direction of vehicles as mentioned above, and
each element can be giving magnetic field detection sensitivity in the
direction vertical to a ground surface.
[0068]18 is a microcomputer judgment part which comprises a
microcomputer, analyzes the Pulse-Density-Modulation output of each
magnetism detecting element of the magnetic sensor 12, and judges
the existence of vehicles. The microcomputer judgment part 18,
Either the timer counter 20 which counts pulse width [ of the control
section 19 which performs whole control and various data processing,
and the Pulse-Density-Modulation output mentioned above ] A, and B
or magnetism detecting elements 11A-11N are chosen. It consists of
the selector 21 which inputs the output pulse into the timer counter
20 and the clock generator 22, the clock divider 23, the low pass filter
24, and the bias circuit (amplifier) 25.
[0069]Dividing is carried out so that the clock signal which the clock
generator 22 oscillates may become the range of 1 kHz - 100 kHz by
the clock divider 23 in this composition, The low pass filter 24 and the
bias circuit 25 let this signal by which dividing was carried out pass,
the signal of the AC bias current of a sine wave or the shape of a
triangular wave is formed, and it is impressed by the coil 2 for bias
which are each magnetism detecting elements 11A-11N of the
magnetic sensor 12. The feed zone of this bias current may be
provided in the magnetic sensor 12 side.
[0070]Next, the vehicle detection operation by the composition of
drawing 8 is explained. First, the initial value of the external magnetic
field intensity used as the standard for asking for external magnetic
field intensity change in the state where there are no vehicles is
measured. For this reason, with the magnetic sensor 12, the pulse
signal which detected external magnetic field intensity by two or
more magnetism detecting elements 11A-11N, and carried out Pulse
Density Modulation is outputted as mentioned above, and it sends to
the selector 21 of the microcomputer judgment part 18.
[0071]With the command from the control section 19, the selector 21
chooses and sends two kinds of pulses A and B further mentioned
above while it chooses the output pulse signal of two or more
magnetism detecting elements 11A-11N which should be sent to the
timer counter 20 one by one and sends it.
[0072]In the timer counter 20, the pulse width of two kinds of said
pulses A and B of two or more magnetism detecting elements sent
one by one is counted and evaluated, and the data is sent to the
control section 19.
[0073]In the control section 19, difference A-B of the pulse width data
of A pulse and B pulse evaluated with the timer counter 20 is
computed for every magnetism detecting element, and the measured
value of external magnetic field intensity is calculated. The measured
data is recorded on memory storage, such as RAM26 in the control
section 19, as initial value data used as a standard.
[0074]Then, in order to detect vehicles, the detection and the
Measurement Division of external magnetic field intensity by each
magnetism detecting element are performed in the same procedure
as the above, In the control section 19, it asks separately, absolute-
value-izes by using the difference of said measurement data and
initial value data as external magnetic field intensity change data,
and asks for the total, and the existence of vehicles is judged by
whether it is over predetermined joint threshold S which the total
mentioned above. And in the case of the vehicle detection system
mentioned later, car presence information etc. are taken out based on
the result of said judgment.
[0075]In order not to treat the amplitude of a Colpitts oscillator as an
absolute value in the circuitry of the magnetism detecting element of
drawing 4 as an advantage of the equipment of these above
embodiments probably but to treat a changed part of amplitude, a
low change of the frequency by change, temperature characteristics,
etc. of power supply voltage can be disregarded.
[0076]Since the detect output of the external magnetic field intensity
in the magnetic sensor 12 is digitized-output-ized by the Pulse
Density Modulation by a comparator, The magnetic sensor 12 and the
microcomputer judgment part 18 connect two or more magnetic
sensors 12 to the microcomputer judgment part 18, and can carry out
common use of the microcomputer judgment part 18 to two or more
magnetic sensors 12 while also being able to perform installation to
isolate and obtaining the flexibility of installation.
[0077]Since the whole equipment which constituted the magnetism
detecting element very small, could constitute the magnetic sensor
12 small, and includes the microcomputer judgment part 18 can be
made small, The burden of installation cost is small, and it is low
power consumption, and since the prolonged energization use which
was poor at conventional loop coil type equipment is possible, the use
of vehicle detection is expandable.
[0078][An embodiment of a vehicle detection system] Next, drawing
9 and drawing 10 explain an embodiment of a vehicle detection
system for parking-vehicles management in a motor pool using a
vehicle detecting device of drawing 8 mentioned above. As for this
vehicle detection system, it is needless to say that a portion of the
magnetic sensor 12 is provided in a ground surface of a motor pool or
underground at least, and it carries out of a vehicle detecting device
of drawing 8.
[0079]Drawing 9 is a block diagram showing functional composition of
a vehicle detection system of this embodiment. Composition of those
other than magnetic sensor 12 is specifically realized in drawing 9 by
hardware and software of the microcomputer judgment part 18 of
drawing 8.
[0080]In drawing 9, it realizes from the control section 19 of drawing
8, the timer counter 20, and the selector 21, and the measurement
means 27 measures external magnetic field intensity change as on
the basis of the state where there are no vehicles based on a
detection result of external magnetic field intensity by the magnetism
detecting elements 11A-11N of the magnetic sensor 12 as mentioned
above. This measurement means 27 has the initial value memory
measure 28 which memorizes a value of external magnetic field
intensity detected by the magnetism detecting elements 11A-11N in
the state where there are no vehicles as an initial value used as a
standard, and measures external magnetic field intensity change on
the basis of an initial value memorized to this memory measure 28.
The memory measure 28 is specifically constituted as RAM26 of
drawing 8.
[0081]It realizes as a function of the control section 19, and the
vehicle detection judging means 29 judges vehicle detection as
mentioned above based on the measuring result of the measurement
means 27.
[0082]Penetration, a stop, and the **** judging means 30 are realized
as a function of processing of Step S3 of below-mentioned drawing 10
by the control section 19, S6, and S9, Based on the decided result of
the vehicle detection by the vehicle detection judging means 29.
[ whether vehicles advanced into the motor pool, and ] It is judged
whether on whether it advanced on the magnetic sensor 12 formed in
the motor pool, whether whether whether it having stopped in the
motor pool and a motor pool having been left and vehicles stopped on
the magnetic sensor 12, and the magnetic sensor 12 was left.
[0083]Car presence and the **** information output means 31 are
realized as a function of Step S7 of drawing 10 by the control section
19, and processing of S10, Based on the decided result of
penetration, a stop, and the **** judging means 30, vehicles have
stopped at the motor pool, the car presence information on the
purport that vehicles have stopped on the magnetic sensor 12, and
vehicles left the motor pool, namely, vehicles output the ****
information on the purport that on the magnetic sensor 12 was left.
[0084]External magnetic field intensity is detected by the basis of
such composition by the magnetism detecting elements 11A-11N of
the magnetic sensor 12, The external magnetic field intensity change
on the basis of the state where there are no vehicles by the
measurement means 27 based on the detection result is measured,
and the judgment of vehicle detection is performed by the vehicle
detection judging means 29 based on the measuring result. And
based on the decided result of vehicle detection, penetration of the
vehicles in a motor pool, a stop, and **** are judged by the judging
means 30, and car presence information thru/or **** information are
outputted by the output means 31 based on the decided result.
[0085]Next, drawing 10 explains the details of vehicle detection
operation of this system. Drawing 10 is a flow chart which shows the
procedure of the vehicle detection processing by the control section
19 of drawing 8 which realizes each means 27, 29, 30, and 31 of
drawing 9.
[0086]On vehicle detection processing and first in Step S1 of drawing
10 the control section 19, External magnetic field intensity by each
magnetism detecting element of the magnetic sensor 12 is made to
detect as mentioned above in the state where there are no vehicles, It
asks for measurement data of external magnetic field intensity of A-B
mentioned above based on the detection result, this is set up as initial
value data used as a standard which asks for external magnetic field
intensity change, and it memorizes to recording equipment of RAM26
grade. Since there are no vehicles into a motor pool at this time, the
control section 19 checks **** information.
[0087]Next, in order to judge penetration of vehicles to the magnetic
sensor 12 top formed in penetration of vehicles into a motor pool, i.e.,
a ground surface of a motor pool, and underground, Detection and
Measurement Division of external magnetic field intensity from
vehicles by each magnetism detecting element are performed in a
procedure mentioned above (Step S2), It judges with vehicles having
advanced into a motor pool, when it absolute-value-ized in quest of a
difference of each measurement data A-B and initial value data
separately and the total was over predetermined joint threshold S,
and when not having progressed and exceeded for the following
procedure, it returns to Step S2 (Step S3).
[0088]When vehicles enter in a motor pool even in a front procedure,
can judge that, but. Since it thinks when passing without stopping
then, after judging penetration of vehicles at Step S3, detection and
Measurement Division of the external magnetic field intensity from
the vehicles by each magnetism detecting element are performed
again (step S4), and it compares with total of the absolute value of
data A-B measured last time (Step S5). When this measurement value
is changing from the last measurement value, it judges with vehicles
moving in the inside of a motor pool, and returns to step S4.
[0089]Since it will be either when vehicles stop in a motor pool or a
passing car comes out out of a motor pool as it is if change of
measured value is lost, In order to carry out that judgment which is
the any, in quest of the difference of an initial value and measured-
value-data A-B, it absolute-value-izes separately by all the magnetism
detecting elements, It judges that the total is in the car presence
state which vehicles have stopped in a motor pool when total exceeds
joint threshold S as compared with the above-mentioned
predetermined joint threshold S (that is, it has stopped on the
magnetic sensor 12) (Step S6), and car presence information is taken
out (Step S7). On the other hand, when total of the absolute value of
aforementioned difference A-B is not over joint threshold S, it judges
with the passing car having come out out of the motor pool as it is,
and returns to Step S2.
[0090]Next, detection of the magnetic field of the vehicles by each
magnetism detecting element in order to detect **** of the parked
vehicles, Measure (Step S8) and it absolute-value-izes in quest of the
difference of measurement data A-B and the data of an initial value
separately, When the total is over predetermined joint threshold S,
vehicles are judged continuously to be under parking, It returns to
Step S8, and when it repeated and is not over measurement, vehicles
judge with having left the inside of a motor pool (that is, on the
magnetic sensor 12 was left), take out **** information (Step S10),
return to Step S2, and are again repeated from detection of
penetration of vehicles.
[0091]Thus, based on the detection result of the magnetic field from
vehicles, a stop and **** can be judged during penetration of the
vehicles in a motor pool, and movement, and car presence
information and **** information can be outputted. And the
advantage of the vehicle detecting device of this invention can be
enjoyed, a stop and **** can be correctly judged during penetration of
vehicles, and movement by highly precise and reliable vehicle
detection, and exact car presence information and **** information
can be outputted. Therefore, the vehicle detection system of this
embodiment is effectively [ as management of parking vehicles /
because of management of parking duration, the empty area display
in a scale parking lot, vehicle guiding, etc. ] available.
[0092]
[Effect of the Invention]According to the vehicle detecting method of
this invention, so that clearly from the above explanation to the
ground surface in the band pass of vehicles, or underground. The
magnetic sensor which put in order two or more magnetism detecting
elements which have magnetic field detection sensitivity in the
direction vertical to a ground surface along with the vehicles
longitudinal direction is installed, The external magnetic field intensity
change as on the basis of the state where each of a magnetism
detecting element detects external magnetic field intensity, and there
are no vehicles is measured, Since total of the absolute value of two
or more measurement values of this measuring result was made to
detect vehicles by the judgment of whether to exceed predetermined
joint threshold S, The influence of the zero crossing point which the
magnetic field polarity looked at by distribution of the magnetic field
strength in the case of measuring the magnetic field generated from
a vehicles pars basilaris ossis occipitalis reverses can be avoided, and
highly precise and reliable vehicle detection can be performed.
[0093]While being able to perform reliable vehicle detection with high
degree of accuracy with the vehicle detecting method of this
invention according to the vehicle detecting device of this invention, a
magnetic sensor, For example, it can constitute from small size which
consists of plurality of the small magnetism detecting element
constituted using the magnetic impedance component as a magnetic
sensor of low power consumption, Compared with the equipment
using the conventional loop coil type sensor, prolonged continuous
use is possible, installation can also be easily performed by low cost,
and the use of vehicle detection can be expanded.
[0094]According to the vehicle detection system using the vehicle
detecting device of this invention. By vehicle detection enjoy the
advantage of the vehicle detecting device of this invention, highly
precise and reliable, exact car presence information, **** information
can be outputted and the outstanding effect of being available is
acquired effectively [ because of management of parking duration,
the empty area display in a scale parking lot, vehicle guiding, etc. ] as
management of parking vehicles.
TECHNICAL FIELD
[Field of the Invention]This invention detects the magnetic field
generated from vehicles, such as a car, with a magnetic sensor, and
detects vehicles magnetically, namely, relates to the vehicle
detecting method which detects the existence of vehicles thru/or
passage, a vehicle detecting device, and a vehicle detection system.
PRIOR ART
[Description of the Prior Art]Conventionally, the sensor which detects
vehicles, such as a car, is used in the use of measuring the distinction
of the existence of parking in the managerial system of a motor pool,
and the traffic of the vehicles in a traffic control system.
[0003]Usually, since vehicles, such as a car, are tinged with
magnetism using the metallic material which is easy to be tinged with
magnetism, such as a steel plate, it is detecting the magnetic field
generated from vehicles with a magnetic sensor, and it is possible to
recognize existence of vehicles or passage.
[0004]Conventionally, in the motor pool, the loop coil type magnetic
sensor was buried in the earth, and it has been used for vehicle
detection in it. A loop coil type magnetic sensor is that generate a
magnetic field by an eddy current in the metal part of the body of
vehicles to the alternating current sent through a coil, or the
magnetic field from the body's own magnetization interlinks with a
loop coil, A coil's own inductance changes, it is changed as change of
oscillating frequency or amplitude in a circuit, and vehicle detection is
performed by the existence of the change.
[0005]However, although the loop coil type magnetic sensor is
spreading by detection of vehicles, it has the following problems.
[0006]- Since a loop coil opens an interval a little with vehicles and is
installed, in order to detect the inductance variation in vehicles
existence, there is the necessity of enlarging size of a sensitivity
secured upper coil (about 1mx1m).
[0007]- If metal bodies, such as a steel rod, are in the neighborhood,
S/N cannot be taken enough.
[0008]- Since a loop coil is large and power consumption is large, it is
not fit for continuous energization use.
[0009]- A coil is a size which is about 1mx1m, and the burden of
construction expense is heavy in subterranean installation.
[0010]Then, although the small magnetic sensor was used and the
substitution was considered, When the magnetic field generated from
a vehicles pars basilaris ossis occipitalis was measured, near the zero
crossing point which remarkable unevenness is made to distribution
of magnetic field strength, and magnetic field polarity reverses by the
local magnetization of Body Manufacturing Division article each which
it has, it turned out that the dead point which does not exceed a
threshold required for the judgment of vehicle detection arises.
EFFECT OF THE INVENTION
[Effect of the Invention]According to the vehicle detecting method of
this invention, so that clearly from the above explanation to the
ground surface in the band pass of vehicles, or underground. The
magnetic sensor which put in order two or more magnetism detecting
elements which have magnetic field detection sensitivity in the
direction vertical to a ground surface along with the vehicles
longitudinal direction is installed, The external magnetic field intensity
change as on the basis of the state where each of a magnetism
detecting element detects external magnetic field intensity, and there
are no vehicles is measured, Since total of the absolute value of two
or more measurement values of this measuring result was made to
detect vehicles by the judgment of whether to exceed predetermined
joint threshold S, The influence of the zero crossing point which the
magnetic field polarity looked at by distribution of the magnetic field
strength in the case of measuring the magnetic field generated from
a vehicles pars basilaris ossis occipitalis reverses can be avoided, and
highly precise and reliable vehicle detection can be performed.
[0093]While being able to perform reliable vehicle detection with high
degree of accuracy with the vehicle detecting method of this
invention according to the vehicle detecting device of this invention, a
magnetic sensor, For example, it can constitute from small size which
consists of plurality of the small magnetism detecting element
constituted using the magnetic impedance component as a magnetic
sensor of low power consumption, Compared with the equipment
using the conventional loop coil type sensor, prolonged continuous
use is possible, installation can also be easily performed by low cost,
and the use of vehicle detection can be expanded.
[0094]According to the vehicle detection system using the vehicle
detecting device of this invention. By vehicle detection enjoy the
advantage of the vehicle detecting device of this invention, highly
precise and reliable, exact car presence information, **** information
can be outputted and the outstanding effect of being available is
acquired effectively [ because of management of parking duration,
the empty area display in a scale parking lot, vehicle guiding, etc. ] as
management of parking vehicles.
TECHNICAL PROBLEM
[Problem to be solved by the invention]Then, a reliable vehicle
detecting method in which SUBJECT of this invention can perform
magnetic detection of vehicles with high precision using a magnetic
sensor which consists of two or more small magnetism detecting
elements, And it is in providing a vehicle detection system which is a
vehicle detecting device which performs vehicle detection by the
method, can attain a miniaturization and can be used effective in
management of parking vehicles using a vehicle detecting device of
low power consumption, and this vehicle detecting device.
MEANS
[Means for solving problem]In a vehicle detecting method which
according to this invention detects a magnetic field generated from
vehicles with a magnetic sensor, and detects vehicles magnetically in
order to solve above-mentioned SUBJECT, A magnetic sensor which
put in order two or more magnetism detecting elements which have
magnetic field detection sensitivity in the direction vertical to a
ground surface along with a vehicles longitudinal direction is installed
in a ground surface in a band pass of vehicles, or underground,
External magnetic field intensity change as on the basis of the state
where each of two or more of said magnetism detecting elements
detects external magnetic field intensity, and there are no vehicles
was measured, and a method of detecting vehicles by the judgment
of whether total of an absolute value of two or more measurement
values of this measuring result exceeds predetermined joint threshold
S was adopted.
[0013]According to such a vehicle detecting method, influence of a
zero crossing point which magnetic field polarity looked at by
distribution of magnetic field strength in a case of measuring a
magnetic field generated from a vehicles pars basilaris ossis
occipitalis reverses can be avoided, and highly precise and reliable
vehicle detection can be performed.
[0014]According to this invention, it is a vehicle detecting device
which detects a magnetic field generated from vehicles with a
magnetic sensor, and detects vehicles magnetically, A magnetic
sensor which consists of two or more magnetism detecting elements
arranged so that it may have magnetic field detection sensitivity in
the direction vertical to a ground surface and may rank with a ground
surface in a band pass of vehicles, or underground along with a
vehicles longitudinal direction, A measurement means which
measures each of external magnetic field intensity change as on the
basis of the state where there are no vehicles to each magnetism
detecting element, based on external magnetic field intensity
detected by each of two or more of said magnetism detecting
elements, Total of each absolute value of a measurement value of
external magnetic field intensity change measured by this
measurement means adopted composition of a vehicle detecting
device which has a judging means which judges vehicle detection by
whether predetermined joint threshold S is exceeded.
[0015]While being able to perform reliable vehicle detection with high
degree of accuracy with a vehicle detecting method of this invention
according to such composition, the magnetic sensor can consist of
small size which consists of plurality of a small magnetism detecting
element constituted, for example using a magnetic impedance
component as a magnetic sensor of low power consumption.
[0016]It is a vehicle detection system which performs vehicle
detection using a vehicle detecting device by above-mentioned this
invention according to this invention, A judging means which judges
whether whether vehicles advanced on a magnetic sensor, whether it
stopped on a magnetic sensor based on a decided result of vehicle
detection by a judging means of said vehicle detecting device, and on
a magnetic sensor were left, Car presence information on a purport
that vehicles have stopped on a magnetic sensor based on a decided
result of this judging means, And it has an output means to which
vehicles output **** information on a purport that on a magnetic
sensor was left, and composition of a vehicle detection system which
enabled it to manage parking vehicles with the output of said car
presence information and **** information was adopted.
[0017]According to such composition, an advantage of a vehicle
detecting device of this invention can be enjoyed, exact car presence
information and **** information can be outputted based on highly
precise and reliable vehicle detection, and it can use effective in
management of parking vehicles.
[0018]
[Mode for carrying out the invention]Hereafter, an embodiment of the
invention is described with reference to figures.
[0019][Embodiment of a vehicle detecting method] Drawing 1 - 3
explain the embodiment of the vehicle detecting method by this
invention first.
[0020]In this embodiment, as shown in drawing 1, to the ground
surface 14 in the width which the vehicles (car) 10 pass, or
underground. The magnetic sensor 12 which has arranged two or
more magnetism detecting elements 11A, 11B, and 11C which have
magnetic field detection sensitivity in the direction (Z direction)
vertical to a ground surface so that it may stand in a line along with
the longitudinal direction of the vehicles 10 is installed, and vehicle
detection is performed.
[0021]The external magnetic field intensity change as on the basis of
the state where each magnetism detecting element of the magnetic
sensor 12 detects external magnetic field intensity, and there are no
vehicles 10 is measured, and total of the absolute value of two or
more measured magnetic-field-strength change detects vehicles by
the judgment of whether to exceed a predetermined joint threshold.
[0022]This method was drawn from the following examining results.
[0023]First, on the ground surface 14 in the width which the vehicles
10 pass as shown in drawing 2, The magnetic sensor 12 which
comprised one magnetism detecting element which has magnetic
field detection sensitivity in the Z direction which is a vertical
direction to the ground surface 14 is arranged, the vehicles 10 were
moved on the sensor 12, the magnetic sensor 12 detected external
magnetic field intensity, external magnetic field intensity change was
measured, and the situation of the change was investigated. The
variation of external magnetic field intensity made the measurement
value in the state where there are no vehicles 10 the initial value
used as a standard, and displayed a changed part from it. The
element using the magnetic impedance component mentioned later
as a magnetic sensing device was used for the magnetism detecting
element. Two or more vehicles performed the sampling. Four data
measuring of a characteristic example is shown in drawing 2 (a) - (d)
in it.
[0024]Generally, magnetic field distribution of the cross direction of a
bar magnet has a peak of reverse polarity at both ends of the bar
magnet 16 like drawing 3, and has a tendency which carries out a
zero cross in the center section. On the other hand, it can guess that
the body of a car constitutes a roughly big bar magnet from a
vehicles longitudinal direction from it being in agreement with how of
data measuring of drawing 2 to lengthen the skirt near the both-ends
peak of magnetic field distribution of drawing 3 by (c) and (d),
especially, if it observes near the both ends of a magnetic field
change. However, attitude of a peak has dispersion considerably by
overall magnetic-field-strength distribution, and it does not become a
beautiful form like a bar magnet because local magnetization exists
by part each of a body pars basilaris ossis occipitalis.
[0025]Since detection of vehicles will detect the magnetic field of a
body center section if detection of parking vehicles is taken into
consideration, for example, it observes the magnetic field of the
center of the body by the width of the length of the half of the body
shown in the range of H seal in a figure of each data measuring of
drawing 2. It is because the movement speed of the difference in the
length of each body and the body at the time of Measurement
Division had dispersion that the length of H seal differs.
[0026]Also when unevenness is looked at by magnetic-field-strength
change within the limits of H seal of the data of four examples and a
zero cross exists, the absolute value of a measurement value may go
into the DETTO point on which it is less than threshold s, and one
magnetism detecting element is not enough as it for vehicle detection
at a certain thing.
[0027]When threshold s of one magnetism detecting element
considers the resolution of a magnetism detecting element, and S/N
of a circuit, 0.05 gauss of a minimum is a limit, and considering that a
maximum has about 0.1 gauss vehicles like drawing 2 (c) in the
maximum of the magnetic field change by vehicles, it is difficult to set
up exceeding 0.1 gauss.
[0028]Then, two or more magnetism detecting elements are arranged
along with a vehicles longitudinal direction, and if vehicle detection is
carried out by whether either exceeds threshold s, detection
probability will increase.
[0029]However, in the case of the vehicles of drawing 2 (d), when
four magnetism detecting elements have been arranged to each of
the position corresponding to four points, a in a figure, b, c, and d, the
measurement value by which element will also be less than 0.05
gauss. If such a case is taken into consideration, the device which
raises detection probability further is required.
[0030]Then, the absolute value of the measurement value of two or
more magnetic-field-strength change which detected external
magnetic field intensity by each of two or more magnetism detecting
elements, and was measured is added, The value of the product
which, on the other hand, hung said number (addition numbers of a
measurement value) n of a magnetism detecting element of added
square roots on threshold s at the time of detection by an
independent magnetism detecting element is set up as joint threshold
S, If vehicle detection is judged by whether total of the added result
of said absolute value exceeds joint threshold S, it is detectable by
high probabilities.
[0031]A noise component serves as a mean square to addition of the
output of each magnetism detecting element, and if it is considered
as the noise component of the respectively same size, this will use
that the product of the noise for one element and the square root of
the addition numbers n serves as a noise at the time of combination,
and will try to earn the whole S/N.
[0032]For example, magnetic-field-strength change, a of the data
measuring of the vehicles of drawing 2 (d), b, c, and d, of four points,
It will be 0.03G-0.04G-0.02G-0.03G, and if threshold s of independent
detection is set to 0.05G, when these are added, it will be 0.12G, and
0.05xroot4=0.1 gauss is set to joint threshold S, total of the added
result of an output will exceed joint threshold S, and detection of it
will be attained.
[0033]Therefore, when the magnetic field component of a direction
vertical to the ground surface of the magnetic field generated from
vehicles is detected by two or more Magnetism detecting elementn
and the magnetic-field-strength change by vehicles existence is
measured, It turned out that it is suitable that the total adding each of
the absolute value of magnetic-field-strength change measured based
on the detection result of n magnetism detecting elements of a result
performs vehicle detection by whether joint threshold S as
independent threshold sxrootn is exceeded.
[0034]By the way, since a magnetic-field-detection output may
become near a zero cross with a certain element and total of the
above-mentioned added result may become low when detecting as
mentioned above by two or more magnetism detecting elements, the
method explained below can also be chosen as a method of raising
vehicle detection efficiency further.
[0035]Arrange in descending each absolute value of the
measurement value of the external magnetic field intensity change
from the initial value which detected external magnetic field intensity
by two or more magnetism detecting elements of the magnetic
sensor mentioned above, and was measured, consider it as |deltaH(k)
| (k= 1, 2, ordinal number of --), and Namely, this value, They are
[ threshold s in the case of one magnetism detecting element, and ]
the following expression about said addition numbers n.[0036]
[Mathematical formula 2]
[0037]It compares whether it is alike, it sets, substitutes one by one
from k= 1, and the above-mentioned expression is satisfied, and
when the above-mentioned expression is satisfied, it judges with
having detected vehicles.
[0038]According to this method, vehicle detection efficiency can be
raised by adding the measurement value of two or more external
magnetic field intensity change to descending one by one, and using
for the judgment of vehicle detection.
[0039]In above-mentioned explanation, the "ground surface of
"underground" meaning the inside of those fields including all the
fields that vehicles, such as a floor line in the building of not only the
ground surface of the ground, and the road surface of a road and the
ground surface of an outdoor parking lot but a multi-level car parking
tower, run fields thru/or park" of 14 is natural.
[0040][Embodiment of a vehicle detecting device] Next, the
embodiment of a vehicle detecting device which enforces concretely
the vehicle detecting method mentioned above, and performs vehicle
detection is described.
[0041]First, the magnetism detecting element of the magnetic sensor
used for a vehicle detecting device is explained. Being required of this
magnetism detecting element should be 10 or more milligauss in (1)
magnetic field detection sensitivity.
[0042](2) There is two or more dispersion [ little ] of the performance
of an element for use.
[0043](3) Considering ground surface installation, the height of an
element should be several millimeters.
[0044](4) The detector circuit of an element is excellent in a noise-
proof and temperature characteristics, and be low power
consumption.
[0045]Although there is a flux gate type magnetism detecting
element as what satisfies the conditions of (1), if it is going to raise
detection sensitivity with this element, several 10 mm of the length of
an element will be needed, and it will not be satisfied with it of the
conditions of (3).
[0046]Since it is easy to come out of dispersion in performance, a
problem produces a flux gate type magnetism detecting element also
on condition of (2).
[0047]Then, the magnetism detecting element constituted using a
magnetic impedance component is seemed that it is the optimal by it.
[0048]The magnetic impedance component is indicated by JP,H7-
181239,A and the element body as a magnetic body is constituted
from an amorphous wire or these days by the magnetic thin film etc.
If the high frequency current of an MHz band is impressed to this
element body, according to a magnetic impedance effect, according
to an external magnetic field, the impedance of an element body
changes several 10%, and can detect an external magnetic field using
this.
[0049]The sensitivity of a magnetic impedance component has the
sensitivity of a 10-5 gauss stand, and number milligauss is securable
and it is satisfied also with the practical resolution in the case where it
connects with the circuit of a magnetism detecting element of the
conditions of (1).
[0050]From there being little influence of a demagnetizing field, it is
easy for the length of an element to be 5 mm or less, and the
conditions of (3) are also cleared.
[0051]About dispersion in performance, when supplied with an
amorphous wire, since it is easy to control thickness, dispersion in the
performance resulting from the outside dimension of the magnetic
body of an element body is pressed down, and is satisfied with that
there is little dispersion in the path of a wire, and a magnetic film of
the conditions of (2).
[0052]Although application was considered according to the contents
reported at the society etc. about the magnetic field detection which
uses the Colpitts oscillating circuit about the conditions of (4), there is
a problem practically.
[0053]For example, the application of the magnetic field sensor as an
azimuth sensor is shown by the "amorphous wire MI Colpitts
oscillation type micro magnetic sensor" announced at the 18th
Maganetics Society of Japan academic lecture meeting (14pB-7).
[0054]In the composition of this azimuth sensor, an amorphous wire
is included in a Colpitts type oscillator, and since change of an
external magnetic field turns into change of oscillation amplitude and
it appears, an output is obtained through a detector circuit. While
sending a direct current through the coil directly twisted around the
wire of the element, applying a DC bias magnetic field and making it
operate in the field where sensitivity is high, he is trying to know the
polarity of the direction of north and south.
[0055]However, in minute magnetic field detection, such as
geomagnetism (about 0.3 gauss) by this method. Change of the
output after a detector circuit is as small as several percent, and in
order to treat absolute value change of oscillation amplitude as an
output as it is, sufficient S/N is not obtained from it being easy to be
influenced by change of power supply voltage, the temperature
characteristics of an element, etc. by amplitude fluctuation, and it is
unreliable.
[0056]So, in this embodiment, the circuitry of the magnetism
detecting element shown in drawing 4 was adopted.
[0057]The circuitry of the magnetism detecting element shown in
drawing 4 consists of a Colpitts oscillator, a detector circuit, and a
comparator, the magnetic impedance component 1 mentioned above
is included in the Colpitts oscillator, it direct-winds, or the magnetic
impedance component 1 is approached, and the coil 2 for bias is
formed.
[0058]In this composition, AC bias current Ib is sent through the coil
2, and an about **1-**2 gauss AC bias magnetic field is impressed to
the magnetic impedance component 1. As shown in (a), amplitude
modulation of the oscillation output which appears like the after-
mentioned by this at the A point in a figure of a Colpitts oscillator
according to the intensity of the external magnetic field Hex for
[ which is impressed to the magnetic impedance component 1 ]
detection is carried out, The ripple waveform corresponding to the
bias magnetic field which has the difference of elevation of the
adjacent peak corresponding to the intensity of the external magnetic
field Hex by detecting this in a detector circuit at a B point as shown
in (b) is acquired, By carrying out a party rate with the comparison
voltage Vref which crosses the voltage waveform of said ripple with a
comparator, the Pulse-Density-Modulation output corresponding to
the intensity of the external magnetic field Hex can be obtained at C
point.
[0059]The signal of AC bias current Ib carries out dividing of the clock
from the microcomputer judgment part mentioned later, with a low
pass filter, it may be made into a sine wave or the shape of a
triangular wave, and it may throw it in, or may provide and throw in
an oscillator individually.
[0060]Next, the details of operation of the circuitry of the magnetism
detecting element of drawing 4 mentioned above are explained.
[0061]the characteristic of a magnetic impedance component is
symmetrical with the direction of +- in several gauss to the external
magnetic field Hex, as shown in drawing 5 -- a V character-like
impedance change is shown in general. As shown in drawing 5 (a) as
a principle of operation of the magnetic impedance component 1 of
drawing 4, when there is no external magnetic field, an AC bias
magnetic field is +. - It touches symmetrically, In change of
impedance to it, an impedance change which the difference of
elevation does not have in peaks on a ripple breaks out by a magnetic
field twice the frequency of AC bias.
[0062]Since an AC bias magnetic field and the unsymmetrical
magnetic field which the external magnetic field superimposed will
start the magnetic impedance component 1 like drawing 5 (b) there if
an external magnetic field is impressed to the longitudinal direction of
the magnetic impedance component 1, The impedance change (ripple
waveform) from which the height of a peak differs by turns on an
impedance change arises.
[0063]The ripple waveform in an impedance change as showed the
output after detection of drawing 4 (b) which appeared as amplitude
modulation in the oscillation amplitude characteristic of the Colpitts
oscillator as change of this impedance was shown in drawing 4 (a),
and detected that oscillation output in the detector circuit by drawing
5 (b), and a similar signal are acquired. The size of an external
magnetic field is changed into the output of a digital signal by which
Pulse Density Modulation was carried out by carrying out a party rate
with the comparison voltage Vref which crosses a ripple waveform as
the signal is shown in drawing 6 in a comparator. That is, the Pulse-
Density-Modulation output in which the pulse which is two kinds from
which pulse width differs according to external magnetic field
intensity appears by turns is obtained.
[0064]Thus, pulse width [ of two kinds of pulses ] A which appears by
turns, and B can be measured and evaluated using the timer counter
of a microcomputer, and the digital data in which external magnetic
field intensity is shown can be obtained by asking for the digital data
of difference A-B of pulse width by an operation after that. Although
the measurement data of pulse width to a actual external magnetic
field is shown in drawing 7, in **0.5 gauss shows an almost linear
change. The numerical input value of joint threshold S mentioned
above can be decided by transposing the magnetic field strength of
magnetism detecting element independent threshold s to the math-
processing value of pulse width based on this data, and hanging the
several n square root of a magnetism detecting element on it.
[0065]And the digital data of difference A-B of the pulse width
measured in the state where there are no vehicles, in detection of
vehicles is memorized as data of the initial value of the external
magnetic field intensity used as a standard, Then, the absolute value
of the difference of difference A-B of pulse width and the initial value
according to the measured external magnetic field intensity is
calculated as data corresponding to the absolute value of intensity
change of an external magnetic field, It can ask for total of the data of
said absolute value called for by further two or more magnetism
detecting elements, and the existence of vehicles can be judged by
whether the figure exceeded the numerical value of joint threshold S.
[0066]Next, drawing 8 explains the composition of the vehicle
detecting device using the magnetism detecting element of drawing
4.
[0067]Colpitts oscillator 3 incorporating the magnetic impedance
component 1 which wound the coil 2 for bias which 12 is a magnetic
sensor and was mentioned above in the composition of the vehicle
detecting device shown in drawing 8, They are the marks 11A and
11B about the magnetism detecting element of drawing 4 which
consists of the detector circuit 4 and the comparator 5. -- As shown in
11N, N pieces are provided and it is constituted. Magnetism detecting
elements 11A and 11B -- 11N is arranged so that it may rank with the
ground surface in the band pass of vehicles, or underground along
with the longitudinal direction of vehicles as mentioned above, and
each element can be giving magnetic field detection sensitivity in the
direction vertical to a ground surface.
[0068]18 is a microcomputer judgment part which comprises a
microcomputer, analyzes a Pulse-Density-Modulation output of each
magnetism detecting element of the magnetic sensor 12, and judges
existence of vehicles. The microcomputer judgment part 18, Either
the timer counter 20 which counts pulse width [ of the control section
19 which performs whole control and various data processing, and a
Pulse-Density-Modulation output mentioned above ] A, and B or
magnetism detecting elements 11A-11N are chosen. It consists of the
selector 21 which inputs the output pulse into the timer counter 20
and the clock generator 22, the clock divider 23, the low pass filter
24, and the bias circuit (amplifier) 25.
[0069]Dividing is carried out so that a clock signal which the clock
generator 22 oscillates may become the range of 1 kHz - 100 kHz by
the clock divider 23 in this composition, The low pass filter 24 and the
bias circuit 25 let this signal by which dividing was carried out pass, a
signal of AC bias current of a sine wave or the shape of a triangular
wave is formed, and it is impressed by the coil 2 for bias which are
each magnetism detecting elements 11A-11N of the magnetic sensor
12. A feed zone of this bias current may be provided in the magnetic
sensor 12 side.
[0070]Next, vehicle detection operation by composition of drawing 8
is explained. First, an initial value of external magnetic field intensity
used as a standard for asking for external magnetic field intensity
change in the state where there are no vehicles is measured. For this
reason, with the magnetic sensor 12, a pulse signal which detected
external magnetic field intensity by two or more magnetism detecting
elements 11A-11N, and carried out Pulse Density Modulation is
outputted as mentioned above, and it sends to the selector 21 of the
microcomputer judgment part 18.
[0071]With the command from the control section 19, the selector 21
chooses and sends two kinds of pulses A and B further mentioned
above while it chooses the output pulse signal of two or more
magnetism detecting elements 11A-11N which should be sent to the
timer counter 20 one by one and sends it.
[0072]In the timer counter 20, the pulse width of two kinds of said
pulses A and B of two or more magnetism detecting elements sent
one by one is counted and evaluated, and the data is sent to the
control section 19.
[0073]In the control section 19, difference A-B of the pulse width data
of A pulse and B pulse evaluated with the timer counter 20 is
computed for every magnetism detecting element, and the measured
value of external magnetic field intensity is calculated. The measured
data is recorded on memory storage, such as RAM26 in the control
section 19, as initial value data used as a standard.
[0074]Then, in order to detect vehicles, the detection and the
Measurement Division of external magnetic field intensity by each
magnetism detecting element are performed in the same procedure
as the above, In the control section 19, it asks separately, absolute-
value-izes by using the difference of said measurement data and
initial value data as external magnetic field intensity change data,
and asks for the total, and the existence of vehicles is judged by
whether it is over predetermined joint threshold S which the total
mentioned above. And in the case of the vehicle detection system
mentioned later, car presence information etc. are taken out based on
the result of said judgment.
[0075]In order not to treat the amplitude of a Colpitts oscillator as an
absolute value in the circuitry of the magnetism detecting element of
drawing 4 as an advantage of the equipment of these above
embodiments probably but to treat a changed part of amplitude, a
low change of the frequency by change, temperature characteristics,
etc. of power supply voltage can be disregarded.
[0076]Since the detect output of the external magnetic field intensity
in the magnetic sensor 12 is digitized-output-ized by the Pulse
Density Modulation by a comparator, The magnetic sensor 12 and the
microcomputer judgment part 18 connect two or more magnetic
sensors 12 to the microcomputer judgment part 18, and can carry out
common use of the microcomputer judgment part 18 to two or more
magnetic sensors 12 while also being able to perform installation to
isolate and obtaining the flexibility of installation.
[0077]Since the whole equipment which constituted the magnetism
detecting element very small, could constitute the magnetic sensor
12 small, and includes the microcomputer judgment part 18 can be
made small, The burden of installation cost is small, and it is low
power consumption, and since the prolonged energization use which
was poor at conventional loop coil type equipment is possible, the use
of vehicle detection is expandable.
[0078][Embodiment of a vehicle detection system] Next, drawing 9
and drawing 10 explain the embodiment of the vehicle detection
system for the parking-vehicles management in the motor pool using
the vehicle detecting device of drawing 8 mentioned above. As for
this vehicle detection system, it is needless to say that the portion of
the magnetic sensor 12 is provided in the ground surface of a motor
pool or underground at least, and it carries out of the vehicle
detecting device of drawing 8.
[0079]Drawing 9 is a block diagram showing the functional
composition of the vehicle detection system of this embodiment.
Composition of those other than magnetic sensor 12 is specifically
realized in drawing 9 by the hardware and software of the
microcomputer judgment part 18 of drawing 8.
[0080]In drawing 9, it realizes from the control section 19 of drawing
8, the timer counter 20, and the selector 21, and the measurement
means 27 measures the external magnetic field intensity change as
on the basis of the state where there are no vehicles based on the
detection result of the external magnetic field intensity by the
magnetism detecting elements 11A-11N of the magnetic sensor 12 as
mentioned above. This measurement means 27 has the initial value
memory measure 28 which memorizes the value of the external
magnetic field intensity detected by the magnetism detecting
elements 11A-11N in the state where there are no vehicles as an
initial value used as a standard, and measures external magnetic field
intensity change on the basis of the initial value memorized to this
memory measure 28. The memory measure 28 is specifically
constituted as RAM26 of drawing 8.
[0081]It realizes as a function of the control section 19, and the
vehicle detection judging means 29 judges vehicle detection as
mentioned above based on the measuring result of the measurement
means 27.
[0082]Penetration, a stop, and the **** judging means 30 are realized
as a function of processing of Step S3 of below-mentioned drawing 10
by the control section 19, S6, and S9, Based on the decided result of
the vehicle detection by the vehicle detection judging means 29.
[ whether vehicles advanced into the motor pool, and ] It is judged
whether on whether it advanced on the magnetic sensor 12 formed in
the motor pool, whether whether whether it having stopped in the
motor pool and a motor pool having been left and vehicles stopped on
the magnetic sensor 12, and the magnetic sensor 12 was left.
[0083]Car presence and the **** information output means 31 are
realized as a function of Step S7 of drawing 10 by the control section
19, and processing of S10, Based on the decided result of
penetration, a stop, and the **** judging means 30, vehicles have
stopped at the motor pool, the car presence information on the
purport that vehicles have stopped on the magnetic sensor 12, and
vehicles left the motor pool, namely, vehicles output the ****
information on the purport that on the magnetic sensor 12 was left.
[0084]External magnetic field intensity is detected by the basis of
such composition by the magnetism detecting elements 11A-11N of
the magnetic sensor 12, The external magnetic field intensity change
on the basis of the state where there are no vehicles by the
measurement means 27 based on the detection result is measured,
and the judgment of vehicle detection is performed by the vehicle
detection judging means 29 based on the measuring result. And
based on the decided result of vehicle detection, penetration of the
vehicles in a motor pool, a stop, and **** are judged by the judging
means 30, and car presence information thru/or **** information are
outputted by the output means 31 based on the decided result.
[0085]Next, drawing 10 explains the details of vehicle detection
operation of this system. Drawing 10 is a flow chart which shows the
procedure of the vehicle detection processing by the control section
19 of drawing 8 which realizes each means 27, 29, 30, and 31 of
drawing 9.
[0086]On vehicle detection processing and first in Step S1 of drawing
10 the control section 19, The external magnetic field intensity by
each magnetism detecting element of the magnetic sensor 12 is
made to detect as mentioned above in the state where there are no
vehicles, It asks for the measurement data of the external magnetic
field intensity of A-B mentioned above based on the detection result,
this is set up as initial value data used as the standard which asks for
external magnetic field intensity change, and it memorizes to the
recording equipment of RAM26 grade. Since there are no vehicles into
a motor pool at this time, the control section 19 checks ****
information.
[0087]Next, in order to judge penetration of the vehicles to the
magnetic sensor 12 top formed in penetration of the vehicles into a
motor pool, i.e., the ground surface of a motor pool, and underground,
Detection and Measurement Division of the external magnetic field
intensity from the vehicles by each magnetism detecting element are
performed in the procedure mentioned above (Step S2), It judges with
vehicles having advanced into the motor pool, when it absolute-value-
ized in quest of the difference of each measurement data A-B and
initial value data separately and the total was over predetermined
joint threshold S, and when not having progressed and exceeded for
the following procedure, it returns to Step S2 (Step S3).
[0088]When vehicles enter in a motor pool even in a front procedure,
can judge that, but. Since it thinks when passing without stopping
then, after judging penetration of vehicles at Step S3, detection and
Measurement Division of the external magnetic field intensity from
the vehicles by each magnetism detecting element are performed
again (step S4), and it compares with total of the absolute value of
data A-B measured last time (Step S5). When this measurement value
is changing from the last measurement value, it judges with vehicles
moving in the inside of a motor pool, and returns to step S4.
[0089]Since it will be either when vehicles stop in a motor pool or a
passing car comes out out of a motor pool as it is if change of
measured value is lost, In order to carry out that judgment which is
the any, in quest of the difference of an initial value and measured-
value-data A-B, it absolute-value-izes separately by all the magnetism
detecting elements, It judges that the total is in the car presence
state which vehicles have stopped in a motor pool when total exceeds
joint threshold S as compared with the above-mentioned
predetermined joint threshold S (that is, it has stopped on the
magnetic sensor 12) (Step S6), and car presence information is taken
out (Step S7). On the other hand, when total of the absolute value of
aforementioned difference A-B is not over joint threshold S, it judges
with the passing car having come out out of the motor pool as it is,
and returns to Step S2.
[0090]Next, detection of the magnetic field of the vehicles by each
magnetism detecting element in order to detect **** of the parked
vehicles, Measure (Step S8) and it absolute-value-izes in quest of the
difference of measurement data A-B and the data of an initial value
separately, When the total is over predetermined joint threshold S,
vehicles are judged continuously to be under parking, It returns to
Step S8, and when it repeated and is not over measurement, vehicles
judge with having left the inside of a motor pool (that is, on the
magnetic sensor 12 was left), take out **** information (Step S10),
return to Step S2, and are again repeated from detection of
penetration of vehicles.
[0091]Thus, based on the detection result of the magnetic field from
vehicles, a stop and **** can be judged during penetration of the
vehicles in a motor pool, and movement, and car presence
information and **** information can be outputted. And the
advantage of the vehicle detecting device of this invention can be
enjoyed, a stop and **** can be correctly judged during penetration of
vehicles, and movement by highly precise and reliable vehicle
detection, and exact car presence information and **** information
can be outputted. Therefore, the vehicle detection system of this
embodiment is effectively [ as management of parking vehicles /
because of management of parking duration, the empty area display
in a scale parking lot, vehicle guiding, etc. ] available.
DESCRIPTION OF DRAWINGS
[Brief Description of the Drawings]
[Drawing 1]It is an explanatory view showing the arrangement and
the direction of magnetic field detection over the vehicles of the
magnetism detecting element of the magnetic sensor in the
embodiment of the vehicle detecting method by this invention.
[Drawing 2]They are the explanatory view and graph charts showing
the situation of the external magnetic field intensity change by
movement of the vehicles detected with the magnetic sensor which
comprised one magnetism detecting element.
[Drawing 3]They are the explanatory view and graph charts showing
the magnetic field distribution of the cross direction of a bar magnet.
[Drawing 4]It is a circuit diagram showing the circuitry of the
magnetism detecting element of the magnetic sensor used for the
embodiment of the vehicle detecting device by this invention.
[Drawing 5]They are graph charts showing the impedance change by
the AC bias magnetic field and external magnetic field of a magnetic
impedance component in drawing 4.
[Drawing 6]It is a wave form chart showing the bias current Ib in
drawing 4, the after-detection output of a detector circuit, and a
comparator output.
[Drawing 7]They are graph charts showing the pulse width and the
count number of a difference of the pulse which is two kinds from
which the pulse width of the comparator output to an external
magnetic field differs.
[Drawing 8]It is a block diagram showing the composition of the
embodiment of a vehicle detecting device.
[Drawing 9]It is a block diagram showing the functional composition
of the embodiment of the vehicle detection system by this invention.
[Drawing 10]It is a flow chart figure showing the vehicle detection
procedure in the vehicle detection system.
[Explanations of letters or numerals]
1 A magnetic impedance component
2 The coil for bias
3 Colpitts oscillator
4 Detector circuit
5 Comparator
10 Vehicles
11A-11N Magnetism detecting element
12 Magnetic sensor
14 Ground surface
18 Microcomputer judgment part
19 Control section
20 Timer counter
21 Selector
22 Clock generator
23 Clock divider
24 Low pass filter
25 Bias circuit
26 RAM
27 The measurement means of external magnetic field intensity
change
28 Initial value memory measure
29 Vehicle detection judging means
30 Penetration, a stop, and a **** judging means
31 Car presence and a **** information output means
DRAWINGS
[Drawing 1]
[Drawing 2]
[Drawing 7]
[Drawing 3]
[Drawing 5]
[Drawing 4]