US3688308A - Apparatus for detecting the volume of traffic - Google Patents

Apparatus for detecting the volume of traffic Download PDF

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Publication number
US3688308A
US3688308A US78525A US3688308DA US3688308A US 3688308 A US3688308 A US 3688308A US 78525 A US78525 A US 78525A US 3688308D A US3688308D A US 3688308DA US 3688308 A US3688308 A US 3688308A
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US
United States
Prior art keywords
output
volume
detecting
traffic
relay device
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US78525A
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English (en)
Inventor
Imamura Makoto
Sato Ikuo
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Toshiba Corp
Original Assignee
Tokyo Shibaura Electric Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Tokyo Shibaura Electric Co Ltd filed Critical Tokyo Shibaura Electric Co Ltd
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Publication of US3688308A publication Critical patent/US3688308A/en
Anticipated expiration legal-status Critical
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    • G—PHYSICS
    • G08—SIGNALLING
    • G08G—TRAFFIC CONTROL SYSTEMS
    • G08G1/00—Traffic control systems for road vehicles
    • G08G1/01—Detecting movement of traffic to be counted or controlled
    • G08G1/042—Detecting movement of traffic to be counted or controlled using inductive or magnetic detectors

Definitions

  • An apparatus for detecting the volume of traffic includes a single oscillator having an oscillating coil [30] APPhcatm Pmmy which is embedded in the roadbed of a roadway.
  • a Oct. 6, 1969 Japan ..44/94502 converter is provided for converting the output Nov. 7, 1969 Japan ..44/05037 frequency signal of the oscillator to a corresponding voltage signal and a relay device is connected to the ⁇ .LtSCCll. ..340/38 output of the converter for responding thereto
  • the I ⁇ o g converter i f d so th t g t an tp t [58] Field of Search ..340/38 L therefrom only in response to a rapid frequency change in the output of the oscillator.
  • the present invention generally relates to an apparatus for detecting the volume of traffic and more particularly to a highly accurate apparatus for detecting the volume of traffic for use in traffic control which employs only a single oscillator and is generally immune from external influences.
  • the output frequency signal thereof would change and thereby cause the mixer to generate a beat signal which in turn would operate a counting device for enabling a count to be made of the number of vehicles that passed over the coil of the second oscillator.
  • Another object of this invention is to provide a new and improved unique apparatus for detecting volume of traffic in which any variations in the constant of the oscillator circuit will not affect the operation thereof.
  • a further object of thisinvention is to provide a new and improved unique apparatus for detecting volume of traffic in which errors resulting from influences due to water soaking into the roadbed of a roadway are effectively eliminated.
  • One other object of this invention is to provide a new and improved unique apparatus for detecting volume of traffic wherein means are provided for inspecting the stagnation of traffic.
  • Yet one other object of this invention is to provide a new and improved unique apparatus for detecting volume of traffic which utilizing only a single oscillator is compact, inexpensive, and easy to install.
  • these and other objects are, in one aspect, attained by the provision of an oscillator having an oscillating coil which is embedded in the roadbed of a roadway.
  • the output frequency of the oscillator is converted into a D.C. voltage proportional to the frequency thereof by the provision of an appropriate converter.
  • This converter is provided with a delay circuit which acts to reduce the output voltage of the converter to a zero level after a predetermined time delay.
  • a relay device is provided which is responsive to the output voltage of the converter for detecting the existence of a vehicle over the oscillating coil of the oscillator.
  • the apparatus for detecting the volume of traffic is shown as including a conventional oscillator 10, the frequency of which is determined by a coil 11 which is embedded in the roadbed of a roadway l2, and which forms a portion of the oscillator.
  • a vehicle such, for example, as an automobile 13
  • the same will function as a secondary coil of the coil 11 and thereby reduce the resultant inductance of the oscillating circuit. This will cause the output frequency of the oscillator 10 to suddenly increase.
  • the output frequency signal of the oscillator 10 is first converted into a current through a converting circuit 14, which includes a capacitor 15 and diodes l6 and 17 connected as shown.
  • the current so developed is then supplied to a conventional operational amplifier 18 which has a feed-back circuit 19 connected in parallel therewith.
  • the feedback circuit 19 includes a resistor 20 and a capacitor 21 which are connected in parallel. The current is thereby converted into a DC. voltage which is proportional to the output frequency of the oscillator 10.
  • the output voltage of the operational amplifier 18 is then simultaneously supplied to a relay 22, for selectively operating the same, as hereinafter explained, and through a resistor 23 to one terminal of a feed-back amplifier 24.
  • the other input terminal of the feed-back amplifier 24 is grounded.
  • the terminal of the feed-back amplifier 24 to which the resistor 23 is connected is grounded through a capacitor 25 which forms a time delay circuit 26 with the serially connected resistor 23.
  • the feed-back amplifier 24 will compare the voltage of the capacitor 25 which is obtained from the time delay circuit 26 with either a zero voltage or the ground voltage level and thereby generate an output signal for reducing the input of the operational amplifier 18 to zero.
  • the operational amplifier 18 will generate an output voltage of a sufficient level to cause the relay 22 to operate only when the output frequency of the oscillator 10 makes a sudden change.
  • the relay 22 will not operate in that because of the feedback from the amplifier 24, the voltage level applied thereto will not be of a sufficient level for activating the same.
  • a sudden change in the output of the oscillator 10 will occur when, for example, a vehicle, such as the automobile 13, passes over the embedded coil 11 and that slow changes will occur from such conditions as when water from rain or the like gradually soaks into the roadbed and when the constant of the oscillator circuit varies due to a deformation of the embedded coil, which may occur by successively passing heavy vehicles thereover or from the influence of temperature variations and moisture.
  • the relay 22 will respond only to the presence of a vehicle over the oscillating coil 11. Under such conditions, the relay 22 will operate and the contacts 221 and 222 thereof will close.
  • a conventional counter 27 such as of the digital type, will-receive a pulse from an electrical voltage source (not shown) to thereby register a count for the vehicle whose presence is thereby indicated.
  • an additional capacitor 28 is connected in parallel with the capacitor 25 such that the time delay of the circuit 26 will increase, and thus the output voltage of the operational amplifier 18 will not be suppressed until after the longer time delay has elapsed.
  • the provision of a long time delay is very effective in surveying the stagnation of traffic at a particular crossing.
  • a vehicle may be present over the oscillating coil 11 of the oscillator 10 for a long period of time.
  • the length of stagnation will depend upon the particular traffic circumstance, it is assumed, for purposes of example, that the longest stagnation time is minutes.
  • this time delay can be easily obtained from the delay circuit 26 with the additional capacitor 28, since the output of the operational amplifier 24 can be held to continue for 5 minutes.
  • the output voltage of the operational amplifier 18 will be suppressed in accordance therewith such that the relay 22 will be reset to cause the contacts 221 and 222 to open.
  • the stagnation time of a vehicle can be readily displayed by the provision of a conventional recorder 29 which is energized through the relay contact 221.
  • a conventional telemetry device 30, which is also energized through the relay contact 221, may be provided for transmitting the information on the volume or stagnation of traffic to a remote traffic control room.
  • An apparatus for detecting the volume of traffic which comprises:
  • an oscillator having an oscillating coil adapted to be embedded in the road bed of a roadway such that the frequency of the output signal of said oscillator will change when a vehicle is present over said coil;
  • a time delay circuit coupled to said means for reducing the output of said means to substantially a zero amplitude within a predetermined time delay
  • a relay device connected to the output of said means for responding to the output voltage thereof.
  • circuit means for receiving the output frequency signal from said oscillator and for producing a corresponding current signal
  • a feed-back amplifier which is provided between the output and the input of the operational amplifier for negatively feeding back the output of the operational amplifier
  • time delay circuit which is provided at the output of the operational amplifier, said time delay circuit including a resistor and a first capacitor coupled in series with each other and for supplying a delayed output from the operational amplifier to said feed back amplifier.
  • a second capacitor is selectively connected in parallel with said first capacitor by said relay device for providing a much longer period of delay whereby the stagnation of trafiic can be determined.
  • said means is combined with said relay device such that when a vehicle is present over said oscillating coil said relay device is actuated for a predetermined time interval, the relay device releasing as soon as the vehicle passes over the coil within the predetermined time interval.
  • An apparatus for detecting the volume of trafiic according to claim 1 wherein said relay device has an output which is connected to a counter for counting the number of vehicles passing over said oscillating coil. 7. An apparatus for detecting the volume of traffic according to claim 1, wherein I said relay device has an output connected to a recorder for recording any traffic stagnation. 8. An apparatus for detecting the volume of traffic according to claim 1, wherein said relay device has an output connected to a telemetry device for transmitting information on traffic to a remote control room.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Traffic Control Systems (AREA)
US78525A 1969-10-06 1970-10-06 Apparatus for detecting the volume of traffic Expired - Lifetime US3688308A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP9450269 1969-10-06
JP10503769 1969-11-07

Publications (1)

Publication Number Publication Date
US3688308A true US3688308A (en) 1972-08-29

Family

ID=26435783

Family Applications (1)

Application Number Title Priority Date Filing Date
US78525A Expired - Lifetime US3688308A (en) 1969-10-06 1970-10-06 Apparatus for detecting the volume of traffic

Country Status (3)

Country Link
US (1) US3688308A (enrdf_load_stackoverflow)
DE (1) DE2049086A1 (enrdf_load_stackoverflow)
GB (1) GB1289208A (enrdf_load_stackoverflow)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5051219A (enrdf_load_stackoverflow) * 1973-08-09 1975-05-08
US5614894A (en) * 1992-07-06 1997-03-25 Centre D'etudes Techniques De 1'est Device to detect particularly one or several wheels of a vehicle or of a wheeled mobile engine and process for using this device
US6337640B2 (en) 1999-03-31 2002-01-08 Diamond Consulting Services Limited Inductive loop sensor for traffic detection, and traffic monitoring apparatus and method using such a loop sensor
GB2368959A (en) * 2000-11-09 2002-05-15 D Systems Ltd Ag Energy management system for vehicle monitoring equipment
US6483443B1 (en) 1999-03-31 2002-11-19 Diamon Consulting Services Limited Loop sensing apparatus for traffic detection

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3451041A (en) * 1966-04-04 1969-06-17 Singer General Precision Vehicle presence detector system

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3451041A (en) * 1966-04-04 1969-06-17 Singer General Precision Vehicle presence detector system

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5051219A (enrdf_load_stackoverflow) * 1973-08-09 1975-05-08
US5614894A (en) * 1992-07-06 1997-03-25 Centre D'etudes Techniques De 1'est Device to detect particularly one or several wheels of a vehicle or of a wheeled mobile engine and process for using this device
US6337640B2 (en) 1999-03-31 2002-01-08 Diamond Consulting Services Limited Inductive loop sensor for traffic detection, and traffic monitoring apparatus and method using such a loop sensor
US6483443B1 (en) 1999-03-31 2002-11-19 Diamon Consulting Services Limited Loop sensing apparatus for traffic detection
GB2368959A (en) * 2000-11-09 2002-05-15 D Systems Ltd Ag Energy management system for vehicle monitoring equipment

Also Published As

Publication number Publication date
DE2049086A1 (de) 1971-04-22
GB1289208A (enrdf_load_stackoverflow) 1972-09-13

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