EP0287250A2
Expired / Lapsed
EP
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Traffic measurement equipment
Assignee: Individual
•
Filing: 1988-03-31
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Granted: —
•
Expires: 2008-03-31
Abstract
Abstract Traffic measurement equipment to provide in an installation comprising a pair of coaxial cables having barium titanate piezo-electric responsive crystals embedded in the polymer together with a vehicle presence detector all measurements required of traffic including vehicle count, vehicle length, vehicle time of arrival, vehicle speed in any required measure, number of axles per vehicle, axle distance per vehicle, vehicle gap, headway and axle weights.
Inventors
- 👤 Franz Josef Gebert
- 👤 Johannes Petrus Theron
- 👤 Rudiger Heinz Gebert
- 👤 Ralf Dieter Heinrich Gebert
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-02 21:03
CPC Classifications
G; G08; G08G; G08G1/00; G08G1/01; G08G1/02
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
147 words
A traffic data acquisition method which comprises laying an electrically conductive cable with at least two conductors separated by a material which has electrical properties selected from one or more of piezo-electric effect, tribo-electric effect, magneto= and/or electro= strictive effects, connecting the conductors to an electronic processing means which includes an amplifier, digitiser and micro-processor, detecting signals induced in the cable by passage of vehicle wheel(s) over it, and processing the signals, characterised in that processing of the signals includes computing total integrated spectral power or an equivalent derivative of the signals, establishing an empirical relationship between speed, weight and total spectral power for the cable which has been laid as above, inputting the computed total spectral power and one of speed or weight of the vehicle wheel(s) into the empirical relationship so as to derive one of the weight or speed respectively of the vehicle wheel(s).
Claim 2
Dependent Claim
147 words
A traffic data acquisition method which comprises laying an electrically conductive cable with at least two conductors separated by a material which has electrical properties selected from one or more of piezo-electric effect, tribo-electric effect, magneto= and/or electro= strictive effects, connecting the conductors to an electronic processing means which includes an amplifier, digitiser and micro-processor, detecting signals induced in the cable by passage of vehicle wheel(s) over it, and processing the signals, characterised in that processing of the signals includes computing total integrated spectral power or an equivalent derivative of the signals, establishing an empirical relationship between speed, weight and total spectral power for the cable which has been laid as above, inputting the computed total spectral power and one of speed or weight of the vehicle wheel(s) into the empirical relationship so as to derive one of the weight or speed respectively of the vehicle wheel(s).
Claim 3
Dependent Claim
23 words
A method as claimed in claim 1, in which the empirical relationship also takes account of tyre configuration and environmental factors including temperature.
Claim 4
Dependent Claim
42 words
A method as claimed in claim 1, in which the speed of the vehicle is derived from an empirical relationship between speed and positive or negative peak voltage of the signals in the case of one wheel passing signals over the cable.
Claim 5
Dependent Claim
31 words
A method as claimed in claim 1, in which the speed of the vehicle is derived from an empirical relationship between speed and positive or negative rise time of the signals.
Claim 6
Dependent Claim
28 words
A method as claimed in claim 1, in which the cable is embedded in a matrix which is laid either on a base plate or in a groove.
Claim 7
Dependent Claim
47 words
A method as claimed in claim 5, in which the groove is cut in the road surface, lined with an epoxy bitumen or other suitable lining material, the lining is formed to a groove of consistent cross sectional shape by drawing a forming tool through the material.
Claim 8
Independent Claim
104 words
A method as claimed in any one of claims 1 to 6, in which the said cable is laid orthogonally across the road and a second cable is laid diagonally across the road, the residence time of the tyre footprint applying pressure to the orthogonal cable is subtracted from the residence time of the tyre foot print applying pressure to the diagonal cable, the difference is converted via a measure of speed to a distance difference which is operated on by a tangent function of the angle of the diagonal cable to the orthogonal cable to give a measure of footprint width and length.
Claim 9
Dependent Claim
36 words
A method as claimed in claim 1, in which an empirical relationship is established between a first derivative of total spectral power, weight and speed and this relationship is used for the inputting and derivation steps.
Claim 10
Independent Claim
30 words
A method as claimed in either one of claims 1 or 2, in which the total spectral power or its derivative is computed by an algorithm employing a regression method.
Claim 11
Independent Claim
33 words
A method as claimed in any one of claims 1 to 3, in which total spectral power of equivalent is derived on the basis of integration of the signals in the frequency domain.
Claim 12
Independent Claim
40 words
A method as claimed in any one of claims 7 to 10, in which axle weight and footprint of the tyre is measured in length and width from which area is estimated and thence tyre pressure on the footprint area.
Claim 13
Independent Claim
35 words
A method as claimed in any one of claims 1 to 11, in which the cable is zig-zagged in a sinuous fashion on a base plate and embedded in a matrix on the base plate.
Claim 14
Dependent Claim
26 words
13 A method as claimed in any one of claims 1 to 12, in which the speed and weight results are applied to vehicle classification parameters.
Claim 15
Dependent Claim
93 words
A traffic data acquisition apparatus which comprises an electrically conductive flexible cable with at least two conductors separated by a material which has electrical properties selected from one or more of piezo-electric effect, tribo-electric effect, magneto= and/or electro= strictive effects, the cable conductors being connected to an electronic processing means which includes an amplifier, digitiser and micro-processor, characterised in that the cable is embedded in a matrix whose natural resonant frequency is preferably more than eight hundred Hertz (800 Hz), a high input impedance preamplifier is placed in close proximity to the cable.
Claim 16
Dependent Claim
93 words
A traffic data acquisition apparatus which comprises an electrically conductive flexible cable with at least two conductors separated by a material which has electrical properties selected from one or more of piezo-electric effect, tribo-electric effect, magneto= and/or electro= strictive effects, the cable conductors being connected to an electronic processing means which includes an amplifier, digitiser and micro-processor, characterised in that the cable is embedded in a matrix whose natural resonant frequency is preferably more than eight hundred Hertz (800 Hz), a high input impedance preamplifier is placed in close proximity to the cable.
Claim 17
Dependent Claim
24 words
An apparatus as claimed in claim 14, in which the proportions of the matrix are that its depth is at least twice its width.
Claim 18
Independent Claim
48 words
An apparatus as claimed in either one of claims 14 or 15, in which the cable is embedded in the matrix in a manner which provides properties of poor acoustic coupling by way of an accoustic discontinuity between cable and matrix for high frequencies above one kilohertz (1kHz).
Claim 19
Independent Claim
44 words
An apparatus as claimed in any one of claims 14 to 16, in which the cable is embedded in the matrix in a manner which favours transmission from the matrix to the cable of normal pressures and only poorly transmits or decouples shear stresses.
Claim 20
Dependent Claim
23 words
An apparatus as claimed in claim 17, in which two longitudinally extended hollows run contiguous with the cable on either side of it.
Claim 21
Dependent Claim
48 words
An apparatus as claimed in claim 17, in which the cable is closely surrounded on all sides except the top and optionally the bottom by a longitudinally extending relatively rigid channel having a modulus of elasticity at least one hundred times as high as that of the matrix.
Claim 22
Independent Claim
27 words
An apparatus as claimed in any one of claims 14 to 19, in which the poisson's ratio of the material of the matrix is close to 0,5.
Claim 23
Dependent Claim
30 words
Traffic data acquisition method or apparatus as claimed in any one of claims 1 to 13, in which the piezo-electric effect predominates over tribo-electric and magneto= and/or electro= strictive effects.
Claim 24
Dependent Claim
40 words
Traffic data acquisition method or apparatus as claimed in claim 21, in which the cable and the matrix are selected to exhibit a pressure sensitivity of the cable in the matrix of at least - 200 dB re 1 V/uPa.
Claim 25
Dependent Claim
48 words
Traffic data acquisition method or apparatus as claimed in either one of claims 14 or 15, in which the predominating piezo-electric properties are provided by granulated crystals in a polymeric material, the crystals being selected from one or more piezo electric ceramics and ceramic composites, polymers and copolymers.
Claim 26
Dependent Claim
38 words
Traffic data acquisition method or apparatus as claimed in claim 16, in which the piezo-electric crystals are a barium titanate or polyvinylidenefluorinate and the matrix or Dow Corning RTV-J silicone rubber intended for use as a moulding rubber.
References Cited (Backward Citations)
No citation records indexed.
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