Device for measuring the speed of displacement of an object deforming the lines of the terrestrial magnetic field

• US 9,092,982 B2
• Filed: 01/07/2011
• Issued: 07/28/2015
• Est. Priority Date: 01/08/2010
• Status: Expired due to Fees

• Current Assignee: Commissariat a L'Energie Atomique (French Alternative Energies and Atomic Energy Commission)
• Original Assignee: Commissariat a L'Energie Atomique (French Alternative Energies and Atomic Energy Commission)
• Inventors: Robinet, Antoine, Blanpain, Roland
• Primary Examiner(s): Hollington, Jermele M
• Assistant Examiner(s): Split, James
• Application Number:
  US13/521,096
• Publication Number:
  US 20130057264A1
• Time in Patent Office: 1,663 Days
• Field of Search: 324/323, 324/345, 324/365, 324/72, 324/207.13, 324/247, 324/302, 702/150, 702/152, 702/5
• US Class Current: 1/1
• CPC Class Codes: G01P 3/42 Devices characterised by the use of electric or magnetic means G01P3/66 takes precedence; measuring electric or magnetic values in general G01R
• CPC Class Codes: G01P 3/66 using electric or magnetic means G01P3/80 takes precedence; measuring short time intervals G04F8/00, G04F10/00
• CPC Class Codes: G01P 3/803 in devices of the type to be classified in G01P3/66
• CPC Class Codes: G08G 1/042 using inductive or magnetic detectors
• CPC Class Codes: G08G 1/052 with provision for determining speed or overspeed speed measuring in general G01P

Abstract

An apparatus for measuring speed of movement of an object deforming lines of Earth'"'"'s magnetic field includes a first and second magnetometer disposed on either side of a traffic roadway for the object and substantially perpendicular to the object. The magnetometers are configured for measuring deformation of Earth'"'"'s magnetic field by the object travelling over the roadway. The apparatus also includes a processing unit configured for extracting, from each of the magnetometers, a measurement value corresponding to a quotient defined by a distance of the object with respect to the magnetometer divided by a speed of movement of the object, and for calculating a speed of the object from the measurement values and a geometrical disposition of the magnetometers with respect to one another and with respect to the traffic roadway.

Claims

1. An apparatus for measuring speed of movement of an object deforming lines of Earth'"'"'s magnetic field when moving over a traffic roadway, said apparatus comprising a first magnetometer and second magnetometer, said first magnetometer being disposed on a first side of said traffic roadway and designed to target for a first measurement a measurement line perpendicular with respect to said roadway, said second magnetometer being disposed on said second side of a traffic roadway, opposite to said first side, and designed to target for a second measurement said measurement line perpendicular with respect to said roadway, said first and second magnetometers being configured for measuring deformation of Earth'"'"'s magnetic field by said object travelling over said roadway, and a processing unit configured for extracting, from said first magnetometer, a first measurement value corresponding to a quotient of the minimum distance of said object with respect to said first magnetometer divided by a speed of movement of said object, and for extracting from said second magnetometer a second measurement value corresponding to the quotient of the minimum distance of the object with respect to said second magnetometer divided by said speed of movement of the object, and for calculating said speed of said object from said first and second measurement values and a geometrical disposition of said magnetometers with respect to one another and with respect to said traffic roadway.

2. The apparatus of claim 1, wherein said magnetometers are selected from a group consisting of single-axis magnetometers, dual-axis, triple-axis magnetometers, scalar magnetometers and gradient fluxgate magnetometers.

3. The apparatus of claim 1, wherein said magnetometers are installed high up with respect to said traffic roadway.

4. The apparatus of claim 3, wherein said magnetometers are installed at a height in the range between 1.5 m and 3 m above said traffic roadway.

5. The apparatus of claim 3, wherein each magnetometer is carried by a road sign.

6. The apparatus of claim 1, wherein said processing unit is further configured for determining a distance between two objects following one another from a speed of movement of said second object and a time interval separating passages of said two objects between said magnetometers.

7. The apparatus of claim 1, wherein said processing unit comprises a comparator for comparing a calculated speed with a setpoint speed, and wherein said processing unit is configured to transmit an alarm signal in response to detecting a calculated speed in excess of said setpoint speed.

8. The apparatus of claim 7, wherein said processing unit comprises a module for identification of said moving object based at least in part on a magnetic signature thereof and a stored set of magnetic signatures and corresponding objects, and wherein said setpoint speed is adapted to correspond to said object identified.

9. The apparatus of claim 5, wherein said processing unit comprises a comparator for comparing a calculated separation distance between two objects with a setpoint inter-distance, and wherein said processing unit is configured to transmit an alarm signal if said calculated separation distance is less than or equal to said setpoint inter-distance.

10. The apparatus of claim 1, further comprising an electrical power supply unit and a transmission unit for radiofrequency transmission of an alarm signal based on said speed of said object, wherein said apparatus, said power supply unit, and said transmission unit define an installation for measurement of speed of an automobile.

11. A road sign configured to be used for said installation recited in claim 10, wherein said road sign carries said first magnetometer.

12. The road sign of claim 11, wherein said sign is made from a non-magnetic material.

13. The road sign of claim 11, further comprising a non-magnetic support for said first magnetometer, said first magnetometer being fixed to a metal structure of said road sign at a predefined distance.