System and method for capacitance sensing of pavement density

• US 6,577,141 B2
• Filed: 06/13/2001
• Issued: 06/10/2003
• Est. Priority Date: 06/13/2001
• Status: Expired due to Fees

• Current Assignee: Sauer-Danfoss Incorporated (Danfoss A/S)
• Original Assignee: Sauer-Danfoss Incorporated (Danfoss A/S)
• Inventors: Gandrud, Michael D.
• Primary Examiner(s): Metjahic, Safet
• Assistant Examiner(s): LEROUX, ETIENNE PIERRE
• Application Number:
  US09/880,400
• Publication Number:
  US 20020190728A1
• Time in Patent Office: 727 Days
• Field of Search: 324/644, 324/663, 324/675, 324/687, 324/698, 702/33, 702/137, 73/32.R, 340/562, 340/601, 340/603, 340/612
• US Class Current: 324/663
• CPC Class Codes: G01N 27/22 by investigating capacitance
• CPC Class Codes: G01N 33/42 Road-making materials G01N33/38 takes precedence

Abstract

The present invention discloses a system and method of determining the density of pavement material. The invention includes positioning a capacitive proximity sensor, adjacent to but not in direct contact with a pavement material, projecting an electrostatic capacitive field from the sensor in the direction of the pavement material, measuring the strength of the electrostatic capacitive field as detected by the sensor, and correlating the strength of the electrostatic capacitive field to the density of the pavement material. The invention further discloses determining a location and associating the location with a pavement material density.

Claims

1. A method of determining density of pavement material comprising:

positioning a capacitive proximity sensor adjacent to but not in direct contact with a pavement material;

projecting an electrostatic capacitive field from the sensor in the direction of the pavement material;

measuring the strength of the electrostatic capacitive field as detected by the sensor; and

correlating the strength of the electrostatic capacitive field to the density of the pavement material.

2. The method of claim 1 further comprising adjusting the sensitivity of the capacitive proximity sensor.

3. The method of claim 1 further comprising adjusting the measured electrostatic capacitive field for moisture content of the pavement material.

4. The method of claim 1 further comprising recording the measured strength of the electrostatic capacitive field as detected by the capacitive proximity sensor.

5. The method of claim 1 wherein the step of correlating is comparing the measured changes associated with the sample pavement material with measured changes associated with a second sample of pavement material, the density of the sample relative to the density of the second sample being known.

6. The method of claim 1 further comprising determining a location of the capacitive proximity sensor and associating that location with a pavement density as determined by said sensor.

7. The method of claim 6 further comprising storing the location and the associated pavement density.

8. A system for measuring pavement material density comprising:

at least one capacitive proximity sensor capable of simultaneously projecting an electrostatic capacitive field and detecting and measuring the strength of that electrostatic capacitive field from a location remote from the pavement material;

a controller cooperatively connected to the capacitive proximity sensor wherein the controller receives the measured strength of the electrostatic capacitive field and correlates the measured strength to a pavement material density.

9. The system of claim 8 further comprising a display, the display operatively connected to the controller, the controller sending a signal to the display, the signal related to pavement density.

10. The system of claim 8 further comprising a data storage component, the data storage component operatively connected to the controller, the controller sending data to the data storage component.

11. The system of claim 10 wherein the data is capacitive proximity sensor measurements.

12. The system of claim 10 wherein the data is pavement material density.

13. The system of claim 8 wherein the pavement material density is a density relative to a known sample standard density.

14. The system of claim 8 further comprising a location determination device, the location determination device operatively connected to the controller.

15. The system of claim 14 wherein the location determination device is a GPS receiver.

16. The system of claim 14 further comprising a memory operatively connected to the controller adapted to store pavement material density data and corresponding location data.

17. The system of claim 14 further comprising a display operatively connected to the controller adapted to display pavement material density data and corresponding location data.

18. The system of claim 8 further comprising a network interface operatively connected to the controller.

19. The system of claim 18 wherein the network interface is a controller area network interface.