Material movement sensing techniques

• US 20070290917A1
• Filed: 06/14/2006
• Published: 12/20/2007
• Est. Priority Date: 06/14/2006
• Status: Active Grant

• Current Assignee: Board of Trustees of The University of Illinois
• Original Assignee: Board of Trustees of The University of Illinois
• Inventors: Huff, Gregory Hilding, Bernhard, Jennifer T., Hagness, Susan, Laefer, Debra
• Granted Patent: US 7,482,969 B2
• Time in Patent Office: Days
• US Class Current: 342/22
• CPC Class Codes: G01S 13/885 for ground probing prospecting or detecting using electromagnetic waves G01V3/12
• CPC Class Codes: G01S 13/89 for mapping or imaging
• CPC Class Codes: G01V 3/12 operating with electromagnetic waves operating with millimetre waves G01V8/005

Abstract

One embodiment of the present invention provides several electromagnetic radiation reflectors within a volume that contains solid portions subject to movement relative to one another. At least a portion of the reflectors are positioned beneath one or more of the solid portions and move in response to movement of at least some of the solid portions. The volume is irradiated with electromagnetic radiation having one or more frequencies in a range from one kHz through one THz, and a reflection is detected of at least a portion of the electromagnetic radiation from each of the reflectors in response to this irradiation. Movement among the solid objects is evaluated from the reflection of each of the reflectors, which includes determining a spatial orientation of each one of the reflectors as a function of at least one of polarization selectivity and frequency selectivity.

Claims

1. A method, comprising:

dispersing several electromagnetic radiation markers within a volume, the volume including several solid objects, at least a portion of the markers being buried beneath at least a portion of the solid objects;

interrogating the volume with electromagnetic radiation, the electromagnetic radiation being in a frequency range of one kHz through one THz;

detecting returned electromagnetic radiation from each of the markers in response to the interrogating; and

evaluating movement among the solid objects from the returned electromagnetic radiation of each of the markers, which includes determining a change in rotational orientation of one of the markers based on selectivity of the one of the markers to one or more properties of the electromagnetic radiation that varies with the rotational orientation of the one of the markers.

2. The method of claim 1, further comprising distinguishing between the markers based on at least one of polarization selectivity and frequency selectivity of each of the markers.

3. The method of claim 1, wherein the several solid objects comprise at least one of soil, grain, sand, geologic strata, and portions of a roadway.

4. The method of claim 1, wherein the markers each include a passive retroreflector and the returned electromagnetic radiation is reflected by each of the markers in the frequency range of one MHz through 100 GHz.

5. The method of claim 1, wherein the one or more properties include one or more of frequency and polarization, and which includes determining a rotational orientation change of each of several of the markers based on the one or more properties.

6. The method of claim 1, wherein the evaluating include generating one or more images as a function of the returned electromagnetic radiation of each of the markers.

7. The method of claim 1, wherein the frequency range is from 100 MHz through 10 GHz.

8. A method, comprising:

providing several electromagnetic radiation reflectors within a volume, the volume including solid portions subject to movement relative to one another, at least a portion of the reflectors being hidden from view external to the volume by one or more of the solid portions and moving in response to movement of at least some of the solid portions;

operating one or more antennas to perform an electromagnetic radiation interrogation of the volume; and

from the interrogation, generating an image representative of an interior of the volume as a function of the electromagnetic radiation reflected by each of the reflectors, the electromagnetic radiation being in a frequency range of one kHz through one THz.

9. The method of claim 8, wherein the frequency range is from 1 MHz through about 100 GHz.

10. The method of claim 8, which includes distinguishing between the reflectors based on at least one of polarization selectivity and frequency selectivity among the reflectors.

11. The method of claim 8, wherein the solid portions comprise at least one of a roadway, soil, and geologic strata.

12. The method of claim 8, detecting a change in position of one or more of the solid portions from the electromagnetic energy reflected by the reflectors.

13. The method of claim 8, which includes evaluating flow of the solid portions with the image.

14. The method of claim 8, wherein the frequency range is 100 MHz through 10 GHz.

15. The method of claim 8, which includes detecting a change in rotational orientation of one or more of the reflectors based on at least one of polarization selectivity and frequency selectivity.

19. The apparatus of claim 15, wherein the frequency range is 100 MHz through 10 GHz, and the one or more antennas number more than two and are operable to irradiate the volume with electromagnetic energy in the frequency range and detect the reflected electromagnetic energy in accordance with a predefined sequence.

20. The apparatus of claim 15, wherein the processing device includes:

means for distinguishing between the two or more reflectors based on one or more of the polarization selectively and the frequency selectivity; and

means for determining a change in rotational orientation of at least one of the two or more reflectors based on one or more of the polarization selectivity and the frequency selectivity.

16. An apparatus, comprising:

several reflectors structured for dispersal in a volume among a number of solid objects subject to movement relative to one another, at least a portion of the reflectors being buried beneath at least a portion of the solid objects;

one or more antennas operable to irradiate the volume with electromagnetic radiation having one or more frequencies in a range of one kHz through one THz and detect reflection of at least a portion of the electromagnetic radiation from each of the reflectors; and

a processing device responsive to detection of the reflection from each of the reflectors to evaluate movement of the solid objects based on at least one of polarization selectivity and frequency selectivity of the reflection for each one of the reflectors.

17. The apparatus of claim 16, wherein the processing device is further operable to generate one or more output signals representative of an image of an interior of the volume;

and further comprising a display device responsive to the one or more output signals to display the image.

18. The apparatus of claim 16, wherein the reflectors are each of a retroreflector type and the frequency range is from 1 MHz through 100 GHz.

21. A method, comprising:

providing several electromagnetic radiation reflectors within a volume, the volume including solid portions subject to movement relative to one another, at least a portion of the reflectors being positioned beneath one or more of the solid portions and moving in response to movement of at least some of the solid portions;

irradiating the volume with electromagnetic radiation, the electromagnetic radiation having one or more frequencies in a range of one kHz through one THz;

detecting a reflection of at least a portion of the electromagnetic radiation from each of the reflectors in response to the irradiating; and

evaluating movement among the solid objects from the reflection of each of the reflectors which includes determining a spatial orientation of each one of the reflectors as a function of at least one of polarization selectivity and frequency selectivity.

22. The method of claim 21, wherein the determining of the spatial orientation includes determining rotational position of each one of the reflectors based on a difference in one or more of the polarization of the reflection and the frequency of the reflection that depends on the rotational position.

23. The method of claim 21, wherein the determining of the spatial orientation includes distinguishing between the reflectors based on one or more of the polarization selectivity and the frequency selectivity that differs among the reflectors.

24. The method of claim 21, wherein the reflectors are each of a retroreflector type and the frequency range is from 1 MHz through 100 GHz.

25. The method of claim 21, which includes generating an image representative of the volume from the spatial orientation of each one of the reflectors.

26. The method of claim 21, wherein the solid portions comprise at least one of a roadway, soil, and geologic strata.

27. The method of claim 21, wherein the evaluating includes detecting a change in position of one or more of the solid portions from the reflection of each of the reflectors.