Detector for embedded elongate objects

• US 7,482,968 B2
• Filed: 04/17/2006
• Issued: 01/27/2009
• Est. Priority Date: 04/26/2005
• Status: Active Grant

• Current Assignee: Hilti Aktiengesellschaft (Hilti Martin Family Trust)
• Original Assignee: Hilti Aktiengesellschaft (Hilti Martin Family Trust)
• Inventors: Kaneider, Wilfried, Schmitzer, Harald, Wuersch, Christoph, Winter, Andreas, Gogolla, Torsten
• Primary Examiner(s): Tarcza; Thomas H
• Assistant Examiner(s): Bythrow; Peter M
• Application Number:
  US11/405,878
• Publication Number:
  US 20060238401A1
• Time in Patent Office: 1,016 Days
• Field of Search: 324/323, 324/326, 324/329, 324/332, 324/334, 324/337, 324/341, 324/344, 324/642, 342/22, 342/27, 342/28, 342/59, 342/85, 342/94, 342/95, 342/97, 342/124, 342/136, 342/137, 342/175, 342176-186, 342/195, 367/88, 367/95, 367/98, 367/101, 367/105, 367/908
• US Class Current: 342/22
• CPC Class Codes: G01V 3/15 specially adapted for use during transport, e.g. by a person, vehicle or boat

Abstract

A detector (1) for detecting embedded elongate objects (5) has an evaluating unit (6), a computing device (7), an output device (8), and a handheld measuring head (9) which can be moved over a surface (F) and which has a path a detector (10) and a transmitting-receiving unit (11a) with an antenna (12a). At least two antennae (12a, 12b) are spaced apart from one another along the surface (F), and the distance (A) therebetween, measured over the surface (F), ranges between 5 cm and 50 cm.

Claims

1. A detector for detecting embedded elongate objects (5), comprising an evaluating unit (6) having computing means (7) and an output device (8);

a handheld measuring head (9) displaceable over a surface (F) and including a path detector (10), a transmitting-receiving unit (11a) with an antenna (12a); and

at least one further antenna (12b) spaced from the antenna (12a) of the transmitting-receiving unit (11a) along the surface (F), by a distance (A) lying in a range from 5 cm and 50 cm;

wherein the detector performs a measurement method of detecting the embedded elongate objects (5) in the surface (F) of a to-be-examined area, including;

a first step (I) which is repeated multiple times and in which, a detector (1) senses a change in a position (Δ

x) of the measuring head (9) displaceable along a scanning direction over the to-be-examined surface (F), and receives separate measurement signals (A(x_A) B(x_B)) from the at least two antennae (12a, 12b), respectively, whose positions (x_A, x_B) are associated with the separate measurement signals (A(x_A) B(x_B));

a second step (II) performed by the computing means (7) in which separate measurement variables (A[A(x_A), x_A], B[B(x_B), x_B]), which contain possible embedded objects (5) that can be identified in the separate measurement signals (A(x_A) B(x_B)), are determined from the separate measurement signals (A(x_A) B(x_B)) using a predetermined A-scan algorithm, respectively; and

a third step (III) in which the at least two separate measurement variables (A[A(x_A), x_A], B[B(x_B), x_B]) are calculated together by the computing means (7) to form a correlation measurement variable.

2. A detector according to claim 1, wherein the transmitting-receiving unit (11a) is formed as a radar transmitting-receiving unit.

3. A detector according to claim 2, wherein the transmitting-receiving unit (11a) has a relative bandwidth in the range of 0.5 to 1.0 in the frequency range between 500 MHz and 10 GHz.

4. A detector according to claim 2, wherein the two antennae (12a, 12b) are formed as monostatic, broadband dipole antennae.

5. A detector according to claim 4, wherein the two antennae have an identically oriented polarization direction (P).

6. A detector according to claim 1, wherein the measuring head (9) includes at least one additional sensor (13a) of a different type.

7. A detector according to claim 6, wherein the additional sensor (13a) extends symmetrically around exactly two antennae (12a, 12b).

8. A detector according to claim 6, wherein the measuring head (9) includes a further additional sensor, the two additional sensors (13a, 13b) extending symmetrically around exactly one antenna (12a, 12b) in each instance.

9. A detector according to claim 6, wherein the at least one additional sensor (13a) is an inductive sensor.

10. A detector according to claim 9, wherein the inductive sensor is formed as a ferrite cross (16) with two different flux paths, in a scanning direction and a direction perpendicular thereto, respectively.

11. A detector according to claim 1, wherein the measuring head (9) includes at least one further transmitting-receiving units (11a, 11b), and wherein the at least one further antenna (12b) is associated with the at least one further transmitting-receiving unit.

12. A detector according to claim 11, wherein the measuring head (9) is formed with collapsible legs (17a, 17b) pivotable by 180°

, wherein the two transmitting-receiving units (11a, 11b) with their respective antennae (12a, 12b) are arranged on different legs (17a, 17b).

13. A detector according to claim 12, wherein the two antennae (12a, 12b) are arranged as to be displaceable relative to one another along the legs (17a, 17b).

14. A detector according to claim 13, wherein at least one wheel (19) rollable along the surface (F) to be examined is arranged at each leg (17a, 17b).

15. A detector according to claim 14, wherein a total of exactly three wheels (19) are arranged so as to be offset relative to one another along the pivot axis (S).

16. A detector according to claim 14, wherein at least one wheel (19) per leg (17a, 17b) is connected to the path detector (10).

17. A measurement method of detecting embedded elongate objects (5) in a surface (F) of a to-be-examined area, comprising a first step (I) which is repeated multiple times and in which, a detector (1) senses a change in a position (Δ

x) of a measuring head (9) displaceable along a scanning direction over the to-be-examined surface (F), and receives separate measurement signals (A(x_A) B(x_B)) from at least two antennae (12a, 12b), respectively, whose positions (x_A, x_B) are associated with the separate measurement signals (A(x_A) B(x_B));

a second step (II) performed by computing means (7) in which separate measurement variables (A[A(x_A), x_A], B[B(x_B), x_B]), which contain possible embedded objects (5) that can be identified in the separate measurement signals (A(x_A) B(x_B)), are determined from the separate measurement signals (A(x_A) B(x_B)) using a predetermined A-scan algorithm, respectively; and

a third step (III) in which the at least two separate measurement variables (A[A(x_A), x_A], B[B(x_B), x_B]) are calculated together by the computing means (7) to form a correlation measurement variable.

18. A measurement method according to claim 17, wherein the separate measurement signal (A(x_A)) is treated as being the separate measurement variable (A[A(x_A), x_A]) in the second step (II).

19. A measurement method according to claim 17, wherein the computing means (7) performs conventional signal processing methods in the second step (II).

20. A measurement method according to claim 17, wherein the computing means (7) uses at least one of following calculation variants in the third step (III) to carry out the correlation of the two separate measurement variables (A[A(x_A), x_A], B[B(x_B), x_B]) to form a correlation measurement variable:

a) the at least two separate measurement variables are correlated to form a correlation measurement variable by an AND operation or multiplication;

b) the at least two separate measurement variables are correlated to form a correlation measurement variable by cross-correlation or cross-variance;

c) a set-theoretical intersection set is formed from the objects of the at least two separate measurement variables which are discretely detected spatially;

d) a superimposed probability distribution of the objects of the at least two separate measurement variables which are detected spatially and fuzzily is formed.

21. A measurement method according to claim 17, further comprising a fourth step (IV), in which the correlation measurement variable and an additional measurement variable which was additionally determined in the first step (I) by an additional sensor (13a) as an additional measurement signal and which was processed in the second step (II) to form an additional measurement variable are combined by the computing means (7) to form a combination measurement variable.

22. A measurement method according to claim 21, wherein, in an additional measurement variable, which is measured by an inductive sensor, a supply frequency of a main power supply is detected by the computing means (7) and is processed together with the additional measurement variable.

23. A measurement method according to claim 17, further comprising another step, in which a plurality of correlation measurement variables and/or combination measurement variables are calculated together with their positions (x_A, x_B) by the computing means (7).

24. A measurement method according to claim 23, wherein the plurality of correlation measurement variables and/or the combination measurement variables are compared to predetermined object parameters, and are processed to form an object variable (O(x, z)) with which a position (x) and depth (z) are associated.

25. A measurement method according to claim 24, comprising a further step (V), in which the object variable (O(x, z)) is calculated with the position (x) and/or depth (z) by the computing means (7) to form a variable image which is displayed, by an output device (8) of an evaluation unit (6).

26. A measurement method according to claim 25, wherein the resulting image is displayed graphically.