Piezoelectric sensor module of a WIM system for two-track vehicles and measurement method

• US 9,488,517 B2
• Filed: 05/15/2013
• Issued: 11/08/2016
• Est. Priority Date: 05/16/2012
• Status: Active Grant

• Current Assignee: Kistler Holding AG
• Original Assignee: Kistler Holding AG
• Inventors: Cornu, David, Hofmann, Adrian
• Primary Examiner(s): Gibson, Randy W
• Application Number:
  US14/400,928
• Publication Number:
  US 20160187183A1
• Time in Patent Office: 1,273 Days
• US Class Current: 1/1
• CPC Class Codes: G01G 19/024 using electrical weight-sensitive devices
• CPC Class Codes: G01P 3/50 for measuring linear speed G01P3/56 takes precedence
• CPC Class Codes: G08G 1/02 using treadles built into the road pads or other sensitive devices responsive to passage of vehicles E01F11/00
• CPC Class Codes: G08G 1/052 with provision for determining speed or overspeed speed measuring in general G01P

Abstract

A sensor module for measuring axle speeds and weights of double-track vehicles which travel in a direction of travel (L) along a carriageway with two lanes includes a plurality of piezoelectric strip sensors (A, B, C, D) that are arranged in a first lane group (I) and a second lane group (II). All the strip sensors (A, B, C, D) are spaced from each other in the direction of travel (L) via a secure longitudinal offset (LAD), which is greater than the maximum wheel contact length, and are offset from one another by between one centimeter and fifteen centimeters in the transversal direction. The sensor module also has a module length (LABCD) of less than 80 centimeters.

Claims

1. Sensor module for measuring the axle speeds and weights of two-track vehicles, which travel in a direction of travel (L) along a roadway with two lanes, comprising a plurality of piezoelectric strip sensors (A, B, C, D), wherein all the strip sensors (A, B, C, D) have axial centerlines that are arranged orthogonally (Q) to the direction of travel (L), wherein a first strip sensor and a second strip sensor in a first pair of strip sensors (A, D) are spaced from each other in the direction of travel (L) in a first lane group of the sensor module via a first fixed longitudinal offset (LAD) which is greater than the maximum wheel contact length, wherein a first strip sensor (B) and a second strip sensor (C) in a second pair of strip sensors (B, C) are spaced from each other in the direction of travel (L) in a second lane group of the sensor module via a second fixed longitudinal offset (LBC) which is greater than the maximum wheel contact length, wherein the strip sensors (A, D) of the first lane group are arranged with an offset from the strip sensors (B, C) of the second lane group transversely (Q) to the direction of travel (L), so that each lane group covers a separate lane of the roadway, wherein the first strip sensor (A) of the first lane group and the first strip sensor (B) of the second lane group are arranged with an offset between 1 and 15 cm relative to each other in the direction of travel, wherein the second strip sensor (D) of the first lane group and the second strip sensor (C) of the second lane group are arranged with an offset (LAB or LCD) between 1 cm and 15 cm relative to each other in the direction of travel, and the sensor module has a module length (LABCD) less than 80 cm in the direction of travel.

2. Sensor module according to claim 1, wherein the distance (LAB) of the offset between the first strip sensors (A, B) in the direction of travel (L) is greater than 1 cm and less than 8 cm and wherein the distance (LCD) of the offset between the second strip sensors (C, D) of the different lane groups in the direction of travel (L) is greater than 1 cm and less than 8 cm.

3. Sensor module according to claim 1, wherein each of the longitudinal offsets (LAD, LBC) is greater than 20 cm.

4. Sensor module according to claim 1, wherein the strip sensors (A, D) of the first lane group are arranged relative to the strip sensors (B, C) of the second lane group in such manner that all strip sensors (A, B, C, D) are arranged completely separately and with no overlap in the direction of travel (L) and with no overlap in the direction transverse (Q) to the direction of travel (L).

5. Sensor module according to claim 1, wherein the longitudinal offset (LAD) of the first lane group is greater than the longitudinal offset (LBC) of the second lane group.

6. Sensor module according to claim 1, wherein the longitudinal offset (LAD) of the first lane group is equal to the longitudinal offset (LBC) of the second lane group.

7. Sensor module according to claim 1, wherein the sensor module is formed by a frame construction, in which the strip sensors (A, B, C, D) of the first lane group and of the second lane group are mounted with fixed intervals relative to each other.

8. Sensor module according to claim 7, wherein the frame construction comprises at least two frame sections, in which either the strip sensors (A, D) of the first lane group and the second (B, C) lane group are fastened separately, or in which each of the first strip sensors (A, B) and the second strip sensors (C, D) are mounted separately.

9. Sensor module according to claim 7, wherein at least one of an electronic signal acquisition unit and an evaluation unit is secured in the frame structure.

10. Sensor module (1) according to claim 7, wherein an output wire is routed from the frame structure and electrically connected so that it forwards bundled measurement signals from all the strip sensors (A, B, C, D).

13. Sensor module according to claim 1, wherein the first strip sensor (A) of the first lane group and the first strip sensor (B) of the second lane group are arranged edge to edge in a direction (Q) transverse to the direction of travel (L).

14. Sensor module according to claim 1, wherein the plurality of strip sensors includes more than four strip sensors (A, B, C, D) and the strip sensors in excess of four strip sensors are arranged additionally to improve the accuracy of the results.

19. Sensor module according to claim 1, further comprising:

an electronic signal acquisition unit connected to the strip sensors and configured to receive a and electric signal upon activation of a respective strip sensor; and

an evaluation unit electronically connected to the electronic signal acquisition unit and configured to determine the time differences between each pair of signals received from the electronic signal acquisition unit, wherein a first one of these time differences occurs between the signal from the first strip sensor of the first lane group and the signal from the first strip sensor of the second lane group, a second one of these time differences occurs between the signal from the first strip sensor of the first lane group and the signal from the second strip sensor of the second lane group, a third one of these time differences occurs between the signal from the first strip sensor of the first lane group and the signal from the second strip sensor of the first lane group, a fourth one of these time differences occurs between the signal from the first strip sensor of the second lane group and the signal of the second strip sensor of the second lane group, a fifth one of these time differences occurs between the signal from the first strip sensor of the second lane group and the second strip sensor of the first lane group, and a sixth one of these time differences occurs between the signal from the second strip sensor of the first lane group and the signal from the second strip sensor of the second lane group.

11. Sensor module for measuring the axle speeds and weights of two-track vehicles, which travel in a direction of travel (L) along a roadway with two lanes, comprising:

a plurality of piezoelectric strip sensors (A, B, C, D), wherein all the strip sensors (A, B, C, D) have axial centerlines that are arranged orthogonally (Q) to the direction of travel (L), wherein a first strip sensor and a second strip sensor in a first pair of strip sensors (A, D) are spaced from each other in the direction of travel (L) in a first lane group of the sensor module via a first fixed longitudinal offset (LAD) which is greater than the maximum wheel contact length, wherein a first strip sensor (B) and a second strip sensor (C) in a second pair of strip sensors (B, C) are spaced from each other in the direction of travel (L) in a second lane group of the sensor module via a second fixed longitudinal offset (LBC) which is greater than the maximum wheel contact length, wherein the strip sensors (A, D) of the first lane group are arranged with an offset from the strip sensors (B, C) of the second lane group transversely (Q) to the direction of travel (L), so that each lane group covers a separate lane of the roadway, wherein the first strip sensors (A) of the first lane group and the first strip sensor (B) of the second lane group are arranged with an offset between 1 and 15 cm relative to each other in the direction of travel, wherein the second strip sensors (D) of the first lane group and the second strip sensor (C) of the second lane group are arranged with an offset (LAB or LCD) between 1 cm and 15 cm relative to each other in the direction of travel, and the sensor module has a module length (LABCD) less than 80 cm in the direction of travel;

wherein the sensor module is formed by a frame construction, in which the strip sensors (A, B, C, D) of the first lane group and of the second lane group are mounted with fixed intervals relative to each other; and

wherein a toothed structure is fastened to at least one surface before or after the frame structure in the direction of travel (L).

12. Sensor module according to claim 11, wherein the toothed structure is positioned at the level of a road surface.

15. Method for dynamically measuring the weight of vehicles travelling on a roadway, wherein a sensor module comprising a plurality of strip sensors (A, B, C, D) is used, wherein all the strip sensors (A, B, C, D) have axial centerlines that are arranged orthogonally (Q) to the direction of travel (L), wherein a first strip sensor (A) and a second strip sensor (D) in a first pair of strip sensors are spaced from each other in the direction of travel (L) in a first lane group of the sensor module via a first fixed longitudinal offset (LAD) which is greater than the maximum wheel contact length, wherein a first strip sensor (B) and a second strip sensor (C) in a second pair of strip sensors are spaced from each other in the direction of travel (L) in a second lane group of the sensor module via a second fixed longitudinal offset (LBC) which is greater than the maximum wheel contact length, wherein the strip sensors (A, D) of the first lane group are arranged with an offset from the strip sensors (B, C) of the second lane group transversely (Q) to the direction of travel (L), so that each lane group covers a separate lane of the roadway, wherein the first strip sensor (A) of the first lane group and the first strip sensor (B) of the second lane group are arranged with an offset between 1 and 15 cm relative to each other in the direction of travel (L), wherein the second strip sensor (D) of the first lane group and the second strip sensor (C) of the second lane group are arranged with an offset between 1 cm and 15 cm relative to each other in the direction of travel (L), and the sensor module has a module length (LABCD) less than 80 cm in the direction of travel, wherein:

a) the sensor module uses time-staggered capture of measurement signals of the strip sensors (A, B, C, D), in order to achieve uncoupled measurement signals, and subsequent

b) calculation of the axle weights of the vehicle by using at least one integral for each lane group of the time-resolved measurement signal curves and at least one of the determined speeds of the vehicle between the strip sensor pairs (AB, AC, AD, BC, BD, CD) while travelling.

16. Method according to claim 15, wherein the measurement signals are captured alternatingly by a strip sensor (A, D) of the first lane group and by a strip sensor (B, C) of the second lane group.

17. Method according to claim 15, wherein the measurement signals are detected from the first strip sensor (A) of the first lane group, from the first strip sensor (B) of the second lane group, from the second strip sensor (C) of the second lane group and finally from the second strip sensor (D) of the first lane group.

18. Method according to claim 15, wherein the measurement signals of the second strip sensors (C, D) are only captured if correct axle weights could not be determined from the measurement signals of the first strip sensors (A, B).