Highway profile measuring system

• US 5,790,243 A
• Filed: 04/22/1996
• Issued: 08/04/1998
• Est. Priority Date: 09/30/1993
• Status: Expired due to Fees

• Current Assignee: William F. Herr
• Original Assignee: William F. Herr
• Inventors: Herr, William F.
• Primary Examiner(s): Buczinski, Stephen C.
• Application Number:
  US08/639,897
• Time in Patent Office: 834 Days
• Field of Search: 356/5.1, 356/2, 356/3.01, 356/28, 356/376, 73/146
• US Class Current: 356/5.1
• CPC Class Codes: G01B 11/24 for measuring contours or curvatures
• CPC Class Codes: G01C 7/04 involving a vehicle which moves along the profile to be traced
• CPC Class Codes: G01S 17/89 for mapping or imaging

Abstract

A system for measuring the quality of pavement surfaces. An amplitude modulated laser scanning system, mounted on a motor vehicle, scans the pavement surface as the motor vehicle travels over it. A detector detects the laser beam reflection from the surface and a phase measuring device counts pulses to digitally determine the phase shift in the reflected laser beam in order to calculate the profile of the surface. The profile information is used to determine various quality features of the pavement surface.

Claims

1. A highway profile measuring system for measuring the profiles of large surfaces comprising:

A) a vehicle defining a forward direction and a transverse direction

B) a laser means mounted on said motor vehicle for producing a laser beam for illuminating small spots on said large surfaces,

C) a first detector means for detecting reflections of portions of said laser beam from said large surface,

D) a first scanner means having a fixed or adjustable scan rate for scanning said laser beam on said large surfaces and reflecting portions of said beam reflected from said surfaces into said detector means,

E) a modulating means for modulating said laser beam with a predetermined frequency of less than 10 GHz,

F) a phase measuring means for digitally determining the phase shift of said portion of said modulated beam reflected into said detector means from a very large number of said small spots on said surfaces.

2. A system as in claim 1 wherein said first scanner means is mounted on said motor vehicle and arranged to scan in a direction essentially parallel to said transverse direction.

3. A system as in claim 1 and further comprising a computer means for calculating data points describing the profile of at least a large portion of the surface scanned by said scanner.

4. A system as in claim 1 wherein said vehicle is predetermined to operate at varying speeds and the scan rate of said scanner is controlled to correspond to the speed of said motor vehicle.

5. A system as in claim 1 and further comprising a roll angle measuring means for determining the roll angle relative to gravitation force vectors and a means for correlating phase shift measurements with gravitation force vector measurements in order to provide a surface profile relative to the gravitation force vector.

6. A system as in claim 5 wherein said first scanner means is mounted on the rear of said motor vehicle and arranged to scan in a direction essentially parallel to said transverse direction.

7. A system as in claim 5 and further comprising a computer means for calculating data points to provide said surface profile.

8. A system as in claim 5 wherein said vehicle is predetermined to operate at varying speeds and the scan rate of said scanner is controlled to correspond to the speed of said motor vehicle.

9. A highway profile measuring system for installation on a vehicle for measuring the profiles of large surfaces comprising:

A) a laser means mounted on said motor vehicle for producing a laser beam for illuminating small spots on said large surfaces,

B) a first detector means for detecting reflections of portions of said laser beam from said large surface,

C) a first scanner means having a fixed or adjustable scan rate for scanning said laser beam on said large surfaces and reflecting portions of said beam reflected from said surfaces into said detector means,

D) a modulating means for modulating said laser beam with a predetermined frequency of less than 10 GHz,

E) a phase measuring means for digitally determining the phase shift of said portion of said modulated beam reflected into said detector means from a very large number of said small spots on said surfaces.

10. A highway profile measuring system for measuring the profiles of large surfaces comprising:

A) a vehicle defining a forward direction and a transverse direction

B) a laser means mounted on said motor vehicle for producing a laser beam for illuminating small spots on said large surfaces,

C) a first detector means for detecting reflections of portions of said laser beam from said large surface,

D) a first scanner means having a fixed or adjustable scan rate for scanning said laser beam on said large surfaces and reflecting portions of said beam reflected from said surfaces into said detector means, said scanner being arranged to scan in a direction parallel to said forward direction and scan both forward and rearward of at least one wheel of said vehicle,

E) a modulating means for modulating said laser beam with a predetermined frequency of less than 10 GHz,

F) a phase measuring means for digitally determining the phase shift of said portion of said modulated beam reflected into said detector means from a very large number of said small spots on said surfaces;

wherein deflection of a road surface is measured by comparing phase data obtained from a second set of reflections from locations near said at least one wheel with data obtained from a first set of reflections when said locations were substantially forward of said at least one wheel.

11. A highway profile system as in claim 10 wherein said at least one wheel defines a deflection zone and said first set of of reflections are obtained at a time when said locations are forward of said deflection zone.

12. A highway profile system as in claim 11 wherein said first set of of reflections are obtained at a time when said locations are forward of said deflection zone by at least three feet.