GPS-BASED MACHINE VISION ROADWAY MARK LOCATOR, INSPECTION APPARATUS, AND MARKER

• US 20130184938A1
• Filed: 12/27/2012
• Published: 07/18/2013
• Est. Priority Date: 01/17/2012
• Status: Active Grant

• Current Assignee: LimnTech LLC
• Original Assignee: Limn Tech LLC
• Inventors: Dolinar, Douglas D., Haller, William R.
• Granted Patent: US 9,298,991 B2
• Time in Patent Office: Days
• US Class Current: 701/41
• CPC Class Codes: B62D 5/0463 calculating assisting torque from the motor based on driver input
• CPC Class Codes: E01C 23/163 for marking-out the location of the markings; Guiding or steering devices for marking apparatus, e.g. sights
• CPC Class Codes: E01C 23/22 by spraying E01C23/206 takes precedence
• CPC Class Codes: F16M 13/022 repositionable
• CPC Class Codes: G01C 15/02 Means for marking measuring points
• CPC Class Codes: G06V 20/56 exterior to a vehicle by using sensors mounted on the vehicle

Abstract

An apparatus for locating, inspecting, or placing marks on a roadway. The apparatus includes a GPS-based machine vision locator for sampling discrete geographical location data of a pre-existing roadway mark evident on the roadway. A computer may determine a continuous smooth geographical location function fitted to the sampled geographical location data. And a marker is responsive to the GPS-based locator and geographical location function for replicating automatically the pre-existing roadway mark onto the roadway. The apparatus is typically part of a moving vehicle. A related method is disclosed for locating, inspecting, and placing marks on a resurfaced roadway. A similar apparatus can be used to guide a vehicle having a snow plow along a snow-covered roadway, or a paving machine along an unpaved roadway surface.

Claims

1. An apparatus for determining a geographical location of a roadway mark from a moving vehicle, comprising:

at least one vehicle mounted imager responsive to a trigger signal for imaging at least one roadway mark located substantially parallel to a direction of travel of the vehicle to provide a triggered roadway mark image;

a GPS antenna;

a GPS receiver responsive to the GPS antenna for determining a geographical location of the GPS antenna;

an apparatus for providing a GPS receiver synchronized image trigger signal to the vehicle mounted imager; and

an apparatus for determining a GPS geographical location of the roadway mark from the triggered roadway mark image and the geographical location of the GPS antenna.

2. The apparatus according to claim 1 wherein the GPS antenna, adapted to receive GPS radio wave signals originating from a GPS satellite system or a GPS-pseudolite array, is connected to the GPS receiver which decodes the GPS signals for determining the geographical location of the GPS antenna.

3. A method for determining a geographical location of a roadway mark from a moving vehicle, comprising:

imaging at least one roadway mark located substantially parallel to a direction of travel of the vehicle with at least one imager responsive to a trigger signal;

determining a geographical location of a GPS antenna using a GPS receiver;

triggering the imager with a GPS receiver synchronized image trigger signal; and

determining a GPS geographical location of the roadway mark from the triggered roadway mark image and the geographical location of the GPS antenna.

4. The method according to claim 3, wherein the GPS receiver outputs a periodic pulse signal and the GPS receiver synchronized image trigger signal occurs simultaneously.

5. An apparatus for inspecting roadway marks comprising:

at least one imager mounted on a moving vehicle and positioned to image at least one roadway mark located substantially parallel to a direction of travel of the vehicle;

a mechanism for determining a GPS geographical location of the roadway mark from the image of the roadway mark; and

a computer for (i) calculating roadway mark characteristics from the roadway mark image and (ii) comparing the calculated roadway mark characteristics against a standard set of roadway mark characteristics.

6. The apparatus according to claim 5, wherein the roadway mark characteristics are at least one of width of the roadway mark, length of the roadway mark, grayscale reflectivity, and fill percentage.

7. The apparatus according to claim 5, wherein the at least one imager is mounted using a mount comprising:

an adjustable mount for aligning an imager so that the imager can focus on at least one roadway mark; and

at least one magnetic clamp affixed to the adjustable mount for removably affixing the adjustable mount to the vehicle.

8. A method for inspecting roadway marks comprising:

imaging at least one roadway mark with an imager mounted on a vehicle and positioned to image at least one roadway mark located substantially parallel to a direction of travel of the vehicle;

determining a GPS geographical location of the roadway mark from the roadway mark image;

calculating roadway mark characteristics from the roadway mark image; and

comparing the calculated roadway mark characteristics against a standard set of roadway mark characteristics.

9. An apparatus for determining a GPS geographical location of a roadway mark from an image of the roadway mark, comprising:

a GPS antenna;

a GPS receiver for determining a geographical location of the GPS antenna and for generating a periodic first signal whose time of occurrence is known;

a circuit responsive to the first signal for generating a trigger signal synchronized to the first signal;

at least one imager responsive to the trigger signal and focused to image at least one roadway mark; and

a computer for determining a GPS geographical location of the roadway mark from the GPS geographical location of the GPS antenna and from the time of occurrence of the first signal and the trigger signal.

10. A method for determining a GPS geographical location of a roadway mark from an image of a roadway mark, comprising:

determining a GPS geographical location of a GPS antenna using a GPS receiver;

generating a periodic first signal whose time of occurrence is known from the GPS receiver;

generating an image trigger signal synchronized to the first signal for triggering an imager focused to image at least one roadway mark; and

determining a GPS geographical location of the roadway mark from the GPS geographical location of the GPS antenna and from the time of occurrences of the first signal and the trigger signal using a computer.

11. An apparatus for locating and placing marks on a roadway, the apparatus comprising:

at least one vehicle mounted GPS-based machine vision locator responsive to a trigger signal for imaging at least one roadway mark located substantially parallel to a direction of travel of the vehicle for automatically sampling discrete geographical location data of an actual pre-existing roadway mark evident on the roadway;

a mechanism for providing a GPS receiver synchronized image trigger signal to the vehicle mounted GPS-based machine vision locator;

a computer for determining a continuous smooth geographical location function best-fitted to the sampled geographical location data; and

a marker responsive to the GPS-based machine vision locator and geographical location function for replicating automatically the pre-existing roadway mark onto the roadway.

12. The apparatus according to claim 11, wherein the GPS-based machine vision locator includes a GPS antenna, adapted to receive GPS radio wave signals originating from a GPS satellite system or a GPS-pseudolite array, connected to a GPS receiver which decodes the GPS signals for determining the geographical location of the GPS antenna.

13. The apparatus according to claim 11 further comprising at least one first imager focusing downwardly onto the roadway and providing an image of the roadway mark and at least one second imager which images the roadway in front of the apparatus.

14. The apparatus according to claim 11 further comprising a speed detector and a nozzle array and control system, the speed detector informing the nozzle array and control system and enabling the nozzle array and control system to adjust the rate at which it places marking material.

15. The apparatus according to claim 11, wherein the computer generates an additional roadway mark function by offsetting the continuous function by an amount consistent with the desired position of a second roadway mark relative to the replicated roadway mark.

16. A moving vehicle for sampling, locating, and placing marks on a roadway at the direction of an operator, the vehicle comprising:

a GPS-based machine vision locator automatically sampling discrete geographical location data of an actual pre-existing roadway mark evident on the roadway and including (a) at least one imager focused downwardly onto the roadway and providing an image of a roadway mark, and (b) a GPS antenna adapted to receive GPS radio wave signals originating from a GPS satellite system or a GPS-pseudolite array and connected to a GPS receiver which decodes the GPS signals for determining the geographical location of the GPS antenna;

a computer for determining the GPS geographical location of the roadway mark from the GPS geographical location of the GPS-based machine vision locator;

a display adapted to present information to the operator; and

a nozzle array and control system responsive to the GPS-based machine vision locator for replicating automatically the pre-existing roadway mark on the roadway by placing a marking material on the roadway.

17. The vehicle according to claim 16 further comprising a vehicle navigation and control system controlling the direction, speed, and acceleration of the vehicle along a predetermined path.

18. The vehicle according to claim 16 wherein the computer comprises program memory having:

a location comparator program which compares the current GPS location received by the antenna and decoded by the GPS receiver to previous GPS locations stored in a data memory, then determines the difference between the current and the stored GPS locations;

a sampling program which receives a GPS reference location and constructs a grid system having the origin defined at the reference location and further, based upon the constructed grid system and a distance sampling interval, samples the geographical location of the pre-existing roadway mark;

a machine vision program which inputs data from the at least one imager and performs generic machine vision operations on the image data from the at least one imager;

a curve fitting program which inputs discrete GPS coordinate data stored in the data memory and determines a first continuous mathematical function which fits the data; and

a curve offsetting program which inputs the continuous function determined by the curve fitting program and generates a second continuous function similar and parallel to the first function but offset from the first function by a given distance.

19. A method for locating and placing marks on a roadway, the method comprising:

automatically sampling a geographical location of an actual pre-existing roadway mark, evident on the roadway, using a GPS-based machine vision locator by imaging at least one roadway mark located substantially parallel to a direction of travel of the vehicle with at least one imager responsive to a trigger signal;

determining a geographical location of a GPS antenna using a GPS receiver;

triggering the imager with a GPS receiver synchronized image trigger signal;

determining the geographical location of the roadway mark from the triggered roadway mark image and the geographical location of the GPS antenna; and

if necessary, marking the roadway with a marking material at the geographical location automatically determined by the GPS-based machine vision locator.

20. An apparatus for guiding a vehicle having a snow plow along a roadway, the apparatus comprising:

a GPS-based machine vision locator automatically sampling discrete geographical location data of an actual pre-existing roadway mark evident on the roadway and including (a) at least one imager focused downwardly onto the roadway and providing an image of a roadway mark, and (b) a GPS antenna adapted to receive GPS radio wave signals originating from a GPS satellite system or a GPS-pseudolite array and connected to a GPS receiver which decodes the GPS signals for determining the geographical location of the GPS antenna;

a computer for determining a continuous smooth geographical location function best-fitted to the sampled geographical location data; and

a system responsive to the GPS-based machine vision locator and geographical location function for positioning the snow plow.

21. A mount for affixing an imager to a vehicle for imaging roadway marks evident on a roadway surface which are substantially parallel to the direction of vehicle travel, comprising:

an adjustable mount for positioning the imager to image at least one roadway mark and including at least one fixably adjustable axis of rotation substantially parallel to the roadway surface, and

at least one magnetic clamp affixed to the adjustable mount for removably affixing the adjustable mount to the vehicle.

22. An apparatus for determining a geographical location of roadway lane demarcation marks from a moving vehicle travelling within a lane, comprising:

a first imager mounted on a vehicle and aligned to image at least one roadway mark substantially parallel to, and to the left of, a direction of travel of the vehicle;

a second imager mounted on the vehicle and aligned to image at least one roadway mark substantially parallel to, and to the right of, the direction of travel of the vehicle;

a GPS antenna mounted on the vehicle;

a GPS receiver responsive to the GPS antenna for determining a geographical location of the GPS antenna;

an apparatus responsive to the first and second imagers and the GPS receiver for determining a geographical location of the vehicle and the geographical location of the first and second roadway marks with respect to the geographical location of the vehicle.