Detecting roadway targets across beams including filtering computed positions

• US 8,665,113 B2
• Filed: 02/23/2010
• Issued: 03/04/2014
• Est. Priority Date: 10/31/2005
• Status: Active Grant

• Current Assignee: Wavetronix
• Original Assignee: Wavetronix
• Inventors: Arnold, David V., Jarrett, Bryan R., Karlinsey, Thomas W., Waite, Jonathan L., St. John, Randy, Giles, Brad
• Primary Examiner(s): HOFSASS, JEFFERY A
• Application Number:
  US12/710,736
• Publication Number:
  US 20100149020A1
• Time in Patent Office: 1,470 Days
• Field of Search: 340/907, 340/916, 340/917, 340/933, 340941-943, 343/700.MS
• US Class Current: 340/907
• CPC Class Codes: G01S 13/48 using multiple beams at emission or reception
• CPC Class Codes: G01S 13/726 Multiple target tracking
• CPC Class Codes: G01S 13/91 for traffic control G01S13/93 takes precedence
• CPC Class Codes: G08G 1/04 using optical or ultrasonic detectors
• CPC Class Codes: G08G 1/08 according to detected number or speed of vehicles

Abstract

The present invention extends to methods, systems, and computer program products for detecting targets across beams at roadway intersections. Embodiments of the invention include tracking a target across a plurality of beams of a multiple beam radar system in a roadway intersection and updating track files for targets within a roadway intersection. Returns from a plurality of radar beams monitoring a roadway intersection are divided into range bins. Identified energy in the range bins is used to compute the position of targets within a roadway intersection. When the position of a target is computed, it is determined if the position is a new position for an existing target or if the position is the position of a new target.

Claims

1. At a computer system, a method for filtering computed positions of targets in a roadway that have been detected using a multiple beam radar system, the method comprising:

an act of detecting one or more targets in a plurality of beams of the multiple beam radar system;

an act of computing positions for the one or more targets for a first detection period;

an act of computing positions for the one or more targets for a second detection period; and

an act of filtering the computed positions for the one or more targets using a subset of computed positions from the first detection period and using a subset of computed positions from the second detection period.

2. The method as recited in claim 1, wherein the act of detecting one or more targets in a plurality of beams of the multiple beam radar system comprises an act of dividing returns from a radio frequency (RF) radar system into a grid of range bins.

3. The method as recited in claim 2, wherein the act of filtering the positions of the one or more targets comprises an act of determining that the magnitude of reflected radio frequency (RF) energy in the specified range bin is above a specified threshold.

4. The method as recited in claim 2, wherein the act of filtering the computed positions of the one or more targets comprises an act of determining that the magnitude of reflected radio frequency (RF) energy in the specified range bin is greater than the magnitude of reflected radio frequency (RF) energy in any of the surrounding adjacent range bins within the grid of range bins.

5. The method of claim 2, wherein the act of computing positions for the one or more targets for a first detection period comprises for at least one roadway target an act of computing a centroid from the magnitude of the reflected radio frequency (RF) energy in the specified range bin and from the magnitude of the reflected radio frequency (RF) energy in any of the surrounding adjacent range bins.

6. The method of claim 5, wherein the act of computing positions for the one or more targets for a first detection period comprises an act of computing Cartesian coordinates for the one or more targets based on the magnitude of the reflected radio frequency (RF) energy in the specified range bin and the magnitude of the reflected radio frequency (RF) energy in any of the surrounding adjacent range bins.

7. The method of claim 2, wherein the act of computing positions for the one or more targets for a first detection period comprises an act of computing Cartesian coordinates for the one or more targets based on the magnitude of the reflected radio frequency (RF) energy in the specified range bin and the magnitude of the reflected radio frequency (RF) energy in any of the surrounding adjacent range bins.

8. The method as recited in claim 1, wherein the computer system is a traffic sensor.

22. A computer storage medium having stored thereon instructions that when executed by a processor cause the method recited in claim 1 to be performed.

9. At a computer system, a method for filtering computed positions of targets in a roadway across a plurality of beams of a multiple beam radar system, the method comprising:

an act of dividing returns from the multiple beam radar system for a first detection period into a grid of range bins, dividing returns into a grid of range bins including dividing each beam in the plurality of beams into a plurality of range bins of uniform varied distances from the multiple beam radar system, each beam divided into a plurality of range bins in accordance with the uniform varied distances;

an act of creating a comprehensive image from the returns for each beam in the first detection period;

an act of dividing returns from the multiple beam radar system for a second detection period into the grid of range bins;

an act of creating a comprehensive image from the returns for each beam in the second detection period;

an act of filtering the comprehensive image from the second detection period using the comprehensive image from the first detection period; and

an act of detecting targets using the filtered comprehensive image.

10. At a computer system, a method for updating track files for targets within a roadway intersection, the method comprising:

an act of accessing a target list for the roadway intersection, the target list including currently computed positions for one or more targets in the roadway intersection, currently computed positions being derived from a grid of range bins dividing returns from a plurality of beams of a multiple beam radar into a plurality of range bins of uniform varied distances from the multiple beam radar system, each beam divided into a plurality of range bins in accordance with the uniform varied distances;

an act of maintaining a track file for each target in the roadway intersection, each track file including target data for a target that is within the roadway intersection, the target data including target position data for a target, the target position data including at least one of;

a last known position for the target and a predicted future position for the target, maintaining track files including;

an act of accessing a currently computed position from the target list;

an act of accessing a specified track file for an existing target, the specified track file having target position data that may correspond to the currently computed position;

an act of determining if the currently computed position is a position of the existing target by comparing the currently computed position to the target position data in the accessed track file;

an act of updating the specified track file for the existing target when the currently computed position is determined to correspond to the position of the existing target; and

an act of creating a new track file for a new target when the currently computed position is determined not to correspond to the position of the existing target.

11. The method as recited in claim 10, wherein accessing a target list comprises accessing a target list including currently computed positions for one or more targets, each target position having been calculated from the magnitude of the energy in range bins of a grid of range bins, the grid of range bins dividing returns from a plurality of beams of a radio frequency (RF) multiple beam radar into a plurality of range bins of uniform varied distances from the radio frequency (RF) multiple beam radar system.

12. The method as recited in claim 10, wherein determining if the currently computed position is a position of the existing target by comparing the currently computed position to the position data in the accessed track file comprises an act of comparing the currently computed position to the last known position of an existing target in the roadway intersection.

13. The method as recited in claim 12, wherein comparing the currently computed position to the last known position of an existing target in the roadway intersection comprises determining if the currently computed position is within a specified distance of the last known position.

14. The method as recited in claim 10, wherein determining if the currently computed position is a position of the existing target by comparing the currently computed position to the position data in the accessed track file comprises comparing the currently computed position to a predicted future position of an existing target in the roadway intersection.

15. The method as recited in claim 14, wherein comparing the currently computed position to a predicted future position of an existing target in the roadway intersection comprises determining if the currently computed position is within a specified distance of the predicted future position.

16. The method as recited in claim 10, wherein determining if the currently computed position is a position of the existing target by comparing the currently computed position to the position data in the accessed track file comprises an act of comparing Cartesian coordinates representing the currently computed position to Cartesian coordinates in the target position data.

17. The method as recited in claim 10, wherein the act of updating the specified track file for the existing target when the currently computed position is determined to be the position of the existing target comprises an act of storing the currently computed position as the last known position for the existing target in a track file for the existing target.

18. A traffic sensor for monitoring a roadway intersection, the traffic sensor comprising:

a multiple beam radar system, including;

transmit antennas for transmitting frequency modulated continuous wave (FMCW) radio frequency (RF) signals into the roadway intersection using a plurality of beams;

receive antennas for receiving reflections of the frequency modulated continuous wave (FMCW) radio frequency (RF) signals reflected off of objects within the plurality of beams in the roadway intersection, the reflections corresponding to two dimensional image data for the roadway intersection;

system memory;

one or more processors; and

one or more computer storage media having stored thereon computer-executable instructions representing one or more modules for identifying targets in a roadway intersection and representing a track file maintenance module for maintaining track files for the roadway intersection, the one or more modules for identifying targets in a roadway intersection configured to;

divide received reflections into a grid of range bins, including dividing each beam in the plurality of beams into a plurality of range bins of uniform varied distances from the multiple beam radar system, each beam divided into a plurality of range bins in accordance with the uniform varied distances;

detect a multi-beam image within the two-dimensional image data, the multi-beam image representing a target within the roadway intersection, the multi-beam image spanning a sub-plurality of the plurality of beams, the multi-beam image also spanning a plurality of range bins within the grid of range bins;

identify an energy peak within the multi-beam image, including;

for a specified range bin in one of the beams of the sub-plurality of beams;

determine that the magnitude of the radio frequency (RF) energy in the specified range bin is above a specified threshold; and

determine that the magnitude of the radio frequency (RF) energy in the specified range bin is greater than the magnitude of the radio frequency (RF) energy in any of the surrounding adjacent range bins within the grid of range bins;

compute the position of the target; and

add the position of the target to the target list for the roadway intersection; and

wherein the track file maintenance module is configured to;

access the target list for the roadway intersection; and

maintain a track file for each target in the roadway intersection, each track file including target data for a target that is within the roadway intersection, the target data including target position data for a target, the target position data including at least one of;

a last known position for the target and a predicted future position for the target, maintaining track files including;

access a currently computed position from the target list;

access a specified track file for an existing target, the specified track file having target position data corresponding to the currently computed position;

determine if the currently computed position is a position of the existing target by comparing the currently computed position to the target position data in the accessed track file;

update the specified track file for the existing target when the currently computed position is determined to be the position of the existing target; and

create a new track file for a new target when the currently computed position is determined not to be the position of the existing target.

19. The traffic sensor of claim 18, wherein the one or more modules for identifying targets in a roadway intersection configured to compute the position of the target based on the magnitude of the radio frequency (RF) energy in the specified range bin and the magnitude of the radio frequency (RF) energy in any of the surrounding adjacent range bins comprises the one or more modules for identifying targets in a roadway intersection configured to compute a centroid from the magnitude of the radio frequency (RF) energy in the specified range bin and from the magnitude of the radio frequency (RF) energy in any of the surrounding adjacent range bins.

20. The traffic sensor of claim 19, wherein the one or more modules for identifying targets in a roadway intersection configured to compute a centroid from the magnitude of the radio frequency (RF) energy in the specified range bin and from the magnitude of the radio frequency (RF) energy in any of the surrounding adjacent range bins comprises the one or more modules for identifying targets in a roadway intersection configured to compute Cartesian coordinates for the target based on the magnitude of the radio frequency (RF) energy in the specified range bin and the magnitude of the radio frequency (RF) energy in any of the surrounding adjacent range bins.

21. The traffic sensor of claim 18, wherein the track file maintenance module being configured to determine if the currently computed position is a position of the existing target by comparing the currently computed position to the position data in the accessed track file comprises the track file maintenance module being configured to compare Cartesian coordinates for representing the currently computed position to Cartesian coordinates in the target position data.

23. A traffic sensor as recited in claim 18, wherein at least one of the transmit antennas and the receive antennas is the same antenna.

24. A traffic sensor as recited in claim 18, wherein at least one of the transmit antennas or the receive antennas is selected from a group consisting of a directional antenna and a steerable antenna.