Traffic light signal system using radar-based target detection and tracking

• US 7,821,422 B2
• Filed: 08/18/2004
• Issued: 10/26/2010
• Est. Priority Date: 08/22/2003
• Status: Expired due to Fees

• Current Assignee: Light Vision Systems Incorporated
• Original Assignee: Light Vision Systems Incorporated
• Inventors: Hutchison, Michael C., Smith, Mark A., Pautler, James A.
• Primary Examiner(s): TWEEL JR, JOHN ALEXANDER
• Application Number:
  US10/920,743
• Publication Number:
  US 20050046597A1
• Time in Patent Office: 2,260 Days
• Field of Search: 340/907, 340/916, 340/917, 340/921, 340/923, 340/933, 340/937, 701/301, 348/149
• US Class Current: 340/907
• CPC Class Codes: G01S 13/343 using sawtooth modulation
• CPC Class Codes: G01S 13/726 Multiple target tracking
• CPC Class Codes: G01S 13/92 for velocity measurement
• CPC Class Codes: G01S 15/88 Sonar systems specially adapted for specific applications seismic or acoustic prospecting or detecting G01V1/00
• CPC Class Codes: G01S 7/003 Transmission of data between radar, sonar or lidar systems and remote stations
• CPC Class Codes: G01S 7/41 using analysis of echo signal for target characterisation; Target signature; Target cross-section
• CPC Class Codes: G08G 1/07 Controlling traffic signals

Abstract

A novel system and method of integrating an RF emissions device, such as a radar system (103A), within a traffic control indicator (101) system. The system and method determines, using LFM-CW radar signals (201) and a multi-stage spectral processing algorithm (600), if one or more object/vehicle targets will enter an intersection and comprises receiving a radar echo response (203) indicating the object/vehicle target (104) is approaching the intersection, receiving range and velocity of the object/vehicle targets (104), and based on the receiving, determining if the object/vehicle target (104) will enter the intersection. The system and method can programmatically be configured to activate red-light-hold, green-light-extension, or left-turn-warning.

Claims

1. A signaling system, comprising;

a traffic signal controller adapted to couple to a traffic control indicator, the traffic signal controller adapted to control different states of the traffic control indicator;

a signal state information module having a state of a traffic control indicator;

an RF transmitter operable to transmit signals toward at least one object/vehicle target;

an RF receiver operable to receive reflected signals from at least one said object/vehicle target; and

a radar/traffic processor coupled to the traffic signal controller and the signal state information module, and adapted to receive signals from the RF receiver;

the radar/traffic processor having an algorithm operable to determine characteristics of the object/vehicle targets and dynamically cause the traffic signal controller to control a state of the traffic control indicator in response thereto.

2. The signaling system of claim 1, further comprising at least one traffic control indicator adapted to control traffic at a pre-determined roadway location;

and

the traffic control indicator controlled by the traffic signal controller.

3. The signaling system of claim 1, further comprising:

the algorithm of the radar/traffic processor being adapted to determine, in advance, a likelihood that an object/vehicle target will run a red light generated by the traffic control indicator;

the algorithm causing the traffic signal controller to maintain the status of an opposing traffic control indicator based on the probability of an object/vehicle target running a red light.

4. The signaling system of claim 1, further comprising:

the algorithm of the radar/traffic processor being adapted to determine, in advance, a likelihood that a first object/vehicle target will make a left turn toward an opposing second object/vehicle target; and

the algorithm causing the traffic signal controller to illuminate a warning on a traffic control indicator to the left turning first object/vehicle target.

5. The signaling system of claim 1, further comprising:

the algorithm of the radar/traffic processor being adapted to determine, in advance, a nature of the flow of approaching object/vehicle targets; and

the algorithm causing the traffic signal controller to extend a green light given to the flow of approaching object/vehicle targets so as to permit the uninterrupted traversal of the flow of object/targets through the intersection.

6. The signaling system of claim 1, further comprising:

a sensor adapted to sense one or more of the following parameters;

precipitation, time of day and temperature; and

the algorithm of the radar/traffic processor adapted to dynamically adjust its signals to the traffic signal controller based on the sensed parameters.

7. The signaling system of claim 1, wherein the radar/traffic processor of a first traffic control indicator is in communication with at least one other radar/traffic processor controlling a second traffic control indicator in order to coordinate the signal status of the traffic control indicators.

8. The signaling system of claim 1, wherein the radar/traffic processor is adapted to log traffic information.

9. The signaling system of claim 8, wherein the logged information is communicated to an application.

10. The signaling system of claim 9, wherein the logged information is communicated to the application by way of a data communication channel.

11. The signaling system of claim 1, wherein the RF transmitter and the RF receiver comprise a radar.

12. The signaling system of claim 11, wherein the radar utilizes LFM-CW radio-frequency signals.

13. The signaling system of claim 11, wherein the radar implements a multi-stage spectral processing algorithm to determine distance, velocity and return-signal magnitude of at least one object/vehicle target.

14. The signaling system of claim 13, further comprising a VCO within the radar operable to transmit an LFM-CW radio-frequency signal.

15. The signaling system of claim 14 wherein, the frequency of the VCO signal appears as a linear ramp on a plot of frequency versus time.

16. The signaling system of claim 15, wherein a frequency difference between the transmitted and received radar signals from a single return is a function of an object/vehicle target'"'"'s distance and velocity.

17. The signaling system of claim 16, further comprising a mixer and low pass filter within the radar operable to extract the frequency difference between a transmitted and received signal by mixing the transmitted and received signal together and then performing a low pass filter operation.

18. The signaling system of claim 17, further comprising a supplemental high pass filter being operable to equalize signals from object/vehicle targets at long range experiencing a large propagation loss with a result that a given object/vehicle target will appear with roughly the same power level at any distance.

19. The signaling system of claim 11, wherein the radar is operable to generate a plurality of ramps with a steep slope having small ramp time.

20. The signaling system of claim 19, wherein the radar is operable to detect both positive and negative velocities.

21. The signaling system of claim 19, wherein the radar implements a multi-stage spectral processing algorithm comprised of fast Fourier transforms (“

FFTs”

).

22. The signaling system of claim 21, further comprising a digital signal processor (“

DSP”

) performing the FFTs.

23. The signaling system of claim 11, in combination with a high-level tracker module coupled to the output of the radar and to the input of the radar/traffic processor.

24. The signaling system of claim 23, wherein the high-level tracker is adapted to process results from several radar observations spaced over time to further refine the estimates made by the radar/traffic processor.

25. The signaling system of claim 23, wherein the high-level tracker is adapted to predict the location of at least one object/vehicle target.

26. The signaling system of claim 25, wherein the prediction is based on the computed acceleration of an object/vehicle target.

27. The signaling system of claim 25, wherein the prediction is based on the computed velocity of the object/vehicle target.

28. The signaling system of claim 23, wherein the high-level tracker is adapted to generate and assign a confidence factor to an object/vehicle target which reflects the probability that the detected object/vehicle target is valid.

29. The signaling system of claim 28, wherein the high level tracker assigns a high confidence factor to object/vehicle targets producing strong radar returns.

30. The signaling system of claim 11, wherein the traffic signal controller and the radar/traffic processor are located in a controller cabinet and the radar is located on a mast arm.

31. The signaling system of claim 11, wherein the radar and radar/traffic processor are located in a traffic control indicator housing.

32. The signaling system of claim 31, wherein the radar/traffic processor and the radar are physically coupled together at a base of a traffic control indicator.

33. The signaling system of claim 11, wherein the traffic control indicator and the radar are housed in a common housing.

34. The signaling system of claim 11, wherein the radar is adapted to determine a position of the object/vehicle target relative to the radar.

35. The signaling system of claim 11, wherein the radar is adapted to determine a distance of at least one object/vehicle target approaching the intersection.

36. The signaling system of claim 11, wherein the radar is adapted to determine both a velocity and distance of multiple object/vehicle targets relative to a traffic control indicator.

37. The signaling system of claim 11, wherein the radar is adapted to determine velocity and distance of object/vehicle targets in multiple lanes of traffic approaching a traffic control indicator.

38. The signaling system of claim 11, wherein the radar is adapted to determine a change in the velocity of an object/vehicle target approaching the intersection.

39. The signaling system of claim 11, further comprising the traffic signal controller controlling a traffic control indicator as a function of the radar and algorithm of the radar/traffic processor.

40. The signaling system of claim 11, wherein the radar/traffic processor is adapted to cause a traffic control indicator to generate an alert upon the occurrence of a pre-determined event.

41. The signaling system of claim 40, wherein the pre-determined event is an object/vehicle target entering an intersection within a pre-determined time frame.

42. The signaling system of claim 40, wherein the pre-determined event is the high probability of an object/vehicle target running a red light.

43. The signaling system of claim 11, further comprising a traffic control indicator adapted to display an alert indicative of an object/vehicle target being likely to run a red light.

47. The apparatus of claim 39, wherein the radar implements a multi-stage spectral processing algorithm.

48. The apparatus of claim 42, wherein the multi-stage spectral processing algorithm is comprised of FFTs.

44. An apparatus for controlling a traffic intersection, comprising;

a traffic signal controller coupled to a traffic control indicator, adapted to change states of the traffic control indicator;

a radar operable to receive signals from a plurality of object/vehicle targets;

a signal state information module having a state of a traffic control indicator;

a radar/traffic processor coupled to the traffic signal controller and signal state information module and adapted to receive signals from the radar;

the radar/traffic processor having an algorithm operable to determine characteristics of the object/vehicle targets and dynamically cause the traffic signal controller to control the states of the traffic control indicator in response thereto.

45. The apparatus of claim 44, further comprising at least one traffic control indicator adapted to control traffic at a roadway intersection.

46. The apparatus of claim 44, wherein the radar transmits an LFM-CW radio-frequency signal.

49. A method for determining if an object/vehicle target will enter an intersection including at least one traffic control indicator, comprising:

receiving a radar echo response indicating the object/vehicle target is approaching the intersection;

determining a range of the object/vehicle target and a velocity of the object/vehicle target; and

based on the object/vehicle range and velocity, determining if the object/vehicle target will enter the intersection; and

wherein the intersection comprises a plurality of the traffic control indicators at the intersection, and the traffic control indicators are a relational distance from one another.

50. The method of claim 49 further comprising based on the object/vehicle range and velocity determination, determining whether the traffic control indicator should re-sequence.

51. The method of claim 50, further comprising performing at least one of a following re-sequence functionality from a group consisting of:

changing a color state of the traffic control indicator;

changing a color state of other traffic control indicators;

changing a directional signal of the traffic control indicator;

changing a directional signal of other traffic control indicators;

changing a color state of a directional signal of the traffic control indicator;

changing a color state of a directional signal of other traffic control indicators;

applying a visual alerting via the traffic control indicator;

applying a visual alerting via other traffic control indicators;

delaying a changing of a color state of the traffic control indicator;

delaying a changing of a color state of other traffic control indicators;

delaying a changing of a directional signal of the traffic control indicator;

delaying a changing of a directional signal of other traffic control indicators;

delaying a changing of a color state of a directional signal of the traffic control indicator;

delaying a changing of a color state of a directional signal of other traffic control indicators;

delaying an applying of a visual alerting via the traffic control indicator; and

delaying an applying of a visual alerting via other traffic control indicators.

52. The method of claim 51 further comprising performing at least one of the re-sequence functionality in at least one of a following location from a group consisting of:

a traffic intersection comprising the traffic control indicator; and

a traffic intersection comprising other traffic control indicators.

53. A method for determining if an object/vehicle target will enter an intersection including a traffic control indicator, comprising:

receiving a radar echo response indicating the object/vehicle target is approaching the intersection;

determining a range of the object/vehicle target and a velocity of the object/vehicle target; and

based on the object/vehicle range and velocity, determining if the object/vehicle target will enter the intersection; and

further comprising comparing the received radar echo response to a pre-existing traffic model that represents a satisfactory condition.

54. The method of claim 53, wherein the satisfactory condition comprises an object/vehicle target approaching at least one of a following element from a group consisting of:

the traffic control indicator; and

the intersection;

at a distance that would avoid entering the intersection during at least one of a following event from a group consisting of;

a red state of illumination of the traffic control indicator; and

an impending red state of illumination of the traffic control indicator.

55. The method of claim 53, wherein the satisfactory condition comprises an object/vehicle target approaching at least one of a following element from a group consisting of:

the traffic control indicator; and

the intersection;

at a velocity that would avoid entering the intersection during at least one of a following event from a group consisting of;

a red state of illumination of the traffic control indicator; and

an impending red state of illumination of the traffic control indicator.

56. The method of claim 53, wherein the satisfactory condition comprises an object/vehicle target approaching at least one of a following element from a group consisting of:

the traffic control indicator; and

the intersection;

on a condition of a road that would avoid entering the intersection during at least one of a following event from a group consisting of;

a red state of illumination of the traffic control indicator; and

an impending red state of illumination of the traffic control indicator.

57. The method of claim 53, wherein the satisfactory condition comprises an object/vehicle target approaching at least one of a following element from a group consisting of:

the traffic control indicator; and

the intersection;

in a type of weather that would avoid entering the intersection during at least one of a following event from a group consisting of;

a red state of illumination of the traffic control indicator; and

an impending red state of illumination of the traffic control indicator.

58. The method of claim 53, wherein the satisfactory condition comprises an object/vehicle target approaching at least one of a following element from a group consisting of:

the traffic control indicator; and

the intersection;

in a traffic condition that would avoid entering the intersection during at least one of a following event from a group consisting of;

a red state of illumination of the traffic control indicator; and

an impending red state of illumination of the traffic control indicator.

59. The method of claim 53, wherein the satisfactory condition comprises an object/vehicle target approaching at least one of a following element from a group consisting of:

the traffic control indicator; and

the intersection;

at a time that would avoid entering the intersection during at least one of a following event from a group consisting of;

a red state of illumination of the traffic control indicator; and

an impending red state of illumination of the traffic control indicator.

60. The method of claim 53, further comprising comparing the received to a pre-existing traffic model on at least one of a following basis:

continually;

intermittently;

based on the determining; and

based on a specific event.

61. A method for determining if an object/vehicle target will enter an intersection including a traffic control indicator, comprising:

receiving a radar echo response indicating the object/vehicle target is approaching the intersection;

determining a range of the object/vehicle target and a velocity of the object/vehicle target; and

based on the object/vehicle range and velocity, determining if the object/vehicle target will enter the intersection;

further comprising determining the red state of illumination by performing at least one of a following action from a group consisting of;

measuring a voltage across a traffic signal controller load switch;

monitoring a traffic signal controller serial bus;

sensing voltages on a conflict monitor; and

using a photo sensor to directly detect light from the activated traffic signal

further comprising monitoring a state of illumination of a traffic control indicator in order to determine at least one of a following attribute from a group comprising;

a color of the state of illumination; and

a length of time of the state of illumination;

wherein such determination is used in determining if the object/vehicle target will enter the intersection; and

further comprising monitoring a state of illumination of a plurality of traffic control indicators.

62. The method of claim 61, wherein the determining if the object/vehicle target will enter the intersection comprises:

determining if a traffic control indicator is in a state that is predeterministic for a red-light run; and

the object/vehicle target, as indicated by the radar echo response, is approaching the intersection in a manner that could improperly place the object/vehicle target in the intersection during at least one of a following event from a group consisting of;

a red state of illumination of the traffic control indicator; and

an impending red state of illumination of the traffic control indicator.

63. The method of claim 61, further comprising determining a probability of running a traffic control indicator in a red state of illumination based upon at least one of a following factor from a group consisting of:

a distance of the object/vehicle target;

a velocity of the object/vehicle target;

a road condition;

a traffic condition;

an intersection condition;

a type of weather;

a time of day; and

a time of night.

64. The method of claim 61, further comprising overriding the traffic signal controller by a traffic light control system.

65. The method of claim 64, wherein the overriding comprises at least one of a following element from a group consisting of:

changing other traffic control indicators to a different state of illumination;

changing other traffic control indicators to a visual signal that indicates an anomaly condition;

holding other traffic control indicators at a given state of illumination; and

holding other traffic control indicators at a visual signal that indicates an anomaly condition.