TRAFFIC FLOW MEASURING APPARATUS AND METHOD, AND COMPUTER-READABLE STORAGE MEDIUM

• US 20150029042A1
• Filed: 06/19/2014
• Published: 01/29/2015
• Est. Priority Date: 07/24/2013
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Ikeya, Tomonori, SHITE, Kazuhiko, Kajiki, Junko, OCHI, Mitsuru
• Granted Patent: US 9,286,796 B2
• Time in Patent Office: Days
• US Class Current: 340/934
• CPC Class Codes: G01S 13/345 using triangular modulation
• CPC Class Codes: G01S 13/583 using transmission of continuous unmodulated waves, amplitude-, frequency-, or phase-modulated waves and based upon the Doppler effect resulting from movement of targets
• CPC Class Codes: G01S 7/354 Extracting wanted echo-signals Doppler systems G01S13/50
• CPC Class Codes: G01S 7/41 using analysis of echo signal for target characterisation; Target signature; Target cross-section
• CPC Class Codes: G08G 1/0116 from roadside infrastructure, e.g. beacons
• CPC Class Codes: G08G 1/0125 Traffic data processing
• CPC Class Codes: G08G 1/0129 for creating historical data or processing based on historical data
• CPC Class Codes: G08G 1/015 with provision for distinguishing between two or more types of vehicles, e.g. between motor-cars and cycles
• CPC Class Codes: G08G 1/052 with provision for determining speed or overspeed speed measuring in general G01P

Abstract

A traffic flow measuring apparatus includes a processor configured to judge a size of a vehicle, depending on a detection frequency or a non-detection frequency of a reflected wave from the vehicle with respect to a transmission wave transmitted from a radar apparatus, within a detection time of the reflected wave from the vehicle, set according to the detection of the reflected wave.

Claims

1. A traffic flow measuring apparatus comprising:

a processor configured

to judge a size of a vehicle, depending on a detection frequency or a non-detection frequency of a reflected wave from the vehicle with respect to a transmission wave transmitted from a radar apparatus, within a detection time of the reflected wave from the vehicle, set according to the detection of the reflected wave.

2. The traffic flow measuring apparatus as claimed in claim 1, wherein the processor is further configured

to estimate an estimated position where the vehicle is likely to be detected after a predetermined time, based on a detected position of the vehicle detected from the reflected wave from the vehicle with respect to the transmission wave,

to store the detected position and the estimated position in a distinguishable manner within a storage unit, in correspondence with the vehicle, and

to judge whether a size of the vehicle is greater than a predetermined size, based on a proportion of a number of estimated positions stored in the storage unit with respect to a sum of a number of the estimated positions and a number of the detected positions stored in the storage unit in correspondence with the vehicle.

3. The traffic flow measuring apparatus as claimed in claim 1, wherein the processor is further configured

to track a traveling locus of the vehicle,

to compute a vehicle detection rate Dr from Dr=(K/Pa)×

100, and

to judge that the size of the vehicle is greater than or equal to a predetermined size when the vehicle detection rate Dr exceeds a threshold value,

where K denotes a count value of a number of times the vehicle is counted at an actual sample position within a detection range DR defined by a first detection boundary B1 and a second detection boundary B2 that are perpendicular to lanes, and Pa denotes a number of traveling loci of vehicles tracked within the detection range DR.

4. The traffic flow measuring apparatus as claimed in claim 1, wherein the processor is further configured

to compute a vehicle detection rate Dr from Dr=(K/P)×

100, and

to judge that the size of the vehicle is greater than or equal to a predetermined size when the vehicle detection rate Dr exceeds a threshold value,

where K denotes a count value of a number of times the vehicle is detected at an actual sample position within a detection range DR defined by a first detection boundary B1 and a second detection boundary B2 that are perpendicular to lanes, and P denotes a parameter represented by a formula P={|B1m−

B2m|/V}×

W, where B1m denotes a horizontal distance from the radar apparatus to the detection boundary B1, B2m denotes a horizontal distance from the radar apparatus to the detection boundary B2, W denotes a number of times a measurement is made per unit time, and V denotes a velocity of the vehicle within the detection range DR.

5. The traffic flow measuring apparatus as claimed in claim 4, wherein the processor is further configured

to count a number of vehicles passing a judging position perpendicular to the lanes,

to track a traveling locus of each vehicle, and

to judge a lane, having known coordinates, on which each vehicle is located at a point in time when each vehicle passes the judging position.

6. The traffic flow measuring apparatus as claimed in claim 5, wherein the processor is further configured

to count the number of vehicles by the count unit and judge the size of the vehicle, for each lane that is judged.

7. A traffic flow measuring method comprising:

transmitting a transmission wave from a radar apparatus and receiving a reflected wave from a vehicle with respect to the transmission wave; and

judging a size of the vehicle, by a signal processing part, depending on a detection frequency or a non-detection frequency of the reflected wave from the vehicle, within a detection time of the reflected wave from the vehicle, set according to the detection of the reflected wave.

8. The traffic flow measuring method as claimed in claim 7, further comprising:

estimating, by the signal processing part, an estimated position where the vehicle is likely to be detected after a predetermined time, based on a detected position of the vehicle detected from the reflected wave from the vehicle with respect to the transmission wave, and

storing, by the signal processing part, the detected position and the estimated position in a distinguishable manner within a storage unit, in correspondence with the vehicle,

wherein the judging judges whether a size of the vehicle is greater than a predetermined size, based on a proportion of a number of estimated positions stored in the storage unit with respect to a sum of a number of the estimated positions and a number of the detected positions stored in the storage unit in correspondence with the vehicle.

9. The traffic flow measuring method as claimed in claim 7, wherein the judging tracks a traveling locus of the vehicle, computes a vehicle detection rate Dr from Dr=(K/Pa)×

100, and judges that the size of the vehicle is greater than or equal to a predetermined size when the vehicle detection rate Dr exceeds a threshold value, where K denotes a count value of a number of times the vehicle is counted at an actual sample position within a detection range DR defined by a first detection boundary B1 and a second detection boundary B2 that are perpendicular to lanes, and Pa denotes a number of traveling loci of vehicles tracked within the detection range DR.

10. The traffic flow measuring method as claimed in claim 7, wherein the judging computes a vehicle detection rate Dr from Dr=(K/P)×

100, and judges that the size of the vehicle is greater than or equal to a predetermined size when the vehicle detection rate Dr exceeds a threshold value, where K denotes a count value of a number of times the vehicle is detected at an actual sample position within a detection range DR defined by a first detection boundary B1 and a second detection boundary B2 that are perpendicular to lanes, and P denotes a parameter represented by a formula P={|B1m−

B2m|/V}×

W, where B1m denotes a horizontal distance from the radar apparatus to the detection boundary B1, B2m denotes a horizontal distance from the radar apparatus to the detection boundary B2, W denotes a number of times a measurement is made per unit time, and V denotes a velocity of the vehicle within the detection range DR.

11. The traffic flow measuring method as claimed in claim 10, wherein the judging includes

counting a number of vehicles passing a judging position perpendicular to the lanes, and

tracking a traveling locus of each vehicle, and judging a lane, having known coordinates, on which each vehicle is located at a point in time when each vehicle passes the judging position.

12. The traffic flow measuring method as claimed in claim 11, wherein the judging counts the number of vehicles by the count unit and judges the size of the vehicle, for each lane judged by the lane judging unit.

13. A non-transitory computer-readable storage medium having stored therein a program for causing a computer to execute a process comprising:

transmitting a transmission wave from a radar apparatus and receiving a reflected wave from a vehicle with respect to the transmission wave; and

judging a size of the vehicle depending on a detection frequency or a non-detection frequency of the reflected wave from the vehicle, within a detection time of the reflected wave from the vehicle, set according to the detection of the reflected wave.

14. The non-transitory computer-readable storage medium as claimed in claim 13, wherein the process further comprises:

estimating an estimated position where the vehicle is likely to be detected after a predetermined time, based on a detected position of the vehicle detected from the reflected wave from the vehicle with respect to the transmission wave; and

storing the detected position and the estimated position in a distinguishable manner within a storage unit, in correspondence with the vehicle,

wherein the judging judges whether a size of the vehicle is greater than a predetermined size, based on a proportion of a number of estimated positions stored in the storage unit with respect to a sum of a number of the estimated positions and a number of the detected positions stored in the storage unit in correspondence with the vehicle.

15. The non-transitory computer-readable storage medium as claimed in claim 13, wherein the judging tracks a traveling locus of the vehicle, computes a vehicle detection rate Dr from Dr=(K/Pa)×

100, and judges that the size of the vehicle is greater than or equal to a predetermined size when the vehicle detection rate Dr exceeds a threshold value, where K denotes a count value of a number of times the vehicle is counted at an actual sample position within a detection range DR defined by a first detection boundary B1 and a second detection boundary B2 that are perpendicular to lanes, and Pa denotes a number of traveling loci of vehicles tracked within the detection range DR.

16. The non-transitory computer-readable storage medium as claimed in claim 13, wherein the judging computes a vehicle detection rate Dr from Dr=(K/P)×

100, and judges that the size of the vehicle is greater than or equal to a predetermined size when the vehicle detection rate Dr exceeds a threshold value, where K denotes a count value of a number of times the vehicle is detected at an actual sample position within a detection range DR defined by a first detection boundary B1 and a second detection boundary B2 that are perpendicular to lanes, and P denotes a parameter represented by a formula P={|B1m−

B2m|/V}×

W, where B1m denotes a horizontal distance from the radar apparatus to the detection boundary B1, B2m denotes a horizontal distance from the radar apparatus to the detection boundary B2, W denotes a number of times a measurement is made per unit time, and V denotes a velocity of the vehicle within the detection range DR.

17. The non-transitory computer-readable storage medium as claimed in claim 16, wherein the judging includes

counting a number of vehicles passing a judging position perpendicular to the lanes, and

tracking a traveling locus of each vehicle, and judging a lane, having known coordinates, on which each vehicle is located at a point in time when each vehicle passes the judging position.

18. The non-transitory computer-readable storage medium as claimed in claim 17, wherein the judging counts the number of vehicles by the count unit and judges the size of the vehicle, for each lane judged by the lane judging unit.