SYSTEMS AND METHODS FOR ESTIMATING TRAFFIC SIGNAL INFORMATION

• US 20150120175A1
• Filed: 10/31/2013
• Published: 04/30/2015
• Est. Priority Date: 10/31/2013
• Status: Active Grant

• Current Assignee: Bayerische Motoren Werke AG
• Original Assignee: Bayerische Motoren Werke AG
• Inventors: VAHIDI, Ardalan, FAYAZI, S. Alireza, MAHLER, Grant, WINCKLER, Andreas
• Granted Patent: US 9,183,743 B2
• Time in Patent Office: Days
• US Class Current: 701/119
• CPC Class Codes: G08G 1/0112 from the vehicle, e.g. floating car data [FCD]
• CPC Class Codes: G08G 1/0125 Traffic data processing
• CPC Class Codes: G08G 1/0133 for classifying traffic situation
• CPC Class Codes: G08G 1/0141 for traffic information dissemination

Abstract

Systems and methods for estimating traffic signal information are provided. According to one aspect, positioning system data is obtained from a plurality of vehicles. Each data set includes the position and the velocity of a vehicle as functions of time. For an intersection having a traffic signal, an average acceleration of the vehicles when leaving the intersection is estimated, and an average deceleration of the vehicles when approaching the intersection is estimated. For each of a subset of the vehicles, a stop duration at the intersection is estimated based on the average acceleration, the average deceleration, and the positioning system data for the respective vehicle. A duration of a red phase of the traffic signal is estimated based on the stop duration of each of the subset of the vehicles.

Claims

1. A method of estimating traffic signal information, the method comprising:

obtaining positioning system data from a plurality of vehicles, wherein each data set comprises position and velocity of a vehicle as functions of time;

for an intersection having a traffic signal, estimating an average acceleration of the vehicles when leaving the intersection and an average deceleration of the vehicles when approaching the intersection;

for each of a subset of the vehicles, estimating a stop duration at the intersection based on the average acceleration, the average deceleration, and the positioning system data for the respective vehicle; and

estimating a duration of a red phase of the traffic signal based on the stop duration of each of the subset of the vehicles.

2. The method according to claim 1, wherein the average acceleration and the average deceleration are estimated based on the positioning system data for the vehicles and a location of a stop bar behind which the vehicles stop at the intersection.

3. The method according to claim 2, wherein estimating the average acceleration and the average deceleration comprises using a least-square estimation and removing outlier data points.

4. The method according to claim 1, wherein the subset of the vehicles is determined by:

selecting vehicles whose positioning system data include data points within a distance interval surrounding the intersection, wherein at least a first one of the data points is before the intersection and at least a second one of the data points is after the intersection;

removing vehicles whose velocity is lower than a threshold;

for each of the remaining vehicles, estimating an intersection delay based on the positioning system data for the respective vehicle; and

removing vehicles whose intersection delay is negative or zero.

5. The method according to claim 1, wherein for each of the subset of the vehicles, estimating the stop duration comprises:

estimating a stop time at which the respective vehicle stops at the intersection based on the positioning system data for the respective vehicle and the average deceleration;

estimating a start time at which the respective vehicle leaves the intersection based on the positioning system data for the respective vehicle and the average acceleration; and

estimating the stop duration based on the stop time, the start time, the average deceleration, and the positioning system data for the respective vehicle.

6. The method according to claim 4, further comprising removing vehicles for which the stop time is greater than the start time.

7. The method according to claim 1, wherein each data set is obtained from at least one of a cellular telephone or a navigation device within the vehicle.

8. The method according to claim 1, wherein the duration of the red phase of the traffic signal is estimated by determining a maximum stop duration of the subset of the vehicles during a time period with relatively light traffic.

9. The method according to claim 1, wherein an update frequency of the positioning system data is not greater than twice per minute.

10. A method of estimating traffic signal information, the method comprising:

obtaining positioning system data from a plurality of vehicles, wherein each data set comprises position and velocity of a vehicle as functions of time;

for an intersection having a traffic signal, estimating an average acceleration of the vehicles when leaving the intersection;

for each of a subset of the vehicles, estimating a start time at which the respective vehicle leaves the intersection based on the positioning system data for the respective vehicle and the average acceleration; and

estimating a cycle time of the traffic signal by;

for each pair of consecutive vehicles in the subset, calculating a difference between the start times of the vehicles; and

solving an optimization problem based on the differences and the cycle time.

11. The method according to claim 10, further comprising:

fitting a Gaussian mixture model to a histogram of a remainder of a division of the difference and the cycle time; and

estimating a signal offset caused by a schedule change of the traffic signal based on clusters within the Gaussian mixture model.

12. A method of estimating traffic signal information, the method comprising:

obtaining positioning system data from a plurality of vehicles, wherein each data set comprises position and velocity of a vehicle as functions of time;

for an intersection having a traffic signal, estimating an average acceleration of the vehicles when leaving the intersection;

for each of a subset of the vehicles, estimating a start time at which the respective vehicle leaves the intersection based on the positioning system data for the respective vehicle and the average acceleration; and

estimating a start of a future green phase of the traffic signal by calculating a moving average of the start times within a time interval defined by a cycle time of the traffic signal.

13. The method according to claim 12, wherein the moving average is calculated by:

mapping the start times within the time interval onto a circle, such that each of the start times is represented as a vector with an angle;

determining an average angle as a direction of a vector sum of the vectors; and

determining the moving average by mapping the average angle to a time axis.

14. The method according to claim 12, further comprising:

for a plurality of times of day, calculating a variance of the moving average based on a minimum cyclic distance to the moving average; and

detecting a schedule change of the traffic signal based on a spike in the variance of the moving average as a function of time.

15. A method of estimating traffic signal information, the method comprising:

obtaining positioning system data from a plurality of vehicles, wherein each data set comprises position and velocity of a vehicle as functions of time;

selecting vehicles whose positioning system data include data points within a distance interval surrounding the intersection, wherein at least a first one of the data points is before the intersection and at least a second one of the data points is after the intersection;

for each of the selected vehicles, estimating an intersection delay based on the positioning system data for the respective vehicle;

removing vehicles whose intersection delay is non-zero;

for each of the remaining vehicles, determining a time at which the traffic signal was green by interpolating between a first time of the first one of the data points and a second time of the second one of the data points; and

estimating an interval during which the traffic signal was green based on the times at which the traffic signal was green.

16. The method according to claim 15, wherein the interval during which the traffic signal was green is estimated by aggregating the times at which the traffic signal was green by mapping the times at which the traffic signal was green onto a reference interval.

17. The method according to claim 16, further comprising predicting a probability that the traffic signal will be green in the future based on the interval during which the traffic signal was green.