METHOD FOR CREATING SPEED PROFILES FOR DIGITAL MAPS

• US 20110307165A1
• Filed: 01/13/2010
• Published: 12/15/2011
• Est. Priority Date: 01/16/2009
• Status: Active Grant

• Current Assignee: Tomtom Global Content B.V (TomTom NV)
• Original Assignee: Tomtom Global Content B.V (TomTom NV)
• Inventors: Hiestermann, Volker, Van Essen, Robert Joannes, Bastiaensen, Edwin, T'Siobbel, Stephen
• Granted Patent: US 10,161,758 B2
• Time in Patent Office: Days
• US Class Current: 701/119
• CPC Class Codes: G01C 21/3469 Fuel consumption; Energy use; Emission aspects
• CPC Class Codes: G01C 21/3492 employing speed data or traffic data, e.g. real-time or historical traffic control systems for road vehicles involving transmission of navigation instructions to the vehicle G08G1/0968
• CPC Class Codes: Y02D 30/00 Reducing energy consumption in communication networks

Abstract

Probe data collected at times of low traffic density is analyzed to derive a Raw Road Design Speed Limit (RRDSL, 16) for each road segment or group of segments in a digital map. The RRDSL (16), comprised of longitudinally distributed Pt speeds, is associated with the road segment and stored in a digital medium to indicate the limits of the road section in free flow traffic. The longitudinally distributed speeds may be limited by local speed limits or other business logic to establish a Legal Raw Road Design Speed Limit (LRRDSL, 17). Either the RRDSL (16) or the LRRDSL (17) can be further modified to smooth acceleration and deceleration rates between changes in the longitudinally distributed speeds to create an Optimal Longitudinal Speed Profile (OLSP, 18), which represents optimized energy consumption. A signal can be produced if a driver'"'"'s current speed rises unacceptably above a longitudinally distributed speed in real time. The signal can be audible, visible and/or haptic. Real-time traffic density information can be inferred by comparing current speed data to the longitudinally distributed speed for that position. If the current speed is consistently lower than the longitudinally distributed speed for that position, an inference is drawn that the road section is inefficient. Road efficiency assessments can be transmitted to a service center and/or other vehicles, and used by navigation software.

Claims

1. A method for creating longitudinally distributed speed data, said method comprising the steps of:

collecting probe data from a plurality of probes traversing a road segment in the form of vehicular traffic flow, each probe developing a respective probe trace comprising a sequence of discrete time-stamped probe positions;

identifying a time span for the road segment with free flow traffic conditions;

selecting probe data for the road segment collected during the identified time span;

statistically deriving longitudinally distributed average speeds at positions along the road segment from the selected probe, the longitudinally distributed average speeds being representative of a free flow speed of vehicular traffic flow along the road segment;

associating the longitudinally distributed average speeds with the road segment; and

storing the longitudinally distributed average speeds in a digital medium.

2. The method of claim 1 further including the step of providing a digital map having at least one link corresponding to the road segment;

and said step of storing the longitudinally distributed includes augmenting the digital map with a data layer containing the stored longitudinally distributed speeds.

3. The method of claim 1 further including the step of creating a Legal Raw Road Design Speed Limit (LRRDSL) by limiting the longitudinally distributed speeds with at least one predetermined threshold.

4. The method of claim 3 wherein said step of creating a Legal Raw Road Design Speed limit (LRRDSL) includes using the established speed limit of the road segment as the predetermined threshold.

5. The method according to claim 1 including the step of creating an Optimal Longitudinal Speed Profile (OLSP) by smoothly transitioning the acceleration and deceleration rates between changes in the longitudinally distributed speeds and thereby maximize energy conservation.

6. The method of claim 5 wherein said step of creating an OLSP includes creating the OLSP on the fly in an in-vehicle application.

10. The method according to claim 1 further including adjusting the longitudinally distributed speeds on the basis of at least one vehicle specific parameter.

11. The method according to claim 1 further including storing unique longitudinally distributed speeds for each lane in a multi-lane road segment.

7-9. -9. (canceled)

12-17. -17. (canceled)

18. A navigation device configured to be carried in a vehicle, comprising:

a position reading device configured to determine the current longitudinal position and speed of a navigation device along a road segment; and

a digital storage medium comprising a digital map having a plurality of links corresponding to road segments traversable by the navigation device, the digital map having a data layer comprising longitudinally distributed speed data representative of the fastest or free flow speed of vehicular traffic flow at a plurality of positions along each road segment;

the navigation device being configured to compare the determined current speed to a speed derived from the longitudinally distributed speed data for;

(i) the determined current position;

or (ii) a position ahead of the determined current position, and to produce a sensory signal when the determined current speed exceeds the speed derived from the longitudinally distributed speed data by a predetermined value.

19. The navigation device according to claim 18, wherein the sensory signal includes at least one of:

an image on a display screen;

an audible sound; and

a haptic feedback.

20. The navigation device according to claim 18, wherein the navigation device is configured to communicate with an ADAS application of the vehicle that acts to actively conform the current speed to a speed derived from the longitudinally distributed speed data.

21. The navigation device according to claim 18, wherein the longitudinally distributed speed data for a road segment is statically derived from a plurality of probes traversing the road segment in the form of vehicular traffic flow, each probe developing a respective probe trace comprising a sequence of discrete time-stamped prove positions.

22. The navigation device according to claim 18, wherein the speed derived from the longitudinally distributed speed data is determined on the basis of at least one dynamic real time parameter.

23. The navigation device according to claim 18, wherein the speed derived from the longitudinally distributed speed data is determined on the basis of at least one vehicle specific parameter.