Detecting location, timetable and travel time estimations for barrier crossings in a digital map
AssigneeTomTom Belgium N.V.
InventorTim Bekaert
Life of this patent
Estimating the term…
Abstract
A method for determining barrier crossing information for convoyed objects (22) using historic trajectory data (28). Trajectories (28) having similar geographical and directional properties are bundled so that trajectory density can be measured as a function of position and time (s, t). Visual presentation of the trajectory information can be used to determine certain types of barrier crossing information useful in a digital map. Frequency analysis on a number of trajectory density time series may be performed to determine specific barrier crossing locations (26) through the detection of vehicle bursts. Such frequency analysis may also indicate barrier crossing times and schedules in the case of crossing patterns.
Claims8
1-19. (canceled)
A method for determining barrier crossing information using historic trajectory data, said method comprising the steps of:
- receiving trajectory data representative of the movements of a plurality of objects over a network of travel paths with respect to time, said trajectory data for an object comprising a plurality of sequential time-stamped geo-positions, and said network of travel paths comprising at least one barrier crossing which periodically impedes or restricts the free flow of objects along the network of travel paths;
- associating the received trajectory data with segments of a digital map, said segments being representative of the network of travel paths;
- determining the trajectory density along at least some of the segments as a function of position and time from the trajectory data, the trajectory density being indicative of the number of objects at a particular location and time;
- identifying locations at which the trajectory density changes periodically from zero to substantially greater than zero;
- using said identified locations to determine the location of a barrier crossing and augmenting the digital map with the determined location of the barrier crossing, the barrier crossing being between a first segment and a second segment;
- determining a crossing timetable and/or crossing frequency for the barrier crossing from the changes in trajectory density;
- and
- associating the determined crossing timetable and/or crossing frequency with the barrier crossing in the digital map.
The method according to claim 1, further including bundling trajectory data from a plurality of objects having similar geographical and directional properties, and associating the one or more bundles with segments of the digital map.
The method according to claim 1, further including determining at least one of a crossing travel time and an average crossing speed for the barrier crossing from the changes in trajectory density.
The method according to claim 1, wherein said step of using said identified locations to determine the location of a barrier crossing includes establishing a threshold criterion (C) equal to the ratio between the two highest frequency peaks of the frequency distribution of trajectory density changes as expressed by the formula:
- C=A(v1)/A(v0)
- where:
- v0=frequency of highest peak in amplitude spectrum
- v1=frequency of 2nd highest peak in amplitude spectrum
- A(v)=|amplitude| in amplitude spectrum of frequency v
The method according to claim 4, wherein the threshold criterion (C) is approximately 0.3.
The method according to claim 1, wherein said step of determining a crossing frequency for the barrier crossing from the changes in trajectory density includes making separate frequency determinations for work days and non-work days.
The method according to claim 1, further including the step of determining crossing timetables for different days.
Dependencies are inferred from the claim text.