Traffic information interpolation system

• US 7,580,788 B2
• Filed: 11/09/2007
• Issued: 08/25/2009
• Est. Priority Date: 11/10/2006
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Kumagai, Masatoshi, Hiruta, Tomoaki, Tanikoshi, Koichiro
• Primary Examiner(s): Black; Thomas G
• Assistant Examiner(s): Chen; Shelley
• Application Number:
  US11/937,668
• Publication Number:
  US 20080114529A1
• Time in Patent Office: 655 Days
• Field of Search: 701117-119
• US Class Current: 701/117
• CPC Class Codes: G08G 1/0104 Measuring and analyzing of parameters relative to traffic conditions

Abstract

In a traffic information system, the principal component analysis of the floating car data collected in the past is performed for each traffic area. From among the bases representing the traffic data collected on the road-links in the traffic area, the bases which have strong correlation to the road-links on which real-time traffic data were collected are selected. The weighting coefficients for the selected bases are calculated by projecting the real-time traffic data onto the selected bases. The traffic estimation data are calculated by linearly combining the selected bases with the obtained weighting coefficients as the coefficients of the respective bases. The calculated traffic estimation data are used for the interpolation of the road-links on which the real-time traffic data were not collected.

Claims

1. A traffic data transmission method for use in a traffic information center for transmitting traffic estimation data, comprising:

a first process for receiving and storing real-time traffic data representing current traffic conditions;

a second process for generating plural bases representing spatial correlation on multiple road-links by using the principal component analysis of the traffic data stored in the past;

a third process for calculating traffic estimation data by linearly combining the generated plural bases;

a fourth process for transmitting the traffic estimation data;

a fifth process for projecting the past traffic data into the feature space subtended by the plural bases, obtaining the weighting coefficients for the plural bases, and calculating traffic estimation data by linearly combining the plural bases and the weighting coefficients;

a sixth process for calculating the precisions in the road-links of the traffic restoration data by using as true values the past traffic data from which the weighting coefficients are obtained, judging on whether the precisions in the road-links exceed a threshold, eliminating the road-links whose precisions exceed the threshold from the group of estimation-available links, and storing the information on the elimination; and

a seventh process for generating degenerate bases by eliminating from the bases the traffic data components for the eliminated road-links,

wherein in the third process, the weighting coefficients for the degenerate bases are obtained by projecting the real-time traffic data into the feature space subtended by the degenerate bases, and the traffic estimation data are calculated by linearly combining the degenerate bases and the weighting coefficients; and

in the fourth process, the traffic interpolation data are transmitted to vehicle-borne terminals.

2. A traffic data transmission method as claimed in claim 1, wherein in the fourth process, statistic traffic data obtained by statistically processing the stored past traffic data are used when traffic data for the road-links eliminated from the group of the estimation-available road-links in the sixth process are interpolated;

and traffic data interpolation is performed by using the traffic estimation data and the statistic traffic data.

3. A traffic data transmission system for use in a traffic information center for transmitting traffic estimation data, comprising:

a real-time traffic reception means for receiving and storing real-time traffic data representing current traffic conditions;

a real-time traffic data memory means for accumulating the real-time traffic data received and stored in the real-time traffic reception means;

a basis calculation means for generating plural bases representing spatial correlation on multiple road-links by using the principal component analysis of the past traffic data stored in the real-time traffic data memory means;

a traffic data estimation means for calculating traffic estimation data by linearly combining the generated plural bases;

a traffic data transmission means for transmitting the traffic estimation data;

a traffic data restoration means for projecting the past traffic data into the feature space subtended by the plural bases, obtaining the weighting coefficients for the plural bases, and calculating traffic estimation data by linearly combining the plural bases and the weighting coefficients;

an estimation-available link judging means for calculating the precisions in the road-links of the traffic restoration data by using as true values the past traffic data from which the weighting coefficients are obtained, judging on whether the precisions in the road-links exceed a threshold, eliminating the road-links whose precisions exceed the threshold from the group of estimation-available links, and storing the information on the elimination; and

a basis degeneracy means for generating degenerate bases by eliminating from the bases the traffic data components for the eliminated road-links,

wherein in the traffic data estimation means, the weighting coefficients for the degenerate bases are obtained by projecting the real-time traffic data into the feature space subtended by the degenerate bases, and the traffic estimation data are calculated by linearly combining the degenerate bases and the weighting coefficients; and

the traffic data transmission means transmits the traffic interpolation data to vehicle-borne terminals.

4. A traffic data transmission system as claimed in claim 3, wherein in the traffic data interpolation means, statistic traffic data obtained by statistically processing the stored past traffic data are used when traffic data for the road-links eliminated from the group of the estimation-available road-links in the estimation-available link judging means are interpolated;

and traffic data interpolation is performed by using the traffic estimation data and the statistic traffic data.