System and method for locating a travelling vehicle

• US 5,283,575 A
• Filed: 11/08/1991
• Issued: 02/01/1994
• Est. Priority Date: 11/08/1991
• Status: Expired due to Term

• Current Assignee: TomTom International BV (TomTom NV)
• Original Assignee: Daihatsu-Nissay, Zexel Corporation
• Inventors: Huang, Liang-Jong, Kao, Wei-Wen
• Primary Examiner(s): Crosland, Donnie L.
• Application Number:
  US07/789,287
• Time in Patent Office: 816 Days
• Field of Search: 340/990, 340/988, 340/995, 364/424.01, 364/449, 364/443, 364/444, 364/450, 364/451, 73/178 R
• US Class Current: 340/990
• CPC Class Codes: G01C 21/30 Map- or contour-matching

Abstract

A vehicle navigation system helps locate the vehicle on a road network by overcoming, through the use of fuzzy logic, the errors of positioning sensors and routing computers. In the system, sensors continually feed position coordinates to a processing unit that traces the vehicle'"'"'s path in a road database. Fuzzy logic-based reasoning is used to determine the most probable location of the vehicle, whether off- or on-road, thereby correcting errors in its raw path as sensed or computed.

Claims

1. A vehicle navigation system, which comprises:

means for sensing a plurality of successive positions of said vehicle to create a sensed representation of a vehicle travel path;

means for storing a map of roads in a vicinity of said vehicle;

means for defining an actual vehicle travel path in said map;

means for matching said sensed representation of a vehicle travel path with said actual vehicle travel path; and

said means for matching including a plurality of fuzzy logic elements;

said fuzzy logic elements including;

a fuzzifier receiving said plurality of successive positions, and effective to produce an initial fuzzy set;

an inference engine receiving said initial fuzzy set, said map, and a set of inference rules and membership functions for producing a plurality of final fuzzy sets;

a defuzzifier effective for producing a set of crisp values from said final fuzzy sets; and

said crisp values being effective to determine a map-matched vehicle position.

2. A vehicle navigation system as in claim 1, wherein said means for sensing includes at least one of GPS, Loran C, and dead reckoning.

3. A method for locating a position of a vehicle comprising:

sensing a plurality of successive positions of said vehicle to produce a stored representation of a vehicle travel path;

comparing said stored representation with a plurality of vehicle travel paths in a map;

the step of comparing including employing fuzzy logic to match said stored representation with a one of said plurality of vehicle travel paths, whereby a best matching path is chosen; and

determining an actual position of said vehicle from said best matching path.

4. A vehicle navigation system comprising:

a plurality of positioning sensors to sense a plurality of successive positions of said vehicle;

means for comparing said plurality of positions with a plurality of roads on a digitized map;

fuzzy logic means for choosing a best fit from among a plurality of fits between said plurality of positions and said plurality of roads; and

means, based on said best fit, for determining a vehicle present position on a one of said plurality of roads.