On-board navigation apparatus
First Claim
1. In an on-board vehicle navigation apparatus comprising:
- a GPS receiver which outputs the coordinates representing the absolute position of a vehicle equipped with said apparatus; and
reading means for reading a map data group from a recording medium, said medium containing road data obtained by translating points of road segments in a map into numerical form, said medium further containing a plurality of map data groups corresponding to a plurality of regions, wherein said navigation apparatus recognizes a current vehicle position on the basis of output data from said GPS receiver, and reads from said recording medium map data of a region having a specific area containing said current position so that a display device may display said current vehicle position and a map of its surroundings, the improvement comprising;
means for acquiring a difference between current measurement values and previous values of longitude and latitude information acquired from the output data from said GPS receiver; and
means for adding said difference to coordinate data of a previously established vehicle position, and determining a result from said addition as the coordinate data of an estimated current position.
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Accused Products
Abstract
An on-board navigation apparatus having a GPS receiver detects a difference between the current and the previous values of the estimated current position in terms of the longitude and latitude information gained from GPS data. The difference is added to the coordinates of the previously established position, the result being taken for the coordinates of the estimated current position. This makes it possible to estimate the current position coordinates accurately even if the accuracy of GPS data is not high enough. When the GPS receiver is in a two-dimensional measuring state, the coordinates of the estimated current position are obtained from a manually or automatically designated elevation value and from the GPS data. This allows the current position coordinates to be estimated with accuracy even if the accuracy of GPS data has dropped due to the two-dimensional measuring instead of a three-dimensional measuring.
104 Citations
14 Claims
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1. In an on-board vehicle navigation apparatus comprising:
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a GPS receiver which outputs the coordinates representing the absolute position of a vehicle equipped with said apparatus; and reading means for reading a map data group from a recording medium, said medium containing road data obtained by translating points of road segments in a map into numerical form, said medium further containing a plurality of map data groups corresponding to a plurality of regions, wherein said navigation apparatus recognizes a current vehicle position on the basis of output data from said GPS receiver, and reads from said recording medium map data of a region having a specific area containing said current position so that a display device may display said current vehicle position and a map of its surroundings, the improvement comprising; means for acquiring a difference between current measurement values and previous values of longitude and latitude information acquired from the output data from said GPS receiver; and means for adding said difference to coordinate data of a previously established vehicle position, and determining a result from said addition as the coordinate data of an estimated current position. - View Dependent Claims (2, 3, 4, 7, 8, 9, 10, 11, 12, 13, 14)
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5. In an on-board vehicle navigation apparatus comprising:
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a GPS receiver which outputs the coordinate data representing the absolute position of a vehicle equipped with said apparatus; a distance sensor for detecting the distance traveled by said vehicle; a direction sensor for detecting the direction in which said vehicle runs; and reading means for reading a map data group from a recording medium, said medium containing road data obtained by translating points on road segments in a map into numerical form, said medium further containing a plurality of map data groups corresponding to a plurality of regions;
wherein said navigation apparatus recognizes a current vehicle position based on output data from said GPS receiver or from said distance and direction sensors, and reads from said recording medium map data of a region having a specific area containing said current vehicle position so that a display device may display said current vehicle position and a map of its surroundings, the improvement comprising;means for acquiring a difference between current measurement values and previous values in terms of longitude and latitude information acquired from the output data from said GPS receiver; means for adding said difference to coordinate data of a previously established vehicle position, determining a result of said addition as coordinate data of a first estimated current position; means for acquiring coordinate data of a second estimated current position on the basis of the output data from said distance and direction sensors and coordinate data of said previously established position; and means for selecting the output data from said GPS receiver as coordinate data of an estimated current position of a present time if an absolute difference in coordinate data between said first and second estimated current positions is above a predetermined value and an applicable PDOP (position dilution of precision) value is below a predetermined value, and for selecting said coordinate data of said first estimated current position as coordinate data of said estimated current position of the present time if said PDOP value is above said corresponding predetermined value. - View Dependent Claims (6)
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Specification