Data processing: vehicles – navigation – and relative location – Navigation – Determination of travel data based on the start point and...
Reexamination Certificate
1999-07-13
2001-07-03
Zanelli, Michael J. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Navigation
Determination of travel data based on the start point and...
C701S209000, C701S210000
Reexamination Certificate
active
06256579
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a vehicle navigation system, and more particularly, to a vehicle navigation system that calculates an optimum route to a destination point.
Such a navigation system has two main and interrelated functions: the first function is to display to the user a map of the present vehicle location; and the second function is to provide guidance on a guided route from a starting point to a destination point. The second function is generally referred to as route guidance or selection. A route is typically optimized for one of various parameters, for instance, minimum travel time, minimum travel distance, maximum use of freeway, or other parameters pertaining to movement of a vehicle on a road network.
It is often the case, however, that an optimum route calculated by the system is not necessarily the most preferable route to the driver. We know that it will be most time-efficient to use highways when going from one point to another. Some drivers, nonetheless, prefer to detour at the expense of their time for purely personal reasons. For instance, some drivers prefer to drive narrow winding roads along seacoasts, rather than driving straight highways. Some drivers detour to visit an intermediate location, such as a store, or to enjoy watching scenery of their favorite spots. In calculating an optimum route, conventional navigation systems are ignorant about the driver's personal preference on roads. As a result, those conventional systems try to guide the driver repeatedly along the same calculated optimum route even in cases where the driver's driving history clearly shows that the driver has never followed the optimum route and takes the same detour every time the optimum route is presented.
BRIEF SUMMARY OF THE INVENTION
The purpose of the present invention is to provide a vehicle navigation system that can customize an optimum route to the driver's road preference. In accordance with the present invention, a vehicle navigation system includes at least one data table that contains sets of road data. Each set of road data represents characteristics of one road segment, such as a travel time, a length and a type of the road segment. The navigation system also includes at least one coefficient table that contains a number of coefficients. Each coefficient corresponds to one road segment and thus one set of road data. In a route search operation, an optimum route is calculated so as to optimize modified road data where the modified road data are the road data weighted by the coefficients. For instance, where a route is selected to minimize the travel time of the route, the navigation system selects a route along which a sum of the travel times weighted by the coefficients is the minimum.
The coefficients are changed, or updated, based on user's personal preference on the corresponding road segments. More specifically, a coefficient is penalized, or increased, when the corresponding road segment that was part of the optimum route was not traveled. On the other hand, a coefficient is credited, or decreased, when the corresponding road segment that was not part of the optimum route was actually traveled. Moreover, the coefficient is increased or decreased along a straight line or a curved line as the number of occurrences that the coefficient is changed increases.
The coefficient table may be renewed on a regular basis in such a way that coefficients are returned to an initial value if they have not been changed for a certain period of time. The coefficient table may be personalized to individual drivers so that the drivers can use a coefficient table personalized to them.
A vehicle navigation system according to the present invention may also include a history table that stores geographical points that have been designated as a starting point or a destination point. When two geographical points are designated, the navigation system first searches the history table. If either of the two designated geographical points is already stored in the table, an optimum route between them will be calculated, using the modified road data. However, if neither of the two geographical points is stored in the table, an optimum route is calculated, using the unmodified road data.
An optimum route may be searched for, using both the modified road data and the unmodified road data. For instance, the modified road data may be used to search for an optimum route in an area within a certain distance of either or each of the two geographical points, and the road data may be used to search areas other than the areas searched with the modified road data. The history table may be renewed on a regular basis in such a manner that geographical points stored therein are deleted from the table if they have not been designated for a certain period of time.
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Alpine Electronics Inc.
Brinks Hofer Gilson & Lione
Zanelli Michael J.
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