Data processing: vehicles – navigation – and relative location – Navigation – Employing position determining equipment
Reexamination Certificate
2000-09-28
2001-10-16
Chin, Gary (Department: 3661)
Data processing: vehicles, navigation, and relative location
Navigation
Employing position determining equipment
C701S210000, C340S990000, C340S995190
Reexamination Certificate
active
06304821
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a navigation device and method therefor which displays a recommended route which can be accomplished with reference to the shortest timeframe, when searching a route from a present position to a destination.
2. Description of the Related Art
Navigation devices for use in a moving body, for example an automobile, have recently enjoyed increasing popularity. Such devices calculate a recommended route from a present position of the vehicle to a destination on the basis of a destination set by a user. The recommended route is then displayed. Some devices provide for indicating the direction of turning with voice commands so that the route may be correctly selected at the next intersection.
Devices which have the function of searching for recommended routes entail the problem of searching for the route on the basis of some kind of standard. Normally this is defined as a route which is “short” with respect to distance or time. However the selection of the shortest route with respect to time entails the use of expressways and the resultant problem of increases in tolls. It is difficult to search for a route in consideration of all parameters. Normally a method of selecting a route, which satisfies a user, is adopted in which the user selects each condition in order of priority.
The present invention proposes an improvement related to a device which searches a route on the basis that travelling time is prioritized. When applied to an automobile, the present invention prioritizes time by analyzing the speed limits set on each road divided into a number of sections. The recommended route is assumed to be the combination of routes having the smallest total for the time required for the divided sections.
However if there is an obstacle such as a railway crossing along such a route which delays the passage of the moving body, the route as calculated above may not be the shortest route as regards time and a detour may be shorter.
An invention which addresses the above problem is disclosed for example in JP-A-9-5100. In this invention, the presence of railway crossings and the timetables of main stations are included in road data. When a route is searched on roads which have railway crossings, routes which include railway crossings with long waiting times are excluded by a weighting process which corresponds to the number of trains passing in unit time.
In this way, the effect of waiting time at railway crossings may be reduced and a destination may be reached generally within a fixed time. However the problem has arisen that the reliability of recommended routes displayed is low due to the fact that it is not possible to determine whether or not a given railway crossing will actually delay the passage of the moving body.
JP-A-7-229746 discloses a device in which the timetables of all modes of transportation are stored. This enables an estimation of the waiting time at railway crossings which intersect with the road by displaying superimposed timetables on the road map in conjunction with the progress of the moving body.
However the above device simply displays timetables and thus the driver or passenger must determine whether it would be quicker to wait at the railway crossing or to make a detour. Such decisions are difficult for a person riding in a moving body and in particular safety considerations arise by a driver being distracted by such decisions.
Since conventional navigation devices are constructed as above, it is possible to select a route on the basis of the presence of an obstruction such as a railway crossing. However the probability that the recommended route is the shortest route is low due to the fact that displayed recommended routes do not consider the amount of time for which the vehicle may actually be delayed.
SUMMARY OF THE INVENTION
The present invention is proposed to solve the above problems and has the object of providing a navigation device and method therefor which can increase the searching accuracy for a recommended route along which a vehicle can travel in the shortest time.
The navigation device of the present invention is provided with a route searching means which refers to delay time information which is obtained from an information acquisition means and which searches for a recommended route along which movement is possible in the shortest time from a present position of a moving body detected by a detection means to a destination which is set by a setting means.
In this way, the effect is obtained of increasing the searching accuracy of a recommended route along which movement is possible in the shortest time from a present position to a destination.
The navigation device of the present invention is provided with a route-searching device. When in a time range in which the forecast time for the vehicle to reach an obstacle will result in a delay, the route searching device searches a recommended route by adding waiting time, which is the time at which the vehicle will pass, to the time taken for the vehicle to travel from a present position to a destination.
In this way, it is possible to search a recommended route on the basis that an obstacle exists.
The navigation device of the present invention is provided with an information acquisition means which reads obstacle time information from a recording medium.
In this way, it is possible to acquire obstacle time information in a simple manner.
The navigation device of the present invention is provided with an information acquisition means which receives radio signals relating to obstacle time information.
In this way, it is possible to increase the accuracy of route searching for a recommended route even when a train schedule is revised or when an accident has occurred which has resulted in the re-scheduling of services.
The navigation method of the present invention consists of searching for a the shortest recommended route with respect to time from a present position to a destination by referring to obstacle time information about obstacles on the route.
In this way, it is possible to increase the searching accuracy of a recommended route along which it is possible to travel in the shortest time from a present position to a destination.
The navigation method of the present invention consists of searching a recommended route by adding waiting time, which is the time by which a vehicle can pass an obstacle, to the time taken for the vehicle to travel from a present position to a destination, when the vehicle is in a time range in which the forecast time of the vehicle to reach an obstacle will result in a delay.
In this way, it is possible to search a recommended route in consideration of the existence of an obstacle.
The navigation method of the present invention consists of reading obstacle time information from a recording medium.
In this way, it is possible to acquire obstacle time information in a simple manner.
The navigation method of the present invention consists of receiving a radio signal related to obstacle time information.
In this way, it is possible to increase the searching accuracy of a recommended route even when the train timetable is revised or when an accident has resulted in the re-scheduling of services.
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patent: A095100 (1997-01-01), None
Chin Gary
Mitsubishi Denki & Kabushiki Kaisha
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