Data processing: vehicles – navigation – and relative location – Navigation – Employing position determining equipment
Reexamination Certificate
1999-01-27
2001-05-29
Gregory, Bernarr E. (Department: 3662)
Data processing: vehicles, navigation, and relative location
Navigation
Employing position determining equipment
C701S207000, C701S208000, C701S209000
Reexamination Certificate
active
06240363
ABSTRACT:
The invention relates to a navigation method, in particular a navigation method which is used in vehicles.
In the case of conventional vehicle navigation systems, all the necessary map material is normally located in the vehicle and is stored, for example, on CD-ROM. At the start of a journey, the driver can then enter the starting point and the destination in the navigation unit, in which the desired route is then calculated at the start of a journey. During the journey, the driver is then guided to his destination with the aid of direction arrows on a display unit or using a map display. In order to allow the required direction information to be displayed to the driver all the time in this case, the current vehicle position is determined continuously during the journey. This can be done, for example, via an integrated navigation system or using a satellite-based position system (GPS—Global Positioning System).
If the driver strays off the originally calculated journey route, then the known vehicle navigation system intrinsically has the capability to calculate a new route to the predetermined destination on the basis of the current position, which is not on the stored route, and using the map material available in the vehicle, and to guide the driver in accordance with the newly calculated route to his destination.
Thus, the navigation method used in this known vehicle navigation system continuously requires access to appropriate map material, which must therefore be stored, and must be accessible to the navigation unit, in a suitable manner.
In order to ensure that reliable guidance is always provided to the desired destination in this case, the map material must be continually replaced in order, to some extent, to keep it at the latest standard. A memory unit, for example a CD-Rom drive, is in this case required for access to the map material, and occupies a relatively large amount of space.
WO 93/13385 has already disclosed a vehicle navigation apparatus having a navigation computer which uses road map data to determine a journey route to a specific destination, with said data being stored in an appropriate memory. During the journey to the desired destination, the driver is then supplied visually and/or audibly with appropriate direction of travel instructions.
If the driver and his vehicle leave the route, either voluntarily or by necessity, then he can enter a “not feasible
ew route” signal via an input device, indicating to the navigation computer that it is no longer possible to continue with the proposed route, and that new route proposals should be calculated, starting from the current vehicle position. The navigation computer then uses the stored road map data to calculate a new route, with the route section which has been designated as not being feasible being ignored.
Furthermore, WO 97/02469 has disclosed a satellite-based vehicle compass, which has a satellite receiver for producing the coordinates of a current position and input means for entering the position of a desired destination. A direction of travel is determined from the destination position and the current position, and is indicated to the driver on a display unit.
In the light of this, the invention is based on the object of specifying another navigation method which allows, in particular, its user to be guided reliably to a desired destination without having to access the map material required for this purpose after determining a desired route.
This object is achieved by the navigation method according to claim
1
.
Thus, according to the invention, in the case of a navigation method which can be used, in particular, in vehicles, a route from a starting point to a destination is first of all determined and stored in order then to indicate to the user, while en route from the starting point to the destination, direction information corresponding to the determined route, as long as the user's current position is on the route, while a direction which leads back to the determined route is indicated if the user's current position is not on the route, because he has left the route.
The navigation method according to the invention has the advantage over the prior art that only the map or road map information relevant to the respective current route need be stored, that is to say—when the navigation method is used in a vehicle—the individual road junctions with the respective direction of travel information, and this is then indicated whenever it is required, automatically or on request, as navigation instructions. If the user, that is to say for example the driver of a motor vehicle, leaves the route owing to a traffic jam or for other reasons, then he is guided back to the route by having indicated to him the direction in which he will return to the route.
The direction which leads back to the route is in this case preferably derived from the determined current position and stored position data relating to the route. In order in this case to indicate to the driver of a vehicle the direction which leads back to the route in a manner which can be perceived as quickly as possible, this direction is indicated relative to the vehicle.
In this case, it is particularly advantageous if the direction which leads back to the route is calculated, relative to the vehicle, from the direction of travel of the vehicle in the reference system of the route and from the direction from the current position to a selected position on the route.
The invention expediently provides in this case that the direction of travel of the vehicle is estimated from the last, preferably from the last three, vehicle positions, including the current vehicle position. Since the indication of a direction of travel of a vehicle and, in particular, its determination from three vehicle positions detected successively at approximately equal time intervals is worthwhile only if the vehicle is travelling in a straight line, the invention provides that in order to estimate the direction of travel of the vehicle, the direction from the last but one vehicle position to the last vehicle position is compared with the direction from the last vehicle position to the current vehicle position, and in that the direction from the last but one vehicle position to the current vehicle position is used as the direction of travel provided the difference between the two directions which are compared with one another is not greater than a predetermined value. Thus, according to the invention, the difference between the last two directions of travel is determined and their magnitude is compared with a predetermined tolerance value (which may be, for example, 5°) in order to decide whether the vehicle is travelling in a straight line or is following a curve. In the latter case, the estimation of the direction of travel is repeated at the earliest after the current vehicle position has been updated.
In order to keep the overall distance as short as possible, despite the diversion carried out in returning to the route, the invention provides that in order to select, on the route, a position which is suitable for returning to the route, that position on the route is determined which is closest to the current position, the distance from the current position to that position on the route which follows the closest position is compared with its distance to the closest position, and, if the closest position is closer to the following position than the current position, the closest position is selected, and otherwise the following position is selected.
Thus, the method according to the invention does not just determine the position closest to the current position, which could lead to the user being guided back to the route in the direction opposite to that desired, which would lead to an unnecessary increase in the distance travelled, but the method determines whether the user is already in the area between the closest position on the route and the position following this, and if this is the case the user is guided in a sensible manner to the latter route position
Hakala Hannu
Kaikkonen Jari
Koskinen Harri
Laine Heikki
Theimer Wolfgang
Gregory Bernarr E.
Nokia Mobile Phones Limited
Perman & Green LLP
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