Method and device to guide a vehicle

p0001The invention relates to a method and apparatus for route guidance of a vehicle, by means of a stored map a route reference on leading route is determined to a destination, which is specified as a specified route the driver of the vehicle by route reference.

p0002The specified route is thereby stored in the form of a sequence of Wegleitpunkten from start to finish. The route reference points are generally turns and intersections. Soft, for example, the driver of a vehicle at one of those route reference points of the given route reference information from him, so that he gets on another street, the other based on the specified route route reference meaningless or misleading. Therefore, it is famous, the deviation of the vehicle from the desired route - also referred to as a false trip - to determine an alternative route and the driver supply necessary for the alternative route route reference. The determination of whether the vehicle is on the specified route may, for example, by comparing the desired route of a positioning system (eg, GPS) position data determined.

p0003The calculating routes, especially in extensive road networks is associated with considerable computational effort and therefore requires a considerable time. In known systems, no route reference information for an alternative route can be specified during this time the leader of a deviated from the set route vehicle. Deviates the vehicle during this time then the absence of route reference information from the assumed alternative route again from the calculation of a further alternative route is required, so that over short periods between Wegleitpunkten a supply of route reference information for a longer time does not occur.

p0004Object of the present invention is to provide a method and apparatus for route guidance of a vehicle, in which route reference are quickly and reliably available even in false trips.

p0005This object is achieved with the inventive method in that are collected during the running of the vehicle leading to the destination alternative routes that will determine whether the vehicle from the respective specified route deviates, and that if a deviation is detected one of the alternative routes stored as new target route to the driver by route reference.

p0006The inventive method has the advantage that once new route reference information is displayed to the leader in a perceived false trip. Several alternative routes ahead are determined and stored for one or more route reference points and also for one Wegleitpunkt.

p0007Depending on local conditions and on the nature of the individual streets is a false drive from Wegleitpunkt to Wegleitpunkt different probably, the probability also depends on the particular path through the Wegleitpunkt. For example, the calculating an alternative route when driving a main road for a Wegleitpunkt representing a branch of a dirt road, hardly necessary. In order to avoid the calculation of such unnecessary alternative routes is provided in a further development of the invention that for those route reference alternative routes are determined, in which due to the local circumstances, the possibility of deviation from the specified route exceeds a predetermined amount. Here, preferably in the stored road map to contain information to Wegleitpunkten drive resistors when passing the respective Wegleitpunktes on different roads.

p0008The probability of false drive can for example be high when the driving of the specified route a turn of a broad good road is displayed in a narrow side street. Furthermore, false trips are at intersections where more than two streets or roads do not intersect at right angles, particularly easy. When tackling such intersections, a running resistance are given, which contains a statement about how it is "difficult" to navigate the respective outgoing of the crossing street.

p0009An advantageous embodiment of the inventive method is that determined alternative routes for route reference points that can be bypassed without deviation from the desired route, will be deleted. This can also be done by overwriting with new alternative routes. This overflow of the foreseen for the alternative routes memory is prevented.

p0010Facilities for guidance may be self-arranged in the vehicle and working largely autonomously. However, it is also possible to perform the route calculation in a central device by means of a powerful computer, which include a bi-directional wireless data transmission between the vehicle and the central facility is required. However, this extra effort is contrary to the advantage that the saved map can be updated, what with the many in the vehicle located preferably on CD-ROMs stored road map is not possible. In both cases, the inventive method can be applied in an advantageous manner.

p0011In a first inventive device is therefore provided that the road map is stored in an on-vehicle device and that the device located in the vehicle, the route determination is made.

p0012A second device according to the invention is that the road map is stored in a fixed device, in that the stationary means and the route determination is done, and that a radio link for bidirectional data transmission between the vehicle and the fixed device.

p0013The invention permits numerous embodiments. One of them is schematically shown in the drawing using several figures and described below. It shows:<dl id="dl0001"><dt>Fig. 1</dt><dd>a schematic representation of a section of a road map with several Wegleitpunkten,</dd><dt>FIG. 2</dt><dd>a flowchart for explaining the inventive method and</dd><dt>Fig. 3</dt><dd>an embodiment of an inventive device.</dd></dl>

p0014In Fig. 1 P1 will start a journey represents, is the aim of Wegleitpunkt P4. To this was previously determined, a target route of a plurality of options not shown in detail according to a method known per se, which leads to the route reference points P2 and P3. To illustrate this, if an incorrect drive is more or less likely, the route reference points P2 and P3 respectively shown as branches, wherein the running resistance to the bending, it is assumed in each case greater.

p0015Once the desired route is calculated with the encircled in Fig. 1 Wegleitpunkten P1, P2, P3, P4, can be started with the identification of alternative routes. The sequence of this determination is shown in Fig. 2. After a start in 1 is read at two for the next Wegleitpunkt WP (n) for all outgoing roads driving resistance from the road map - both the running resistance of alternative roads RA and the running resistance RS for lying on the specified route road.

p00163 at a branch is taken depending upon whether roads with drive resistors RA are present, smaller for a function of RA and RS than a predetermined threshold value. This function can, for example, RA - RS be, so that then an alternative route is calculated when the running resistance RA is not the threshold value S is greater than the running resistance RS. This is for example in the Wegleitpunkt P2 (Fig. 1), which is a turn off to a Wegleitpunkt P2.1, not the case. There are thus calculated is no alternative routes for P2.

p0017In the case of Wegleitpunktes P3 however, there is a running resistance RA for the road to Wegleitpunkt P3.1, which is smaller than RS. Therefore, in 4 an alternative route A calculated and entered into a Wegleitpunktliste when Wegleitpunkt P3. At 5 then the following Wegleitpunkt is assumed, followed by a repeat of the program 2 at the following Wegleitpunkt WP (n + 1) is performed.

p0018The case 4 (Fig. 2) calculated alternative route includes the route reference P3.1, P3.2, and the destination P4. Once after passing the Wegleitpunktes P3 an incorrect drive is detected, the driver is supplied to the routing information for this alternative route. Does he, however to the routing information for driving the Wegleitpunktes P3, the alternative route is discarded and the original desired route continues to be displayed.

p0019The embodiment 3, shown as block diagram in Fig. A device according to the invention consists of an in-vehicle unit 10 and a central body 11, between which each with a transmitter / receiver 12, 13 is a radio connection, for example according to the GSM standard. In the central device 11 there is a traffic computer 14, has access to a stored map 15 and performs the route determination for many vehicles.

p0020The vehicle unit 10 consists essentially of an onboard computer 16, a GPS receiver 17, an input device 18, a display device 19 and a memory 20. These components are known per se and need not be explained in more detail to understand the invention. The GPS receiver 17 continuously performs the on-board computer 16 information on the current position of the vehicle. With the input device 18 of the driver of the vehicle can enter a destination. This is the traffic computer 14 is supplied together with the current position, which determines the desired route based on the road map 15, and transmits to the vehicle unit 10 in the form of a Wegleitpunktliste. For carrying out the process of the traffic computer also calculated for each Wegleitpunkten, as described above, alternative routes which are also transmitted to the vehicle unit.

p0021By position reports of the GPS receiver 17 on-board computer is notified route reference points are reached on the specified route in extent, so that the display means displays 19 route reference information for each lying ahead Wegleitpunkt. If a deviation from the specified route is found, the respective alternative route of the display is used. The inventive method that can be done in no time, without any connection to the central unit 11 and a time-consuming calculation of the alternative route are required.