FR2655449A1 - NAVIGATION SYSTEM FOR A MOTOR VEHICLE. - Google Patents

Abstract

The present invention relates to a navigation system. According to the invention the system comprises a distance sensor (10), a direction sensor (12), a processing unit (14) which contains an arithmetic section (16) and a memory section (18), a keyboard ( 20) a power switch (22), a road map data storage unit (24), a display control unit (26) and a display unit (28). The invention applies in particular to the automotive industry.

Description

The present invention generally relates to

  to a navigation system for a motor vehicle.

  More particularly, the present invention relates to an automobile navigation system which provides better navigation information, on a display screen, along a predetermined road of the vehicle, to ensure better guidance to a destination. One of the systems previously proposed for the navigation of a vehicle is represented by the

  first patent publication in Japan No. 62-93617.

  In this publication, as shown in Figures 1a and 1b, when the vehicle is in a predetermined range of distance from one of the known intersections along a preset route to a given destination, a display unit 1 presents M 1, M 2 and M 3 track and direction designation marks (Figure 1 (a)) or a M 4 direction designation mark (Figure 1 (b)) so that a driver of the vehicle can choose a good path before reaching the intersection. However, in the above-mentioned prior art, since only the designation of the track and the direction or the designation mark of the direction is displayed on the display screen near the intersection, the driver of the vehicle is forced to determine the manner of driving the vehicle based solely on this information without any other information concerning the intersection which arrives, which is inconvenient for the driver of the vehicle, considering in particular that an intersection itself even

  is sometimes inconvenient for the driver of the vehicle.

  Accordingly, the present invention aims to provide a navigation system for a motor vehicle, to eliminate defects

  above noted inherent in the prior art.

  Another object of the present invention is to provide a navigation system for a motor vehicle where journey information to a next target point is presented on a display screen together with a summary of the point configuration.

next target.

  To achieve the above and other objectives, according to one aspect of the present invention, a navigation system for a motor vehicle comprises: first means for storing first known target points and adjacent target points; second means for storing a first group of data associated with each of the first target points, each of the first group of data containing a second group of data corresponding to each of the target points adjacent to the corresponding first target point, each of the second group of data comprising a summarized configuration of the corresponding first target point and a required guidance information at the corresponding first target point to the corresponding adjacent target point; third means for selecting second target points from the first target points for defining a vehicle route passing through the second target points; fourth means for storing the second target points in series; fifth means for establishing third and fourth target points selected from the stored second target points, the third target point being a forward target point and the fourth target point being one of the target points adjacent to the third target point and being placed forward of the third target point along the road; sixth means for monitoring the position of the vehicle; seventh means for monitoring the positional relationship between the monitored position of the vehicle and the third target point; an eighth means responsive to the monitored positional relationship for selecting one of the second data groups based on the third target point using it as the target point and the fourth target point using it as an adjacent target point to visualizing the corresponding guidance information as well as the summary configuration of the third target point before the vehicle reaches the third target point. The eighth means displays the corresponding guidance information by hatching, on the

  summed configuration, the third target point.

  The third target point is an intersection or a branch on a road and the guidance information displayed by the eighth means at the same time as the summed configuration of the third target point is a direction and a way to be selected by the vehicle at that time.

third target point.

  The third target point may be a lane change point and the guidance information displayed by the eighth means together with the summed configuration of the third target point is a lane that the

  vehicle must choose at the third target point.

  Each of the first data groups includes a third data group corresponding to each of the target points adjacent to the corresponding first target point, each of said third data groups including guidance signaling data required at the corresponding first target point to go to the target point. corresponding means and the eighth means displays the signaling data in the form of letters together with the corresponding guidance information and the summary configuration of the third

target point.

  Each of the first groups of data includes a name of the corresponding first target point and the eighth means displays the name of the third target point together with the corresponding guidance information.

  and the summarized configuration of the third target point.

  The guidance information further comprises an indication representative of a lane change end point and the eighth means comprises a ninth means for comparing a monitored speed of the vehicle to a first preset value and the eighth means displays the third target point with the indication displayed in a lower portion on a screen when the speed of the vehicle is higher than the preset value. The eighth means includes a tenth means for comparing a monitored volume of traffic to a second preset value and displays the third target point with the indication displayed at the lower portion of the screen when the traffic volume is no longer

  important than the second pre-established value.

  The fifth means further establishes a selected backward target point in the stored second target points, the rearward target point being placed rearward of the third target point along the route and the third target point being the same. one of the points

  adjacent targets among the target points to the rear.

  Each of the first groups of data includes a fourth group of data corresponding to each of the target points adjacent to the corresponding first target point, each of these fourth groups of data including free driving information representative of the vehicle that can ride freely and the eighth means selected the second group of data to visualize, from one point in time, the moment when the vehicle enters a pre-established range of distance from the third target point to a point where the vehicle passes this third target point while the eighth average chooses one of the fourth groups of data based on this target point backward using it as the target point and the third target point using it as an adjacent target point to view the free driving information at when the vehicle is outside the pre-established range from

the third target point.

  Each of the first data groups includes a fifth data group corresponding to each of the target points adjacent to the corresponding first target point, each of the fifth data groups comprising a simplified configuration representative of the summarized configuration and guidance of the corresponding second data group and the eighth means chooses one of the fifth data groups based on the third target point using it as the target point and the fourth target point using it as an adjacent target point to view the simplified data item.

  same time as free driving information.

  The fifth means readjust the target point to the rear, the third target point and the fourth target point each time the vehicle passes through the third target point so that the third target point is set to the target point towards the rear, that the fourth target point is set at the third target point and another forward target point selected from the second stored target points is set at the fourth target point, the other forward target point being placed near the fourth target point; target point and being one

  target points adjacent to the fourth target point.

  Each of said second data groups further comprises a summarized configuration of the corresponding adjacent target point and the eighth means displays the summed configuration of the fourth target point in addition to the corresponding guidance information and the

  summarized configuration of the third target point.

  The eighth means produces a flashing display of the hatched guidance information when the vehicle enters a predetermined range of distance

the third target point.

  The fifth means additionally establishes a fifth target point chosen from the second stored target points, this fifth target point being one of the target points adjacent to the fourth target point and being placed towards the front of the fourth target point along the road. ; each of the first data groups each comprises a fifth data group corresponding to each of the target points adjacent to the corresponding first target point, each of the fifth data groups comprising another simplified configuration representative of the summary configuration and the guidance of the second data group. corresponding; the eighth means comprises an eleventh means for comparing a first distance between the monitored position of the vehicle and the third target point with a predetermined distance, the first distance being monitored by the seventh means; the eighth means selects one of the fifth data groups based on the third target point using it as the target point, and the fourth target point using it as the adjacent target point, the eighth means visualizing the other configuration simplified on a display screen at a position corresponding to the first distance while the vehicle is out of a predetermined distance range of the third target point in the case where the first distance is not greater than the preset distance; the eighth means comprises a twelfth means for deriving a second distance by adding the first distance to a stored distance between the third target point and the fourth target point and for comparing the second distance with the preset distance; the eighth means selects one of the fifth data groups based on the fourth target point using it as the target point and the fifth target point using it as an adjacent target point, the eighth means visualizing the other simplified configuration identified by the fourth and fifth target points on the display screen at a position corresponding to the second distance in addition to the other simplified configuration identified by the third and fourth target points in the case where the second distance

  represents no more than the preset distance.

  The invention will be better understood and other purposes, features, details and advantages thereof

  will become clearer during the description

  following explanatory diagram with reference to the accompanying schematic drawings given solely by way of example illustrating several embodiments of the invention and in which: Figures 1 (a) and 1 (b) show, respectively, examples of visualization navigation information on a display screen according to the prior art; Figure 2 shows a circuit block diagram of a navigation system according to first to third preferred embodiments of the present invention; Figs. 3 (a) to (d) show an example of the structure of road map data stored in a road map storage unit; FIG. 4 shows an exemplary display of navigation information according to the first preferred embodiment; Figure 5 shows another example of viewing navigation information according to the first preferred embodiment; Figure 6 shows another example of viewing navigation information according to the first preferred embodiment; Figure 7 shows an example of viewing an index for choosing a starting point of the vehicle and a destination; Fig. 8 is a flowchart showing a method for deriving an initial target point, a final target point and a route to be traveled by the vehicle; Fig. 9 is a diagram explaining how to derive the initial target point; Fig. 10 is a diagram explaining how to derive the final target point; Fig. 11 is a flowchart of a subroutine for deriving a route to be traveled by the vehicle; Fig. 12 is a diagram explaining how one can derive the shortest path; Fig. 13 shows an example of visualization for navigation of the vehicle from the starting point to the initial target point; Fig. 14 is a flowchart of a main routine for navigation of the vehicle from the initial target point to the final target point; Fig. 15 is a flowchart of an interrupt routine for deriving a coordinate position of the vehicle and a distance between the vehicle position and a next target point; Fig. 16 is a flowchart of a subroutine for performing a target point navigation process and a free driving navigation process; Fig. 17 is a flowchart of an interrupt routine for deriving an approach verification area, an error checking area, and a zeroing of the direction for a next target point; Fig. 18 is a diagram explaining an approach verification area, an error checking area and a refocusing of the direction; Fig. 19 is a flowchart of an interrupt routine for detecting whether the vehicle is out of the pre-established route, using the approach verification area and the error checking area; Fig. 20 is a flowchart of a subroutine for performing the target point navigation method; Fig. 21 is a flowchart of a subroutine for performing the target point navigation method in the case where the next target point is an intersection or a branch, according to the first preferred embodiment; Fig. 22 is a flow chart of a subroutine for performing the target point navigation method in the case where the next target point is a lane change point, according to the first preferred embodiment; Fig. 23 is a flowchart of a subroutine for performing the free or autonomous driving method according to the first preferred embodiment; Fig. 24 shows an exemplary display of the navigation information according to the second preferred embodiment; Fig. 25 shows another example of viewing navigation information according to the second preferred embodiment; Fig. 26 shows another example of viewing the navigation information according to the second preferred embodiment; Fig. 27 is a flowchart of a subroutine for performing the target point navigation method according to the second preferred embodiment; Fig. 28 is a flowchart of a subroutine for performing the autonomous navigation method according to the second preferred embodiment; and FIGS. 29 and 30 show an example of visualization of the navigation information according to the

  third preferred embodiment.

  Referring now to the drawings, the first to third embodiments of a navigation system for a motor vehicle according to the present invention will be described with reference to FIGS.

30.

  FIG. 2 is a block diagram of the navigation system circuit which is used in the first to third preferred embodiments. In FIG. 2, the navigation system comprises a distance sensor 10 which emits a pulse signal per unit of distance traveled. by the vehicle and a steering sensor 12 such as a geomagnetic steering sensor, which emits a signal indicating the direction of travel of the vehicle by

  based on the geomagnetic field around the vehicle.

  The system further comprises a processing unit 14, a microprocessor in practice, which has an arithmetic section 16 and a processing data memory section 18 The outputs of the distance sensor 10 and the direction sensor 12 are applied from the 8 entering the arithmetic section 16 to sequentially derive a current position of the vehicle The processing data memory section 18 stores data relating to a predetermined route of the vehicle including known target points therealong,

  a starting point and a destination, and so on.

  The input side of the arithmetic section 16 is further connected to a data receiving keyboard 20, such as, for example, the starting point and destination on which the processing unit 14 is based to derive the shortest route in front of it. be traversed by the

  vehicle, which will be described later in detail.

  The input side of the arithmetic section 16 is further connected to a start switch 22 and a road map data storage unit 24. The switch 22 is manually operated when the vehicle reaches an initial target point, which is which will be described later in detail The road map data storage unit 24 stores a large volume of road map data, so it is preferable to use an external memory having a large storage capacity. arithmetic section 16 is connected to a display control unit 26 for controlling the display on a display of a display unit 28 such as, for example, a visualization

with cathode ray tube.

  The display unit 28 displays navigation information such as, for example, a direction and a lane or path to be selected by the vehicle at a next target point as the vehicle approaches to enter a given distance range of the vehicle. next target point The target point comprises an intersection, a branch and a point of change of lane on the preset road The display unit 28 may be arranged near the driver's seat but a direct visualization on a windshield of the vehicle in using for example a visualization to read head

  high (HUD) may be preferable.

  Figs. 3 (a) to 3 (d) show an example of the structure of the road map data stored in the storage unit 24 of Fig. 2 As shown in Fig. 3 (a), the storage area of the Storage unit 24 comprises a large number of memory blocks, each representing a large map area. A memory block 30 of Fig. 3 (a) is one of the memory blocks representing the large map area above. As shown in FIGS. 3 (a) and (b), the memory block 30 is divided into a number of blocks such as, for example, nine memory blocks 30-1 to -9, each of which represents a smaller area. of the map and is further divided into a number of target point areas 1, 2, 3, 4, 5 15,16 as shown in Fig. 3 (c) Each of the target point areas includes point data. target identified by an identification code of the corresponding target point area (hereinafter referred to as "point code"). target ") and adjacent target points around the target point identified by the target point code. More particularly, as shown in FIG. 3 (d), each target point area comprises first to sixth memory sections 31 to 36. The first memory section 31 stores the data relating to the target point identified by the target point code. including a type of the target point, the coordinates

  X and Y of the target point and the name of the target point.

  The type of the target point includes a first type where the target point is an intersection or a junction between general roads and receives the "O", a second type where the target point is an intersection between an expressway and an incoming road. receives the "1", a third type where the target point is an intersection between an expressway and a road that leaves and receives the "2" and a fourth type where the target point is an intersection or a junction on the expressway and receives the "3" and a fifth type where the target point is a lane change point and

receives the "4".

  The second memory section 32 is divided into a number of memory sections, each storing data relating to an adjacent target point which is adjacent to the target point stored in the first section. Each adjacent target point is identified by an identification code. of the corresponding memory section (hereinafter referred to as "adjacent target point code") Each memory section includes a target point code of the adjacent target point, a code of a route connecting the stored target point to the first section 31 and the adjacent target point, a direction in which the target point link route is stored in the first section 31 and the distance between the target point

and the adjacent target point.

  As can be noted from the description

  above, each target point on the road map is stored in the first section 31 as shown in Fig. 3 (d) and has its own pre-selected adjacent target point from the stored target points Accordingly, each target point on the map may be identified by the code of the target point or the code

of the adjacent target point.

  The third section 33 stores guidance signaling data that corresponds to each adjacent target point. The guidance signaling data is stored in the form of a letter code as indicated by reference numeral 52 in FIG. it is similar to an actual guidance signaling on the actual road at the intersection or branch. For example, if the adjacent target point is identified by the code of the adjacent target point 32-2 in Figure 3 (d) and that guidance signaling at the target point in the first section 31 for this direction is "AAA, BBB", then, "AAA, BBB" is stored in the corresponding section of memory 33-2 of the

  third section 33 in letter code.

  The fourth section 34 stores the data relating to a configuration of the target point stored in the first section 31, a course direction to be chosen at the target point and a path to be chosen at the target point. More particularly, the fourth section 34 stores the data item below. noted above corresponding to each of the adjacent target points The data for each adjacent target point includes a summary or simplified configuration of the target point, a course direction to be chosen at the target point to move to the corresponding adjacent target point and a path to be chosen at the point Therefore, the course direction and the path to be chosen at the target point are visualized on the display screen together with the summary of the target point configuration as shown in FIG. that the above data for each adjacent target point includes the target point configuration summary, the a direction of travel and the route to be chosen (hereinafter referred to as "CDL") in the case where the target point is an intersection or a junction while the data includes the configuration summary of the target point and the route to choose (hereinafter referred to as "CL") in the case where the point

  target is a lane change point.

  FIG. 4 shows an example of visualization for an exchange on an expressway. The name of the target point 50 is presented on the display screen of the unit 28 of the upper right part, the guidance signaling 52 on the lower right part. and CDL information 54 to the left According to CDL information 54, a driver of the vehicle readily understands, at a glance, that this target point has a Y configuration and that the course direction to be selected is the left and one of the two lanes can be chosen to go to the left as indicated

by hatching.

  FIG. 5 shows an example of visualization of the lane change point where the information CL 54 is displayed on the left of the screen The information CL 54 shows that the target point is the lane change point and that left lane must be chosen to pass

  to a next target point as indicated by hatching.

  The CL 54 training further indicates that the change of

  path must be finished before a line ZL.

  The fifth section 35 stores the data relating to a configuration summary of the route with the selectable path (s) between the target point and the adjacent target point, corresponding to each adjacent target point. The data stored in the fifth section 35 is presented on the viewing screen when the distance to the next target point, i.e. the corresponding adjacent target point, is long, as shown in Fig. 6 The data stored in the fifth section 35 will be called "information of free conduct "In Figure 6, the information of

  Free Driving 56 is shown to the left of the screen.

  The sixth section 36 includes data relating to another simplified information summary (hereinafter referred to as "FS information") corresponding to each CDL or CL information stored in the fourth section 34. In FIG. 58 is shown at the top of the viewing screen with

free driving information 56.

  The storage area of the road map data storage unit 24 further comprises an index of the major areas of the map, one of which is designated by the reference numeral 30 in Fig. 3 (a), as well as

  the corresponding small areas on the map.

  The operation of the navigation system according to the first embodiment of the invention will be

described below.

  When energy is applied to the system,

  enter a waiting state of the data entry.

  The entry of the data is accomplished by hand by the keyboard 20 designating a starting point of the vehicle and a destination. The system allows the entry of the starting point and the destination in two modes In a mode, the starting point and the destination are introduced using precise coordinate positions while in the other mode the starting point and the destination are introduced using unit areas to which the starting point and the destination respectively belong. unitary areas for data entry, index of large areas on the map, and corresponding small areas on the map as described above and presented on the viewing screen as shown in Figure 7 L index includes the names and codes of large areas on the map and the names and codes of small areas or areas on the map, each corresponding to the unit area es is accomplished by introducing codes of unit areas for the starting point and destination

using the keyboard 20.

  When the system recognizes the input of the above noted data, an initial target point, a final target point and a route to be traveled by the vehicle are automatically derived by a method identified by

the flowchart in Figure 8.

  In a first step 100, the initial target point is determined. FIG. 9 explains the determination of the initial target point. In FIG. 9, a coordinate position Zs (Xs, Ys) designates the starting point of the vehicle. The position Zs is defined by the position of coordinates introduced by hand in the precise mode noted above and by a center of the unitary input area in the other mode noted above In general, a stored target point Za closest to the point Zs is chosen as the initial target point among the stored target points Za, Zb, Zc and Zd around the

departure Zs.

  However, it is preferable to choose the initial target point that is distant from the starting point by more than a predetermined distance, especially when the starting point is designated by the unit area. This is because when the starting point is is identified by the unit area, the navigation to the initial target point from the starting point Zs may become incorrect or false in cases where the initial target point is close to the starting point Zs, especially when the navigation between them is accomplished by an arrow indication, described below, on the screen

of visualization.

  In this case, the initial target point is chosen from the target points Za, Zb, Zc and Zd, are closest to the starting point Zs among the target points satisfying the following equations (1) and (2): y (D Ys) <X (XD Xs) (1) (X Xs) 2 + (y Ys) 2 30002 (2) wherein XD and YD designate the X and Y coordinates, respectively, of a ZD position of the destination of entry and the value is 3000 is used in the case where the unit area is 1km 2 and so we can adjust it

  to another value depending on the size of the unit area.

  Consequently, in FIG. 9, the target point placed in the hatched area and closest to the starting point Zs is chosen as the initial target point, that is to say that the target point included in the zone having a predetermined radius from starting point Zs is

  excluded from the selection of the initial target point.

  Subsequently, at a step 102, the final target point is determined. Fig. 10 explains the determination of the final target point. In Fig. 10, the final target point is selected from the stored target points Z1, Zn, and Zo closest to destination ZD (XD, YD) As a result, the target point

  Zm is chosen as the final target point.

  In practice, the stored target point that gives the lowest D value in the following equation (3) is chosen as the final target point: D 2 = (XX) 2 + (Y y 2) (3) Note that a stored target point that is an intersection between the expressway and the associated route or an intersection or branch line on the expressway or the lane change point is excluded from the initial target point section and that a stored target point that is an intersection between the expressway and the road that arrives therein, or an intersection or a junction on the expressway or the lane change point is excluded from the selection of the final target point The exclusion noted above is executed by checking the type of the target point stored at the first

  section 31 which can be seen in Figure 3 (d).

  The routine then proceeds to a step 104 o a route which is the shortest from the starting point Zs to the destination Zd is derived so that the

vehicle goes through it.

  Fig. 11 is a flow chart showing a subroutine of step 104 to be executed by the unit of

  14 treatment to derive the shortest route.

  In a first step 106, a value K initialized to "O" is increased by "1" each time this step is executed Subsequently, in a step 108, all the target points adjacent to the initial target point are searched using a code From the initial target point as first-order target points At a subsequent step 110, the target point codes and the adjacent target point codes of the sought-after adjacent target points are extracted and at a step 112, the distance between the initial target point and each adjacent target point is read from the second section 32 of the

  map data that can be seen in Figure 3 (d).

  At a subsequent step 118, it is checked whether there is a target point code which is already stored at a step 114, which will be described later. If the answer at step 118 is NO, that is that is, there is no target point code that is already stored in step 114, then the routine proceeds to step 114 where the target point code and the corresponding read distance are stored as of a pair for each of the first-order target points At a subsequent step 116, it is checked whether the final target point is embedded in the first-order target points If the answer in step 116 is NO, that is that no final target point is incorporated, then the routine returns to step 106 to increase the K value of "1". Subsequently, at step 108, all adjacent target points for each of the target points of first order are searched using the code of each first-order target point, as second gold target points The target point codes and the adjacent target point codes of all the second order target points are extracted in step 110 and in step 112 the distance between each second order target point and the point is derived. initial target In the case where the answer in step 118 is NO, then the routine proceeds to steps 114 and 116 as described above and steps 106 to 116 are repeated until the response to

step 117 becomes YES.

  On the other hand, if the answer at step 118 is YES, then the routine proceeds to a step 120 where the distance Ds stored in step 114, in pair with the target point code, is compared with the distance Dn

  newly derived at step 112 More specifically

  for example, in cases where a target point A is stored in step 114 as a first-order target point with the distance read in step 112 and the target point A is again searched in an execution subsequent to the routine and that the distance is derived in step 112, step 120 compares the distance stored in step 114 with the newly derived distance at step 112 to determine which value is the largest If the answer at step 120 is YES, i.e., the stored distance Ds is not more than the new derived distance Dn, then the routine proceeds to a step 122 where the new derived distance Dn is erased. that the stored distance Ds remains effective Furthermore, if the answer in step 120 is NO, then the distance Dn is stored in pairs with the code of the corresponding target point and the stored distance

Ds is erased.

  By repeating the method described above, all the target points leading to the initial target point are

searched in sequence.

  As can be appreciated, since step 120 serves to erase a longer distance for a duplicate target point as described above, each target point stored in step 114 is paired with the most

  short distance from the initial target point.

  If the answer at step 116 is YES, i.e., the final target point is found in the stored target points, then the routine proceeds to a step 124 where the final target point code is paired with the distance between the initial target point and the final target point Subsequently, in a step 125, it is checked whether all possible target points are searched, for example, by checking whether all the target points adjacent to the final target point are stored at the target point. step 114 If the answer in step 125 is NO, then the routine returns to step 106 to increase the K value of "1" so as to search for higher order target points until all target points adjacent to the final target point are stored in step 114 Furthermore, if the answer in step 125 is YES, then the routine proceeds to steps 126 to 130 where the target points that give the shortest route between the point initial target and the final target point, ie between the starting point Zs and the destination Zd, are chosen and established. FIG. 12 explains this process. In FIG. 12, when all the adjacent target points CP 1, CPJ and CPK 1 of the final target point CPK are read at step 126 looking for the data on the map of Fig. 3 (d) using the code of the final target point CPK, step 128 chooses one of the adjacent target points CP K 11 which gives the shortest distance between the target point Final CPK and the initial target point CPO and establishes the code of the stored target point of CPFK 1 in pair with the stored distance Subsequently, step 130 checks whether CPK 1 is one of the target points adjacent to the initial target point CP O Si the answer at step 130 is YES, then the routine of Fig. 11 ends. Otherwise, if the answer at step 130 is NO then the routine returns to step 126 o all target points adjacent to CPFK 1 are read by searching the data on the map using the code of the Next, step 128 selects one of the adjacent target points CP 4 which gives the shortest distance between CP K 1 and CPF and sets the point code.

  stored target of CP 4 in pair with the stored distance.

  Subsequently, step 130 checks whether CP 4 is one of the target points adjacent to CPF. In this way, steps 126 to 130 are repeated to choose CP 3, CP 2 and CP in sequence until the response to step 130 i becomes YES, i.e. until one of the points

  adjacent targets C Pl is selected and set at step 128.

  If the answer in step 130 becomes YES, the subroutine of FIG. 11 ends and the routine

  main figure 8 also ends.

  As can be appreciated by the routines of Figures 8 and 10, the initial and final target points and the shortest route as well as the included target points to be traveled by the vehicle are automatically derived and established. After establishing the shortest route, a direction indication 60, as shown in Figure 13, is displayed on the screen to guide the vehicle to the initial starting point. This direction indication is also displayed on the screen. when the vehicle passes from the final target point to the destination When the vehicle reaches the initial target point being guided by the direction indication 60, the start switch 22 is manually controlled to turn on. how to start navigating the vehicle from the initial target point

to the final target point.

  Figure 14 shows a flowchart of a

  main routine for vehicle navigation.

  In a first step 140, it is verified whether a pulse signal indicating a unit distance i D traveled by the vehicle is introduced by the distance sensor 10. If the response in step 140 is YES, then an interrupt routine shown in FIG. figure 15 is

executed at a step 142.

  As can be noted, the interrupt routine is executed by unit distance & D traveled by the vehicle. In a first step 144, the travel direction O of the vehicle is extracted from an output of the direction sensor 12. step 146, the distance AX and the distance Y are respectively derived using the following equations: X = t AD x cose t Y = AD x sine where X and Y are the distances traveled by the vehicle along the X axis and the Y axis, respectively, on the XY coordinate plane, by unit distance AD, traveled by the vehicle in a

direction 8.

  Subsequently, at a step 148, X and t Y are added to the distances X and Y, respectively, which are the accumulated distances traveled by the vehicle along the X axis and the Y axis, respectively, in order to derive the common accumulated distances X and Y that define

  a current coordinated position Z (X, Y) of the vehicle.

  On the other hand, at a step 150, the DCP distance between a current vehicle position and a next target point is reset by subtracting the unit distance AD each time that interrupt routine is executed to sequentially monitor the distance. D between the vehicle and the next target point The distance DCP is initialized at a distance L 1 at a step 166 in FIG.

we will describe later.

  On the other hand, if the answer to the first step is NO, i.e. no interruption is required, then step 152 executes the process of

  navigation that will be described later.

  Fig. 17 shows a flowchart of an interrupt routine that is triggered by a positive response issued at a step 194 in Fig. 19 that is

  will also describe later.

  It is assumed that the vehicle is traveling along a preset road at a position behind a target point T and that a target point T P1 is placed near TPO with respect to the direction of travel of the vehicle along the road. the preset route and that a target point TP 2 is placed near T Pl with respect to the direction of travel of the vehicle along the pre-established road In

  the whole description, the position relation among TPO,

  T Pl and TP 2 is the same as that noted above.

  When a positive response is issued in step 194 of Fig. 19 this means that when the vehicle reaches or passes Tpo, the target point codes of Tpo, Tp 1 and TP 2 are read from the data memory section 18. which stores the predetermined route with the selected target points therealong, and is set at a first step 160. Subsequently, the ZO coordinate positions Z1 and Z2 of the Tp Tp I and TP 2 are respectively read from the first section 31 of the data of the card shown in FIG. 3 (d) and established in a step 162. At a subsequent step 164, the distance L 1 between TPO and T P1 and the distance L between T P1 and TP 2 are respectively read from the second section 32 of the data of the map of FIG. 3 (d) and established. Then, at a step 166, a current coordinate position Z derived at step 148 in FIG. 15 is set to ZO of TPO and the DCP distance derived at step 150 of FIG. 15 is established At a distance L 1 between TPO and T P1 'Subsequently, at a step 168, the input direction Qen and the output direction esor of the vehicle path through the target point T P1 are respectively derived based on information concerning the direction in which the road that is stored in the second section 32 of the map data of Figure 3 (d), using the

  target point of Tp O, Tp F and TP 2 set in step 160.

  Then, at a step 170, an approach verification zone, an error checking zone and a refocusing direction are established, which one

  will describe below with reference to Figure 18.

  In Fig. 18, it is assumed that the vehicle passes straight through Tp 1, i.e. the preset route established in step 104 of Fig. 8 extends directly through T P1 and the vehicle turn left at TP 2, ie the pre-established route requires a change of vehicle travel direction to TP 2 When the vehicle has reached or passed Tpo, an approach check area 300 and a zoned

  error checking 304 are set in step 170.

  Likewise, when the vehicle has reached or passes through T P1, an approach verification zone 302, an error checking zone 306 and a delivery direction

  point are established in step 170.

  It should be noted that when the vehicle has reached or goes through T P1, step 194 of FIG. 19 emits a positive response to execute the interrupt routine of FIG. 17. Accordingly, at step T T T is set to Tp, 0 TP 2 is set at Tpl and a target point further forward, close to TP 2, is set at TP 2 and likewise at step 162, Z 1 is set at ZO 'Z 2 is set to Z, and a position of the coordinates of the

  target point further ahead is set to Z 2.

  Approach verification zone 300 has the shape of a circle which is centered on Z 1 of T 1 and whose radius is 0.15 L and the approach verification zone 302 is a circle centered on Z 2 TP 2 with a radius of 0.1 L 2 Each spoke has a limit

lower, for example, 500 m.

  The error checking area 304 or 306 has the shape of a rectangle whose central longitudinal axis passes through ZO (TPO) and Z 1 (TP 1) or Z 1 (T Pl) and Z 2 (TP 2) , respectively, and its width is 0.5 L 1 or 0.5 L 2, respectively As a consequence, the error checking area 304 or 306 covers a width of 0.25 L 1 or 0.25 L 2 for each c 8 t of the corresponding central longitudinal axis Furthermore, the longitudinal ends of the error checking area 304 or 306 are defined by arcs of circle each of which has a radius of 1.2 L 1 or 1.2 L 2, which are centered on ZO and Z 1 or Z and Z 2, respectively It should be noted that the error checking area 304 or 306 is not derived in step 170 when a target point Tp is a

point of lane change.

  The refocusing direction is selected at a value between Gen and esor via the target point TP 2, that is to say in a rotation angle of the vehicle at Tp 2 * It should be noted that the direction of delivery at the point is not derived in step 170 when the target point Tp is the lane change point because all lane change points are configured as

rights.

  Subsequently, in step 184, it is checked whether TP is the final target point If the answer to step 184 is NO, the interrupt routine ends. Otherwise, if the answer to step 184 is YES, the routine goes to a step 186 which presents a comment that

T Pl is the final target point.

  Fig. 19 shows a flowchart of an interrupt routine executed, for example, per unit of time to detect whether the vehicle is out of the pre-established route, using the verification area

  approach and the error checking area.

  It is assumed that step 194 has determined, in an earlier cycle of execution of the interrupt routine, that the vehicle has reached or passes through the target point TPO '. As previously described, the interrupt routine of FIG. 17 is triggered by this

  determination to perform the foregoing steps.

  In a first step 187, it is checked whether the vehicle is in a TPO approach verification zone (not shown), that is to say if the vehicle has passed through the Tpo O approach verification zone. using the current position of the derived vehicle at step 148 of Fig. 15 If the answer at step 187 is YES, i.e. the vehicle is in the approach check zone of Trop then the routine repeats step 187 until the vehicle exits the approach verification area TPO 'If the answer in step 187 is NO, then the routine proceeds to a step 188 where it is checked whether the vehicle is in the approach check area 300 If the answer in step 188 is NO, then the routine proceeds to a step 190 which checks whether the

  vehicle is in error checking area 304.

  If the answer in step 190 is NO, then the routine proceeds to a step 192 where an indication such as "OFF RUN" is presented on the display screen and this interrupt routine ends. in step 190 is YES, then the routine returns to step 188 It should be noted that a step 154 of a subroutine shown in FIG. 16 emits a negative response to execute a step 156 when a method of free driving is accomplished while the response at step 187 or 190 is YES, which will be described later. On the other hand, if the answer at step 188 is YES, that is, the vehicle is in the approach check area 300, then the routine proceeds to step 194 which checks whether the vehicle has reached or passed through the target point Tp It should be noted that, in this preferred embodiment, step 194 determines that the vehicle reaches or passes through the target point T when the distance DCP derived at step 150 of FIG. becomes zero in the case where the pre-established route through the target point T becomes straight, and when the vehicle rotates to take a direction within a predetermined range with respect to the direction of delivery to the

  point which is established in step 170 of Figure 17.

  If the answer at step 194 is YES, that is, the vehicle has reached or passes through T 1, then the routine ends As described above, if the response to the step 194 is YES, the interrupt routine of Fig. 17 is triggered to be executed so that, for example, in the step, T Pl is set to TP, 0 TP 2 is set to T Pl and a target point Tp close to TP 2 is set to TP 2, and step 162 is executed accordingly. Furthermore, if the answer in step 194 is NO, then the routine proceeds to a step 196 which checks whether the vehicle is in the If the answer to step 196 is NO then the routine goes to step 192 which has the indication "OFF RUN" and the routine ends. Otherwise, if the answer to step 196 is YES, then the routine returns to step 188 It should be noted that step 154 of the subroutine shown in Fig. 16 gives a positive response for perform step 158 when a target point process is performed while the answer at step 196 is YES, what is

will describe below.

  FIG. 16 shows a flow chart of the subroutine of step 152 of FIG. 14 to execute the navigation method. It is assumed that the vehicle is moving between the target points TPO and TP. In the first step 154, we check if the vehicle is in the approach check area 300 of T Pl * In practice, as described above, the first step 154 makes it possible to check whether the answer to step 187 or 190 is YES or if the answer at step 196 is YES If the answer at step 154 is NO, i.e., the answer at step 187 or 190 is YES then the routine proceeds to

  step 156 o is performed the free driving method.

  In the free driving method, the free driving information stored in the fifth section of Fig. 3 (d) is as shown by the reference numeral 56 in Fig. 6 is presented on the display screen. previously described, it is better to view the more simplified information 58 in addition to the free driving information

56.

  On the other hand, if the answer at step 154 is YES, that is, the answer at step 196 is YES, then the routine proceeds to step 158 where the target point method is executed. figure 20 shows a

subroutine of step 158.

  In a first step 198, it is checked whether the vehicle is within 100 m of the target point T Pl * This check is performed based on the distance DCP derived in step 150 in FIG. step 198 is NO, then the routine proceeds to a step 200 where the CDL or CL information is displayed on the screen The information CDL or CL is as shown in FIG. 4 in the case where the target point T Pl is the intersection or branch and as shown in FIG. 5 in the case where T P1 and the lane change point Subsequently, at a step 202, the DCP distance derived at step 150 of FIG. 15 is also viewed as visualization by

segments 64 in FIGS. 4 and 5.

  On the other hand, if the answer at step 198 is YES, that is, the vehicle is within the limits of m of Tp 1, the routine proceeds to a step 204 where the CDL or CL information and the distance DCP, as described in steps 200 and 202, are visualized with the hatched portions shown in FIGS. 4 and 5 flashing Subsequently, at a step 206, it is checked whether the vehicle has reached or passes through the target point T Pl. in

  based on the response at step 194 of FIG.

  If the answer at step 206 is NO, then the routine repeats step 206 until the answer at this step becomes YES, i.e., the vehicle has reached or passes through the target point. T Pl 'If the answer to step 206 is YES, then the routine proceeds to a step 208 o viewing the CDL or CL information on

the screen is over.

  Fig. 21 shows a subroutine of the step of Fig. 20 for viewing the CDL information as shown in Fig. 4, i.e. when the target point is the intersection or branch. Fig. 22 shows a subroutine of step 200 of Fig. 20 for displaying CL information as shown in Fig. 5, i.e., when the target point is the lane change point. selecting one of the subroutines of FIGS. 21 and 22 is accomplished by checking the type of the target point stored in the first section 31 that can be seen in FIG.

3 (d).

  In the subroutine of Fig. 21, at a first step 210, the target point data T Pl is read from the data on the map of Fig. 3 (d) using a target point code of T P established. in step 160 of Fig. 17 At a subsequent step 212, a target point code of TP 2 is retrieved from the step of Fig. 17 Subsequently, at a step 214, an adjacent target point code of TP 2 is read from the second section 32 of the data on the card read at the first step 210 using the target point code TP 2 read in step 212 At a subsequent step 216, the CDL data for the adjacent target point TP 21 stored in the fourth section 34, ie the data relating to a configuration of Tp 1, a direction and a path to be chosen, is extracted from the extracted map datum and is displayed on the screen Subsequently, at a step 218, the data for the adjacent target point TP 2 stored in the third section 33 is ie a guidance signaling for the adjacent target point TP 21 is extracted from the extracted map data and is displayed on the screen Then, in a step 220, the target point name T Pl is read from the first section 31 of the

  card data read and viewed.

  In the subroutine of Fig. 22, in a first section 222, the data on the target point T Pl is read from the data on the map of Fig. 3 (d) using a target point code of T P established. in the step of Fig. 17 At a subsequent step 224, a target point code of TP 2 is read from step 160 of Fig. 17 Subsequently, at a step 226, an adjacent target point code of TP 2 is read from the second section 32 of the map datum read in the first step 222 in

  using the target point code of TP 2 read in step 224.

  Subsequently, at a step 228, a current speed V of the vehicle is compared with a preset value VO. As can be noted, the current speed of the vehicle is derived based on the outputs of the distance sensor 10. step 228 is YES, i.e., the current speed V is larger than VO, then the routine proceeds to a step 232 o the CL data for the adjacent target point TP 2, stored in the fourth section 34 and as shown in FIG. 5, is read from the card data read and is displayed on the screen at its lower position in FIG. 5, that is to say below the vertical center of the display screen. On the other hand, if the answer at step 228 is NO, that is, the current speed V is not greater than VO, then the routine proceeds to a step 230 where the current traffic volume C is compared to a pre-established value CO Current traffic volume C can be derived at the bottom on the vehicle acceleration data and vehicle deceleration data derived from the outputs of the distance sensor 10 as disclosed in US Patent Application Serial No. 07 / 432,937 filed November 7, 1989, the contents of which are incorporated here for reference If the answer in step 230 is YES, that is, the current traffic volume C is larger than CO, then the routine proceeds to step 232 where the CL data for the adjacent target point TP 2 is presented on the display screen at its center

  vertical as shown in Figure 5.

  By following the execution of step 232 or 234, the routine proceeds to a step 236 where the data of the adjacent target point TP 2, stored in the third section 33, that is to say a guide signal for the adjacent target point TP 22 is read from the read map data and is displayed on the screen Then, in a step 238, the name of the target point T Pl is read from the first section 31

  of the map data and is visualized.

  Note that in cases where no guidance signaling data is stored in the third section 33 of the map data for a target point which is a lane change point, step 236 may be omitted by elsewhere, in cases where no title is stored in the first section 31 of the map data for a target point which is the

  lane change point, step 238 may be omitted.

  It should also be noted that the display mode executed by step 232 is required because: As shown in Fig. 5, the line ZL indicates the end point for the vehicle to change lanes and, therefore, the portions hatched behind ZL with respect to the direction of travel of the vehicle imply a margin zone for the vehicle to change lane Consequently, in cases where the speed V of the vehicle or the volume C of the traffic represents more VO or CO , respectively, it is preferable to move the viewing position of the target point, i.e. the line ZL downwards in FIG. 5 to shorten the displayed margin area so that the driver of the vehicle can finish more t 8 t its lane change It should be noted that a coordinate position Z of a target point Tp stored in the first section 31 of the map data may be a coordinate position of the line ZL in the case where T p is the point of

change of lane.

  Fig. 23 shows a subroutine of step 156 of Fig. 16 for executing the method of

  free driving as shown in Figure 6.

  It is assumed that the vehicle is moving between the target points TPO and T P1 and that in response to step 154 of FIG. 16 is NO A first step 240, the data relating to the target point TPO is read from the data on the map of Figure 3 (d) using a code of

  TPO target point set in step 160 of FIG. 17.

  At a subsequent step 242, a target point code of T P1 is read from step 160 of FIG. 17 Subsequently, at a step 244, an adjacent target point code of T P1 is read from second section 32 of FIG. map data read at a first step 240 using the target point code of T Pl read in step 242 At a subsequent step 246, the free driving information for the adjacent target point T Pl stored in the fifth section of the card data is read from the card data read at the first step 240 and is displayed as shown by the reference numeral 56 on the

figure 6.

  Subsequently, at a step 248, the target point data T Pl is read from the data on the map of Fig. 3 (d) using the target point code of T Pl read in step 242 at a step 250 Subsequently, a target point code of TP 2 is read from step 160 of Fig. 17. Subsequently, at a step 252, an adjacent target point code of TP 2 is read from the second section 32 of the data on the map. read in step 248, using the target point code of TP 2 read in step 250. Then, at a step 254, the information FS for the adjacent target point TP 2 stored in the sixth section 36 of the given on the card is read from the data on the card read in step 248 and is displayed as shown in reference numeral 58 in FIG.

  As can be noted from the description

  above, the first preferred embodiment provides, for example, the following advantages. It is assumed that the vehicle is moving from the target point TPO to the target point.

T Pl.

  Until the vehicle reaches the approach check area 300 of Tp 1, as shown in FIG. 6, the free driving information 56 with the information FS 58, which shows a direction to be chosen at Tp 1 The driver of the vehicle readily recognizes that free driving is permitted, and furthermore, that the driver of the vehicle receives the information concerning the direction to be chosen at T well before the driving. that is to say that the way to choose is appreciated well before TP 1, a steady and stable driving of the vehicle

is guaranteed.

  Furthermore, after entering the vehicle in the approach verification area 300 and until the vehicle reaches Z of Tpl, as shown in Figure 4 or 5, the CDL or CL information is presented on the display screen As the CDL or CL information contains the summary or simplified configuration of the target point Tp 1, the driver of the vehicle easily recognizes, at a glance, the direction and

  way to choose at T Pl or the path to choose at TP 1.

  Furthermore, the mode of visualization of the point of change of lane, that is to say the display position of the lane change point on the display screen is adjusted according to the speed of the vehicle and the volume of the traffic, which guarantees the operation

  regular and safe change of lane.

  The second preferred embodiment of the navigation system according to the present invention will be

described below.

  In the second preferred embodiment, the type of the target point stored in the first section 31 of the map datum of Fig. 3 (d) does not include the fifth type above where the target point is a point of change of Furthermore, in the second preferred embodiment, step 160 of the interrupt routine of FIG. 17 establishes a target code of Tp 3 in addition to those of Tpo, Tpl and TP 2 T, is a target point. close to TP 2 compared to the direction of

  route of the vehicle along the pre-established road.

  As described in the first embodiment, the fourth section 34 of the data on the map of Fig. 3 (d) stores a summed configuration of the target point with a direction and a way or with a path to be selected at target point for passing to each of the adjacent target points Furthermore, in the second preferred embodiment, if there is an adjacent target point which is close to the target point, i.e. at a predetermined distance from the target point, the storage area for this nearby adjacent target point (hereinafter called IL ST) is further divided into smaller storage areas (hereinafter referred to as "I S ST"), each storing a a summed configuration of that near the adjacent target point with a direction and a path or with a path to be selected at that near adjacent target point to move to one of the other adjacent adjacent target points which are the adjacent target points of that adjacent target point near the area LST storage is identified by an adjacent target point code of that near-adjacent target point and the SST storage area is identified by a target code of the other corresponding adjacent target point for an adjacent target point which is remote from the target target point. the predetermined distance, the storage area for this target point adjacent to a greater distance stores the data as in the

first embodiment.

  The operation of the second embodiment will now be described with reference to Fig. 27 which shows a subroutine of step 200 of Fig. 20 according to the second preferred embodiment for viewing the CDL or CL information as the show it

Figure 24 or 25.

  It is assumed that the vehicle passes from TPO to T P1. At a first step 210, the data relating to T P1 is read from the datum on the map of FIG. 3 (d) using a target code of T P1 established in FIG. step 160 of Figure 17 At a subsequent step 212, a point code

  target of TP 2 is read from step 160 of FIG.

  Subsequently, at a step 214, a target point code adjacent to TP 2 is read from the second section 32 of the card data read at the first step 210.

  using the target point code of TP 2 read in step 212.

  At a subsequent step 2140, it is checked whether the adjacent target point TP 2 contains SST, that is if the adjacent target point is LST comprising the smallest storage areas SST. This check at step 2140 is easy to accomplish, for example, assigning "O" to LST and "1" to other adjacent target points having no SST. If the answer to step 2140 is NO, that is, the target point adjacent TP 2 is not LST, then the routine proceeds to a step 216 where the CDL data for the adjacent target point TP 2 is read from the map data read using the code of the adjacent read target point of TP 2 and is visualized on the display screen, like the CDL information 54 that can be seen in the figure Furthermore, if the answer to step 2140 is YES, then the routine goes to a step 2141 or a code of

target point of TP 3 is read from step 160 of FIG.

  Subsequently, the routine proceeds to a step 2160 where the CDL data for the adjacent target point TP 2 is read from the data read from the card using the target target point code of TP 2 and the target point code of TP 3 and viewed on the viewing screen as

  CDL information in Figure 24.

  After execution of step 216 or 2160, the routine proceeds to steps 218 and 220 Since these steps 218 and 220 are the same as steps 218 and 220 of FIG. 21, their explanation is omitted in order to avoid a

redundancy of the description.

  It should be noted that the storage area for the next adjacent area can store only the adjacent adjacent area configuration in addition to the target point configuration with a direction and a path to be selected at the target point to move to that adjacent target point. In this case, as can be noted, the storage area of this adjacent adjacent area does not contain the smallest areas S ST. Accordingly, step 160 of Fig. 17 does not need to establish TP 3. and the subroutine indicated in FIG. 21 of the first preferred embodiment can

to be used as it is.

  In the second preferred embodiment, another modification is made to the first preferred embodiment. More particularly, Fig. 28 shows a subroutine of step 156 of Fig. 16, which differs from the subroutine of Fig. 23 of the first embodiment The subroutine of FIG. 28 executes the free driving method without using the free driving information stored in the fifth section 35 of the data of the card shown in FIG.

3 (d).

  It is assumed that the vehicle is moving between the target point TPO and Tp1 and that the response at step 154 of FIG. 16 is NO At a first step 266, the data relating to the target point TPO is read from the data on the FIG. 3 (d) map using a TPO target point code set in step 160 of FIG. 17. At a subsequent step 268, a target point code of T P1 is read from step 160 of FIG. Fig. 17 Subsequently, at a step 270, the distance DCP is read from step 150 of Fig. 15 At a subsequent step 272, it is checked whether the read DCP distance is in a preset range of display on the screen In practice the distance DCP is compared with a predetermined distance Dp If the response in step 272 is NO, that is, DCP is larger than Dp, then the routine proceeds to a step 274 where only the center line indicated by a reference numeral 78 in FIG. 26 is displayed on the screen. a central line is stored, for example, in a read-only memory of the processing unit 14 of FIG. 2 Furthermore, if the answer to the step 272 is YES, then the routine proceeds to a step 276 where the data item the target point TP is read from the data on the map of Figure 3 (d) in

  using the target point code of T Pl read in step 268.

  At a subsequent step 278, a target point code of TP 2 is read from step 160 of Fig. 17. Subsequently, at step 280, an adjacent target point code of TP 2 is read from the second section 32 of the given on the card read in step 276 using the target point code of TP 2 read in step 278 Then, at a step 282, the information FS for the adjacent target point TP 2 stored in the sixth section 36 of the data on the card is read from the data on the card read in step 276 and displayed on the screen at a position corresponding to the distance read DCP as shown in Figure 26 by a figure of

reference 72.

  Subsequently, the routine proceeds to a step 284 where the distance L 2 between T P 1 and TP 2 is read from step 164 of FIG. 17. At a subsequent step 286, it is checked whether the total distance DCPT (DCP + L 2) does not represent more than the predetermined distance Dp, If the answer in step 286 is NO, that is, DCPT is greater than Dp, then the routine ends Otherwise, if the answer to step 286 is YES, then the routine proceeds to a step 288 where the data on the target point TP 2 is read from the data on the map of Figure 3 (d).

  using the target point code of TP 2 read in step 278.

  Then, at a step 290, a target point code of Tp 3 is read from step 160 of Fig. 17 Subsequently, the routine proceeds to a step 292 o an adjacent target point code of Tp 3 is read from the second section 32 of the data on the card read in step 288 using the code of the target point of TP 3 read in step 290 Then, in a step 294, the information FS for the adjacent target point TP 3, stored in the sixth section 36 of the data on the card is read from the data on the card read in step 288 and is displayed on the screen in a position corresponding to the total distance DCPT as shown

  Figure 26 with a reference number 74.

  If it is desired to view target points farther forward on the screen, for example TP 3, TP 4 and other steps corresponding to steps 276 to 294 can be executed after step 294 with the step of FIG. 17 establishing the other target points as TP 4. Moreover, since the information FS is displayed on the screen at a position corresponding to DCP and DCPT 'the visualization on the screen seems to be

move continuously.

  As we can appreciate from the description

  above regarding the second preferred embodiment, in cases where the distance between T 1 and TP 2 is short, i.e. within the preset value, the target point TP 2 further to the is also displayed on the screen in addition to Tp 1, either in the target point process or in the free driving method Consequently, the driver of the vehicle can determine how to drive the car to

  target point Tp 1, considering the target point TP 2.

  A third preferred embodiment will now be described below with reference to the figures

29 and 30.

  In FIGS. 29 and 30, it is assumed that the target points A and B are intersections on the general road and that the distance between the target points A and B is short, for example, less than 500 m. In FIG. it is assumed that the vehicle moves to a position C towards the target point B via the target point A, a direction indication AO for the target point A is displayed which is larger than a direction indication BO for the target point B On the other hand, as shown in Fig. 3, after the vehicle has passed the target point A, the direction indication BO is displayed larger with a smaller indication of the vehicle route A 1 to the target point A. As can be noted in the third preferred embodiment, the driver of the vehicle can easily recognize a current position of the vehicle with respect to target points A and B, so this ensures

  regular driving of the vehicle.

Claims (13)

R E V E N D I C A T IO N S   A navigation system for a motor vehicle, characterized by comprising: first means for storing first known target points and adjacent target points; second means for storing a first group of data associated with each of said first target points, each of said first group of data containing a second group of data corresponding to each of said target points adjacent to the corresponding first target point, each of said second group of data comprising a summarized configuration of said corresponding first target point and guidance information required at said corresponding first target point to go to the corresponding adjacent target point; third means for selecting second target points from the first target points to define a route of the vehicle passing through said second target points; fourth means for storing said second target points in series; fifth means for establishing selected third and fourth target points from said stored second target points, said third target point being a forward target point and said fourth target point being one of said target points adjacent said third target point; and being placed forward of said third target point along said road; sixth means for monitoring the position of the vehicle; seventh means for monitoring the positional relationship between the monitored position of the vehicle and the third target point; an eighth means responsive to the monitored positional relationship for selecting one of said second data groups based on said third target point using it as the target point and said fourth target point using it as an adjacent target point to visualizing the corresponding guidance information and the summary configuration of said third target point before the vehicle reaches said third target point.   System according to claim 1, characterized in that said eighth means displays said corresponding cross-hatching information on said summed configuration, said third target point.   The system of claim 1, characterized in that said third target point is an intersection or a branch on a road and said guidance information displayed by said eighth means at the same time as the summed configuration of said third target point is a direction and a way to   choose by the vehicle at the third target point.   The system of claim 1, characterized in that said third target point is a lane change point and said guidance information displayed by said eighth means together with the summed configuration of the third target point is a lane that the vehicle is to choose third audit target point.   A system as claimed in claim 1, characterized in that each of the first data groups comprises a third data group corresponding to each of the target points adjacent to the corresponding first target point, each of said third data groups comprising a guidance signaling data required by said corresponding first target point to go to the corresponding adjacent target point and that said eighth means displays said signaling data in the form of letters together with the corresponding guidance information and   said summed configuration of said third target point.   System according to claim 1, characterized in that each of said first groups of data comprises a name of the corresponding first target point and in that said eighth means displays the name of said third target point together with the corresponding guide information and said   summarized configuration of the third target point.   System according to claim 4, characterized in that the guidance information further comprises an indication representative of a lane change end point and said eighth means comprises a ninth means for comparing a monitored speed of the vehicle with a first value. pre-established and in that said eighth means displays said third target point with said indication displayed in a lower portion on a screen when said vehicle speed   is greater than said preset value.   System according to claim 7, characterized in that the eighth means comprises a tenth means for comparing a monitored volume of the traffic with a second preset value and that said eighth means displays said third target point with said indication displayed at the lower portion. screen when the traffic volume is larger than said second preset value.   The system of claim 1, characterized in that the fifth means further establishes a selected rear target point in the stored second target points, said rearward target point being rearward of the third target point the along the road and said third target point being one of said adjacent target points among said points targets backwards.   A system according to claim 9, characterized in that each of said first data groups comprises a fourth data group corresponding to each of the target points adjacent to the corresponding first target point, each of said fourth data groups including free driving information representative of the vehicle which can roll freely and in that said eighth means selects said second group of data to view, from a point in time, the moment when the vehicle enters a predetermined range of distance from said third target point to a point o said vehicle passes said third target point while the eighth means selects one of said fourth data groups based on said target point backward using it as a target point and said third target point using it as a point adjacent target to visualize the free driving information at the time the vehicle is s from the preset range from said third target point.   The system of claim 10, characterized in that each of said first data groups comprises a fifth data group corresponding to each of said target points adjacent to the corresponding first target point, each of said fifth data groups comprising a simplified configuration representative of the configuration summarizing and guiding the corresponding second data group and in that the eighth means selects one of said fifth data groups based on the third target point using it as the target point and said fourth target point using it as an adjacent target point for viewing said simplified data along with the information of free driving.   System according to claim 9, characterized in that the fifth means readjust the target point towards the rear, said third target point and said fourth target point each time the vehicle passes through the third target point so that said third point target is established at said rearward target point, said fourth target point is set at said third target point and another forward target point selected from the second stored target points is set at said fourth target point, said other point forward target being placed near said fourth target point and being one of the points   targets adjacent to the fourth target point.   The system of claim 1, characterized in that each of said second data groups further comprises a summarized configuration of the corresponding adjacent target point and in that said eighth means displays the summed configuration of said fourth target point in addition to the corresponding information guide and said configuration   summarized of said third target point.   System according to claim 2, characterized in that said eighth means produces a blinking visualization of said hatching guide information when the vehicle enters a range.   predetermined distance from said third target point.   The system of claim 9, characterized in that said fifth means further establishes a fifth target point selected from the second stored target points, said fifth target point being one of the target points adjacent to said fourth target point and positioned at least one of said target points. before said fourth target point along said route, and in that each of said first data groups comprises a fifth data group corresponding to each of said target points adjacent the corresponding first target point, each of said fifth data groups comprising another simplified configuration representative of the summarized configuration and guidance of the corresponding second data group and in that said eighth means comprises an eleventh means for comparing a first distance between the monitored position of the vehicle and said third target point with a predetermined distance, said first distance being monitored by said seventh means and in that said eighth means selects one of said fifth data groups based on said third target point using it as the target point, and said fourth target point using it as an adjacent target point, said eighth means viewing said other simplified configuration on a display screen at a position corresponding to the first distance while the vehicle is out of a predetermined range of distance from said third target point in the case where said first distance is not greater than at said predetermined distance, and in that said eighth means comprises a twelfth means for deriving a second distance by adding said first distance to a distance stored between said third target point and said fourth target point and for comparing said second distance with said predetermined distance and in that said eighth means chooses one of said fifth grou data based on said fourth target point using it as the target point and said fifth target point using it as an adjacent target point, said eighth means displaying said further simplified pattern identified by said fourth and fifth target points on the target point. display screen at a position corresponding to said second distance in addition to said other simplified configuration identified by said third and fourth target points in the case where said second distance does not represent more than the pre-established distance.