NAVIGATION APPARATUS AND NAVIGATION METHOD

Abstract: A navigation apparatus to be mounted on a mobile body. The apparatus includes an input device (1), a central processor (2), a display (3) and a memory (6). When the present position of the mobile body and a destination are given to the central processor, the processor produces at least two possible routes to the destination from the present position using data stored in the memory such as a map, and displays the present position (21), the destination (22) and the possible routes (23, 24) on a screen (3a) of the display. The preparation of at least two possible routes is effected by a processor (4) and computation/retrieval means (5). Connecting routes (25) existing between two or more possible routes can be retrieved and displayed. Furthermore, a possible area (26) inclusive of the possible routes can be retrieved and displayed.

Description: TECHNICAL FIELD The present invention relates to a navigation apparatus and navigation method, and more particularly, to a navigation apparatus and navigation method for determining route (or passage) between the present position of a moving object and the destination to be reached by the moving object, along which the moving object can reach the destination. BACKGROUND ART A conventional navigation apparatus applied, for example, to an automobile can be roughly classified to a route-guiding type apparatus and a non-route-guiding type apparatus. The route-guiding type navigation apparatus displays information about an optimum route for reaching a destination on the screen of a display device. The optimum route for reaching the destination is automatically calculated by the computer accommodated in the navigation apparatus by inputting the present position and the destination of the automobile before starting a travel. While travelling, a driver drives the automobile by being guided by the information about the route displayed on the display screen until the automobile reaches the destination. Nevertheless, the conventional route-guiding type apparatus is insufficient for practical use because it has difficulty in the ability of the driver, errors of a locator and timing for indicating the route. The non-route-guiding type navigation apparatus only displays a map as well as a present position, travelling locus, travelling direction and the like in the map on the screen of the display device and does not positively provide the driver with guiding information. Therefore, this navigation apparatus cannot achieve the original purpose of navigation. As described above, the information presented by the non-route-guiding type navigation apparatus is less valuable to the driver. Further, the driver is prevented from paying attention to a forward direction by observing the map on the screen while driving and thus a problem arises in safety drive. On the other hand, the information presented by the route-guiding type navigation apparatus forces the driver to travel along the designated route and gives a strong psychological stress to the driver and thus has a possibility to cause danger. Further, according to the technology employed at present, since an instruction on the route is given to the driver without taking actual traffic conditions while travelling into consideration, a problem arises in that the navigation apparatus is less valuable when practically applied. According to the precharacterizing clauses of claims 1 and 6, the present invention starts from the teaching of JP-A-1 130 299. What is known from said prior art document is a navigation apparatus and a navigation method adapted to calculate two or more possible routes along which a moving object can reach a destination starting from a given position. Said possible routes are, for example, the shortest time route, the minimum expensive and so on. According to JP-A-1 180 413, the shortest time route is displayed together with peripheral roads. WO 92/08952, published on May 29, 1992 and enjoying the priority date November 8, 1990, discloses a navigation apparatus and a navigation method in which two or more possible routes are displayed and the driver is asked to select his preferred route. Alternatively, the vehicle operator has a choice of routes for route guidance to the destination without requiring operator input after calculation of a first route to specify how to obtain a second route. DE 41 04 351 Al, published on August 22, 1991 and enjoying the priority date February 15, 1990 discloses a navigation apparatus and a navigation method in which a possible route is determined by using polygons, wherein the possible route consists of borderlines between said polygons. Taking the problems of the conventional navigation apparatus and the conventional navigation method into consideration, an object of the present invention is to provide a practical and safe navigation apparatus and navigation method which can present valuable information to a driver without applying stress to him. According to the invention, the above object is achieved by a navigation apparatus mounted on a moving object and including a central processing section, an input section for inputting the present position and the destination of said moving object to said central processing section, a memory section and a display section, said central processing section comprising a possible route operation means for determining two or more possible routes along which said moving object can reach the destination by using map data stored in said memory section, and for driving said display section so that the present position and the destination are indicated on the screen of said display section when the present position and the destination of said moving object are provided, characterized in that said central processing section includes a possible area operation means for determining a possible area defined as a closed area enclosed by the outermost two of said possible routes, said possible area being indicated on said display section visually well confirmable, together with at least said two outermost possible routes as the boundaries of said possible area. Preferably, said possible routes and said possible area are displayed by using thick lines and colors. Said central processing section may include a connection route operation means for determining a connection route for connecting between said two or more possible routes, said connection route being indicated on said display section. According to the invention, the present position of said moving object may be treated as a point contained in an area having a predetermined extent and said possible routes may be determined by using a route contained in said area as a starting point. Furthermore, said possible area may be determined by using a route contained in said area as a starting point. Moreover, according to the invention, the above object is achieved by a navigation method comprising the steps of producing two or more possible routes for making a moving object reach a destination from a present position by using prepared map data when the present position and the destination are provided; and presenting the present position and the destination to a user, characterized by the steps of: determining a possible area defined as a closed area enclosed by the outermost two of said possible routes; and presenting said possible area visually well confirmable to the user, together with at least said outermost possible routes as the boundaries of said possible area. Furthermore, said two or more possible routes and said possible area are presented by using thick lines and colors. The method may further comprise the steps of determining a connection route for connecting between said two or more possible routes and presenting said connection route together with said possible routes to the user. The present position of said moving object may be treated as a point contained in an area having a predetermined extent and said possible routes may be determined by using a route contained in the area as a starting point. Furthermore, said possible area may be determined by using a route contained in the area as a starting point. Preferably, a possible area is determined and displayed on the basis of an initial position of said moving object, said possible area being maintained on the screen even if the position of said moving object is changed. Moreover, it is preferred that said possible area is renewed by operating said input section. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a diagram showing the arrangement of an embodiment of a navigation apparatus according to the present invention. Fig.2 is a flowchart showing the basic operation for navigation. Fig.3 is a diagram showing an example displayed on the screen of a display section. Fig.4 is a diagram showing another example displayed on the screen of the display section. Fig.5 is a diagram showing a further example displayed on the screen of the display section. BEST MODE OF CARRYING OUT THE INVENTION A preferred embodiment of the present invention will be described below with reference to the attached drawings. In Fig.1, a numeral 1 designates an input device; a numeral 2 designates a central processing device; and a numeral 3 designates a display device as an output device. A navigation apparatus according to the present embodiment fundamentally comprises the input device 1, the central processing device 2 and the display device 3. The navigation apparatus having the arrangement is mounted on a moving object such an automobile and the like. The present embodiment will be described in the assumption that the moving object is an automobile. The input device 1 is installed in a front panel in the vicinity of a driver's seat in the automobile. Operation keys are disposed on the input device 1 to input various instructions or data. These operation keys are operated by, for example, a driver to input necessary instructions or data. A voice input type input device or a touch screen type device may be employed as the input device 1. The central processing device 2 is composed of a microcomputer which includes a processing means 4, a calculation/retrieval means 5, and a memory device 6. The memory device 6 stores a program for carrying out calculation necessary for performing navigation according to this embodiment and data such as maps, roads and the like necessary for the navigation. The processing means 4 has a processing function realized by the program stored in the memory device 6. The concrete content of the processing performed by the processing means 4 will be described later. The calculation/retrieval means 5 has a function for retrieving various kinds of data about the maps or the roads stored in the memory device 6 in accordance with instructions from the processing device 4 in order to obtain necessary data. The display device 3 is any one of a CRT, a liquid crystal display, head-up display (HUD) on a window shield or the like, and disposed on the front panel or the shield glass in the vicinity of the driver's seat. The driver can obtain information necessary for reaching a destination through the drive of the automobile by visually confirming the content displayed on the screen of the display device 3. The navigation apparatus includes a locator 7 in addition to the basic arrangement. The locator 7 is used to measure the present position of the automobile on which the navigation apparatus is mounted. Various systems may be employed as the concrete arrangement of the locator 7. That is, there are various systems, such as, an arrangement making use of a radio wave from a satellite; an arrangement making use of a distance sensor or a directional sensor; and an arrangement making use of oscillators disposed along roads to provide positional information, and the like. Next, the operation of navigation (travelling support) carried out by the navigation apparatus having the arrangement as described above will be explained with reference to Fig.2. The operation by the navigation apparatus is carried out by the various functional means realized by the processing means 4 and the calculation/retrieval means 5. First, the operation key of the input device 1 is operated so that the destination is set and input to the central processing device 2 (step 11). The destination may be input by any arbitrary method. For example, the destination may be input by inputting a number allocated to it. Next, the present position of the automobile is set by operating the operation key of the input device 1 and input to the central processing device 2 (step 12). The initial input of the present position at step 12 should be preferably performed by the setting and inputting operation of the driver to ensure the accuracy of the present position. Further, the present position can be automatically input by fetching an output signal from the locator 7. The processing means 4 of the central processing device 2 maintains the respective data about the destination and the present position. Next, the processing means 4 determines respective positional data on the basis of the data of the destination and the present position. Then, the calculation/retrieval means 5 is operated so that a route (hereinafter, referred to as a possible route), along which the automobile can travel from the present position to the destination, is determined by calculation on the basis of the respective data of the maps and the roads stored in the memory device 6 in addition to the coordinate data of the destination and the present position. Two or more of the above possible routes are determined and taken out by the calculation/retrieval operation. The calculation/retrieval operation is carried out by the calculation/retrieval means 5 at step 13. A possible route calculation means is realized by the processing means 4 and calculation/retrieval means 5 to carry out step 13 for determining the two or more possible routes. Next, at step 14, tne coordinate data or the two or more possible routes determined by the calculation/retrieval means 5 is maintained in the processing means 4 and then further supplied to the display device 3. At this time, the coordinate data about the destination and the present position input by the input device 1 is also supplied from the processing means 4 to the display device 3. The processing means 4 has an image displaying and processing function for displaying a required image on the screen of the display device 3. Therefore, the above various kinds of data supplied to the display device 3 are converted to a form which can be displayed on the screen thereof as figures. As explained above, the present position, the destination, and the two or more possible routes therebetween are displayed on the screen of the display device 3 in the state that their positional relationship is accurately indicated on the basis of their coordinate data (step 14). According to the invention a possible area is calculated/retrieved by the calculation/retrieval effected at step 13. When a lot of possible routes are determined by calculation/retrieval, the possible area is determined in such a manner that the outermost two possible routes of them define the possible area, and the possible area is displayed on the screen of the display device 3. So long as the automobile travels toward the destination within the possible area, it is ensured to reach the destination. In Fig. 4, a numeral 26 designates the possible area. With respect to the retrieval and the display of the possible area 26, it is preferable that when a possible area is initially displayed on the screen by using an initial present position of the automobile, the displayed possible area is maintained on the screen even if the present position is changed. This is because the possible area is a reference area which is used for determining whether the automobile is located within the possible area where it can reach the destination. When it is desired to change to a reduced scale, or there are a lot of available routes and therefore it is easy to calculate/retrieve a possible area, the possible area may be of course renewed, if necessary. In the above description, a possible area operation means can be realized by the processing means 4 and the calculation/retrieval means 5. While travelling, the present position of the automobile is periodically confirmed by making use of an output from the locator 7 at step 12 in order to retrieve the possible routes between a new present position and the destination. A timing for checking the present position is determined, for example, by the timing determined by a predetermined time interval; the timing determined by an output from a sensor for sensing a turning angle of a steering wheel when the automobile turns to the right or left; the timing sensed by a direction sensor when the automobile turns to the right or left; and the like. Furthermore, the driver may renew the possible routes on the display screen by operating the input device 1 while driving if necessary. Furthermore, when it is taken into consideration that errors are included in data regarding the present position of the automobile obtained by the locator 7, it is preferable that after determing an area including the present position, two or more possible routes leading to the destination or the possible area or both of them are obtained on the basis of a part or all of the routes included in the area, and they are displayed on the display device 3. The extent of the area is determined by taking the errors of the locator into consideration. With respect to the contents displayed on the screen of the display device 3, a travelling locus up to the present position, a travelling direction and the like may be displayed thereon in addition to the aforesaid display items. In Fig.4, an arrow 27 indicates the travelling direction. The data displayed on the screen of the display device 3 is designed so that it can be visually confirmed well. Fig.5 shows an example of the design concerning the displayed data, wherein a numeral 28 designates the travelling direction. Furthermore, in the display screen, an image to be displayed may be processed so that the upward direction of the image always coincides with the travelling direction. In this case, the image on the screen is subjected to a rotation processing. Since the displayed routes are difficult to be visually confirmed in the area where a lot of routes are available, the present position, the travelling locus, the travelling direction and the like are preferably displayed by changing the color or the kind of lines. With respect to the display on the screen of the display device 3, a map may be displayed in the possible area or the entire screen as background information in such a degree that the display of the possible routes, possible area and the like does not become obscure, in order to improve the visual Interest of the displayed content. Furthermore, the possible routes and the possible area may be displayed by using thick lines or colors to improve the clarity thereof. Fig.3 shows an example displayed on the screen of the display device 3. On the display screen 3a, a numeral 21 designates a point indicating the present position of the automobile; a numeral 22 designates a point indicating the destination; and numerals 23 and 24 designate the possible routes existing between the present position and the destination. In this example, the two possible routes are displayed. In the function executed by the calculation/retrieval means 5 to determine the two or more possible routes, it is usually preferable to obtain all the possible routes. However, when there may be many appropriate possible routes between the present position and the destination, it is preferable to select the suitable number of possible routes which are suited for display by adding conditions for selecting. The conditions for the selection includes, for example, a condition for selecting possible routes along which the destination can be reached in a shorter time; a condition for selecting possible routes along which the destination can be reached in a shorter distance; a condition for selecting possible routes along which the destination can be reached by turning to the right and left less times. These conditions can be arbitrarily combined by giving them priority. Also, it is preferable to select the routes which do not have a directional regulation or other regulation as the possible routes. Furthermore, when determing the possible routes in the renewal of them, there may be only one possible route. In this case, the display of the possible route on the display device 3 is identical with that effected by the route-guiding type navigation apparatus. Therefore, the display before the renewal is maintained. Furthermore, when the only one possible route is a route where it is not required to turn right or left, or a route which has a less complicated traffic condition, or a route which does not cause danger at a crossing point where the automobile must be turned right or left because the locator 7 has a smaller amount of error, this route may be displayed by the renewal. When information of jamming and traffic accident in a road is obtained, a possible route is selected in view of the information into consideration. When such information is not obtained, a usual required time is used. Unless the present position of the automobile does not reach the destination, the present position is changed as the automobile travels. When the present position is changed, the possible routes must be determined between a new present position and the destination. Thus, as shown in Fig. 2, it is determined at step 15 whether the present position of the automobile coincides with the destination. In this determining operation, the processing means 4 fetches the present position of the automobile measured by the locator 7 and determines whether this present position coincides with the previously set destination. When the present position does not coincide with the destination at step 15, the process returns to step 12 at which a new present position from the locator 7 is supplied to the processing means 4. At next step 13, possible routes are calculated/retrieved between the new present position and the destination. Then, the retrieved new possible routes are displayed on the screen of the display device 3 and the possible routes on the screen are renewed at step 14. When new possible routes are not retrieved, the possible routes on the screen are not renewed and maintained as they are. So long as the present position of the automobile does not coincide with the destination, steps 12 to 15 are repeated, and when the present position coincides with the destination, the operation of the navigation is completed. The arrangement and the operation of the above navigation apparatus may be modified as described below. In calculating/retrieving possible routes at step 13, a route connecting between the possible routes may be also calculated/retrieved in addition. In this case, a connection route operation means is realized by the processing means 4 and the calculation/retrieval means 5. The connection route is supplied to the display device 3 together with the possible routes and the like and displayed on the screen thereof. A route 25 shown by a dot-dash line in Fig. 3 shows a connecting route between the possible routes 23 and 24. When a plurality of possible routes, connection routes, regulated routes are to be displayed on the screen of the display device 3, they are preferably displayed by changing the color or the kind of lines. When a travelling direction is regulated at many places, or available routes are few, or routes are complicated, in the area adjacent to the destination, it is preferable to prepare the data for first routes leading to the destination and for second routes for allowing the first routes to access to a main route and store the first and second data in the memory device 6 so that the data can be arbitrarily retrieved, or to determine the first and second data by the calculation effected by the processing means 4. This processing is carried out at step 13. The obtained routes are displayed on the screen of the display device 3 together with the possible routes and the connection routes. Both of the present position 21 of the automobile and the destination 22 to be reached are displayed on the screen of the display device 3, as described above. In order to display the present position and the destination on the single screen, an area including both of them must be determined by calculation. This calculation is performed by the processing means 4 and includes, for example, a method of calculating a line segment connecting the present position to the destination and calculating an area to which this line segment belongs; and a method of calculating an area including the coordinate values of the X-axis and Y-axis of both the present position and the destination as an upper limit value and lower limit value. Furthermore, with respect to the present position and the destination on the display screen, it is also possible that both present position and destination are displayed in a wide area and the wide area is divided into four segments for example, or a segment as large as the segment divided into the one fourth portion is established at the center of the wide area, numbers are allocated to the respective segments, and a desired segment specified by a user by using its number is enlarged to the full scale of the screen so that a suitable size of an enlarged display can be obtained by repeating this operation. On the contrary, a display of suitable reduction scale may be performed by reversing the above operation. Furthermore, it is preferable that the processing concerning highways and the like having a specific entrance and exit is different from that concerning usual roads, and that the respective possible routes and the like are independently determined. Since the shape of the highways is simple, no problem is arisen even if the route-guiding system is employed. According to the present invention arranged as described above, the following effects can be obtained. When the present position and the destination of the moving object such as an automobile are input, the two outermost possible routes along which the moving object starting from the present position can reach the destination are displayed on the screen of the display device, and thus the destination can be securely reached on the basis of the plural possible routes used for driving or travelling. In this case, since the two outermost possible routes are displayed for guidance, the driver need not strictly follow to one route. Furthermore, even if a route with a directional regulation, which imposes a heavy load on a computer for performing navigation control, is not contained in possible routes, the driver may use the route with the directional regulation by travelling from one possible route to another possible route based on his arbitrary decision at a field, and thus the driver can utilize the navigation apparatus with a light heart. Furthermore, one of the two outermost possible routes can be selected by the driver who determines the actual conditions of the routes and thus this system includes convenience satisfying the psychological state of the driver. In the arrangement that connecting routes are displayed between a plurality of possible routes, the possible routes can be easily changed and thus a freedom of drive can be increased to the driver. Furthermore, in the arrangement according to the invention that the possible area is displayed, since the destination can be reached so long as the moving object travels within the area and information for guiding the driver to the destination is given in the form of the area, a stress given to the driver is considerably reduced. Since the possible area is not displayed as a map but as a figure, not only a load is not imposed on the driver when visually confirming the figure but also a display on a window shield (HUD) is made possible. As described above, the psychological burden to the driver that there is a possibility that he may be dropped out from a guided route can be reduced. Since the present position of the moving object need not be matched to a route along which the moving object travels in the screen, the mental burden of the driver to the navigation system and designation is reduced as well as a degree of attention of the driver paid to the screen is eased and thus a more safe drive can be ensured. Furthermore, errors of the locator which have been said to be fatal to the navigation apparatus is allowed and even if the present position of the moving object is not strictly measured, the possible routes and the possible area can be presented, and thus a system having a high practical applicability can be realized. Since the guidance made by navigation is not concentrated to a less number of limited routes, a problem of jamming can be solved to enable routes to be effectively used. INDUSTRIAL APPLICABILITY The navigation system is used for a moving object such as an automobile for the purpose of the solution of the problem of accuracy errors of a locator, reduction of the driving stress of a driver to thereby enable the driver to perform driving with safe, increase of the efficiency of routes by preventing the concentrated use of particular routes, and easing of jamming.

Claims: A navigation apparatus mounted on a moving object and including a central processing section (2), an input section (1) for inputting the present position (21) and the destination (22) of said moving object to said central processing section (2), a memory section (6) and a display section (3), said central processing section (2) comprising a possible route operation means for determining two or more possible routes (23, 24) along which said moving object can reach the destination (22) by using map data stored in said memory section (6), and for driving said display section (3) so that the present position (21) and the destination (22) are indicated on the screen of said display section (3) when the present position (21) and the destination (22) of said moving object are provided, characterized in that said central processing section (2) includes a possible area operation means (4, 5) for determining a possible area (26) defined as a closed area enclosed by the outermost two of said possible routes (23, 24), said possible area (26) being indicated on said display section (3) visually well confirmable, together with at least said two outermost possible routes (23, 24) as the boundaries of said possible area (26). A navigation apparatus according to claim 1, wherein said possible routes (23, 24) and said possible area (26) are displayed by using thick lines or colors. A navigation apparatus according to claim 1 or 2, wherein said central processing section (2) includes a connection route operation means for determining a connection route (25) for connecting between said two or more possible routes (23, 24), said connection route (25) being indicated on said display section (3). A navigation apparatus according to any preceding claim, wherein the present position (21) of said moving object is treated as a point contained in an area having a predetermined extent and said possible routes (23, 24) are determined by using a route contained in said area as a starting point. A navigation apparatus according to claim 4, wherein said possible area (26) is determined by using a route contained in said area as a starting point. A navigation method comprising the steps of: producing two or more possible routes (23, 24) for making a moving object reach a destination (22) from a present position (21) by using prepared map data when the present position (21) and the destination (22) are provided; and presenting the present position (21) and the destination (22) to a user, characterized by the steps of: determining a possible area (26) defined as a closed area enclosed by the outermost two of said possible routes (23, 24); and presenting said possible area (26) visually well confirmable to the user, together with at least said outermost possible routes (23, 24) as the boundaries of said possible area (26). A navigation method according to claim 6, wherein said two or more possible routes (23, 24) and said possible area (26) are presented by using thick lines and colors. A navigation method according to the claim 6 or 7, further comprising the steps of: determining a connection route (25) for connecting between said two or more possible routes (23, 24) ; and presenting said connection route (25) together with said possible routes (23, 24) to the user. A navigation method according to any of claims 6 to 8, wherein the present position (21) of said moving object is treated as a point contained in an area having a predetermined extent and said possible routes (23, 24) are determined by using a route contained in the area as a starting point. A navigation method according to claim 9, wherein said possible area (26) is determined by using a route contained in the area as a starting point. A navigation method according to any of claims 6 to 10, wherein a possible area (26) is determined and displayed on the basis of an initial position of said moving object, said possible area (26) being maintained on the screen even if the position of said moving object is changed. A navigation method according to claim 11, wherein said possible area (26) is renewed by operating said input section (1).

Inventors: TSUYUKI TOSHIO, TSUYUKI, TOSHIO
Applicants: TSUYUKI TOSHIO, TSUYUKI, TOSHIO
Application year: 1992
Main classification: G01C21
IPC codes: G01C21, G08G1