JPH0820264B2 - Navigation device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a navigation system that allows a vehicle or the like to move accurately and efficiently.

Conventional example and its problems Conventionally, as the information prepared as map information, information that is stored in a raster scan image of a map that is used daily, or that that is approximated by a polygonal line, or a road distance and a branch point (intersection) Etc.) was to memorize the branch angle. As a method for determining the position, the estimated position (X, Y) on the map is calculated from the course and the traveling distance on the assumption that the departure point has been confirmed, or there is a branch point after traveling a predetermined distance. It was assumed that which branch was selected based on the course change in the vicinity. The former requires considerable arithmetic processing to compare the relationship between the raster scan image information and the course, travel distance, or estimated position (X, Y) on the map and determine the position, which simplifies the device. Was hindering The latter solves the above problem, but since the position is fixed only at the branch point, if there is no course change at the branch point for several km, the branch point may be erroneous due to the accumulation of the measurement error of the road distance. appear. In addition, in any of the methods, there is a common drawback in that it is considerably difficult to determine the position when the position is missed.

Example of the Present Invention In order to solve the above problems, the present invention introduces the following ideas.

1. When a function (f) that represents information that changes according to the movement of a moving body, a map (G (f)) of the function (f) by all useful maps (G) is converted into a map (map information). )
Is defined.

2. The function (f) is constantly detected in a predetermined cycle according to the movement of the moving body, and converted by the mapping (G). The map is described in the format corresponding to the mapping (G) at the predetermined cycle or a predetermined cycle different from the predetermined cycle.

3. The map (G) has a filter characteristic, grasps the movement information of the moving body from the viewpoint according to the frequency characteristic of the filter, and records it as map information on the recording medium.

This proposal assumes the following as a function that changes according to the movement of the moving body.

1, a function having variables of the detected amount of the acceleration detector of the moving body and the operating amount of the moving mechanism used for traveling 2, a variable of the detected amount of the magnetic course detection device of the moving body, and the operating amount of the moving mechanism used for traveling Function 3, the detection amount detected by the radio wave label detection device of the moving body, and the function 4 having the operating amount of the moving mechanism used for traveling as variables, the operating amount of the moving mechanism used for changing the course of the moving body and the moving mechanism Functions whose variables are actuation quantities are not necessarily required to be used alone and can be used while compensating each other for their advantages and disadvantages.

 The following examples will be described below.

1. Regarding the map, set a trajectory that is considered as the movement path of the standard moving body on the map of the Geographical Survey Institute (1 / 2,500), and draw and measure the azimuth at every 52.083 cm (latitude 1/3600 second of latitude) along the road. As data, the method of creating map information and the description format will be explained in sequence.

2. As the movement information, the road distance traveled is 8.6806 (latitude 21
The detection by the acceleration detector and the magnetic course detector for every 1/600 second) cm, the information processing method, and the storage format in the running information storage device will be described.

3. The position determination of the moving body and the movement tracking operation are performed by the moving mechanism of the moving body (the mechanism for changing the course and the mechanism for running).
It will be explained based on the driving information.

First, a recording medium such as map information (hereinafter, also referred to as a map) will be described.

 Maps are classified into the following three types.

(1) National map, (2) Prefecture map, (3) City map Also, the map consists of the following four parts.

(1) Index part, (2) Scenario part, (3) Relative display map information part, (4) Absolute display map information part Explanation of the index part The map is subdivided sequentially and expressed as follows.

(1) country, (2) prefecture, (3) city, (4) town, chome (area of similar size), (5) address (area of similar size), (6) arc ( Directional road), (7) (Area about the size of a single household), (8) Node (intersection) The position on the map indicates the name of each area or the video display screen. It is specified by Area (street address, indicated by multiple points (arc, issue, node)
A representative point is set in each area (town, city, etc.) and is specified by the representative point. A code indicating the subdivision level, a latitude and longitude indicating a representative point, area name patterning information, area name pronunciation information, and a scenario search address are associated with the name of each area.

Description of the scenario part The scenario is specified with the scenario search address of the current location as the upper address and the scenario search address of the destination as the middle address. Lower address (up to 8 bits)
Indicates an address within one scenario (up to 256 bytes).

As mentioned above, scenarios are identified by arcs, numbers (eg, city hall, post office, apartment building, single-family house, etc.) or two locations indicated by nodes. One scenario consists of 32 bytes and a maximum of 256 bytes. Absolute storage type (resolution code B, absolute storage address X, Y, resolution code F, display range (x, y), display type), relative storage type (relative Memory address X, Y), route display formula (starting position (current position) address, traveling direction, branching position address 1, 2, 3, 4, ... N, destination position address) are described. The video display screen is directly controlled by absolute storage. The lower screen is displayed by the resolution B, the absolute storage address indicating the unit area displayed in the approximate center of the screen, and the upper screen is displayed by the resolution F, the display range (x, y), and the display type. Also, the display of the upper screen is at the specified resolution,
The predetermined unit areas are sequentially reproduced in accordance with the movement of the moving body so that the moving body position is displayed in the center.

 The relative display map information will be explained.

Relative display map information part is all sectors (512 bytes)
Comprised of units, resolution, subroutine level, storage address X, Y, unit area address x, y, direction, direction change speed, direction change acceleration, bandpass direction change speed, bandpass direction change acceleration, bandpass displacement distance,
Branch SYNC, branch destination unit area and area address,
The traveling pattern selection code, the character / graphic pattern selection code, the announcement selection code, and the incorrect memory detection code in the map information memory are described.

Next, the unit area address x, y of each resolution, azimuth, azimuth change speed, azimuth change acceleration, bandpass azimuth change speed,
The method of calculating the bandpass azimuth change acceleration and the bandpass displacement distance is described.

As described above, a trajectory regarded as a standard travel route is set on the map, and the azimuth (C) is plotted and measured at every 50,083 cm of the travel route, and two rows of C columns arranged in the order of travel route are arranged. Apply digital filters F _A and F _B sequentially F ₁ C = F _A C, F ₂ C
= F _B (F ₁ C), F ₃ C = F _B (F ₁ C), F ₄ C = F _B (F ₂ C), F ₅ C =
F _B (F ₃ C), F ₆ C = F _B (F ₄ C), 5m, 30m, 300m, 1.
The azimuth of each resolution is 8km and 18km.

The digital filters F _A and F _B are represented by the following equation.

F _A C _I = (1 * C _I-5 + 3 * C _I-4 + 8 * C _I-3 + 13 * C _I-2 + 15 * C _I-1 + 16 * C _I + 15 * C _{I + 1} + 13 * C _{I +2} + 8 * C _{I + 3} + 3 * C _{I + 4} + 1 * C _{I + 5} ) / 96 F _B C _I = (1 * C _I-59 + 2 * C _I-58 + 3 * C _I-57 + ...・ ・ ＋ N * C _{I-60 + N} ＋ ・ ・ ・ ＋ 119 ＊ C _{I +} 59/3600 The direction change speed is expressed by the following formula.

FC _I ′ = FC _I-1 −FC _I (F indicates F _A or F _B. ) Band pass direction change speed is expressed by the following equation.

B _N C _I ′ = F _N-1 C _I −F _N C _I Direction change acceleration is expressed by the following equation.

FC _I ″ = FC _I-1 ′ + FC _I ′ (F indicates F _A or F _B. ) Band pass direction change acceleration is expressed by the following equation.

B _N C _I ″ = F _N-1 C _I ″ + F _N C _I ″ The unit area address (x _CN , y _CN ) is expressed by the following formula.

Y = ΣD _N * sin (F _N-1 C-F _N C) X = ΣD _N * cos (F _N-1 C-F _N C) y _CN = Y-INT (Y / 60) x _CN = X- INT (X / 60) Bandpass displacement distance is expressed by the following equation.

A _N = K * A _N-1 + Σsin (F _N-1 C−F _N C) K is a real number satisfying K <1, for example, 0.95.

Addresses within a unit area such as azimuth, azimuth change speed, azimuth change acceleration, displacement distance, etc. are recorded in a cycle for each predetermined distance of D _N represented by the following equation.

D _N = D _N-1 * cos (F _N-1 C-F _N C) Next, the absolute display map information section will be described.

The path pattern of the absolute display map of each resolution is created in a format corresponding to the latitude Y and the longitude X calculated by the above equation.

The absolute display map information section is divided into unit area pattern display, running pattern display, character / graphic pattern display, and video memory format description, all sectors (512 bytes)
Composed of units.

The unit area pattern display includes resolution, description content code, display color code, storage addresses X and Y, mis-detection code for erroneous storage in video memory in map information memory, unit area map latitude / longitude, corresponding lower resolution section recording start address, The magnification code, magnetic needle orientation deviation, map information memory storage address, unit area true latitude / longitude, and unit area display pattern are described.

Resolution, display color code,
Memory address, error detection code in map information memory,
Twenty-five unit area storage addresses, video memory erroneous storage detection codes, selection codes, and twenty-five traveling display patterns are described.

The character graphic pattern display includes resolution, display color code, memory content code, memory address, map information memory incorrect memory detection code, 25 unit area memory addresses, video memory incorrect memory detection code, magnification code,
And 25 character graphic patterns are listed.

The format content description for the video memory includes resolution, description content code, storage address, map information memory incorrect memory detection code, video memory incorrect memory detection code, running pattern or character / graphic pattern selection code.

 Next, the route display device will be described.

The route instruction device is a traveling information processing unit that processes traveling information and stores it in a traveling information memory in a predetermined format, a traveling information memory unit that stores traveling information and feature matching degree, a traveling information memory, a traveling information and map information memory. A feature tracking device that compares the direction change speed and direction change acceleration of the map information and determines the position and tracks the feature while storing the feature matching degree in the running information memory, the direction of the running information in the running information memory and the map information in the map information memory. Relative tracking device that tracks the position by comparing, the traveling pattern to be displayed, the selection code of the character / graphic pattern and the mobile body position are sequentially transmitted to the map information control unit to calculate various correction coefficients and transmitted to the traveling information processing unit, The movement information of the moving body is compared with the travel information in the travel information memory and the latitude and longitude information of the map information in the map information memory, even when not indicated on the relative display. Absolute tracking device for tailing, map information memory for storing map information of recording medium, traveling pattern to be displayed from relative tracking device, selective transmission from map information memory to video memory by selection code of character / graphic pattern, and mobile unit The information to be stored is confirmed by the map information storage address corresponding to the position, and the corresponding resolution section recording start address is used to selectively store the map information memory from the reproduction information of the map information recording medium according to the storage address. Map information control unit that sequentially stores map information in the map information memory and video memory according to the scenario of the department, and the mis-memorization that detects the mis-memorization of the map information memory and the video memory and transmits the mis-memorized information to the map information control unit Detection device, specified scenario, message, route guidance, syn Oh like memory unit, corresponding video signal display patterns on the display color codes, red, blue and green each 2 bits, and the display color control unit for converting the overlay 2 bits.

 Next, a detailed description will be given with reference to the drawings.

FIG. 1 is a block diagram of a main part of the traveling route indicating device. The traveling information processing unit counts down the detected traveling information to about 1/256 of the pulse P _d from the device that generates the number of pulses proportional to the operation amount of the moving mechanism used for traveling by the programmable counter. Approx.8.6806c
Generate a sample pulse every m. Magnetic needle direction C _M , course change acceleration C ″, and operation amount of movement mechanism used for course change
C _{a and the} like are sampled by the sample pulse, sequentially filtered by two kinds of digital filters, and the azimuth, azimuth change speed, azimuth change acceleration, bandpass azimuth change speed, bandpass azimuth change acceleration are processed in the same manner as in the above processing. , Latitude, longitude, unit area address x _CN , y _CN , recording cycle and bandpass direction change speed level are calculated and stored in the travel information memory. The magnetic head direction correction, course change operation amount correction, and sampling cycle correction (program counter setting) are performed based on the azimuth error, latitude / longitude error, and their sampling cycle error corresponding to the position determined by the relative tracking device to be described later, and the optimum correction is always made. Calculate and store the coefficient.

The feature tracking device functions as a position determination device when the position is not determined, and as a tracking confirmation device when the position is determined. FC ', FC ", BC', BC", AC 'of each resolution are sequentially read from the traveling information memory, and if the position is not fixed by the relative tracking device, FC', FC of each resolution in the map information memory ″, B
A matching position is searched for as a combination of C ′, BC ″ and AC ′, and if there is no match with all the traveling information in the map information memory, new map information is stored in the map information memory and the above operation is repeated. If a matching position is found, the positions are sequentially compared and tracked according to the travel route of the map information in descending order of matching degree. If tracking is possible, the tracking position is transmitted to the relative tracking device. Then, the new map information is stored in the map information memory and the above operation is repeated.If the position is fixed by the relative tracking device, the tracking of the fixed position is sequentially confirmed according to the tracking of the relative tracking device, and the tracking is impossible. If there is a feature tracking operation within the range of the map information stored in the map information memory and the position can be determined, the tracking position is transmitted to the relative tracking device.

Relative tracking device, traveling information corresponding to the tracking position from the feature tracking device FC _S, the difference a correction coefficient map information FC _T (delta
Determine the C), map information FC _T by true bearing FC = FC _S -ΔC
To track. If tracking is impossible, the above operation is repeated according to the newly transmitted characteristic tracking position. When tracking becomes impossible during relative tracking, tracking by the absolute tracking device is started.

The absolute tracking device calculates the latitude Y and longitude X from the true azimuth FC while the relative tracking is possible, and confirms and corrects the relative tracking position according to the tracking of the relative tracking device, and corrects when the relative tracking becomes impossible. And stop by dead reckoning for latitude Y and longitude X
Is calculated and compared with the pattern of the arc node and the movable area of the absolute display section in the map information memory, and when it is located in the area, the latitude Y and the longitude X indicated by the position are detected, and the position is determined by the relative tracking device. Is confirmed, and the position is fixed by the relative tracking or the characteristic tracking device according to the subsequent process.

When the current location is unknown, the map information control unit controls the map information according to the determination made by each of the tracking devices. When the destination is unknown (hereinafter referred to as free running), relative display and absolute display map information is reproduced from the map information recording medium according to the movement of the mobile body and sequentially stored in the map information memory. If the current location and the destination are clear, the scenario is specified, and the map information control unit controls the map information according to the description of the scenario according to the movement of the mobile body. Absolute display map information stored in the video memory, by the description of the absolute memory type,
The relative display map information stored in the map information memory is controlled by the description of the relative storage type. The traveling pattern and the character / graphic pattern are sequentially displayed by the traveling pattern and the character / graphic pattern selection code described in the relative display map section according to the tracking by the relative tracking or the like.

The device for detecting an erroneous memory in the map information memory uses a sector (512
The CRC error check code written in byte units detects erroneous memory, and the memory address detects unmemory, and transmits it to the map information control unit.

The error memory detection device in the video memory detects the error memory by the CRC error check code written in the sector (512 bytes) unit and detects the unmemory by the memory address and transmits it to the map information control unit. The running pattern and character / figure pattern are detected as unmemorized by the CRC error check code written in the format in the video memory, and during sequential display in the sector, unmemorized by the running pattern and character / figure pattern selection code are detected and the map information is displayed. To transmit.

The display color unit generates a video signal according to each display color code and each display pattern stored in the video memory.

In the announcement memory, the announcement information reproduced from the recording medium is stored together with the announcement information selection code, and according to the tracking by relative tracking, etc., the announcement information is selectively transmitted to the announcement device by the announcement information selection code written on the relative display map. To do.

The announcement memory false memory detection device has 128 sectors (6
The CRC code described in units of 4 Kbytes) is used to detect mis-memorization of the announcement information and transmit it to the map information control unit using the CRC code described.

Next, a specific example of the optimum route instruction device configured in a small scale will be described in more detail together with the details of the map information description format.

The various memories (driving information memory, map information memory, video memory, scenario memory, announcement memory) are configured by one memory device, and the traveling information processing unit, each tracking device, map information control unit, and each erroneous memory detection The device is composed of one information processing device.

The memory device is composed of eight 256K * 4 bit memory chips (1M bytes), and has a video display storage unit (address 00000 to 2FFFF) and an absolute display storage unit (address 30).
000 to 3FFFF), relative display storage units 1, 2, 3, 4 (addresses 40000 to BFFFF), running information storage unit (address C000)
0 to DFFFF), scenario storage (addresses E0000 to E)
3FFF), place name pattern storage unit (E4000 to E7FFF), place name announcement storage unit (addresses E8000 to EFFFF), and fixed phrase storage unit (addresses F0000 to FFFFF).

 Each storage unit will be described sequentially.

Video display storage unit is a 48-unit area (192 Kbytes) *
It consists of a 4-bit * 2 screen, and what is displayed on the video display device is 480 horizontal dots and 360 vertical dots. Each screen is controlled according to the absolute memory type and the path display type during scenario travel, and is controlled according to the movement of the moving body during free travel. The pattern display mode is a mode that expresses 60 dots * 60 dots (picture, arc node, movable range, area, target display mode) and a mode that expresses 12 dots * 12 dots (running pattern, character / graphic display Mode), and the 62-byte format content storage mode is stored in the format content description section corresponding to each unit area in the video memory.

The relative display storage unit is composed of four storage units (512 Kbytes), and each storage unit is controlled according to the relative storage type during scenario traveling and controlled according to the movement of the moving body during free traveling. . The relative display map information part of the recording medium is 12
It is reproduced from the recording medium in units of 8 Kbytes and stored in the relative display storage unit.

1.8K including each unit area of each mode of 30m, 5m, 50cm and 300m mode area corresponding to a quarter of the area represented by the unit area of 300m mode resolution on the national map
Each unit area of m, 18Km, 108Km mode is described in 128K bytes.

In each prefecture map, 300m, 1,8Km, 18Km, 108K including each mode area of 5m, 50cm and 30m mode corresponding to the area represented by the unit area of resolution 30m mode
m Each unit area of each mode is described in 128K bytes.

30m, 300m, 1.8Km, 18K including each 50m mode unit area and the 5m mode area corresponding to a quarter of the area represented by the unit area of resolution 5m mode on each city map
Each unit area for m and 108Km modes is described in 128K bytes.

The driving information storage unit is 256 units (1 unit is 512 bytes)
And data calculated by the traveling information processing unit (50 cm mode 30 samples, 5 m mode 15 samples, 30
m, 300m, 1.8Km, 18Km, 108Km each mode 1 sample)
Are sequentially stored for each unit. One sample is composed of 8 bytes, and the stored contents are in the same format as the relative display map information part of the recording medium, and are in the unit area address, direction, direction change speed, direction change acceleration, band pass direction change speed, band pass The azimuth change acceleration and the bandpass displacement distance are stored.

The scenario storage unit stores the scenario of the recording medium specified by the current location and the destination together with the CRC code.

The place name pattern storage unit stores the place name pattern data together with the storage addresses X and Y and the selection code.

The place name announcement storage unit stores place name announcement data together with storage addresses X, Y, a selection code, and a CRC code.

The fixed phrase storage unit stores the fixed phrase data in the selection code and CR.
Store with C code.

Next, the description format of the relative display map information and the operation of each tracking device will be described in detail.

It can be said that the relative display map information is a kind of so-called Neumai-type stored program in which work procedures are sequentially described when the viewpoint is changed. This program is composed of innumerable two conditional branches and arithmetic conditional branches, a large number of conditional multi-branches, simple JUMP, image display command, and voice display command, and the scenario describes conditions of various display commands. Further, the displayed image information and audio information are recorded in a predetermined format, reproduced from the recording medium by the program, and displayed as images and audio. The difference between a computer running the program and an ordinary computer is a program counter.
The computer progresses the processing of the program according to the operation amount of the moving device provided for traveling of the moving body. The processing of the program includes the traveling information including the data processed by the traveling information processing unit and the map information condition data. Data correlation sets the speed and identifies the processing statement. In this program, it is not determined from which statement to start processing, and processing can be started from an arbitrary statement. If the approximate position of the moving body is set, the statement is specified by the correlation between the travel data processed by the travel information processing unit and the condition data of the relative display map information corresponding to the approximate position, and the program progresses. Set the speed and proceed the program sequentially. The correlation S is represented by the following equation.

S _I = K * S _I-1 + Σ _M (f _SM −f _TM ) ^{2 A} real number satisfying K <1 is 0.95, for example.

f _SM is each item of traveling data obtained by processing the traveling information f _TM is each item condition data of the map information The program describes the traveling route as follows.
The arc (road that is not an intersection) is described as each item condition data string (8 bytes) in the predetermined cycle. This part indicates the innumerable two-condition branch, and if the condition is satisfied, the two-condition branch processing is similarly performed using the following item condition data.
If the condition is not satisfied, the absolute tracking device sequentially calculates the estimated latitude y and longitude x based on the latitude Y, longitude X and azimuth at the time and the azimuth change after that, and the traveling distance, and then the absolute display map information section can be moved. The latitude Y and the longitude X of the position considered to be located in the area of the area display and the arc node area display are set as the estimated positions, and the travel position is determined based on the subsequent travel information. (Countless number of calculation condition branches) Nodes (intersections) indicate branches other than roads and paths.
NC, each term condition data of that branch is described up to the distance (number of each term condition data) that can be identified by the above correlation equation with other term and condition condition data of the road crossing, and finally JU
Describe the MP destination address (a large number of multi-branches), similarly describe the branches other than the other road paths in turn, and finally describe the SYNC indicating the road path and each item condition data of that path. Further, the relative display map information section divides for each unit area and describes a JUMP destination address (a number of simple branches) to be shifted to the next unit area each time. Further, an image (absolute map information, traveling pattern, character / graphic pattern) display command and voice display command are described at a predetermined position as necessary for display (navigation).

Effect Since the map is created in the same format as the result of performing the predetermined processing on the information that is sequentially detected when moving the moving path of the moving body, information processing on the moving body is facilitated, processing speed is improved, and the device is To be simplified.

By subjecting the travel information to a low-pass filter or a band-pass filter, the characteristics of the travel information according to the characteristics within the pass characteristics can be grasped, and the accuracy and the certainty of position determination can be improved.

By converting the road-movement distance into a predetermined road-distance according to the low-pass filter characteristic, processing such as meandering outside the passing characteristic, changing lanes, and detours becomes easy.

By describing the azimuth change speed or the azimuth change acceleration as each item condition data, it is possible to determine the position and indicate the route without measuring the magnetic azimuth.

As each item condition data, describe the azimuth, azimuth change speed, azimuth change acceleration, low-pass filtered azimuth, azimuth change speed, azimuth change acceleration, bandpass filtered azimuth change speed, azimuth change acceleration, displacement distance, etc. As a result, the position can be determined quickly and accurately.

Accurate and reliable position determination can be performed by so-called dead reckoning navigation by detecting the trajectory corresponding to the azimuth on which a predetermined low-pass filter is applied and correlating with the similarly described absolute display map information.

By sequentially recording the relative display map information and the absolute display map information for each area divided into a predetermined area, necessary information can be sequentially searched and used according to the moving position.

By clearly patterning the movement locus according to the movement of the moving body, recording it together with a predetermined selection code and an address within the unit area, and sequentially reproducing and displaying according to the movement, clear display can be performed at high speed.

Characters and figures corresponding to the movement of the moving body are patterned in advance and recorded together with a predetermined selection code and unit area address, and reproduced sequentially according to the movement, so that clear display can be performed at high speed.

By operating the relative tracking device, absolute tracking device, and characteristic tracking device in series and in parallel, the position is determined from the state where the position is unknown, and when traveling on a path not shown on the map, the position is calculated by dead reckoning navigation. It is possible to realize reliable and accurate navigation that does not require human judgment operation such as relative tracking immediately after returning to the described path area.

[Brief description of drawings]

FIG. 1 is a block diagram of a main part of the traveling route indicating device.

Claims (1)

[Claims] 1. A means for specifying a destination and / or a planned travel route on map information, and a moving body carrying out a predetermined movement when a predetermined destination and / or a predetermined planned travel route are specified. Predetermined first map information displayed when moving a route, and predetermined second map information displayed when the moving body moves a predetermined moving route when a destination and / or a planned moving route is not specified, When the standard moving body moves along the moving path corresponding to the first and second map information, the operation amount of the acceleration detector, the magnetic heading detector, the radio wave signal detector or the moving mechanism for changing the course of the standard moving body. A partial data sequence that is continuous with multiple data of the first data sequence, such as the acceleration data sequence, magnetic course data sequence, two-dimensional coordinate data sequence, or operation amount data sequence that is considered to be detected by the detector, and the moving path of the moving body. An acceleration detector of the moving body when moving, The second data such as the acceleration data string, magnetic heading data string, two-dimensional coordinate data string, or operation amount data string detected by the course detector, the radio wave signal detector or the operation amount detector of the moving mechanism used to change the course. A means for identifying a partial data string of the first data string corresponding to the partial data string of the second data string by correlation of the entire partial data string of the continuous partial data string including the latest data of the data string of , When the first partial data string is identifiable, depending on whether the predetermined destination and / or the predetermined planned travel route is specified, or not, the specified first A navigation device having means for selectively displaying the first and second map information corresponding to a first data string including a partial data string.