JP2006189387A - Navigation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a navigation device capable of realizing a guide easy to be understood, and capable of lowering the possibility of executing an incorrect guide. <P>SOLUTION: The present invention provides a navigation system for conducting the introduction guide up to a destination. The navigation system stores information of landmarks on a map. The navigation system stores also a value of a variable set in every of the landmarks, and a reduction condition for reducing the value in response to a lapse of time, to be correlated each other. When a current position approaches within a prescribed distance from an intersection, the navigation system calculates the present value of the set variable as to the each landmark positioned in the vicinity of the intersection, using the stored variables and reduction conditions. The landmark is selected out of the variable-value calculated landmarks, in response to a level of the calculated value. The guide for the intersection is carried out using the selected landmark. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a navigation device, and more particularly to a navigation device that performs guidance at an intersection using landmarks.

  Navigation devices such as car navigation systems calculate the recommended route from the current position to the set destination, and guide the user to the destination by executing route guidance based on the recommended route. . Such a navigation device displays a current position, a recommended route, and the like on a display in a superimposed manner when a route guidance is executed. When the current position approaches the intersection to be turned, guidance that is easy to understand for the user is executed, such as guiding the direction of turning by voice while displaying an enlarged view of the intersection.

  In the guidance of the intersection, the navigation apparatus performs guidance using landmarks that are present in the vicinity of the intersection so that the user can quickly find the target intersection (intersection to bend). For example, the user can easily find the target intersection by performing voice guidance for landmarks near the intersection, such as “There is OO near”.

Here, when there are multiple landmarks near the intersection, there is no time for guiding all the landmarks, and if too much information is presented, the user will be confused. A landmark used for guidance is selected. That is, priorities are assigned to landmarks in advance, and landmarks to be guided are selected according to the priorities (see, for example, Patent Documents 1 and 2). Specifically, a high priority is set for landmarks such as convenience stores and gas stations that are conspicuously easy for the user to find. As a result, landmarks that are easily noticeable by the user can be used for the guidance of the intersection, so that the effect of the guidance is further increased, that is, guidance that is more easily understood by the user can be performed.
Japanese Patent Laid-Open No. 10-122684 JP 2000-131084 A

  In general, when the map data becomes old after the lapse of time, the landmark recorded in the map data may not actually exist as a result of the landmark being discarded or the name being changed. Here, the more prominent landmarks such as convenience stores and gas stations, the more frequently the stores are changed and the names change. In other words, the more prominent landmarks tend to be more likely not to exist even if they are recorded in the map data. Since the conventional method provides easy-to-understand guidance by assigning high priority to prominent landmarks, in other words, the conventional method does not actually exist because it is discarded or the name is changed. A landmark with a high possibility is given a high priority. Therefore, while the conventional method can provide easy-to-understand guidance while the map data is new, when the map data is old and there are no landmarks to guide, the wrong guidance is always given. It will end up.

  SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a navigation device capable of providing easy-to-understand guidance and reducing the possibility of wrong guidance.

The present invention employs the following configuration in order to solve the above problems. Note that the reference numerals in parentheses and supplementary explanations in this column show the correspondence with the embodiments described later in order to help understanding of the present invention, and do not limit the present invention.
In other words, the first invention is a navigation apparatus that performs guidance guidance to a destination, a landmark storage unit that stores landmark information (landmark attribute information 32) on a map, and a setting for each landmark A variable storage unit that stores a value of a variable to be selected (degree of selection) and a decrease condition (attenuation coefficient) that decreases the value with the passage of time, and a current position approaches a predetermined distance from the intersection A calculation unit that calculates a current value of a variable set for each landmark located in the vicinity of the intersection using the value of the variable stored in the variable storage unit and the decrease condition; and a calculation unit Using each of the landmarks for which the value of the variable is calculated, a selection unit that selects the landmark according to the magnitude of the calculated value, and the landmark selected by the selection unit And a guide unit that performs the guidance of satin.

  In the second invention, the selection unit may select a landmark having the largest calculated value from the landmarks whose variable values are calculated by the calculation unit.

  In the third invention, the selection unit randomly selects a landmark from the respective landmarks for which the value of the variable has been calculated by the calculation unit with a probability corresponding to the calculated value. Also good.

  Moreover, in 4th invention, you may further provide the reference | standard date memory | storage part which memorize | stores the reference | standard date (construction date) set to a landmark. At this time, the decrease condition is a condition for determining the current value of the variable so that the value decreases according to the difference from the reference date to the current date.

  In the fifth invention, the reduction condition may include an attenuation coefficient indicating a value for reducing the value of the variable per unit time. At this time, the calculation unit calculates, as the current value of the variable, a value obtained by subtracting the product of the difference from the reference date to the current date and the attenuation coefficient from the value of the variable stored in the variable storage unit.

  In the sixth invention, the guidance unit may perform voice guidance only for the landmark selected by the selection unit.

  In the seventh invention, the guide unit may display the landmark selected by the selection unit in a manner different from that of the unselected landmark.

  The eighth invention is a program for causing a computer of a navigation device that performs guidance guidance to a destination to be executed. Here, the navigation device includes a landmark storage unit that stores information on landmarks on the map, a value of a variable set for each landmark, and a reduction condition for decreasing the value as time passes. And a variable storage unit for storing the information in association with each other. When the current position approaches the computer within a predetermined distance from the intersection, the program sets each landmark located in the vicinity of the intersection using the variable value and the decrease condition stored in the variable storage unit. A calculation step (step S203) for calculating the current value of the variable being selected, and selecting a landmark according to the magnitude of the calculated value from the landmarks for which the variable value was calculated in the calculation step A selection step (step S205) to be performed, and a guidance step (step S206) to perform guidance guidance for the intersection using the landmark selected by the selection unit are executed.

  According to the present invention, the landmark selected for use in the guidance can be changed with the passage of time. As a result, the landmark selected at a certain point of time differs from the landmark selected after a lapse of time. Here, a landmark A that is easy for the user to find, but highly likely not to exist after time, and a landmark B that is difficult for the user to discover but less likely to not exist even after time has passed. As an example. In the present invention, first, the value of the variable of the landmark A becomes larger than the value of the variable of the landmark B, and then the value of the variable of the landmark B becomes larger than the value of the variable of the landmark A. It is possible to set a decrease condition. Therefore, by setting the reduction condition in this way, guidance guidance is performed using the landmark A when the landmark A is considered to exist, and when the landmark A is no longer present. Guide guidance can be performed using the landmark B. That is, according to the present invention, landmarks used for guidance guidance can be selected in consideration of both the effect of guidance guidance by using conspicuous landmarks and the correctness of information. And the possibility of performing wrong guidance is reduced.

  Hereinafter, a navigation device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the navigation device according to the present embodiment. In FIG. 1, the navigation device includes an input unit 1, a position detection unit 2, a data storage unit 3, an arithmetic processing unit 4, and an output unit 5. The navigation apparatus shown in FIG. 1 calculates a recommended route from a current position to a destination, and guides the user to the destination by executing route guidance based on the recommended route. Further, when the current position approaches the intersection to be bent, the navigation apparatus performs voice guidance using landmarks present in the vicinity of the intersection so that the user can quickly find the intersection to be bent.

  The input unit 1 is a dedicated remote controller for operating the navigation device, a microphone for collecting sound, a mobile phone or a personal digital assistant (PDA) equipped with an IrDA (infrared communication) function. The user sets a destination or performs various navigation operations through operations using the input unit 1. The operation information input to the input unit 1 is transmitted to the arithmetic processing unit 4.

  The position detection unit 2 includes a speed sensor, a gyro sensor, a GPS receiver, and the like. The position detector 2 may be configured by combining two or more of these sensors and receivers. In the present embodiment, the position detection unit 2 includes a speed sensor, a gyro sensor, and a GPS receiver. The speed sensor detects the moving speed of the vehicle, the gyro sensor detects the traveling direction of the vehicle, and the GPS receiver detects the absolute position of the vehicle on the earth. Information detected by these sensors and receivers is input to the arithmetic processing unit 4, and is used for map matching processing for correcting the current position on the road in the arithmetic processing unit 4.

  The data storage unit 3 includes a CD-ROM, DVD-ROM, HDD (hard disk drive), memory, and the like. The data storage unit 3 stores map data 31, landmark attribute information 32, and a selection degree calculation table 33. The map data 31 includes road network data used in processing such as route search, guidance, and map matching in the arithmetic processing unit 4, and background data used when displaying a map. The landmark attribute information 32 includes landmark information on the map of the map data. The selection degree calculation table 33 includes information necessary for calculating the selection degree. The degree of selection is a value that serves as an index for selecting a landmark to be used when performing guidance at an intersection. Details of the landmark attribute information 32 and the selection degree calculation table 33 will be described later. Although not shown, the data storage unit 3 stores, in addition to the above data, search data used for searching for a location when the user sets a destination.

  The arithmetic processing unit 4 includes a route search unit 41, a calculation unit 42, a selection unit 43, and a guide unit 44. The arithmetic processing unit 4 is configured by a CPU that executes a predetermined program. When the predetermined program is executed by the CPU, each of the route search unit 41, the calculation unit 42, the selection unit 43, and the guide unit 44 is executed. Function is realized. The arithmetic processing unit 4 uses the information input from the input unit 1 and the position detection unit 2 and the map data 31 to perform various processes such as a route search process, a map matching process, and a guidance guidance process. The route search process is performed by the route search unit 41 and is a process for obtaining a recommended route from the current position of the vehicle to the destination set by the user using the input unit 1. The map matching process is a process that is performed by the route search unit 41 and corrects the position when the current position of the vehicle deviates from the road based on the information detected by the position detection unit 2. The guidance guidance process is a process that is performed by the guidance unit 44 and performs guidance guidance according to the recommended route obtained in the route search process for the user of the vehicle. In addition, when performing guidance at an intersection, the calculation unit 42 and the selection unit 43 perform a process of selecting landmarks used for guidance from among the landmarks present near the intersection. The “landmark used for guidance” is a landmark whose name is output by voice when guidance guidance is performed by voice, for example. Details of the process of selecting landmarks used for guidance will be described later.

  The output unit 5 includes a display device and a speaker. The output unit 5 outputs an image and sound for performing guidance guidance along the recommended route in accordance with an instruction from the guide unit 44. The display device displays a map, a current position of the vehicle, a recommended route, and the like. From the speaker, for example, a voice for guidance is output such as “About 700m ahead, right at the XX intersection. There is XX bank (name of landmark) nearby”.

  Next, the data structure of the landmark attribute information 32 will be described with reference to FIG. FIG. 2 is a diagram showing an example of the landmark attribute information 32 shown in FIG. The landmark attribute information 32 is created in advance according to the contents of the map data 31 and stored in the data storage unit 3. The landmark attribute information 32 includes information regarding landmarks recorded in the map data 31. Specifically, the landmark attribute information 32 stores an ID, a name, a type, a position, and a building date in association with each landmark recorded in the map data 31.

  The ID is a number assigned to each landmark so that all landmarks recorded in the map data can be uniquely identified. The landmark ID is preferably recorded in association with the intersection information recorded in the road network data. As a result, landmarks existing in the vicinity of an arbitrary intersection can be easily referred to. The name is the name of a landmark facility or the name of a store. The type is a type of landmark, such as “convenience store”, “gas station”, “family restaurant”, “bank”, “school”, “post office”, and the like. The position is position information indicating a position where the landmark exists. The position information may be expressed by an absolute longitude / latitude that can represent an arbitrary position on the earth, or may be expressed by a relative distance from an intersection to which a landmark belongs (intersection associated with an ID). . The construction date is the date on which the landmark facility or structure was constructed. If the landmark is a commercial facility or a store, the date of construction may be the date of commencement of business.

  Next, the data structure of the selection degree calculation table 33 will be described with reference to FIG. FIG. 3 is a diagram showing an example of the selection degree calculation table 33 shown in FIG. Similar to the landmark attribute information 32, the selection degree calculation table 33 is also created in advance according to the contents of the map data 31 and stored in the data storage unit 3. The selection degree calculation table 33 stores an initial selection degree value and an attenuation coefficient in association with each landmark type. The selection degree calculation table 33 is used to calculate the selection degree.

  The selection degree initial value is an initial value of the selection degree. Here, the initial value of the selection degree is set high for the landmark type that is easy for the user to find. For example, it can be said that a user can easily find a landmark having a flashy appearance or a landmark in a conspicuous place. In general, convenience stores and gas stations are easy to find because there are many conspicuous buildings. Therefore, in FIG. 3, the initial value of the selection degree is set high for convenience stores and gas stations. On the other hand, schools and post offices do not have many flashy appearances, and it can be said that they are less noticeable to users than convenience stores and gas stations. Therefore, in FIG. 3, the initial value of the selection degree is set lower for schools and post offices than for convenience stores and gas stations.

  The attenuation coefficient is a value used together with the initial value to calculate the selection degree. The degree of selection is calculated by multiplying the attenuation coefficient by a value that increases with time, and subtracting the multiplied value from the initial value. That is, the attenuation coefficient indicates the degree to which the selection degree becomes smaller as time passes. In other words, the attenuation coefficient is a condition (decrease condition) for decreasing the initial value of the selection degree with the passage of time. In the present embodiment, the attenuation coefficient is set as follows.

  If the map data becomes old after a lapse of time since the map data was created, the landmarks recorded in the map data do not actually exist as a result of the actual landmarks being closed or moved. Sometimes. In FIG. 3, a large attenuation coefficient is set for a type of landmark that is highly likely not to exist. That is, the attenuation coefficient is set larger as the landmark has a lower reliability regarding the existence of the landmark. For example, convenience stores and gas stations are generally closed and replaced frequently, so there is a relatively high possibility that they will not exist. Therefore, in FIG. 3, the attenuation coefficient is set relatively large for convenience stores and gas stations. Schools and post offices, on the other hand, are unlikely to become non-existent because they are unlikely to be closed or relocated. Therefore, in FIG. 3, the attenuation coefficient is set smaller for schools and post offices than for convenience stores and gas stations.

  Note that the initial selection value and the attenuation coefficient shown in FIG. 3 are created in advance using statistical data or the like. In FIG. 3, one initial value of selection degree and an attenuation coefficient are determined for each type of landmark. However, if these values are uniquely determined for each type of landmark, they vary depending on individual landmarks. It can be considered that becomes larger. Therefore, in another embodiment, for each landmark, that is, for each of the landmarks shown in the landmark attribute information 32 shown in FIG. 2, the initial selection value and the attenuation coefficient are stored in association with each other. Also good. Specifically, the items of initial selection value and attenuation coefficient may be provided in the landmark attribute information 32 shown in FIG.

  Next, the processing of the navigation device will be described with reference to FIG. FIG. 4 is a flowchart showing a flow of processing of the navigation device according to the present embodiment. First, in step S101, the route search unit 41 sets a destination. That is, when the user designates the position of the destination by using the input unit 1, the route search unit 41 receives the position designated by the user from the input unit 1 and sets it as the destination. In addition, as a specific designation method of the destination in the input unit 1, a method of searching for and specifying a destination from an address, a zip code, or a telephone number, or directly specifying a destination on a map displayed on the screen There is a way.

  In step S102, the route search unit 41 searches for a route from the current position to the destination set in step S101. That is, a route search from the current position to the destination is performed, and a recommended route from the current position to the destination is calculated. A well-known Dijkstra method is used as a route search algorithm. The route search unit 41 may calculate a recommended route according to the instruction content such as “general road priority” or “high speed priority” from the user, or obtains a plurality of routes at the same time and uses one route as a recommended route. You may let the user choose. If the navigation device can communicate with an external device via a network, the route search process may be performed by the external device without being performed within the navigation device. For example, the navigation device connects to a server on a network using a communication module such as a mobile phone, and transmits the current position and destination position information to the server. The server performs a route search based on the received position information and transmits the searched recommended route to the navigation device. As a result, the navigation device can obtain a recommended route without performing route search processing.

  In step S <b> 103, the route search unit 41 acquires the current position of the vehicle from the position detection unit 2. That is, the position detection unit 2 detects various information on the moving speed, the moving direction, and the longitude / latitude coordinates on the earth by the speed sensor, the gyro sensor, and the GPS receiver. Various types of detected information are input to the route search unit 41. The route search unit 41 performs matching processing on the road network data included in the map data 31 using the various types of input information, and identifies the current position of the vehicle. Information on the recommended route calculated in step S102 and the current position specified in step S103 is passed from the route search unit 41 to the guide unit 44.

  In step S104, the route search unit 41 determines whether or not the current position specified in step S103 is located near the intersection. The determination in step S104 is processing for determining whether to perform guidance guidance at an intersection or guidance guidance at a place other than an intersection. Specifically, the route search unit 41 uses the map data 31 to determine whether or not an intersection exists within a predetermined first distance from the current position. If it is determined in step S104 that there is no intersection within the first distance from the current position, that is, it is determined that the current position is not located near the intersection, the process of step S105 is performed. In step S105, the guide unit 44 performs guidance guidance (other guidance guidance) at a place other than the intersection as necessary. The guide unit 44 obtains information necessary for guidance (intersection name and recommended route information included in the map data) from the route search unit 41, for example, the distance to the next intersection to be turned, Information on the remaining distance to the destination, the estimated arrival time, the entrance / exit of the expressway, and the like are output to the output unit 5. After step S105, the process of step S107 is performed.

  On the other hand, if it is determined in step S104 that an intersection exists within the first distance from the current position, that is, it is determined that the current position is located near the intersection, an intersection guidance process in step S106 is performed. The intersection guidance process is a process for performing guidance guidance at an intersection. Hereinafter, details of the intersection guidance process will be described.

  FIG. 5 is a flowchart showing details of the processing in step S106 shown in FIG. In the intersection guidance process shown in FIG. 5, first, in step S201, landmarks existing near the intersection are specified. The intersection is an intersection that is a guidance target (hereinafter referred to as a target intersection), that is, an intersection that is determined to be located within the first distance from the current position in step S104. Specifically, the route search unit 41 uses the map data 31 to identify landmarks located within a predetermined second distance from the target intersection. Further, the route search unit 41 refers to the landmark attribute information 32 to acquire the specified landmark attribute information (ID, type, date of construction, etc.), and calculates the acquired attribute information. Send to. When there are a plurality of landmarks located within the first distance from the target intersection, the attribute information of each landmark is sent to the calculation unit 42. Referring to FIG. 2 as an example, when landmarks whose ID is 0 and landmarks whose ID is 1 are specified as landmarks located within the first distance from the target intersection, attribute information about these landmarks is specified. Is sent to the calculation unit 42.

  In the present embodiment, landmarks that exist in the vicinity of the target intersection are specified using the position of the target intersection and the position of each landmark. Here, in another embodiment, the intersection and a landmark existing in the vicinity thereof may be associated with each other and stored in the landmark attribute information 32. At this time, in step S201, the landmark associated with the target intersection in the landmark attribute information 32 can be easily specified as a landmark existing in the vicinity of the target intersection.

  In step S <b> 202, the calculation unit 42 acquires from the selection degree calculation table 33 the initial value and the attenuation coefficient of the landmark specified in step S <b> 201. Specifically, the calculation unit 42 specifies the type of the landmark specified in step S201 from the attribute information sent from the route search unit 41 in step S201. Then, an initial selection degree value and an attenuation coefficient are acquired from the selection degree calculation table 33 for the specified landmark type. For example, referring to FIG. 2 and FIG. 3, a case where the attribute information of the landmark whose type is “convenience store” and the attribute information of the landmark whose type is “gas station” is sent from the route search unit 41. Think. In this case, the convenience store selection degree initial value “0.99” and the attenuation coefficient “0.0012” are acquired from the selection degree calculation table 33, and the gas station selection degree initial value “0.9” and the attenuation coefficient are obtained. “0.0005” is acquired from the selection degree calculation table 33. The acquired selection degree initial value and attenuation coefficient are sent to the selection unit 43 in association with landmark attribute information.

In step S203, the calculation unit 42 calculates the current selection degree for each landmark existing in the vicinity of the target intersection. Specifically, the selection degree is calculated using the following equation (1).
(Selection degree) = (Selection degree initial value)-(Number of days from construction date to present) x (Attenuation coefficient) (1)
In Expression (1), the number of days from the date of construction to the present is calculated in advance from the date of construction and the current date included in the landmark attribute information. Here, the unit of the number of days is “day” here. The calculation unit 42 calculates the selection degree for all landmarks present in the vicinity of the target intersection, and sends the calculated selection degree of each landmark to the selection unit 43.

  As can be seen from the above formula (1), the value of the landmark selection degree is a value close to the initial selection degree when the landmark is constructed, and time (number of days) elapses. Decreases as Here, as shown in FIG. 3, as the initial selection value, a large value is set for a type of landmark that is easy for the user to find, such as a convenience store or a gas station. Therefore, at a short time after the construction, the value of the convenience store and the gas station landmark selection degree becomes larger than the value of the post office and school landmark selection degree built at the same time. In addition, as shown in FIG. 3, the attenuation coefficient is set to a relatively large value for convenience stores and gas stations, and relatively small for landmarks such as post offices and schools that are unlikely to exist. Is set. Therefore, after a certain number of days have passed since the landmark was built, the value of the post office or school landmark selection is the same as that of a convenience store or gas station landmark built at the same time. Larger than the value.

  In step S204, the selection unit 43 adjusts the value of the selection degree of each landmark calculated in step S203. Specifically, each selection degree is adjusted so that the sum of the values becomes 1. For example, there are three landmarks associated with the target intersection, and the selection degrees of the three landmarks are A, B, and C, respectively. By defining α = 1 / (A + B + C) and setting A ′ = αA, B ′ = αB, and C ′ = αC, the selection degrees A ′, B ′, and C ′ after adjustment can be calculated. . That is, the selection degrees A, B, and C can be adjusted to A ′, B ′, and C ′ so that A ′ + B ′ + C ′ = 1. Specifically, for example, when A = 0.5, B = 0.3, and C = 0.8, α = 1 / (0.5 + 0.3 + 0.8) = 0.625. The selection degrees A ′, B ′, and C ′ are: A ′ = 0.5 × 0.625, B ′ = 0.3 × 0.625, C ′ = 0.8 × 0.625 = 0.5 It becomes.

  In step S205, the selection unit 43 selects a landmark to be used for guidance from the landmarks specified in step S201 based on the selection degree of each landmark adjusted in step S204. As a landmark selection method in step S205, there is a method in which each selection degree is considered as a value representing a probabilistic selection rate and is randomly selected with a probability according to each selection degree. For example, suppose that there are three landmarks L1, L2, and L3 near the target intersection, and the selection degrees are 0.2, 0.3, and 0.5, respectively. At this time, the landmark L1 is randomly selected with a probability of 20%, the landmark L2 is 30%, and the landmark L3 is 50%. In order to realize this selection method, for example, a random number in a numerical range of 1 to 100 is generated, and if the generated random number is a value from 1 to 20, L1 is generated and a value from 21 to 50 is generated. If L2 is a value between 51 and 100, L3 is selected. In addition, the landmark attribute information selected by the selection unit 43 is sent to the guide unit 44.

  In step S206, the guide unit 44 performs guidance guidance at the target intersection using the landmark selected in step S205. Specifically, the guide unit 44 obtains information (such as intersection name and recommended route information included in the map data) necessary for guidance guidance from the route search unit 41, and from the current position to the target intersection. Information on the distance, the name of the target intersection, the position of the appropriate lane, and the landmark landmark is output to the output unit 5 by voice. For example, the guidance “To the right, about 700m away, turn right at the XX intersection. Please come to the right lane. There is a △△ bank nearby.” Note that various types of information to be output by voice can be obtained from landmark attribute information, map data, or the like. Note that in the guidance guidance in step S206, guiding all landmarks in the vicinity of the target intersection is not sufficient in terms of time for voice output. Also, presenting too much information will only confuse the user. Therefore, in the present embodiment, the landmark that is most effective for the guidance is selected (step S205), and only one selected landmark is used for the guidance (step S206). Upon completion of step S206, the intersection guidance process shown in FIG.

  As described above, in the present embodiment, landmarks are selected from the respective landmarks present in the vicinity of the target intersection with a probability corresponding to the value of the current selection degree, and guided using the selected landmarks. Guidance is provided. Here, as mentioned above, at the time when the landmark was built, the value of the convenience store or gas station landmark selection value is the value of the post office or school landmark built at the same time. It becomes larger than the value of selection. Therefore, at the time when the landmark is just built, there is a high possibility that the landmark of a convenience store or a gas station is used for guidance. On the other hand, after a certain amount of time (days) has passed since the landmark was built, the value of the post office or school landmark selection rate is the same as that of a convenience store or gas station landmark built at the same time. It becomes larger than the value of selection. Therefore, after a certain period of time has elapsed since the landmark was built, there is a high possibility that the landmark of the post office or school will be used for guidance. As described above, in the present embodiment, since the value of the selection degree changes according to the number of days since the landmark was built, the landmark used for guidance guidance changes with the passage of time.

  Returning to the description of FIG. 4, after step S106, the process of step S107 is performed. In step S107, the route search unit 41 determines whether or not the destination has been reached. If it is determined in step S107 that the destination has been reached, the navigation apparatus ends the process shown in FIG. On the other hand, if it is determined in step S107 that the vehicle has not arrived at the destination, the process of step S103 is performed again. Thereafter, the processes in steps S103 to S107 are repeated until the destination is reached.

  As described above, according to the navigation device of the present embodiment, the landmark used for the guidance guidance changes with the passage of time. Here, in order to perform guidance guidance that is easy for the user to understand in guidance guidance at intersections, guidance guidance may be performed using landmarks that are conspicuous and easily noticeable, such as convenience stores and gas stations. In practice, however, the more prominent landmarks are, the more likely they are to disappear due to name changes or closures. Therefore, if the landmark of a convenience store or gas station is always used for guidance only because it is conspicuous, if the landmark does not actually exist, incorrect information will be guided. . As a result, rather than providing easy-to-understand guidance, the user is confused. On the other hand, in order to surely present information without error to the user, it is conceivable to use landmarks of post offices or schools that are relatively few in relocation and closure for guidance. However, always using a post office or school landmark for guidance does not mean that guidance is easy to understand if there is a conspicuous landmark such as a convenience store at the same intersection.

  On the other hand, in the navigation device according to the present embodiment, in a situation where there is a high possibility that a conspicuous landmark exists, that is, in a situation where not much time has passed since the landmark was built, It is used preferentially for guidance. On the other hand, in a situation where there is a low possibility that a conspicuous landmark exists, that is, in a situation where a certain amount of time has elapsed since the landmark was built, a landmark that has a higher probability of being present than a conspicuous landmark is preferentially used. Guidance guidance is provided. As described above, in the present embodiment, landmarks to be used for guidance are selected in consideration of both the effects of guidance by using conspicuous landmarks and the correctness of information. Therefore, it is possible to provide easy-to-understand guidance and reduce the possibility of performing wrong guidance.

  In the present embodiment, the initial value of the selection degree and the attenuation coefficient are used as data for calculating the selection degree. Here, the attenuation coefficient is a condition (decrease condition) for decreasing the initial value of the selection degree with the passage of time. However, in other embodiments, the decrease condition is expressed in a form different from the attenuation coefficient. May be. That is, the value of the selection degree may be calculated so as to decrease with the passage of time, and the data prepared for calculating the selection degree is not limited to the selection degree initial value and the attenuation coefficient. For example, the table shown in FIG. 6 may be used instead of the selection degree calculation table 33. FIG. 6 is a diagram illustrating an example of a table used for calculating the selection degree in another embodiment. In the table shown in FIG. 6, a reduction condition is stored in association with each landmark type. As a decrease condition, the number of years since the date of construction and the value of the selection degree at that time are associated. For example, if the type is a “Convenience Store” landmark, the value of the selection degree is 0.9 when the age since the date of construction is between 0 and 1, and the age since 1 year. The value of the degree of selection is 0.8 for 3 years, and the value of the degree of selection is 0.3 after 3 years. By using a table as shown in FIG. 6, the same effects as in the present embodiment can be obtained.

  In the present embodiment, as a guidance guidance method at an intersection, a method of outputting landmark information by voice has been described as an example, but the guidance guidance method using landmarks is not limited to this. For example, guidance guidance using landmarks may be performed by display. Specifically, the landmark selected for use in the guidance guidance may be displayed in a different display form from the other landmarks. For example, the selected landmark may be enlarged or blinked, or the color may be changed, or only the selected landmark may be displayed and other landmarks may not be displayed. . Further, the display form may be different according to the value of the selection degree.

  Further, in the present embodiment, the building date is stored in the landmark attribute information 32. However, the landmark attribute information 32 may be any date that serves as a reference for calculating the elapsed days for each landmark. New days may be stored. For example, instead of the construction date, the update date of the data of the map data 31 and the landmark attribute information 32 may be stored.

  In the present embodiment, when the map data 31 is updated, the landmark attribute information 32 needs to be updated according to the contents of the map data 31. That is, it is necessary to add / delete the landmark newly added / deleted on the map data also in the landmark attribute information 32. Further, when the data update date is stored in the landmark attribute information 32, the update date is changed according to the update of the map data 31.

  In the present embodiment, when a plurality of landmarks exist near the target intersection, one landmark is selected from the plurality of landmarks with a probability corresponding to the value of the selection degree. Here, in another embodiment, one landmark having the largest selection degree may be selected from a plurality of landmarks. In another embodiment, it is not necessary to select only one of a plurality of landmarks. For example, two having a large selection degree may be selected.

  The navigation apparatus according to the present invention is useful as a navigation apparatus that performs route guidance and the like.

The block diagram which shows the structure of the navigation apparatus which concerns on this embodiment. The figure which shows an example of the landmark attribute information 32 shown in FIG. The figure which shows an example of the selection degree calculation table 33 shown in FIG. The flowchart which shows the flow of a process of the navigation apparatus concerning this embodiment. The flowchart which shows the detail of a process of step S106 shown in FIG. The figure which shows an example of the table used in order to calculate the selection degree in other embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Input part 2 Position detection part 3 Data storage part 31 Map data 32 Landmark attribute information 33 Selection degree calculation table 4 Operation processing part 41 Route search part 42 Calculation part 43 Selection part 44 Guide part 5 Output part

Claims (8)

A navigation device that provides guidance to a destination,
A landmark storage unit for storing information on landmarks on the map;
A variable storage unit that associates and stores a value of a variable set for each landmark and a reduction condition for decreasing the value with the passage of time;
When the current position approaches within a predetermined distance from the intersection, the current value of the variable set for each landmark located in the vicinity of the intersection is determined using the variable value and the decrease condition stored in the variable storage unit. A calculation unit for calculating the value of
A selection unit that selects a landmark according to the size of the calculated value from the landmarks for which the value of the variable has been calculated by the calculation unit;
A navigation device comprising: a guidance unit that guides an intersection using landmarks selected by the selection unit.   The navigation device according to claim 1, wherein the selection unit selects a landmark having the largest calculated value from the landmarks whose variable values are calculated by the calculation unit.   The navigation according to claim 1, wherein the selection unit randomly selects a landmark with a probability according to the magnitude of the calculated value from the landmarks for which the value of the variable has been calculated by the calculation unit. apparatus. A reference date storage unit for storing a reference date set for the landmark;
The navigation device according to claim 1, wherein the decrease condition is a condition for determining a current value of a variable such that the value decreases according to a difference from a reference date to a current date. The decrease condition includes an attenuation coefficient indicating a value for decreasing the value of the variable per unit time,
The calculation unit calculates, as a current value of a variable, a value obtained by subtracting a product of a difference from a reference date to the current date and the attenuation coefficient from a value of a variable stored in the variable storage unit. Item 5. The navigation device according to Item 4.   The navigation device according to claim 1, wherein the guidance unit performs voice guidance only for the landmark selected by the selection unit.   The navigation device according to claim 1, wherein the guide unit displays the landmark selected by the selection unit in a manner different from a landmark that is not selected. A program for causing a computer of a navigation device to perform guidance guidance to a destination,
The navigation device
A landmark storage unit for storing information on landmarks on the map;
A variable storage unit that stores a value of a variable set for each landmark and a reduction condition for reducing the value as time passes,
In the computer,
When the current position approaches within a predetermined distance from the intersection, the current value of the variable set for each landmark located in the vicinity of the intersection is determined using the variable value and the decrease condition stored in the variable storage unit. A calculation step for calculating the value of
A selection step of selecting a landmark according to the magnitude of the calculated value from the landmarks for which the value of the variable has been calculated in the calculation step;
The program which performs the guidance step which performs guidance guidance of an intersection using the landmark selected in the said selection part.

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