JP2010096721A - Navigation system - Google Patents

Abstract

A navigation system capable of presenting an alternative route or giving a warning even in a situation where external information cannot be obtained.
A vehicle information acquisition unit for acquiring a signal relating to a road condition as vehicle information from a vehicle information sensor provided on the vehicle, and road information obtained by adding date and time information to the vehicle information acquired by the vehicle information acquisition unit. A road information storage unit 3b that accumulates sequentially, a current position detection unit 11 that detects a current position, a destination setting unit 12 that sets a destination, and a destination setting unit based on the current position detected by the current position detection unit Route search unit 13 that searches for a route to the destination set in step 1 and route information that calculates the status of the road that forms the route searched by the route search unit based on the road information stored in the road information storage unit The calculating part 19 and the output parts 20 and 21 which output the information which alerts driving | running | working according to the condition of the road calculated by the route information calculating part are provided.
[Selection] Figure 2

Description

  The present invention relates to a navigation system that is mounted on a vehicle and guides a user to a destination, and more particularly to a technology that supports safe driving.

  Conventionally, considering the seasonal information and weather information obtained from VICS (Vehicle Information and Communication System / Registered Trademark: not described below), the road gradient of the route on the map is calculated and a warning message or warning sound is sent to the user. A navigation system for presenting is known.

  For example, Patent Document 1 discloses a navigation system that can guide an optimal travel route that reflects characteristics unique to a vehicle. The navigation system detects a road surface condition of a road on which the host vehicle is traveling based on a vehicle control signal for controlling the host vehicle that is running, and the detected road surface condition and basic map information included in map data And the other information distributed from the information server device outside the host vehicle, another road on which the host vehicle may slip is detected and recognized as an unrunable section.

JP 2006-242901 A

  However, in the navigation system disclosed in Patent Document 1 described above, functions such as alternative route presentation and warning do not operate when external information cannot be obtained. For example, when a mobile phone is used to collect external information, the external information cannot be obtained when traveling outside the range of the mobile phone. As a result, there is a problem that functions such as an alternative route presentation or warning cannot be used.

  The present invention has been made in order to solve the above-described problems, and its task is to provide a navigation system capable of presenting an alternative route or giving a warning even in a situation where external information cannot be obtained. There is to do.

  In order to solve the above problems, a navigation system according to the present invention includes a vehicle information acquisition unit that acquires a signal related to road conditions as vehicle information from a sensor provided in the vehicle, and vehicle information acquired by the vehicle information acquisition unit. A road information storage unit that sequentially accumulates road information with date and time information, a current position detection unit that detects a current position, a destination setting unit that sets a destination, and a current position detected by the current position detection unit Based on the road information stored in the road information storage unit, the route search unit that searches for a route from the destination to the destination set by the destination setting unit and the road conditions that form the route searched by the route search unit A route information calculation unit to be calculated and an output unit to output information for calling attention to traveling according to the road condition calculated by the route information calculation unit.

  According to the navigation system of the present invention, the route searched by the route search unit is formed based on the road information stored in the road information storage unit even when traffic information or traffic jam information from outside cannot be collected. Since it is possible to calculate road conditions and output information that alerts driving according to the calculated road conditions, it is possible to present or warn for alternative routes even in situations where external information cannot be obtained. And so on.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
Embodiment 1 FIG.
FIG. 1 is a block diagram showing a configuration of a navigation system according to Embodiment 1 of the present invention. This navigation system is used by being mounted on a vehicle, and includes a position detection sensor 1a, a vehicle information sensor 1b, an input device 2, a map disk 3, a VICS receiver 4, a display 5, an audio unit 6, a speaker 7, and a navigation ECU (Electronic Control). Unit) (hereinafter abbreviated as “Navi ECU”) 8.

  The position detection sensor 1a includes a GPS (Global Positioning System) receiver, a vehicle speed sensor, an angular velocity sensor, and the like (all not shown). The GPS receiver receives a GPS signal transmitted from a GPS satellite, and detects its current position and current date and time based on the received GPS signal. The current position detected by the GPS receiver is sent to the navigation ECU 8 as a current position signal, and the current date / time is sent to the navigation ECU 8 as a date / time signal.

  The vehicle speed sensor detects the rotation of the wheel and generates a vehicle speed pulse corresponding to the rotation of the wheel. The vehicle speed pulse generated by this vehicle speed sensor is sent to the navigation ECU 8 as a vehicle speed pulse signal. The angular velocity sensor detects a change in the traveling direction of the vehicle. A change in the traveling direction of the vehicle detected by the angular velocity sensor is sent to the navigation ECU 8 as an angular velocity sensor signal.

  The vehicle information sensor 1b includes an outside air temperature sensor, a humidity sensor, a raindrop sensor, a wiper operation sensor, a light operation sensor, a front defogger operation sensor, a rear defogger operation sensor, and the like (all not shown). Signals detected by these sensors are sent to the navigation ECU 8 as vehicle information.

  Specifically, the outside air temperature sensor detects the outside air temperature and sends it to the navigation ECU 8 as an outside air temperature signal. The humidity sensor detects the humidity and sends it to the navigation ECU 8 as a humidity signal. The raindrop sensor detects raindrops due to rainfall and snowfall and sends them to the navigation ECU 8 as raindrop signals.

  The wiper operation sensor detects the presence / absence and speed of the wiper operation, and sends it to the navigation ECU 8 as a wiper operation signal. The light activation sensor detects whether the light is lit and sends it to the navigation ECU 8 as a light activation signal. The front defogger operation sensor detects whether or not the front defogger is in operation, and sends it to the navigation ECU 8 as a front defogger operation signal. The rear defogger operation sensor detects whether or not the rear defogger is operating and sends it to the navigation ECU 8 as a rear defogger operation signal.

  The vehicle information sensor 1b includes a tire information storage unit (not shown) that stores tire information. The tire information includes tire types such as summer tires, studless tires, and chain attachments, and is set in the tire information storage unit in advance by the user. The tire information stored in the tire information storage unit is sent to the navigation ECU 8 as a tire type signal.

  The input device 2 includes, for example, an operation panel, a touch panel, or a voice input device, and is used by a user to give various instructions to the navigation system. A signal generated by operating the input device 2 is sent to the navigation ECU 8 as an input signal.

  The map disk 3 is composed of an HDD (Hard Disk Drive), for example, and includes a map information storage unit 3a and a road information storage unit 3b. Map information is stored in the map information storage unit 3a. The map information includes facility information in addition to road data and road attribute data. The road information storage unit 3b sequentially stores road information obtained by adding date and time to vehicle information and tire information obtained from the vehicle information sensor 1b. The map information and road information stored in the map disk 3 are read out by the navigation ECU 8.

  The map information storage unit 3a of the map disk 3 can be composed of a DVD drive that reproduces information recorded on a DVD (Digital Versatile Disk). In this case, the map information is stored on the DVD loaded in the DVD drive.

  The VICS receiver 4 receives, for example, a signal including traffic information such as whether there is a traffic accident or traffic regulation, and traffic information indicating the degree of traffic. The signal received by the VICS receiver 4 is sent to the navigation ECU 8 as a received signal. A mobile phone can be used instead of the VICS receiver 4. In this case, a signal including traffic information and traffic jam information received by the mobile phone is sent to the navigation ECU 8 as a received signal.

  The display 5 is composed of, for example, a liquid crystal display device, and in accordance with display data sent from the navigation ECU 8, a map, a vehicle position mark, a route to a destination, information for alerting driving, and other various types Display information of. The audio unit 6 converts the audio data sent from the navigation ECU 8 into an analog audio signal and sends it to the speaker 7. The speaker 7 outputs, for example, guidance voice according to the audio signal sent from the audio unit 6.

  The navigation ECU 8 is composed of a microcomputer, for example, and controls the entire navigation system. FIG. 2 is a block diagram showing the functional configuration of the navigation ECU 8 in detail, and each block is realized by software processing that operates on a microcomputer.

  The navigation ECU 8 includes a current position detection unit 11, a destination setting unit 12, a route search unit 13, a traffic information acquisition unit 14, an alternative route search unit 15, a route guidance unit 16, a vehicle information acquisition unit 17, and a tire information acquisition unit 18. , A route information calculation unit 19, a display control unit 20, and an audio output unit 21. In addition, in order to avoid that drawing becomes complicated, the connection between each component is abbreviate | omitted, However, The connection which abbreviate | omitted is demonstrated as needed below.

  The current position detector 11 calculates the current position of the vehicle based on the current position signal acquired from the GPS receiver included in the position detection sensor 1a, the angular velocity sensor signal acquired from the angular velocity sensor, and the vehicle speed pulse signal acquired from the vehicle speed sensor. Further, the current position on the map is determined by collating with the map information read from the map information storage unit 3a of the map disk 3. The current position determined by the current position detection unit 11 is sent to the route search unit 13 and the alternative route search unit 15 as current position data. The date / time signal obtained from the GPS receiver of the position detection sensor 1 a and the vehicle speed pulse signal obtained from the vehicle speed sensor are sent to the route information calculation unit 19.

  The destination setting unit 12 instructs the facility indicated by the facility information included in the map information stored in the map information storage unit 3 a of the map disk 3 by the user operating the input device 2, or on the display 5. The destination is set in response to scrolling the displayed map screen to indicate a desired point. The destination set by the destination setting unit 12 is sent to the route search unit 13 and the alternative route search unit 15 as destination data.

  The route search unit 13 reads the map information read from the map information storage unit 3a of the map disk 3 based on the current position data sent from the current position detection unit 11 and the destination data sent from the destination setting unit. To find the optimal route from the current position to the destination. The optimum route searched by the route search unit 13 is sent to the alternative route search unit 15, the route guide unit 16, and the route information calculation unit 19 as route data.

  The traffic information acquisition unit 14 acquires traffic information and traffic jam information from the reception signal sent from the VICS receiver 4. The information acquired by the traffic information acquisition unit 14 is sent to the alternative route search unit 15 as traffic information.

  When the alternative route search unit 15 can acquire the traffic information and the traffic jam information from the traffic information acquisition unit 14, based on these, the route searched by the route search unit 13 has a traffic accident, traffic regulation, or a traffic jam. Is determined, an alternative route different from the route indicated by the route data sent from the route search unit 13 is searched. In addition, the alternative route search unit 15 receives an instruction from the route information calculation unit 19 that a re-search is necessary, and is different from the route indicated by the route data sent from the route search unit 13. Explore. The alternative route searched by the alternative route search unit 15 is sent to the route guide unit 16 and the route information calculation unit 19 as alternative route data.

  The route guidance unit 16 generates guidance screen data for guiding the optimum route by display based on the route data sent from the route search unit 13 or the alternative route data sent from the alternative route search unit 15. Then, while sending it to the display 5, guidance voice data for guiding the optimum route or alternative route by voice is generated and sent to the voice output unit 21.

  The vehicle information acquisition unit 17 acquires vehicle information from the vehicle information sensor 1 b and sends it to the route information calculation unit 19. Specifically, the vehicle information acquisition unit 17 includes an outside temperature signal from the outside temperature sensor, a humidity signal from the humidity sensor, a raindrop signal from the raindrop sensor, a wiper operation signal from the wiper actuation sensor, and a light from the light actuation sensor. An operation signal, a front defogger operation signal from the front defogger operation sensor, a rear defogger operation signal from the rear defogger operation sensor, and the like are received, and information corresponding to these signals is sent to the route information calculation unit 19 as vehicle information.

  The tire information acquisition unit 18 acquires tire information from the vehicle information sensor 1 b and sends the tire information to the route information calculation unit 19. Specifically, the tire information acquisition unit 18 reads tire information stored in a tire information storage unit (not shown) of the vehicle information sensor 1 b and sends the tire information to the route information calculation unit 19.

  The route information calculation unit 19 periodically sends the vehicle information sent from the vehicle information acquisition unit 17 and the tire information sent from the tire information acquisition unit 18 from the GPS receiver of the position detection sensor 1a. The road information storage unit of the map disk 3 generates date information with date information indicating the date indicated by the date signal, and further generates road information with speed information based on the vehicle speed pulse signal obtained from the vehicle speed sensor of the position detection sensor 1a. Send to 3b. Thereby, road information as shown in FIG. 3 is sequentially accumulated in the road information storage unit 3b. The information corresponding to each sensor of the vehicle information and the tire information are weighted to indicate the degree of danger, and are used to determine whether to present an alternative route, which will be described later, and whether to output a warning. The

  Further, the route information calculation unit 19 indicates the situation of the road that forms the route indicated by the route data sent from the route search unit 13 or the alternative route data sent from the alternative route search unit 15 on the map disk 3. Calculation is based on the road information read from the road information storage unit 3b.

  More specifically, the route information calculation unit 19 checks whether or not the road information storage unit 3b has road information with a date and time that approximates (similar to) the date and time indicated by the date and time signal obtained from the GPS receiver of the position detection sensor 1a. When it is determined that it exists, a value obtained by adding up the weights indicated by the road information stored in the road information storage unit 3b (hereinafter referred to as “old road information”) and the vehicle information acquisition unit 17 are sent. The vehicle information and the weight information indicated by road information (hereinafter referred to as “new road information”) composed of tire information sent from the tire information acquisition unit 18 are compared.

  As a result of this comparison, if the value indicated by the new road information is smaller than the value indicated by the old road information, the risk is judged to be low, and the speed limit indicated by the road data included in the map information is displayed as a safe speed. The data is sent to the control unit 20 and the audio output unit 21. On the other hand, if the value indicated by the new road information is greater than or equal to the value indicated by the old road information, it is determined that the degree of danger is high, and the speed indicated by the speed information of the old road information is used as the safe speed. The data is sent to the output unit 21.

  On the other hand, when the route information calculation unit 19 determines that there is no road information in the road information storage unit 3b that has a date and time approximate to (similar to) the date and time indicated by the date and time signal obtained from the GPS receiver of the position detection sensor 1a. The predetermined value α is compared with the sum of the weights indicated by the new road information including the vehicle information sent from the vehicle information acquisition unit 17 and the tire information sent from the tire information acquisition unit 18.

  As a result of this comparison, if the value indicated by the new road information is smaller than a predetermined value α (for example, “10”), it is determined that the risk is low, and the speed limit indicated by the road data included in the map information is safe. The speed is sent to the display control unit 20 and the audio output unit 21. The route information calculation unit 19 has a high degree of risk when the value indicated by the new road information is equal to or greater than a predetermined value α and smaller than another predetermined value β (for example, “15”, β> α). For example, 2/3 of the speed limit indicated by the road data included in the map information is sent to the display control unit 20 and the audio output unit 21 as a safe speed. In addition, the route information calculation unit 19 determines that the degree of risk is higher when the value indicated by the new road information is equal to or greater than a predetermined value β and smaller than another predetermined value γ (for example, “20”, γ> β). For example, it is determined that the speed is quite high, and, for example, 1/3 of the speed limit indicated by the road data included in the map information is sent to the display control unit 20 and the voice output unit 21 as a safe speed.

  Further, when the value indicated by the new road information is equal to or greater than the predetermined value γ, the route information calculation unit 19 determines that the route cannot be traveled and indicates that a re-search is necessary. 15 and instruct the display control unit 20 to display that the route is an alternative route.

  The display control unit 20 corresponds to the output unit of the present invention, and does not perform a special process when a speed limit is sent from the route information calculation unit 19 as a safe speed. In addition, when the speed indicated by the speed information of the old road information is sent from the route information calculation unit 19 as a safe speed, the display control unit 20 generates a message indicating that the vehicle should travel at that speed and displays the message. Send to 5. In addition, when the speed limit, 2/3 of the speed limit or 1/3 of the speed limit is sent from the route information calculation unit 19 as a safe speed, the display control unit 20 should drive at the safe speed. Is generated and sent to the display 5. As a result, for example, as shown in FIG. 4, a message such as “Safe speed is OO km / h” is displayed on the display 5 on which the route is displayed.

  Further, when instructed by the route information calculation unit 19 to display that it is an alternative route, the display control unit 20 generates a message indicating that it is an alternative route and sends it to the display 5. As a result, for example, as shown in FIG. 5, a message such as “alternative route” is superimposed on the display 5 on which the alternative route is displayed.

  The voice output unit 21 corresponds to the output unit of the present invention, and does not perform any special processing when a speed limit is sent from the route information calculation unit 19 as a safe speed. When the speed indicated by the speed information in the old road information is sent from the route information calculation unit 19 as a safe speed, the voice output unit 21 generates a voice message indicating that the vehicle should run at that speed. Send to audio unit 6. Further, when the speed information, 2/3 of the speed limit or 1/3 of the speed limit is sent from the route information calculation unit 19 as the safe speed, the voice output unit 21 should run at those safe speeds. Is generated and sent to the audio unit 6. As a result, for example, a voice message “safe speed is OO km / h” is output from the speaker 7.

  Further, the voice output unit 21 generates a voice message indicating that it is an alternative route and sends it to the audio unit 6 when it is sent from the route information calculation unit 19 that it is an alternative route. As a result, a voice message such as “alternative route” is output from the speaker 7.

  Next, the operation of the navigation system according to Embodiment 1 of the present invention configured as described above will be described with reference to the flowchart shown in FIG.

  When the operation of the navigation system is started, first, the current position is detected (step ST11). That is, the current position detection unit 11 calculates the current position of the vehicle based on the signal sent from the position detection sensor 1a, and further compares the current position on the map with the map information read from the map information storage unit 3a. Determine the position. The determined current position is sent to the route search unit 13 and the alternative route search unit 15 as current position data.

  Next, the destination is set (step ST12). That is, the destination setting unit 12 sets the destination in response to the operation of the input device 2 by the user. The set destination is sent to the route search unit 13 and the alternative route search unit 15 as destination data.

  Next, a route search is performed (step ST13). That is, the route search unit 13 reads the map information read from the map information storage unit 3a based on the current position data sent from the current position detection unit 11 and the destination data sent from the destination setting unit 12. Use to find the best route from your current location to your destination. The searched optimum route is sent as route data to the alternative route search unit 15, the route guide unit 16, and the route information calculation unit 19.

  Subsequently, it is investigated whether traffic information is usable (step ST14). That is, it is checked whether or not the current position is a radio wave dead zone. If it is determined in step ST14 that the traffic information is usable, normal route guidance is performed (step ST25). The normal route guidance process is well known and will not be described. Thereafter, the process ends.

  On the other hand, if it is determined in step ST14 that the traffic information is not usable, tire information is then acquired (step ST15). That is, the tire information acquisition unit 18 acquires tire information from the vehicle information sensor 1 b and sends the tire information to the route information calculation unit 19. Subsequently, vehicle information is acquired (step ST16). That is, the vehicle information acquisition unit 17 acquires vehicle information from the vehicle information sensor 1 b and sends it to the route information calculation unit 19.

  Next, date information is acquired (step ST17). That is, the route information calculation unit 19 acquires date information from the date signal sent from the GPS receiver of the position detection sensor 1a. In the first embodiment, the date / time information is acquired based on the date / time signal sent from the GPS receiver. However, the date / time information is acquired from a clock mechanism normally provided in the navigation system. Can be configured.

  Next, a safe speed is calculated (step ST18). Specifically, the route information calculation unit 19 determines whether or not the old road information having a date and time approximate to (similar to) the date and time indicated by the date and time signal obtained from the GPS receiver of the position detection sensor 1a exists in the road information storage unit 3b. If it is determined that it exists, the sum of the weights indicated by the old road information is compared with the sum of the weights indicated by the new road information sent from the vehicle information acquisition unit 17. If the value indicated by the new road information is smaller than the value indicated by the old road information, the speed limit is the safe speed, otherwise the speed indicated by the speed information of the old road information is the safe speed.

  On the other hand, when the route information calculation unit 19 determines that there is no road information in the road information storage unit 3b that has a date and time approximate to (similar to) the date and time indicated by the date and time signal obtained from the GPS receiver of the position detection sensor 1a. The predetermined value α is compared with the sum of the weights indicated by the new road information. If the value indicated by the new road information is smaller than the predetermined value α, the speed limit is set to the safe speed and indicated by the new road information. If the value to be displayed is equal to or greater than the predetermined value α and smaller than the predetermined value β, 2/3 of the speed limit is set as the safe speed, and the value indicated by the new road information is equal to or greater than the predetermined value β and When the speed is small, 1/3 of the speed limit is set as the safe speed. Further, when the value indicated by the new road information is equal to or greater than the predetermined value γ, the route information calculation unit 19 determines that the route cannot be traveled.

  Next, road information is accumulated (step ST19). In other words, the route information calculation unit 19 uses the vehicle information from the vehicle information acquisition unit 17 acquired at step ST16 and the tire information from the tire information acquisition unit 18 acquired at step ST15 to determine the position detection sensor 1a acquired at step ST17. Date and time information indicating the date and time indicated by the date and time signal from the GPS receiver is attached, and road information with speed information is generated based on the vehicle speed pulse signal obtained from the vehicle speed sensor of the position detection sensor 1a. It is sent to the road information storage unit 3b and stored.

  Next, it is checked whether re-search is necessary (step ST20). That is, the route information calculation unit 19 checks whether or not it is determined that the route cannot be traveled in the safe speed calculation in step ST18. If it is determined in step ST20 that re-search is necessary, route re-search is performed (step ST21). That is, the alternative route search unit 15 searches for an alternative route different from the route indicated by the route data sent from the route search unit 13 upon receiving an instruction from the route information calculation unit 19 that re-search is necessary. . The alternative route searched by the alternative route search unit 15 is sent to the route guide unit 16 and the route information calculation unit 19 as alternative route data. Thereafter, the sequence returns to step ST15.

  If it is determined in step ST20 that a re-search is not necessary, it is then checked whether a warning is necessary (step ST22). That is, the route information calculation unit 19 checks whether or not the safe speed has been calculated in step ST18. If it is determined in step ST22 that a warning is necessary, an appropriate speed is displayed (step ST23). That is, when the safe speed is sent from the route information calculation unit 19, the display control unit 20 generates a message indicating that the vehicle should travel at the safe speed and sends the message to the display 5. Similarly, when the safe speed is sent from the route information calculation unit 19, the voice output unit 21 generates a voice message indicating that the vehicle should travel at the safe speed and sends the voice message to the audio unit 6. As a result, a message indicating that the vehicle should travel at the safe speed calculated in step ST18 is displayed on the display 5, and is output from the speaker 7 by voice. If it is determined in step ST22 that no warning is necessary, the process in step ST23 is skipped.

  Next, route guidance is performed (step ST24). That is, the route guidance unit 16 displays guidance screen data for guiding the optimum route based on the route data sent from the route search unit 13 or the alternative route data sent from the alternative route search unit 15. Is generated and sent to the display 5, and guidance voice data for guiding the optimum route or alternative route by voice is generated and sent to the voice output unit 21. As a result, route guidance using the screen and voice is performed. Thereafter, the sequence returns to step ST15.

  As described above, according to the navigation system according to the first embodiment of the present invention, even when traffic information or traffic jam information from the outside cannot be collected, it is stored in the road information storage unit 3b of the map disk 3. Functions such as an alternative route presentation and warning can be operated based on the road information.

  Also, the safe speed can be calculated by estimating the road surface condition based on the vehicle information, and the safe speed considering the braking distance can be calculated according to the type of tire that is installed, so that the user can use a safer speed. It becomes possible to travel.

  In addition, since an appropriate speed is displayed on the display 5 as a safe speed, if the vehicle travels in accordance with the safe speed, it is possible to avoid sudden braking, a sudden steering wheel or a rear-end collision, and the user performs safe driving. It becomes possible.

It is a block diagram which shows the structure of the navigation system which concerns on Embodiment 1 of this invention. It is a block diagram which shows in detail the functional structure of navigation ECU of the navigation system which concerns on Embodiment 1 of this invention. It is a figure which shows an example of road information with the navigation system which concerns on Embodiment 1 of this invention. It is a figure which shows the example of the message displayed with the navigation system which concerns on Embodiment 1 of this invention. It is a figure which shows the other example of the message displayed with the navigation system which concerns on Embodiment 1 of this invention. It is a flowchart which shows operation | movement of the navigation system which concerns on Embodiment 1 of this invention.

Explanation of symbols

  1a position detection sensor, 1b vehicle information sensor, 2 input device, 3 map disk, 3a map information storage unit, 3b road information storage unit, 4 VICS receiver, 5 display, 6 audio unit, 7 speaker, 11 current position detection unit, DESCRIPTION OF SYMBOLS 12 Destination setting part, 13 Route search part, 14 Traffic information acquisition part, 15 Alternative route search part, 16 Route guidance part, 17 Vehicle information acquisition part, 18 Tire information acquisition part, 19 Route information calculation part, 20 Display control part , 21 Audio output unit.

Claims (4)

A vehicle information acquisition unit for acquiring a signal related to road conditions as vehicle information from a sensor provided in the vehicle;
A road information storage unit that sequentially accumulates road information with date and time information added to the vehicle information acquired by the vehicle information acquisition unit;
A current position detector for detecting the current position;
A destination setting section for setting a destination;
A route search unit for searching for a route from the current position detected by the current position detection unit to the destination set by the destination setting unit;
A route information calculation unit that calculates the state of the road forming the route searched by the route search unit based on the road information stored in the road information storage unit;
A navigation system comprising: an output unit that outputs information for calling attention to travel according to the road condition calculated by the route information calculation unit.   The vehicle information acquisition unit acquires vehicle information from at least one of an outside air temperature sensor, a humidity sensor, a raindrop sensor, a wiper operation sensor, a light operation sensor, a front defogger operation sensor, and a rear defogger operation sensor. The navigation system according to 1. A tire information acquisition unit that acquires tire information indicating the type of tire that is installed,
2. The road information storage unit sequentially stores vehicle information acquired by a vehicle information acquisition unit and road information with date / time information added to tire information acquired by the tire information acquisition unit. Navigation system. The route information calculation unit calculates an appropriate speed for traveling on the road forming the route searched by the route search unit based on the road information stored in the road information storage unit,
The navigation system according to claim 1, wherein the output unit outputs an appropriate speed calculated by the route information calculation unit as information for alerting the user to travel.

Images