JP2014029281A - Navigation system, method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique enabling returning to a state of quickly update-displaying a GPS position while preventing update-displaying of a less accurate GPS position.SOLUTION: A navigation system includes: position acquisition means for acquiring a GPS position that is a current position of a vehicle on the basis of a vehicle GPS signal; and display control means for update-displaying the GPS position on a display part. Further, in a case where the vehicle travels a blocking space in which the GPS signal is blocked, the display control means executes a blocking mode to update-display the GPS position under a condition that an acquisition state of the GPS position satisfies a predetermined display reference, or inhibits execution of the blocking mode in a case where the vehicle travels outside the blocking space and in a case where the vehicle travels a branching point in the blocking space.

Description

  The present invention relates to a navigation system, method, and program for updating and displaying the current position of a vehicle.

  Conventionally, a technique for updating and displaying a GPS position is known if the GPS position, which is the current position based on the GPS signal, can be measured (see Patent Document 1). Further, a technique for stopping reception of GPS signals when a vehicle travels through a tunnel or an underground road is known (see Patent Document 2).

JP-A-5-312933 JP 2004-286495 A

In Patent Document 1, if the GPS position can be measured, the GPS position is displayed even if the reception state of the GPS signal is bad. On the other hand, in Patent Document 2, since reception of GPS signals is started after exiting a tunnel or an underground road, there is a problem that it is not possible to return to a state in which the GPS position is updated and displayed at an early stage after exiting from a tunnel or an underground road. It was.
The present invention has been made in view of the above problems, and an object of the present invention is to provide a technique capable of returning to a state where the GPS position is updated and displayed at an early stage while preventing the update and display of the inaccurate GPS position. .

  In order to achieve the above object, a navigation system according to the present invention includes position acquisition means for acquiring a GPS position, which is the current position of a vehicle based on a GPS signal, and display control means for updating and displaying the GPS position on a display unit. . The display control means starts execution of a blocking mode in which the GPS position is updated and displayed on condition that the GPS position acquisition state satisfies a predetermined display standard when the vehicle enters the blocking space where the GPS signal is blocked. . Further, the display control means cancels the execution of the blocking mode when the vehicle travels at a branch point in the blocking space.

  In the above configuration, the display control means starts executing the blocking mode when the vehicle enters the blocking space. That is, when the vehicle travels in the blocked space, the GPS signal reception state is deteriorated, so that the GPS position is updated and displayed only when the GPS position acquisition state satisfies the display standard. As a result, when the vehicle travels in the shut-off space, it is possible to prevent the GPS position with a low accuracy based on the GPS signal received in a bad reception condition from being updated and displayed. Since the execution of the blocking mode is started when the vehicle enters the blocking space, the blocking mode is not executed before the vehicle enters the blocking space. That is, before the vehicle travels in the blocking space, the GPS signal reception state is better than when the vehicle travels in the blocking space. Therefore, regardless of whether the GPS position acquisition state satisfies the display standard or not, the GPS signal is received. The position is updated and displayed.

  Even when the vehicle travels in the blocked space, the display control means cancels the execution of the blocked mode when the vehicle travels a branch point in the blocked space. In other words, when traveling at a branch point in the blocking space, the execution of the blocking mode is canceled as before the vehicle enters the blocking space. As a result, when there is a high possibility that the vehicle travels at a branch point and escapes from the blocking space, without waiting until the acquisition state of the GPS position satisfies the display standard as in the execution of the blocking mode, early, It is possible to return to a state where the GPS position is updated and displayed. Here, it can be estimated that a plurality of branch roads branch at the branch point, and that the branch roads that can escape from the blocking space are likely to be included in the plurality of branch roads. In other words, it can be estimated that any of a plurality of branch roads having different exit directions is likely to be a road that can escape from a blockage space existing along the branch road and other branch roads. Therefore, when traveling at a branch point in the blocked space, it can be estimated that the vehicle is more likely to escape from the blocked space than when traveling in another section of the blocked space.

  The position acquisition unit may acquire the GPS position based on the GPS signal, and may acquire the GPS position continuously so that the GPS position can be updated and displayed. Further, the position acquisition unit may not acquire the GPS position based only on the GPS signal, and may correct the GPS position based on correction elements such as a road shape and a past trajectory shape. The display control means may update and display the GPS position on the display unit, and may continuously display the GPS position. The update display mode of the GPS position is not particularly limited, and the display control unit may update the display content so that the marker is positioned at a position corresponding to the GPS position on the map. In this case, the marker may move on the display unit, the map may move on the display unit, or both may move on the display unit.

  The cut-off space is a section in which a GPS signal emitted from a GPS satellite is blocked and is difficult to reach the inside, and is a section in which the radio wave intensity of the GPS signal is at least attenuated compared to the outside. The interruption of the GPS signal may be that the GPS signal is reflected or absorbed by a structure surrounding the interruption space, or that the GPS signal is electromagnetically interrupted by an electromagnetic field formed in the interruption space. May be. That the GPS position acquisition state satisfies the display standard means that the GPS position acquisition state is good enough that the GPS position accuracy can still be considered high despite the doubt of the GPS position accuracy in the shut-off space. It means that there is. The GPS position acquisition state may be an index that can evaluate the accuracy of the GPS position, and may be the state of the received GPS signal, or the processing state of the process of acquiring the GPS position based on the GPS signal. There may be the state of the acquired GPS position itself.

  The position acquisition means may acquire not only the GPS position but also a current position that is an alternative to the GPS position. That is, when the vehicle is traveling in the blocking space, the GPS position cannot be acquired, or even if the GPS position can be acquired, the accuracy is doubtful. Therefore, the position acquisition unit may acquire the current position not based on the GPS signal. . And a display control means may display the present position used as an alternative of GPS position on a display part, when the vehicle is drive | working the interruption | blocking space. Further, the display control means may use the current position, which is an alternative to the GPS position, for various position determinations of the vehicle when the vehicle is traveling in the blocking space.

  The case where the vehicle enters the blocking space is not limited to the case where the vehicle actually travels at the entry point of the blocking space, but may be a case where the vehicle travels a predetermined distance before the blocking space. It may be a case where the vehicle has traveled a predetermined distance after entering. The blocking mode only needs to be canceled when the vehicle escapes from the blocking space after traveling at the branch point. The display control means may cancel the execution of the blocking mode when the vehicle has traveled a predetermined distance before the branch point so as to be in time to escape from the blocked space after traveling at the branch point. Of course, the display control means may cancel the execution of the cut-off mode at the timing when the branch point travels.

  In addition, when the vehicle travels at a branch point in a shut-off space, the display control means can acquire a GPS position with a reliability greater than or equal to a predetermined reliability regardless of whether the GPS position acquisition state satisfies the display standard. On the condition that this is the case, the cut-off branch mode for updating and displaying the GPS position may be executed. That is, in the cut-off branch mode, the GPS position having a reliability higher than the predetermined reliability is updated and displayed, although it is not required until the GPS position acquisition state satisfies the display standard unlike the cut-off mode. Good. Thereby, when the vehicle travels at a branch point in the shut-off space, a highly accurate GPS position can be updated and displayed at an early stage.

  Furthermore, the display control unit may update and display the GPS position on the condition that the cumulative number of acquisitions of the GPS position in the cutoff mode is equal to or greater than a predetermined first reference number. That is, when the cumulative number of acquisitions of GPS positions after the start of the blocking mode is equal to or greater than the first reference number, it is considered that the cumulative reliability of the GPS position is sufficiently improved, and the GPS position is It may be updated and displayed. As described above, by evaluating the cumulative reliability of the GPS position, it is possible to update and display only the accurate GPS position in a situation where the reception state of the GPS signal is poor. In general, the GPS position is acquired at every acquisition timing of a predetermined time period or travel distance period. Therefore, in the cut-off mode, after the GPS position can be acquired first near the exit of the cut-off space, it is not possible to return to the state where the GPS position is updated and displayed unless the acquisition timing for the first reference number has passed at the shortest. .

  On the other hand, the display control means updates the GPS position on the condition that the number of times the GPS position with the reliability higher than the predetermined reliability has been acquired reaches the second reference number less than the first reference number in the interruption / branch mode. You may make it display. As described above, when the GPS position is only temporarily obtained by evaluating the cumulative reliability of the GPS position, the GPS position with low accuracy is then updated and displayed. Can be prevented. Here, in the interruption / branch mode, the GPS position can be returned to the state in which the GPS position is updated and displayed after the acquisition of the second reference number of times has passed in the shortest time after the GPS position can be acquired first near the exit of the interruption space. Since the second reference number in the blocking branch mode is smaller than the first reference number in the blocking mode, the blocking branch mode can return to the state where the GPS position is updated and displayed earlier near the exit of the blocking space than the blocking mode. . That is, when traveling at a branch point where there is a high possibility of escape from the blocking space, the GPS position can be returned to the state of being updated and displayed at an early stage.

  Further, the position acquisition means may acquire a sensor position that is a current position of the vehicle based on signals output from the vehicle speed sensor and the direction sensor. Thereby, the current position of the vehicle can be acquired regardless of the reception state of the GPS signal. And a display control means is good also as the reliability of a GPS position being more than predetermined reliability, when the GPS position similar to a sensor position is acquired in interruption | blocking branch mode. This is because when the GPS position is similar to the sensor position specified by a method different from the GPS position, it can be estimated that the reliability of the GPS position is high. Here, the fact that the GPS position is similar to the sensor position may be that the GPS position is within a predetermined distance from the sensor position, or that the difference between the direction of the GPS position trajectory and the direction of the sensor position trajectory is predetermined. It may be within an angle. When the navigation system is a separate device from the vehicle, the position acquisition unit may acquire signals output from the vehicle speed sensor and the direction sensor provided in the vehicle by communication with the vehicle. The sensor position specified by the ECU or the like may be acquired by communication. The direction sensor may be a sensor that generates a signal that can specify the direction of the vehicle, and may be a steering sensor or a gyro sensor.

  Further, the position acquisition means may acquire the sensor position corrected so that the road shape of the road on which the vehicle travels matches the locus of the sensor position before the vehicle passes through the branch point in the shut-off space. Here, the sensor position is obtained by updating the latest sensor position to a position advanced from the past sensor position by the movement distance based on the vehicle speed sensor in the movement direction based on the direction sensor. Therefore, by increasing the accuracy of the sensor position based on the road shape in advance before the vehicle passes the branch point in the blocking space, the sensor position when executing the blocking branch mode can also be increased. it can. Therefore, it is possible to determine with high accuracy that the reliability of the GPS position is high due to similarity to the sensor position in the cutoff branch mode. Of course, the position acquisition means may correct the sensor position even after the vehicle passes through the branch point in the blocking space, or may correct the sensor position during execution of the blocking branch mode.

  The display control means may update the sensor position on the display unit when the GPS position is not updated and displayed. Thereby, even when the vehicle travels in the shut-off space, the current position of the vehicle can be continuously displayed. Furthermore, if the sensor position and the GPS position are similar in the interruption / branch mode, if the GPS position is returned to the state of being updated and displayed, the current position that is updated and displayed greatly changes from the sensor position to the GPS position for driving. It can prevent the person from feeling uncomfortable.

  Furthermore, the method of updating and displaying the GPS position as in the present invention can also be applied as a program or method. In addition, the system, program, and method as described above may be realized as a single device, or may be realized by using components shared with each unit provided in the vehicle when realized by a plurality of devices. It can be assumed and includes various aspects. For example, it is possible to provide a navigation system, method, and program including the above-described devices. Further, some changes may be made as appropriate, such as a part of software and a part of hardware. Furthermore, the invention can be realized as a recording medium for a program for controlling the system. Of course, the software recording medium may be a magnetic recording medium, a magneto-optical recording medium, or any recording medium to be developed in the future.

It is a block diagram of a portable terminal. 2A is a diagram showing a road, FIGS. 2B to 2D are diagrams showing a locus of sensor positions, and FIGS. 2E and 2F are timing charts of operations. It is a flowchart of an update display object setting process. It is a flowchart of the update display object setting process concerning other embodiment.

Here, embodiments of the present invention will be described in the following order.
(1) Configuration of mobile terminal:
(2) Update display target setting process:
(3) Other embodiments:

(1) Configuration of mobile terminal:
FIG. 1 is a block diagram showing a configuration of a mobile terminal 10 as a navigation system according to an embodiment of the present invention. The mobile terminal 10 is connected to be communicable with the vehicle. The mobile terminal 10 includes a control unit 20, a recording medium 30, a GPS receiving unit 41, a display 42, and a terminal side communication unit 43. The control unit 20 includes a CPU, a RAM, a ROM, and the like, and executes a program stored in the recording medium 30 or the ROM. The recording medium 30 records map information 30a. The map information 30a specifies node data indicating nodes set corresponding to the end points (intersections) of road sections, link data indicating information on road sections between nodes, and the shape of road sections between nodes. Shape interpolation point data and the like. In the link data, information for identifying a portion of the road section in the blocked space where the GPS signal is blocked is associated with each road section. In the present embodiment, information for specifying a portion corresponding to an underground expressway in which GPS signals are blocked in the road section is associated with each road section. In addition, the portable terminal 10 may acquire a part required for the update display object setting process mentioned later and the display of a map among map information 30a from an external server etc. suitably by communication.

  The GPS receiver 41 receives a GPS signal emitted from a GPS satellite, and outputs a signal for calculating a GPS position that is the current position of the vehicle via an interface (not shown). The display 42 is a video output device that outputs various guides based on the video signal output from the control unit 20. In the present embodiment, a map in which a marker is superimposed on coordinates corresponding to the current position of the vehicle is displayed on the display 42. The terminal side communication unit 43 includes a communication circuit for communicating with the vehicle. The terminal side communication unit 43 may perform wired communication with the vehicle or may perform wireless communication.

  The vehicle includes a vehicle-side communication unit 50, a steering sensor 51, and a vehicle speed sensor 52. The steering sensor 51 is an azimuth sensor and outputs a signal corresponding to the steering angle of the vehicle to the vehicle-side communication unit 50. The vehicle speed sensor 52 outputs a signal corresponding to the rotational speed of the wheels included in the vehicle to the vehicle-side communication unit 50. The vehicle-side communication unit 50 transmits a signal corresponding to the steering angle and a signal corresponding to the rotation speed of the wheel to the terminal-side communication unit 43 of the mobile terminal 10.

The control unit 20 of the mobile terminal 10 executes the navigation program 21. The navigation program 21 includes a position acquisition unit 21a and a display control unit 21b.
The position acquisition unit 21a is a module that causes the control unit 20 to execute a function of acquiring the GPS position that is the current position of the vehicle based on the GPS signal. That is, the control unit 20 acquires a signal from the GPS reception unit 41 by the function of the position acquisition unit 21a, and acquires a GPS position based on the acquired signal. In the present embodiment, the control unit 20 acquires the GPS position at every acquisition timing of the Δt second period.

  The display control unit 21b starts execution of a blocking mode in which the GPS position is updated and displayed on condition that the acquisition state of the GPS position satisfies a predetermined display standard when the vehicle enters the blocking space where the GPS signal is blocked. This is a module that causes the control unit 20 to execute the function to be performed. That is, the function of the display control unit 21b allows the control unit 20 to display the GPS position only when the GPS position acquisition state satisfies the display standard in a blocking space where the GPS position accuracy is doubtful even though the GPS position can be acquired. Update display with. Note that since the blocking mode is started when the vehicle enters the blocking space, the blocking mode is not executed before the vehicle enters the blocking space. That is, before the vehicle travels in the shut-off space, the GPS signal reception state is better than when the vehicle travels in the shut-off space. Therefore, regardless of whether or not the GPS position acquisition state satisfies the display standard, The position is updated and displayed. Here, the GPS position acquisition state satisfies the display standard means that the GPS position acquisition state is such that the accuracy of the GPS position can still be considered good despite the doubt of the GPS position accuracy in the blocking space. In the present embodiment, the following display standard is adopted.

  That is, by the function of the display control unit 21b, the control unit 20 causes the GPS position to be updated and displayed on the condition that the cumulative number of times the GPS position has been acquired is equal to or greater than the predetermined first reference number in the cutoff mode. That is, even when the control unit 20 travels in a blocking space where the accuracy of the GPS position is suspected, if the GPS position can be acquired more than the first reference number after starting the blocking mode, the accuracy of the GPS position is determined. The GPS position is updated and displayed on the display 42. Thus, by accumulating the acquisition status of the GPS position, it is possible to prevent the inaccurate GPS location temporarily acquired in a situation where the reception status of the GPS signal is bad from being updated and displayed on the display 42. . When the first reference number is expressed as X times, in the blocking mode, the GPS position is updated and displayed if (X · Δt) seconds have not elapsed even after the GPS position is first acquired in the vicinity of the exit of the blocking space. It will not be possible to return to.

  Furthermore, the control part 20 cancels | releases execution of interruption | blocking mode, when the vehicle drive | works the branch point in interruption | blocking space by the function of the display control part 21b. That is, even when the vehicle travels in the shut-off space, the control unit 20 stops execution of the shut-off mode when the vehicle travels at a branch point in the shut-off space. In other words, when the vehicle travels at a branch point where it is estimated that the vehicle is likely to escape from the blocked space, the execution of the blocked mode is canceled in the same manner as before the vehicle enters the blocked space. Here, one of the branch roads branched from the branch point provided in the underground expressway is a main road on the underground expressway, while the other is a ramp road that escapes from the underground expressway to the ground. Can be estimated. Therefore, when the vehicle travels at a branch point in the blocking space, it can be estimated that the vehicle is likely to escape from the blocking space.

FIG. 2A is a plan view of a road. In the figure, at the branch point P ₃ , two road sections W ₂ and W ₃ branch off as a branch road from the branch road section W ₁ . The road section W ₂ branches in the straight direction, and the road section W ₃ branches in the left direction. The cut-off space U (in the solid line frame) corresponding to the underground part of the road is a part of the road section W ₁ (P _{0 to} P ₃ ) that is the branch source and a part of the road section W ₂ that branches in the straight direction (P ₃ It is present along the ~P _5). A road section W ₂ that branches in a straight direction is a main road of an underground expressway. On the other hand, the road section W ₃ that branches to the left is a ramp road that goes from the underground highway to the ground, and the vehicle escapes from the blocking space U after traveling on the road section W ₃ for a while from the branch point P _3. It becomes. Therefore, when the vehicle travels at the branch point P ₃ , it can be estimated that the vehicle is likely to escape from the blocking space U.

Control unit 20 of the function of the display control unit 21b, when the vehicle travels through the branch point P ₃ in the blocked space U, regardless of whether the acquired status of the GPS position satisfies the display reference, reliability predetermined trust The execution of the cut-off branch mode for updating and displaying the GPS position at or above the degree is started. That is, when the vehicle travels at the branch point P ₃ in the blocking space U, the control unit 20 cancels the execution of the blocking mode and executes the blocking branch mode instead. In this cut-off branch mode, the control unit 20 does not request until the GPS position acquisition state satisfies the display standard unlike the cut-off mode, but updates and displays a GPS position having a reliability higher than a predetermined reliability. To. Thereby, a highly accurate GPS position can be updated and displayed at an early stage.

Specifically, the function of the display control unit 21b allows the control unit 20 to reach the second reference number in which the number of times the GPS position having the reliability higher than the predetermined reliability is acquired is less than the first reference number in the cutoff branch mode. The GPS position is updated and displayed on condition that it has been done. As described above, by evaluating the cumulative reliability of the GPS position, even if a GPS position with high reliability can be temporarily acquired, the GPS position with low accuracy acquired after that is updated and displayed. Can be prevented. Here, in the interruption / branching mode, after the GPS position can be acquired first near the exit of the interruption space U, the GPS position is updated and displayed when the acquisition timing for the second reference number of times has passed in the shortest time. obtain. If the second reference number of times is expressed as Y (<X) times, in the cut-off branch mode, the GPS position is updated and displayed after the shortest (Y · Δt) seconds have elapsed since the GPS position was first acquired. Can return. Here, since the second reference number in the cutoff branch mode is smaller than the first reference number in the cutoff mode, the GPS position is updated earlier in the cutoff branch mode (Y · Δt) than in the cutoff mode (X · Δt). The display state can be restored. That is, when the vehicle travels at a branch point P ₃ where there is a high possibility of exiting the underground expressway as the blocking space U, it is possible to return to the state where the GPS position is updated and displayed at an early stage near the exit of the blocking space U.

  It is assumed that the reliability of the GPS position is equal to or higher than the predetermined reliability when the GPS position similar to the sensor position is acquired in the cutoff branch mode by the function of the display control unit 21b. This is because when the GPS position is similar to the sensor position specified by a method different from the GPS position, it can be estimated that the reliability of the GPS position is high. In the present embodiment, the GPS position is similar to the sensor position when the GPS position is within a predetermined distance of the sensor position acquired almost simultaneously. Hereinafter, the sensor position will be described.

  With the function of the position acquisition unit 21 a, the control unit 20 acquires a sensor position that is the current position of the vehicle based on signals output from the vehicle speed sensor 52 and the steering sensor 51 of the vehicle. Thereby, the control part 20 can acquire the present position of a vehicle irrespective of the reception state of a GPS signal. The control unit 20 acquires the movement direction based on the azimuth sensor and the movement distance based on the vehicle speed sensor at a predetermined time period, and sets the position advanced by the movement distance in the movement direction from the sensor position acquired immediately before as the latest sensor position. get. For this reason, errors in the moving direction are likely to accumulate at the sensor position, and the accuracy of the sensor position tends to deteriorate when a complicated turn is performed.

Control unit 20 of the function of the position acquisition unit 21a, before the vehicle passes through the branch point P ₃ in the blocked space U, the locus of the road shape and the sensor position of the road on which the vehicle is traveling is corrected to match the sensor Get the position. In Figure 2B shows the trajectory of the acquired sensor position (open circles) before the vehicle passes through the branch point P ₃ in the cut-off spatial U. As shown in Figure 2B, the direction of the trajectory of the sensor position (two-dot chain line) are shifted by an angle θ in the clockwise direction with respect to the direction of the branch source road road section W _1. As shown in FIG. 2C, the control unit 20, by only rotation correction θ angle trajectory of the sensor position in the counterclockwise direction, matching the shape of the road trajectory and the branch origin road section W ₁ of the sensor position Let Thus, by increasing the accuracy of the sensor position based on the road shape in advance, the accuracy of the sensor position (double circle) acquired after passing through the branch point P ₃ as shown in FIG. 2D is also increased. Can be made. Therefore, it is possible to determine with high accuracy that the reliability of the GPS position is high due to similarity to the sensor position in the cutoff branch mode. Note that the control unit 20 only has to correct the sensor position so that the road shape matches the trajectory shape of the sensor position, and the correction method is not limited to rotation correction.

  Further, the control unit 20 causes the display 42 to update and display the sensor position when the GPS position is not updated and displayed by the function of the display control unit 21b. Thereby, also in the interruption | blocking space U, the present position of a vehicle can be displayed continuously. Furthermore, in the interruption / branch mode, when the sensor position and the GPS position are similar, the GPS position is returned to the state of being updated and displayed, so that the current position that is updated and displayed is not greatly changed from the sensor position to the GPS position. it can. For example, as shown in FIG. 3D, when the GPS position is within a predetermined distance E (within the range of the broken line) of the sensor position acquired at the same time, if the sensor position and the GPS position are similar, the GPS is calculated from the sensor position. The transition distance to the position can be suppressed to about the predetermined distance E.

As described above, in the present embodiment, when traveling on the branch point P ₃ where there is a high possibility of exiting the underground highway as the blocking space U, the GPS position is updated and displayed early in the vicinity of the exit of the blocking space U It can return to the state to do. In particular, when escaping from an underground highway to a general road, it is assumed that a complicated turn is made on the general road. Therefore, when exiting from an underground expressway to a general road, a complicated turn on the general road can be realized by returning from the state of updating and displaying the sensor position where errors are likely to occur due to turning to the state of updating and displaying the GPS position at an early stage. Can be provided.

(2) Update display target setting process:
FIG. 3 is a flowchart of the update display target setting process. The update display target setting process is a process executed when the GPS signal becomes unreceivable and the GPS position cannot be acquired. In addition, in the update display target setting process, one of the normal mode, blocking mode, and blocking branch mode is set exclusively, and in the initial state at the start of the update display target setting process, the operation mode is set to normal mode. ing. When the operation mode is set to the normal mode, the update display target is the GPS position. During execution of the update display target setting process, the control unit 20 uses the function of the position acquisition unit 21a to determine the GPS position (if it can be acquired) and the sensor at every acquisition timing of the Δt second period regardless of whether or not it is an update display target. Get position and. Note that the period of the acquisition timing may be different between the GPS position and the sensor position.

  First, by the function of the display control unit 21b, the control unit 20 determines whether or not the vehicle is traveling in a tunnel (step S100). For example, the control unit 20 refers to the map information 30a, identifies a road section in the blocked space U, and determines whether the sensor position is within a predetermined distance from the road section in the blocked space U. To do. When it is not determined that the vehicle is traveling in the blocked space U (step S100: N), the control unit 20 returns to step S100. That is, since the vehicle has not entered the blocking space U, it can be estimated that the GPS position could not be temporarily acquired. Therefore, assuming that accurate GPS position acquisition can be expected, the operation mode remains in the normal mode and the update display target remains at the GPS position.

  On the other hand, when it determines with the vehicle drive | working the interruption | blocking space U (step S100: Y), the control part 20 sets an operation mode to interruption | blocking mode by the function of the display control part 21b (step S110). Furthermore, the control unit 20 sets the sensor position as an update display target by the function of the display control unit 21b (step S115). That is, when the vehicle is traveling in the blocking space U and it is not possible to expect accurate GPS position acquisition for a while, the operation mode is set to the blocking mode, and the sensor position is updated and displayed on the display 42. In steps S100 to S115, when the vehicle turns from a state in which the vehicle is not traveling in the blocked space U to a state in which the vehicle is traveling in the blocked space U, that is, when the vehicle has entered the blocked space U, the normal mode Is canceled and the execution of the blocking mode is started.

Next, the control unit 20 of the function of the display control unit 21b determines whether the vehicle is traveling on a start point P ₁ of the predetermined distance K before the branching point P ₃ (step S120). For example, the control unit 20, when the most recent sensor position is from the start point P ₁ within the predetermined distance, it may be determined that the vehicle is traveling on a start point P _1. In addition, the control unit 20 specifies the travel distance that the vehicle has traveled from the time when it entered the shut-off space U to the present based on the signal from the vehicle speed sensor, and the travel distance starts from the entry point P ₀ of the shut-off space U. when it becomes equal to the length of the road section W ₁ to the point P _1, it may be determined that the vehicle is traveling on a start point P _1. Further, the control unit 20 determines that the linear distance between the latest sensor position and the sensor position at the time of entering the blocking space U is equal to the length of the road section W ₁ from the entry point P ₀ to the start point P _{1 in the} blocking space U. if it becomes, it may determine that the vehicle is traveling on a start point P _1.

When it is not determined that the vehicle is traveling at the start point P ₁ before the predetermined distance K of the branch point P ₃ , the function of the display control unit 21b causes the control unit 20 to determine that the cumulative number of GPS positions is the first reference. It is determined whether or not the number of times (X times) or more (step S125). That is, in a state where the operation mode is the cutoff mode, the control unit 20 determines whether or not the GPS position acquisition state satisfies the display standard. In the present embodiment, the number of times the GPS position can be continuously acquired without failure at the acquisition timing every Δt seconds is set as the cumulative acquisition number, and when the GPS position cannot be acquired at the acquisition timing, the cumulative acquisition number is set to 0. Reset to. That is, the control unit 20 determines whether or not the reception state of the GPS signal is good for (X · Δt) seconds or more. In addition, even if the GPS position cannot be acquired at the acquisition timing, the accumulated number of times of adding 1 each time the GPS position is acquired may be adopted without resetting.

When it is not determined that the cumulative number of GPS position acquisitions is equal to or greater than the first reference number (step S120: N), the control unit 20 returns to step S120 by the function of the display control unit 21b. That is, when the vehicle travels in the blocking space U, the cumulative number of GPS positions acquired is the first reference except when the vehicle travels at the start point P ₁ before the predetermined distance K of the branch point P ₃ (step S120: Y). Whether or not the number is greater than or equal to the number of times will be repeatedly determined. Therefore, if the vehicle travels through the cut-off space U, except when traveling branch point P _3, as far as the cumulative number of acquisition times of GPS position is not a first reference number of times or more, the operation mode is maintained in the shut-down mode sensor position Will continue to be maintained as an update display target. Therefore, when the GPS position can be temporarily acquired, for example, when traveling on a half-roof section where a part of the roof is open on the underground highway, the GPS position can be prevented from being updated and displayed. In such a case, since the reception state of the GPS signal becomes unstable, an inaccurate GPS position is updated and displayed.

  On the other hand, when it is determined that the cumulative number of acquisitions of the GPS position is equal to or greater than the first reference number, the control unit 20 sets the operation mode to the normal mode by the function of the display control unit 21b (step S130). And the control part 20 sets a GPS position as update display object by the function of the display control part 21b (step S135). That is, if it is determined that the cumulative number of GPS position acquisitions is greater than or equal to the first reference number, it is possible to update and display a sufficiently accurate GPS position, return the operation mode from the cutoff mode to the normal mode, Return to the updated display state. It is desirable that the execution timing is adjusted so that step S125 is executed at every GPS position acquisition timing.

On the other hand, when it is determined that the vehicle is traveling at the start point P ₁ before the predetermined distance K of the branch point P ₃ (step S120: Y), the control unit 20 has the sensor position determined by the function of the display control unit 21b. It is determined whether or not correction is possible (step S140). Specifically, the control unit 20, near the front of the road shape in a linear than a predetermined reference branch point P _3, and the locus L ₁ of the sensor position after traveling a start point P ₁ is a straight line than a predetermined reference It is determined that the sensor position can be corrected at the stage where the distance is close. That is, it is determined that the sensor position can be corrected when the angle θ (FIG. 2B) formed by the direction of the road of the branch road section W ₁ and the direction of the locus L ₁ of the sensor position can be specified. . When it is not determined that the sensor position can be corrected (step S140: N), the control unit 20 returns to step S100 by the function of the display control unit 21b. In other words, it is impossible to obtain a highly accurate sensor position, and the reliability of the GPS position cannot be determined with high accuracy in the later-described branching mode. To do. In the present embodiment, the controller 20 travels the start point P ₁ , and even if the vehicle travels a predetermined distance less than K, the sensor position trajectory after traveling the start point P ₁ is straighter than the predetermined reference. When it is not close, it is determined that the sensor position cannot be corrected.

When it is determined that the sensor position can be corrected (step S140: Y), the control unit 20 sets the operation mode to the cut-off branch mode by the function of the display control unit 21b (step S145). That is, the control unit 20 starts executing the cut-off branch mode, assuming that the reliability of the GPS position can be determined with high accuracy when it is determined that the sensor position can be corrected after traveling at the start point P _1. Let Note that starting execution of the interrupted branch mode means canceling execution of the branch mode. In the present embodiment, a point between the branch point P ₃ from the starting point P _1, so that the execution of the interrupting mode is canceled at the point where the correction is determined to be the sensor position. Since the execution of the interrupting mode is canceled before traveling branch point P _3, the execution of the shut-down mode before traveling escape point P ₆ to escape from the cut-off spatial U after traveling junction P ₃ It can be released.

Next, the control part 20 correct | amends a sensor position by the function of the position acquisition part 21a (step S150). That is, as shown in FIG. 2C, the trajectory L ₁ of the sensor position from running on the start point P ₁ to running on the branch point P ₃ matches the road shape of the branch road section W _1. Next, the locus L ₁ of the sensor position is corrected. The sensor position may be corrected before the vehicle travels on the branch point P _3. Every time the sensor position is obtained before traveling on the start point P ₁ , the sensor position is the road from which the vehicle is branched. it may have been corrected to match the shape of the road section W _1.

Next, the control unit 20 of the function of the display control unit 21b determines whether the vehicle is present within finished the distance S (FIG. 2A) from the branching point P ₃ (step S155). That is, the control unit 20 determines whether or not the vehicle has passed the branch point P ₃ by the end distance S. For example, the control unit 20 may determine whether or not the linear distance between the branch point P ₃ and the sensor position is equal to or less than the end distance S. If the vehicle is determined to be present within finished the distance S from the branch point P ₃ (step S155: Y), the control unit 20 of the function of the display control unit 21b whether the GPS position and the sensor position is similar If the determination is similar, the release counter is incremented by 1 (step S160). That is, in the shut-off branch mode, the control unit 20, when the GPS position of the latest (most recent acquisition timing) is acquired, the latest GPS location: (white triangles Figure 2D), after running a branch point P ₃ within the linear distance between the predetermined distance E of the sensor position (white double circle: Figure 2D) latest sensor position (Figure 2D the upper end of the white double circle trajectory of the sensor position L ₂₎ of the locus L ₂ of It is determined whether or not there is. Then, when the linear distance between the latest GPS position and the latest sensor position is within the predetermined distance E, the control unit 20 is similar to the GPS position and the sensor position, and the reliability of the GPS position is greater than or equal to the predetermined reliability. If there is, the release counter is incremented by one. If the latest GPS position cannot be obtained, and if the obtained latest GPS position is not similar to the latest sensor position, step S160 is terminated without increasing the release counter.

Next, by the function of the display control unit 21b, the control unit 20 determines whether or not the release counter is equal to or greater than the second reference number (Y times) (step S165). That is, the control unit 20 determines whether or not the release counter indicating the number of times the GPS position having the reliability equal to or higher than the predetermined reliability has reached the second reference number less than the first reference number in the cutoff branch mode. judge. When it is not determined that the release counter is greater than or equal to the second reference number (step S165: N), the control unit 20 returns to step S155 by the function of the display control unit 21b. That is, as long as the vehicle exists within the end distance S from the branch point P ₃ in the cutoff branch mode, the control unit 20 repeats the process of incrementing the release counter in step S160. It is desirable that the execution timing is adjusted so that step S160 is executed every time the GPS position is acquired.

On the other hand, when it is determined that the release counter is equal to or greater than the second reference number (step S165: Y), the control unit 20 sets the operation mode to the normal mode by the function of the display control unit 21b (step S130). And the control part 20 sets a GPS position as update display object by the function of the display control part 21b (step S135). That is, when it is determined that the release counter is equal to or greater than the second reference number, it is possible to update and display the GPS position with high accuracy. Return. Incidentally, if the release counter without a second reference number of times or more, the vehicle is no longer determined to be present within finished the distance S from the branch point P ₃ (step S155: N), after a predetermined time period elapses, the flow returns to step S100 . That is, although the vehicle has traveled at the branch point P ₃ , the operation mode is returned to the shut-off mode, assuming that the vehicle has not traveled on the road section W ₃ that can escape from the shut-off space U (step S 110).

Here, in step S125 of the cut-off mode, a period of only (X · Δt) seconds corresponding to the first reference number is required at the shortest until the operation mode can be returned to the normal mode after the GPS position is first acquired. Cost. On the other hand, in step S165 in the cutoff branch mode, a period of (Y · Δt) seconds corresponding to the second reference number of times is the shortest until the operation mode can be returned to the normal mode after the GPS position is first acquired. Cost. Since the second reference number is smaller than the first reference number (X> Y), it can be said that the cutoff branch mode can return to the normal mode earlier than the cutoff mode. Accordingly, when there is a high possibility that the vehicle travels at the branch point P ₃ and escapes from the blocking space U of the underground highway, it is possible to return to the state where the GPS position is updated and displayed at an early stage.

FIG. 2E is a timing chart showing the operation of the control unit 20 when the vehicle leaves the road section W ₂ in the straight direction from the branch point P ₃ in FIG. 2A. First, when the vehicle travels through the entry point P ₀ of the blocked space U in the branch road section W ₁ , it is determined that the vehicle has entered the blocked space U and the execution of the blocked mode is started. Vehicle at the stage where the correction is judged to be the sensor position in the interval from the start point P ₁ of the predetermined distance K before the branch point P ₃ to the branch point P _3, the execution of the cut-off branch mode execution of the cutoff mode is canceled Is started. When the vehicle travels on the limit point P ₄ that is advanced by the end distance S from the branch point P _3, the execution of the cutoff mode is canceled and the execution of the cutoff mode is started. That is, a road that can quickly escape from the shut-off space U when the vehicle is separated from the branch point P ₃ by the end distance S without the number of times the GPS position having the reliability equal to or higher than the predetermined reliability has been acquired. without vehicle exit to section W _3, as the vehicle for a while blocking space U travels to start the execution of the cut-off mode. In FIG. 2A, it is assumed that the vehicle escapes from the blocking space U at the escape point P ₅ in the straight road section W ₂ and thereafter the GPS position can be always acquired. In this case, the vehicle can return to the normal mode in which the GPS position is updated and displayed after (X · Δt) seconds have passed since the acquisition timing for the first reference count has elapsed after traveling through the escape point P ₅ .

FIG. 2F is a timing chart showing the operation of the control unit 20 when the vehicle leaves the road section W ₃ in the left direction from the branch point P ₃ in FIG. 2A. In FIG. 2A, the vehicle escapes from the blocking space U at the escape point P ₆ in the road section W ₃ in the left direction, and thereafter, a GPS position whose reliability is higher than the predetermined reliability can always be acquired. . In this case, the vehicle can return to the normal mode in which the GPS position is updated and displayed after (Y · Δt) seconds have passed since the acquisition timing for the second reference number has elapsed after traveling through the escape point P ₆ . As shown in FIG. 2F, the normal mode in which the GPS position is updated and displayed earlier in the case of exiting the shut-off space U in the shut-off branch mode than in the case of exiting the shut-off space U in the shut-off mode as shown in FIG. 2E. It will be possible to return. Furthermore, when there is a high possibility of exiting the blocking space U of the underground expressway, it is possible to return to the state where the GPS position is updated and displayed at an early stage, so that it is possible to cope with complicated turning on a general road. On the other hand, when exiting the blocking space U in the blocking mode, it is considered that the underground highway has changed to a ground highway along the road. In this case, since there is little possibility of complicated turning, the current position of the vehicle can be accurately updated and displayed even if the sensor position is updated and displayed for a while after the GPS position can be acquired. .

(3) Other embodiments:
FIG. 4 is a flowchart of an update display target setting process according to another embodiment. In embodiments of the present invention, when the vehicle travels through the branch point P _3, may if releasing the execution of the cut-off mode. Accordingly, when it is determined that the vehicle has traveled the start point P ₁ before the predetermined distance K of the branch point P ₃ (step S120: Y), the control unit 20 immediately sets the operation mode to the normal operation mode by the function of the display control unit 21b. The mode may be set (step S130). Thereby, when the vehicle travels at the branch point P ₃ , it is possible to return to the state where the GPS position is updated and displayed at an early stage. Of course, the execution of the blocking mode may be canceled when the vehicle travels at the branch point P ₃ regardless of whether or not the sensor position can be corrected.

  Further, the control unit 20 does not have to acquire the GPS position based only on the GPS signal due to the function of the position acquisition unit 21a, and the position based on the GPS signal is determined based on a correction element such as a road shape or a past trajectory shape. You may acquire GPS position by correct | amending. The blocking space U may be a tunnel section where a GPS signal is reflected and absorbed by a structure surrounding the blocking space U, a dense section of a high-rise building, or the like, or the GPS signal may be disturbed by an electromagnetic field formed by a radio tower or the like. It may be a section. The GPS position acquisition state may be an index that can evaluate the accuracy of the GPS position, and may be a processing state of processing until the GPS position is acquired, or a state of the acquired GPS position itself. It may be.

  With the function of the position acquisition unit 21a, the control unit 20 specifies the vehicle speed when entering the blocking space U based on the locus of the GPS position immediately before the vehicle travels in the blocking space U, and the vehicle travels while maintaining the vehicle speed. It may be assumed that the current position is substituted for the GPS position. By the function of the position acquisition unit 21a, the control unit 20 may acquire the sensor position specified by the vehicle ECU or the like based on signals output from the vehicle speed sensor and the direction sensor by communication. The direction sensor may be a sensor that generates a signal that can specify the direction of the vehicle, and may be a gyro sensor.

Further, the control unit 20 of the function of the display control unit 21b, after traveling junction P _3, until the predetermined distance running is low and the estimated likelihood to escape breaking space U, after the branch point P ₃ running, predetermined The execution of the cut-off mode may be canceled at the timing of traveling a distance. Control unit 20 of the function of the display control unit 21b, when the direction of the locus L ₂ direction and the sensor position of the trajectory of the GPS position is within a predetermined angular, GPS position may be determined to be similar to the sensor position .

  Further, the control unit 20 may display only the map on the display 42 without displaying the marker indicating the current position of the vehicle when the GPS position is not updated and displayed by the function of the display control unit 21b. Even in this case, it is possible to return to the state where the current position is updated and displayed at an early stage by executing the cut-off branch mode.

DESCRIPTION OF SYMBOLS 10 ... Portable terminal, 20 ... Control part, 21 ... Navigation program, 21a ... Position acquisition part, 21b ... Display control part, 30 ... Recording medium, 30a ... Map information, 41 ... GPS receiving part, 42 ... Display, 43 ... Terminal Side communication section, 50 ... vehicle side communication section, 51 ... steering sensor, 52 ... vehicle speed sensor, P ₃ ... branching point, U ... blocking space.

Claims (8)

A navigation system comprising: position acquisition means for acquiring a GPS position that is a current position of a vehicle based on a GPS signal; and display control means for updating and displaying the GPS position on a display unit,
The display control means includes
When the vehicle enters a shut-off space where the GPS signal is shut off, start execution of a shut-off mode for updating and displaying the GPS position on the condition that the acquisition state of the GPS position satisfies a predetermined display standard,
When the vehicle travels at a branch point in the blocking space, the execution of the blocking mode is canceled.
Navigation system. The display control means includes
When the vehicle travels at the branch point in the shut-off space, the GPS position having a reliability equal to or higher than a predetermined reliability can be acquired regardless of whether the acquisition state of the GPS position satisfies the display criterion. The execution of the blocking branch mode for updating and displaying the GPS position is started on the condition that,
The navigation system according to claim 1. The display control means includes
In the blocking mode, the GPS position is updated and displayed on condition that the accumulated number of times the GPS position has been acquired is a predetermined first reference number or more,
In the blocking branch mode, the GPS position is updated and displayed on condition that the number of times the GPS position having the reliability equal to or higher than the predetermined reliability has been acquired reaches the second reference number that is smaller than the first reference number. ,
The navigation system according to claim 2. The position acquisition means acquires a sensor position that is a current position of the vehicle based on signals output from a vehicle speed sensor and a direction sensor of the vehicle,
The display control means includes
In the blocking branch mode, when the GPS position similar to the sensor position is acquired, the reliability of the GPS position is greater than or equal to the predetermined reliability.
The navigation system according to any one of claims 2 and 3. The position acquisition means includes
Acquiring the sensor position corrected so that the road shape of the road on which the vehicle travels matches the trajectory of the sensor position before the vehicle passes through the branch point in the shut-off space;
The navigation system according to claim 4. The display control means includes
When the GPS position is not updated and displayed, the sensor position is updated and displayed on the display unit.
The navigation system according to claim 4 or 5. A navigation method including a position acquisition step of acquiring a GPS position that is a current position of a vehicle based on a GPS signal, and a display control step of updating and displaying the GPS position on a display unit,
In the display control step,
When the vehicle enters a shut-off space where the GPS signal is shut off, start execution of a shut-off mode for updating and displaying the GPS position on the condition that the acquisition state of the GPS position satisfies a predetermined display standard,
When the vehicle travels at a branch point in the blocking space, the execution of the blocking mode is canceled.
Navigation method. A navigation program for causing a computer to execute a position acquisition function for acquiring a GPS position, which is a current position of a vehicle based on a GPS signal, and a display control function for updating and displaying the GPS position on a display unit,
The display control function allows the computer to
When the vehicle enters a shut-off space where the GPS signal is shut off, start execution of a shut-off mode for updating and displaying the GPS position on the condition that the acquisition state of the GPS position satisfies a predetermined display standard,
When the vehicle travels at a branch point in the blocking space, the execution of the blocking mode is canceled.
Navigation program.

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