JP2001280985A - Automobile navigation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an automobile navigation system capable of determining whether a vehicle ascends to an elevated road or descents to a road beneath the elevated road. SOLUTION: The automobile navigation system includes a velocity vector detecting means for detecting a velocity vector of a vehicle on the basis of a Doppler shift amount of a GPS signal, and a determining means for determining whether the vehicle ascends to the elevated road or descends to the road beneath the elevated road on the basis of a moving distance of the vehicle in a horizontal direction and a height direction obtained from the velocity vector. In this case, the determining means determines whether the vehicle ascends to the elevated road or descends to the road beneath the elevated road when the vehicle ascends or descends a distance (b) while running a distance (a) in a horizontal direction on the basis of the moving distance of the vehicle in the horizontal and height directions obtained from the velocity vector calculated on the basis of the Doppler shift amount of the GPS signal, a value (a) little larger than a length L0 of a slope for entering and leaving the elevated road in a horizontal direction, and a value (b) little smaller than a height H0 at the highest point of the slope.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle navigation system using a GPS as a positioning means, and more particularly to a method for determining whether a vehicle has risen on an elevated road or descended on a road under an elevated road.

[0002]

2. Description of the Related Art In a recent vehicle navigation system, G
GPS positioning results based on PS and dead reckoning (Dead
Navigation is performed by comprehensively judging the positioning result based on the Reckoning (dead reckoning) function, selecting a positioning result estimated to be more accurate, and performing map matching on the selected positioning result, thereby performing navigation. The position estimation accuracy of the device has been improved.

[0003] However, in such a conventional vehicle navigation device, whether the vehicle has risen to an elevated road or descended to a road under an elevated road by using any of positioning means of GPS positioning, dead reckoning, and map matching. Was extremely difficult to determine. For example,
Although it is possible to obtain the coordinates of the vehicle in the three-dimensional space by the GPS positioning calculation, the accuracy of the three-dimensional coordinates obtained here is not accurate enough to distinguish an elevated road from a road under the elevated road.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances. That is, the present invention provides a vehicle navigation device, a GPS receiver, and a vehicle navigation method capable of determining whether the vehicle is traveling on an elevated road or a road under an elevated road, and uses the vehicle navigation method as a program. It is an object of the present invention to provide a storage medium storing the stored information.

[0005]

Therefore, a vehicle navigation apparatus according to a first aspect of the present invention uses a vehicle speed vector obtained by measuring a Doppler shift amount of a GPS signal, and allows a vehicle to travel on an elevated road. It is determined whether the vehicle has risen or has descended on an underpass.

According to a second aspect of the present invention, there is provided a vehicle navigation apparatus including speed vector detecting means for detecting a speed vector of a vehicle based on a Doppler shift amount of a GPS signal. A determination unit configured to determine whether the vehicle has risen to the height of an elevated road or has descended on a road under an elevated road, based on a moving distance of the vehicle in a horizontal direction and a height direction. That is, when the vehicle moves a predetermined distance in the horizontal direction and rises / falls a predetermined distance in the height direction, the determination means determines whether the own vehicle has risen on an elevated road or descended on a road under an elevated road. be able to.

[0007] Further, the determination means determines the moving distance of the vehicle in the horizontal direction and the height direction obtained from the speed vector calculated based on the Doppler shift amount of the GPS signal, and the distance of the ramp for entering and exiting the elevated road. By comparing the horizontal length L ₀ and the top height H ₀ of the ramp,
It is also possible to determine whether the vehicle has risen on an elevated road or descended on a road under an elevated road (claim 3).

[0008] Further, the judging means determines the moving distance of the vehicle in the horizontal direction and the height direction obtained from the speed vector calculated based on the Doppler shift amount of the GPS signal, and the information of the slope for entering and exiting the elevated road. based slightly smaller value b than the height H ₀ of the uppermost horizontal length L ₀ from a value slightly larger a and ramps, until the vehicle travels the distance a in the horizontal direction, the vehicle distance b When the vehicle rises or descends, it is determined whether the vehicle has risen on an elevated road or descended on a road under an elevated road. By performing the determination in this way, the determination is quickly and reliably performed (claim 4).

The vehicle navigation apparatus is further provided with a map database including data on the length and height in the horizontal direction of each of the ramps as information on the ramps for entering and exiting the elevated road. The means obtains data on the length and height in the horizontal direction for each ramp from the map database, and can determine whether the vehicle has risen on an elevated road or descended on a road under an elevated road. Item 5).

According to a sixth aspect of the present invention, there is provided a vehicle navigation method for determining a moving distance of a vehicle in a horizontal direction and a height direction based on a velocity vector calculated based on a Doppler shift amount of a GPS signal. It is characterized in that it is determined whether the vehicle has risen to the height of an elevated road or has descended on a road under an elevated road based on the moving distance. By reflecting this determination result in map matching, it is possible to distinguish whether the vehicle is traveling on an elevated road or traveling on a road under an elevated road.

In this case, by comparing the moving distance obtained based on the speed vector with the horizontal length L ₀ and the top height H ₀ of the ramp for entering and exiting the elevated road, It can be determined whether the vehicle has risen on an elevated road or descended on a road under an elevated road (claim 7).

Further, a moving distance obtained based on the velocity vector, the horizontal length L slightly larger value a and the top of the height H ₀ from ₀ ramp for and out of the elevated road
If the vehicle moves up or down the distance b before the vehicle travels the distance a in the horizontal direction based on the slightly smaller value b, the vehicle rises on the elevated road or descends on the road under the elevated It is also possible to determine whether it has been done (claim 8).

Further, the storage medium according to the present invention uses the above-described vehicle navigation method as a C medium in a vehicle navigation device.
The program is stored as a program processed by a PU (claim 9).

A GPS receiver according to a tenth aspect of the present invention includes a speed vector detecting means for detecting a speed vector of a vehicle based on a Doppler shift amount of a GPS signal, and a horizontal direction and a height direction of the vehicle obtained from the speed vector. Determining whether the vehicle has risen to the height of an elevated road or has descended on a road under an elevated road, based on the moving distance of the elevated road, and outputs the determination result as a message.

[0015]

FIG. 1 shows the configuration of a vehicle navigation apparatus 100 according to an embodiment of the present invention.
2 shows a detailed block diagram of the GPS receiver 20 in FIG. Hereinafter, first, the operation of the GPS receiver 20 will be described in detail with reference to FIG.

The GPS signal captured by the antenna 1 is input to a frequency conversion circuit 2. Further, the frequency conversion circuit 2
Is supplied with a signal of a local oscillation frequency generated by the synthesizer unit 3 based on the frequency generated by the reference frequency generator 4. The frequency converter 2 mixes the GPS signal and the signal of the local oscillation frequency, and converts the GPS signal into an intermediate frequency (IF) signal. The GPS signal converted into the IF by the frequency conversion circuit 2 is converted into a digital signal by the AD conversion unit 5 and output to the digital signal processing unit 12.

The carrier correlator 6 of the digital signal processor 12 multiplies and integrates a GPS signal as an IF signal input from the AD converter 5 and an output signal from a carrier NCO 7 for generating a carrier (carrier) frequency. Thus, the correlation value of these signals is calculated. The operation unit 11 performs feedback control on the carrier NCO control signal 18 so that the amplitude of the correlation value obtained by the carrier correlation unit 6 is maximized. With this feedback control, synchronization with the carrier is maintained. Further, the arithmetic unit 11 acquires the value of the Doppler shifted carrier frequency by synchronizing with the carrier in this way.

The output from the carrier correlator 6 is input to the CA code correlator 8 with the carrier components removed. In the code NCO 10 and the CA code generator 9,
A signal of the same pseudo-random code as the pseudo-random code unique to the GPS satellite to be acquired is generated, and this pseudo-random code signal is input to the CA code correlator 8. These input signals to the CA code correlator 8 are multiplied and integrated in the CA code correlator 8 to calculate a correlation value. The arithmetic unit 11 operates the code NCO 10 so that the amplitude of the correlation value output calculated by the CA code correlator 8 is maximized by the code NCO control signal 19.
And the phase of the pseudo random code signal generated by the CA code generator 9. At this time, by measuring the phase shift of the pseudo random code signal, the GPS satellite
The distance to the PS receiver (pseudo distance) is measured.

By providing a plurality of digital signal processing units 12, it is possible to simultaneously capture signals from a plurality of GPS satellites. The GPS receiver 20 of FIG. 2 includes four digital signal processing units 12. In this case, it is possible to capture signals from four GPS satellites at the same time.

The arithmetic unit 11 demodulates an input signal from the digital signal processing unit 12 and obtains a GPS message including orbit information (ephemeris) of a GPS satellite. Arithmetic unit 1
1 calculates the position of the GPS receiver itself (vehicle) by a geometric calculation based on pseudoranges and orbit information obtained for a plurality of GPS satellites.

The operation unit 11 further performs an operation described below.
Thus, the vehicle speed vector U is calculated. One GPS satellite
GPS calculated based on ephemeris for star j
Velocity vector V of satellite j_j(V_xj, V_yj,
v_zj), G from the vehicle calculated in the GPS positioning calculation process
Unit direction vector A toward PS satellite j_j(A_xj, A
_yj, A _zj) Is known as
d_jGet. d_j= ｛C (f_j−f_Tj) / F_Tj｝ + V_xja_xj
+ V_yja_yj+ V_zja_zj  Where c is the propagation speed of the radio wave f_TjThe carrier frequency f of the GPS satellite j_j; Doppler shift observed by the GPS receiver
Carrier frequency f_RjFrom the GPS satellite clock
GPS receiver clock rate of change t _UExcluding the effect of
Value.

The above d_jAnd the vehicle speed vector U
(X_u, Y_u, Z_uThe following equation is established between the parentheses. d_j= V_xja_xj+ V_yja_yj+ V_zja_zj-C
t_u  The unknowns contained in this equation are (x_u, Y_u, Z_u,
t_u), So from four GPS satellites
Measuring these signals leads to these unknowns.
Will be. The above equation is
It is represented by the definition of Equation 1 above.

(Equation 1)

The GPS receiver 20 outputs the speed vector U of the vehicle obtained by the above calculation as a GPS output message together with the information obtained from the GPS signal and the information obtained by the GPS positioning calculation.

Next, the operation of the vehicle navigation device 100 will be described with reference to FIG. The DR operation unit 32 in the CPU 50 performs dead reckoning (DR) based on a signal from the gyro sensor 28 and a sensor signal such as a vehicle speed pulse. In addition, the GPS operation result is input from the GPS receiver 20 to the DR operation unit 32. The DR calculation unit 32 selects a positioning result determined to be highly accurate by comparing the DR positioning result and the GPS positioning result with error estimation values of the respective positioning results, and maps the selected positioning result to map matching. Output to the unit 34.

The determination unit 38 calculates the GPS receiver 20
The speed vector U of the issued vehicle is input. Judgment unit 3
At 8, the vehicle goes up or down from the elevated road
A determination is made as to whether it has been performed. Here, the vehicle runs on a ramp
Fig. 3 (a) shows the state of reaching the elevated road
As the vehicle travels on a ramp.
The state of reaching the road under the bridge is shown in FIG. 3 (b).
You. In FIG. _X[M / s] is the traveling direction of the vehicle 55
Speed component, μ_Z[M / s] is μ_XAnd vertical speed
Component, which is a velocity level given from the GPS receiver 20.
It is calculated based on the vector U. As shown in FIG._Z
Occurs when the vehicle 55 goes up or down a ramp.
You. Also, in FIG.₀Is the horizontal length of the ramp
H₀Represents the height of the ramp. On the ramp
Related information (L₀, H₀) As described below
The map database of the vehicle navigation system 100
Source 24. Note that μ_ZThe polarity of the vehicle
Positive direction to climb, minus direction to descend vehicle
And

FIGS. 4 and 5 are flowcharts showing the operation of the judgment processing executed by the judgment section 38. 4 and 5 are executed as a subroutine of the navigation application executed by the CPU 50. GPS positioning result, velocity vector U
The GPS output message including information such as the above is updated at predetermined time intervals and sent from the GPS receiver 20 to the CPU 50. In the present embodiment, this time interval is 1 second, and G
It is assumed that a PS output message is sent to the CPU 50 every second.

When the subroutine of FIG. 4 is called, it is determined in step S1 whether the GPS output message has been updated. If the GPS output message has not been updated (S1: NO), the processing after S2 is not executed, and the process returns to the main routine of the application. If the GPS output message has been updated (S1: YES), the processing from S2 on is executed.
That is, the processing of S2 and subsequent steps is executed every second.

In step S2, the flag Height1 indicating that the vehicle has risen to the elevated road and the flag Height2 indicating that the vehicle has descended to the road under the elevated road are invalidated. In step S3, whether the road and the vertical velocity component mu _Z becomes a value greater than 0 is checked. Here, mu _Z is 0 if (i.e., the vehicle is traveling on a horizontal road not ramp), the determination is NO, S8 of the determination is NO, the S3, the variable H in S9, variable D is set to 0 and the subroutine ends.
mu _Z becomes a value greater than 0 (i.e., the vehicle has increased the ramp) if (S3: YES), mu _Z for the variable H for holding the height the vehicle has increased It added, mu _X is added to the variable D to hold the distance the vehicle is horizontal advanced (S4).

By executing step S4, it is possible to know the height at which the vehicle has risen by checking the variable H, and to know the horizontal distance the vehicle has moved by checking the variable D. It becomes possible. In step S5, the moving distance D in the horizontal direction of the vehicle is compared with horizontal length L ₀ of the ramp slightly lower estimated values a. While the condition of D <a is satisfied (S5: YES), if the ascending distance H of the vehicle is equal to or larger than the value b that slightly lowers the height of the ramp (S6: YES), the vehicle is elevated. It is determined that the vehicle has risen to the road, the flag Height1 is made valid (S7), and the subroutine ends.

In the determination in step S5, the value of D is a
If this is the case (S5: NO), the variables H and D are initialized to 0 (S9), and the subroutine ends. If it is determined in step S6 that the ascending distance H of the vehicle is smaller than b (S6: NO), the vehicle is on an inclined road and has not yet reached the elevated road, and the subroutine ends. I do. The main routine of the navigation application checks whether the flag Height1 is valid at the end of each of the subroutines shown in FIGS. 4 and 5 to determine whether the vehicle has climbed up a ramp and reached an elevated road. Know what.

On the other hand, when it is determined that the vehicle has started to descend on the slope (S8: YES), the processing shown in FIG. 5 is executed. The process in FIG. 5 is the same as the process shown in FIG. 4 when the vehicle goes up a ramp. Here, the variable J in FIG. 5 is a variable representing the distance that the vehicle has descended. That is, the transfer distance D in the horizontal direction of the vehicle is less than slightly smaller estimated values a horizontal length L ₀ of the ramp (S22: YES), drop distances J of the vehicle is high the ramp It is in when it becomes the _{H 0} over slightly smaller estimated value b (S23: YES), it is determined that the vehicle has fallen to the road underpass, flag Height
2 is enabled.

In the main routine of the navigation application, the flag Height2 is checked every time the subroutine shown in FIGS. 4 and 5 is completed, so that it is known that the vehicle has descended on the slope and reached the road under the elevated road.

Map matching section 34 in CPU 50
Receives the variables Height1 and Height2, which are the processing results of the determination unit 38. Map matching unit 34
In the situation where the elevated road and the road under the elevated road are in parallel, by checking Height1 and Height2, it is possible to identify whether the vehicle is traveling on the elevated road or the road under the elevated road, Matching can be performed correctly. The map database 24
Contains information on the height H ₀ and the length L ₀ of the ramp entering and exiting the elevated road (hereinafter referred to as “ramp information”) for each ramp along with map data mainly including roads. ing. The map matching unit 34 uses the map database 2
4 is read as appropriate and sent to the determination unit 38.

The position of the vehicle obtained by the map matching unit 34 is used as an application output 36 for displaying the position of the vehicle on a display device (not shown).

The above description has been made on the assumption that the ramp information is stored in the map database. However, the ramp information is not stored in the map database, and the determination unit 38 cannot acquire the ramp information. In this case, the judgment unit 38
In, it is also possible to make a determination using predetermined numerical values as the height H ₀ and the length L ₀ of the ramp.

In the embodiment described above, the determination unit 3
8 is provided inside the CPU 50,
The determination unit 38 can be realized as one function in the arithmetic unit 11 of the GPS receiver 20. In this case, the GPS receiver 20 receives the ramp information from the CPU 50 or uses a predetermined value as the ramp information, and the determination unit 38 provided as one function in the arithmetic unit 11 allows the vehicle to move to the elevated road. It is determined whether the vehicle has risen or descended on an elevated road. Furthermore, GP
The S receiver 20 outputs a variable High indicating the determination result.
t1 and Height2 are included in the GPS output message and output to the CPU 50.

[0037]

As described above, according to the present invention, it is possible to determine whether a vehicle has risen from an underpass to an overpass or has descended from an overpass to an underpass. . At this time, as a numerical value for comparison, a value a in which the horizontal length L ₀ of the ramp is slightly smaller and a value b in which the height H ₀ of the ramp is slightly smaller are used quickly and reliably. It is possible to make a determination.

By using this determination result when performing map matching, the navigation application can correctly perform map matching even in a situation where an elevated road and a road under an elevated road are parallel. . In particular, since the map matching is correctly executed when the vehicle travels in an urban area where a number of elevated roads are installed, the accuracy as a navigation application is dramatically improved.

[Brief description of the drawings]

FIG. 1 is a block diagram of a vehicle navigation device according to the present invention.

FIG. 2 shows a G provided in the vehicle navigation device of FIG.
It is a detailed block diagram of a PS receiver.

FIG. 3 is a diagram illustrating a speed vector of a vehicle traveling on an inclined road.

FIG. 4 is a flowchart showing a process of determining whether the vehicle has risen on an elevated road or descended on an elevated road together with FIG. 5;

FIG. 5 is a flowchart showing a process of determining whether the vehicle has risen on an elevated road or descended on an elevated road together with FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 GPS antenna 2 Frequency conversion circuit 3 Synthesizer part 4 Reference frequency generator 6 Carrier correlation part 7 Carrier NCO 8 CA code correlation part 9 CA code generation part 10 Code NCO 11 Operation part 20 GPS receiver 24 Map database 32 DR judgment part 34 Map Matching unit 38 Judgment unit 36 Application output 50 CPU 100 Vehicle navigation device

Claims (10)

[Claims] 1. GPS (Global Positioning System)
A vehicle navigation device including speed vector detection means for detecting a speed vector of a vehicle based on a Doppler shift amount of a signal, wherein the vehicle has risen to an elevated road or descended to a road under an elevated route based on the speed vector. A vehicle navigation device, comprising: 2. GPS (Global Positioning System)
A vehicle navigation device including speed vector detection means for detecting a speed vector of a vehicle based on a Doppler shift amount of a signal, wherein the vehicle is controlled based on a moving distance in a horizontal direction and a height direction of the vehicle obtained from the speed vector. A vehicle navigation device comprising: a determination unit that determines whether the vehicle has risen to the height of an elevated road or has descended to a road under an elevated road. 3. The method according to claim 1, wherein the determining means includes: a moving distance in a horizontal direction and a height direction of the vehicle obtained from the velocity vector; and a horizontal length L of a ramp for entering and exiting the elevated road.
₀ and by comparing the height H ₀ of the top of the ramp, according to claim 2, characterized in that determining whether the vehicle has fallen on the road under or elevated rose to flyover Car navigation equipment 4. The method according to claim 1, wherein the determining unit determines a moving distance in a horizontal direction and a height direction of the vehicle obtained from the speed vector, and a length L in a horizontal direction of a ramp for entering and exiting the elevated road.
_The value a slightly greater than ₀ and the height H ₀ at the top of the ramp
The car navigation device according to claim 2, wherein it is determined whether the vehicle has risen on an elevated road or has descended on a road under an elevated road by comparing the value with a slightly smaller value b. 5. A map database including data on a length and a height in a horizontal direction of each of the ramps as information on the ramps for entering and exiting the elevated road, wherein the determination unit includes the map database. The vehicle navigation device according to any one of claims 2 to 4, wherein a horizontal length and a height of the ramp are obtained from the control information. 6. Global Positioning System (GPS)
In a vehicle navigation device including a speed vector detecting means for detecting a speed vector of a vehicle based on a Doppler shift amount of a signal, a moving distance in a horizontal direction and a height direction of the own vehicle is obtained based on the speed vector. Determining whether the vehicle has risen to the height of an elevated road or descended on a road under an elevated road based on the vehicle navigation method. 7. GPS (Global Positioning System)
In a vehicle navigation device including a speed vector detecting means for detecting a speed vector of a vehicle based on a Doppler shift amount of a signal, a moving distance in a horizontal direction and a height direction of the own vehicle is obtained based on the speed vector. Is compared with the horizontal length L ₀ of the ramp for entering and exiting the elevated road and the height H ₀ at the top of the ramp, so that the vehicle has risen to the elevated road or Determining whether the vehicle has descended on a road. 8. Global Positioning System (GPS)
In a vehicle navigation device including a speed vector detecting means for detecting a speed vector of a vehicle based on a Doppler shift amount of a signal, a moving distance in a horizontal direction and a height direction of the own vehicle is obtained based on the speed vector. When, slightly smaller than the height H ₀ of the uppermost ramp value slightly larger a and the ramp than the horizontal length L ₀ of the for and out of the elevated road b
And the vehicle travels a distance a in the horizontal direction based on
A vehicle navigation method, comprising: determining that a vehicle has risen on an elevated road or has descended on a road under an elevated road when the vehicle has risen or descended a distance b. 9. A recording medium storing the vehicle navigation method according to claim 6 as a program read and executed by a CPU in a vehicle navigation device. 10. A GPS (Global Positioning System)
m) GPS having speed vector detecting means for detecting the speed vector of the vehicle based on the Doppler shift amount of the signal
A receiver, which determines whether the vehicle has risen to the height of an elevated road or descended to a road under an elevated road, based on a moving distance of the vehicle in a horizontal direction and a height direction obtained from the speed vector. A GPS receiver comprising: means for outputting the determination result as a message.