JP2744664B2 - Vehicle navigation system - Google Patents

Description

The present invention relates to a navigation device for a vehicle.

(Prior Art) Now, for example, suppose that a driver is driving to a certain destination while driving a car. In a lonely space isolated from the outside of a car, a driver maps a strange land with a map. It can be said that he is simply stepping on the accelerator to his intended destination, relying on road signs and landscape. In other words, even today, when computers and data communication have been developed and information is said to be excessive, the essence of driving a car has hardly changed since the time when the car was invented.

In view of such circumstances, recently, a vehicle travel guidance device generally called a navigation system has been increasingly developed.

The navigation system detects, for example, a horizontal component of a geomagnetic vector and uses it as a direction parameter (hereinafter, referred to as a geomagnetic method) or a gas rate gyro using inertia of helium gas as a direction sensor. In addition to so-called dead reckoning systems such as those that detect the
GPSS system (Global Positioning System) that can accurately detect the position of the vehicle anywhere on the earth using multiple circular orbiting satellites (called GPS navigation satellites)
A so-called satellite navigation system such as a system with satellite has been proposed.

By the way, in such a vehicle navigation device, it is most important that the guidance accuracy is high first, in addition to the cost problem. It is the vehicle position detection performance of the vehicle position recognition means that basically determines the guidance accuracy. Therefore, the most promising from this point of view is the satellite navigation system based on the GPSS method using an artificial satellite among the above two types of navigation systems.

In the case of the satellite navigation system, a plurality (at least three,
(Preferably four or more satellites) can receive the distance information and the time information from the respective satellites and recognize the absolute position of the vehicle in two or three dimensions. However, there is an advantage that a sufficiently high own-vehicle position detection capability (positioning error of about ± 30 m) can be ensured. Further, even when the vehicle is transported by sea on a ferry board or the like, it is not necessary to reset the own vehicle position, which is convenient.

However, at present, the number of navigation satellites launched in a circular orbit around the earth is not enough, and it is practically difficult to secure four or more preferable navigation satellites at all times.
Also, even if four or more navigation satellites can be secured, the satellites are in their own orbits, and the arrangement between the satellites is poor depending on the timing. It may be impossible to receive a signal from the GPS, and eventually a proper three-dimensional positioning may not be possible.

That is, in the above navigation satellites, there are a time zone in which positioning is possible even within one day (Th) and a time zone in which positioning is impossible (other than Th), as shown in FIG. Therefore, in a time zone where positioning is not possible, a positioning error becomes large, and positioning data during that period cannot be used originally.

For this reason, conventionally, for example, JP-A-63-26529
As described in the invention described in Japanese Patent Application Laid-Open Publication No. H10-260, two positioning systems, a three-dimensional positioning system using a satellite and a two-dimensional positioning system based on dead reckoning using the above-mentioned azimuth sensor, are combined, and the latter two-dimensional positioning system is used. If appropriate three-dimensional positioning by four or more satellites is possible, accurate navigation data such as the current position is detected and stored by the three-dimensional positioning system. When proper three-dimensional positioning becomes impossible due to worsening conditions, etc., the two-dimensional positioning data obtained by the dead reckoning navigation system is modified based on the relationship with the road network data to make the vehicle position display data as accurate as possible. Some adopt a complex system configuration to be formed.

(Problems to be Solved by the Invention) However, at present, the area that can be corrected by the map matching means, that is, the area in which road data for navigation for performing map matching is created is extremely limited. Even if the road data for the map matching is created nationwide, it is virtually impossible to completely cover all areas in Japan. And impossible areas occur.

As a result, in the configuration of the related art, there is a problem that a difference occurs in the recognition accuracy of the current position of the vehicle between when the vehicle is traveling in the map matching area and when it is not.

(Means for Solving the Problems) The present invention has been made for the purpose of solving the above-mentioned problems, and has a satellite navigation system for recognizing an absolute position of a vehicle based on information from a satellite; A dead reckoning system that determines the estimated position of the vehicle based on the mileage;
A vehicle navigation device comprising: a map matching unit that performs matching on the dead reckoning system in relation to actual road network data.
Positioning error level detecting means for detecting the level of the positioning error in the satellite navigation system, positioning error level determining means for comparing the level of the positioning error detected by the positioning error level detecting means with a predetermined determination reference value, A determination reference value setting means for setting and holding two determination reference values, a first determination reference value for determining the positioning error level and a second determination reference value having a determination level higher than the first determination reference value. And when the positioning error level detected by the positioning error level detecting means is equal to or greater than a first criterion value set by the criterion value setting means while the map matching means is being used, the map is recognized by the satellite navigation system. The current position is recognized using the own vehicle position data
When the map matching means is not used, the vehicle position data recognized by the satellite navigation system is used only when the positioning error level detected by the positioning error level detecting means is equal to or greater than the second determination reference value. And satellite data use control means for recognizing the current position.

(Operation) In the above-described vehicle navigation device of the present invention, the vehicle navigation device including the satellite navigation system, the dead reckoning navigation system, and the map matching means detects the positioning error coefficient indicating the reliability of the positioning data of the satellite. In the map matching area where the map matching means is used, even if the positioning error level of the satellite navigation system is high to some extent, the current position is recognized using the positioning data by the satellite, while the map matching means is used. In the non-map matching area where is not used, only the satellite positioning data with a positioning error level lower than a certain level, that is, the vehicle position data with high positioning accuracy is adopted.

(Effects of the Invention) Therefore, according to the vehicular navigation device of the present invention, it is possible to maintain substantially constant recognition accuracy of the current vehicle position in both the inside and outside of the map matching area.

(Embodiment) FIGS. 2 to 8 show the configuration and operation of a vehicle navigation device according to an embodiment of the present invention.

First, FIG. 2 shows a system structure of a vehicle navigation system in the embodiment. Reference numeral 10 denotes a navigation control unit which is a center of a control unit, and the navigation control unit 10 is a central information processing device. (Hereinafter simply referred to as CPU) 11, a built-in control program or read-only memory (hereinafter referred to as ROM) 12, a random access memory (hereinafter simply referred to as RAM) 13, which stores various control data as needed,
It comprises an interface circuit 14 for inputting and outputting data between various types of external devices described later and the CPU 11 and the like.

And the above navigation control unit 10
As an external device to be combined with a vehicle, first, a car-mounted device for reading out the map information from a CD-ROM (compact disk type read-only memory) 1 storing a large number of the above-described map-type travel guidance information at a plurality of different scales. CD player 2, operation switch section 3 for performing various operations such as setting and changing and resetting of destinations, changing of optimum route, detailed display of map contents, etc., and detecting current vehicle position Pn (Xn, Yn) A display control circuit 5 for inputting an image signal output from the CPU 11 and displaying the image signal output from the CPU 11 on a screen of a CRT display 6 of a meter cluster unit, for example, and a video memory 7 attached to the display control circuit 5 Etc. are provided.

The CD player 2 drives the CD-ROM 1 and drives the CD-RO
The information of the required predetermined area in the map information of the whole of Japan stored in M1 is output according to the designated address (designated by longitude X and latitude Y), and the decoder 8 and the interface circuit 14 are output. Input to the CPU 11 via the above. These read information are temporarily stored in the RAM 13. The output of the CD player 2 decoded via the decoder 8 is also output to the side of a normal in-vehicle audio device (AMP, equalizer, speaker, etc.) 9.

The CD-ROM 1 stores, for example, map information of about 30,000 color still images. For example, in the case of this embodiment, at least two types of scales (normal / enlarged)
Are available.

Next, the operation switch 3 is formed of, for example, a screen touch type, and includes (1) menu, (2) information, and (3)
Reset, (4) enlarge, (5) shrink, (6) detail, (7)
Various operation switches for correction and the like are provided. The ON output of the operation switch 3 is coded by the encoder 16 and then input to the CPU 11 via the interface circuit 14. The CPU 11 performs a predetermined operation (program processing) in response to the input of the operation switch 3 to operate the display control circuit 5 for driving the CRT, thereby displaying an image corresponding to the instruction.

Further, in the case of the present embodiment, the own vehicle position recognizing device 4 which recognizes the current own vehicle position is, for example, as shown in FIG.
And the second vehicle position recognizing means 4B based on the GPSS method described above.
These two sets of different vehicle position recognizing means are combined, and their respective outputs are selectively input to the CPU 11 via the switching circuit 20.

First, the first vehicle position recognizing means 4A includes, for example, a geomagnetic sensor 41 for detecting geomagnetism such as a flux gate as shown in FIG. 3, a traveling speed of the vehicle and a traveling distance (1 km = 637 revolutions: JIS), and receives the outputs from both sensors 41, 42 to detect the traveling direction (azimuth θ) of the vehicle and the relative distance 1 from a predetermined reference point Pstart to detect the current position of the vehicle. It comprises a first output signal processing circuit 43 for recognizing Pn (Xn, Yn) (the recognition mechanism will be described later; see FIG. 6) 43.

That is not least if accurate travel distance l to the running direction θ of the vehicle is known, the relative positional relationship between two points from one point a ₁ to a certain point an can easily know, is mean that will be able to the certain point a ₁ to know the vehicle position an traveling if the starting point Pstart known (set at the start).

For example FIG. 4 shows the basic principle, when now the vehicle A is to be traveling from the known starting point a ₁ to an point, (about 5m) at a distance a ₁ ~a _2, a ₂ ~ A ₃ , a ₃ ~ a ₄ , a _{4
~a 5, a 5 ~a 6,} a 6 ~a 7, a 7 ~a 8, a 8 ~a 9, a 9 ~an ( unit moving distance l ₁ between the points, l _2, l ₃ · .. Ln is calculated from the output of the wheel speed sensor 42) and changes in the traveling direction θ (θ ₁ , θ ₂ , θ ₃ ) by the geomagnetic sensor 41 every time the vehicle travels.
... Θn), coordinate conversion is performed, and the distances Δx = lcosθ and Δy = lsinθ between the east-west and the north-south between the above two points are calculated, and the grounds are sequentially added. as a result,
Eventually, the vehicle position (Pn) at point an is specified.

The second vehicle position recognizing means 4B uses, for example, a global positioning satellite system (GPSS) shown in FIG. 5, and transmits a radio wave from a ground station antenna 75 as shown in FIG. Main control station 76, at least four execution navigation satellites (GPS satellites) 77A to 77D each receiving a radio wave transmitted from the ground station antenna 75, and each of these satellites 77A to 77D.
A ground station system including a monitor station 85 which receives a transmission radio wave from D, calculates a positioning error coefficient GDOP value indicating the degree of a positioning error of the radio wave, and superimposes the GDOP value on the transmission radio wave from the terrestrial antenna 75. For each vehicle A
As shown in the figure, a GPS receiver 44 for receiving transmission radio waves from the four GPS navigation satellites 77A to 77D, and the four satellites based on the reception timing between the respective satellite radio waves received by the GPS receiver 44. And the satellite navigation system-side second signal processing circuit 45 for detecting the distance, altitude, and time between the satellites 77A to 77D and the vehicle A, and absolutely detecting the current position Pn of the vehicle A, A positioning error coefficient detection means (determination circuit) 46 for specifically detecting and determining the level of the positioning error coefficient GDOP value of the satellite radio wave. The positioning error coefficient detecting means (judgment circuit) 46 detects when the GDOP value included in the entire radio wave received by the GPS receiver 44 is equal to or less than a predetermined value with poor satellite constellation, and when the radio wave intensity (electric field strength D _B ) outputs a positioning error increase signal when the value itself is equal to or smaller than a predetermined value (for example, when a vehicle is traveling in a tunnel or the like and cannot receive a radio wave).

Further, the switching circuit 20 selects the second self-vehicle position recognizing means (satellite navigation system) 4B of the satellite type when the positioning error coefficient detecting means (judging circuit) 46 does not output the positioning error increase signal. On the other hand, when the positioning error increase signal is output, the first self-vehicle position recognizing means (dead-reckoning navigation system) 4A of the geomagnetic type is selected, and the current own-vehicle position signal of the selected vehicle is transmitted to the navigation control unit. This is output to the CPU 11 of 10.

Then, the navigation control unit 10 shown in FIG. 2 always sets the optimal route in relation to the destination Po set in advance based on the actual vehicle position Pn recognized as described above. Navigation control is performed so as to follow the route, and the display of the optimum route in relation to the destination Po is performed, for example, as shown in FIG.

That is, first, before starting operation,
It was loaded vehicle position above the CD player 2 in S ₁ driving the CD player 2. As a result, the map information (normal scale) of the optimal traveling route set corresponding to the destination Po to be made from now on can be read.

Next, in step S _2, specifically set a destination Po to go from now by operating the operation switch 3.

Further, in this state, the above-mentioned own-vehicle position recognizing device 4 is operated to read an accurate own-vehicle position Pstart (input to the RAM).

Then, the in the subsequent step S ₃ the current vehicle position Pstart
From the start point Pstart based on the optimal route, and displays an initial page (No. 1 map) on the screen of the CRT display 6 on the meter cluster side. The vehicle position mark MP is plotted on the map road in a superimposed state. And step
As shown in S ₄ and S ₅ , the current position is sequentially recognized at predetermined cycles as the vehicle advances, and the display of the own vehicle position is sequentially updated based on the current position.

By the way, when displaying the position of the own vehicle, although the size is increased or decreased depending on the accuracy of the positioning method to be used, errors due to positioning cannot be avoided. Particularly, in dead reckoning navigation, errors are accumulated. There is a possibility that the current position of the car is gradually shifted from the road on which the vehicle is traveling and is displayed on the wrong road.

For this reason, in the vehicle navigation device of the present embodiment, among the roads near the own vehicle, the current position of the own vehicle is corrected by pulling the current position on the road that is most likely to be running. Map matching is performed as necessary, such as every predetermined distance or every predetermined time, thereby correcting the positional deviation as needed and preventing the accumulation of the error. Then, in order to perform this map matching, all the roads in the vicinity of the own vehicle are listed up, a candidate list is created and stored, and at the same time, the own vehicle is traveling on that road for each road accompanying the own vehicle. It is designed to evaluate the possibility of running. Then, the plot display of the position of the own vehicle is performed.

Next, the control operation related to the GPS three-dimensional positioning system by the navigation control unit 10 and the two-dimensional positioning system by dead reckoning and the map matching system will be described in detail with reference to the flowchart of FIG.

First, at a step S _1, and inputs the current value data starting point Pstart (longitude X = Xo, latitude Y = Yo) by a manual operation in the memory.

Thereafter, the process proceeds to step S ₃ after confirming the lapse of a predetermined time t at step S _2, actually determines whether the vehicle has moved (running).

In the case of YES determination that the vehicle has started traveling, in step S _4, and inputs the vehicle direction θ detected by the geomagnetic sensor when its memory. Step S ₅
Generates the moving distance 1 by the traveling based on the output of the wheel speed sensor.

Then, further proceeds to step S _6, the movement distance l between the vehicle direction θ on the basis of the measurement principle of FIG. 4 described above, calculates the current moving point _{Pn (X 1, Y 1)} (X 1 = lcosθ , X ₂ = lsinθ)
I do.

Moreover the process proceeds to step S7, the data of the road corresponding to the movement point calculated in step _{S 6 Pn (X 1, Y} 1) determines whether is in the memory. Consequently, YES (Yes in road data) when it comes to, the moving point in the subsequent step S ₈ Pn
Is compared with the road data, and coordinates X ₁ , Y on the actual road are compared.
₁ determined (map matching), sets the value of the judgment reference value CL of the positioning error count GDOP values mentioned earlier in step S ₉ to a first reference value 0.

On the other hand, if it is determined that there is no corresponding road data to the mobile point Pn at step S ₇ (NO), the setting value of the judgment reference value CL to the second reference value 3 proceeds to step S ₁₀ I do.

As described above, the determination reference value CL of each positioning error coefficient
When the setting is finished, turn willing GPS receiver 77A~77D described above in step S ₁₁ proceeds to the determination of whether it can receive.

When it is confirmed that the GPS receiver 44 can receive, the process proceeds to step S _12, S _13, the positioning error coefficients G
GDOP value detected by the DOP value detecting means performs the above step S ₉ or step S ₁₀ at the set criterion value CL (CL =
0 or CL = 3) or less, and if YES (good), the positioning data X _G , Y _G of the satellite is obtained.

On the other hand, or it is impossible to receive the GPS receiver 77a to 77d (NO at step S _11), the positioning error coefficient GDOP value is higher than the determination reference value CL (bad) when (NO at step S ₁₂₎
Indicates the values of the positioning data X _G and Y _{G obtained} by the above satellites as X _G = 0 and Y _G =
0 to the current position X in step S ₁₅ on was reset, the process proceeds to the calculation operation of the Y.

Current position coordinates X of the step S _15, the calculation of Y the coordinates X _1, Y ₁ and positioning data X _G by the satellites on the road obtained in step S _8, as shown by using the Y _G It is obtained by calculating.

When the operation is completed, the process proceeds to step S _16,
The current position of the vehicle is displayed based on the calculated values X and Y.

As a result, according to the present embodiment, it is possible to improve the accuracy of recognizing the current vehicle position in the inside and outside regions of the map match area as much as possible.

Note that the flowchart of FIG. 7 is configured to determine whether or not the area is the map match area based on whether or not there is road data corresponding to the area of the moving points X ₁ and Y _1. determination may be determined by the fact that for example directly "or the map matching area", also step S ₇ of the flowchart in Figure 8 ', S _8' can be determined in two operations as shown in the Needless to say.

[Brief description of the drawings]

FIG. 1 is a diagram corresponding to a claim of the vehicle navigation device of the present invention, FIG. 2 is a block diagram showing the overall system configuration of the device, and FIG. 3 is a vehicle position recognition device of FIG. FIG. 4 is an explanatory diagram showing the principle of recognition by a first vehicle position recognition means in the vehicle position recognition device, and FIG. 5 is a second vehicle position; FIG. 6 is an explanatory diagram showing the recognition principle of the recognition means, FIG. 6 is a flowchart showing the basic operation of the navigation control unit in the configuration of FIG. 2, and FIG. 7 uses map matching of the main part of the embodiment of the present invention. FIG. 8 is a flowchart showing a current position recognition display operation, FIG. 8 is a flowchart of a main part showing a modification of the flowchart of FIG. 7, and FIG.
It is a satellite arrival forecast figure which shows a satellite state in one day (24 hours). DESCRIPTION OF SYMBOLS 1 ... CD-ROM 2 ... CD player 3 ... Operation switch 4 ... Local vehicle position recognition device 4A ... First vehicle position recognition means 4B ... Second vehicle position recognition means 6 ... CRT Display 10 Navigation control unit 11 CPU 41 Geomagnetic sensor 42 Wheel speed sensor 44 GPS receiver 77A to 77D Navigation satellite

Claims (1)

(57) [Claims] 1. A satellite navigation system for recognizing an absolute position of a vehicle based on information from a satellite, a dead reckoning system for obtaining an estimated position of the vehicle based on an azimuth and a traveling distance, and a dead reckoning navigation system. A vehicle navigation apparatus comprising a map matching means for performing matching in relation to actual road network data, wherein a positioning error level detecting means for detecting a level of a positioning error in the satellite navigation system; Positioning error level determining means for comparing the level of the positioning error detected by the detecting means with a predetermined determination reference value, a first determination reference value for determining the positioning error level, and the first determination reference value A criterion value setting means for setting and holding two criterion values of a second criterion value having a higher criterion level; While the switching means is in use, the vehicle recognized by the satellite navigation system when the positioning error level detected by the positioning error level detecting means is equal to or greater than a first criterion value set by the criterion value setting means. While the current position is recognized using the position data, when the map matching means is not used, the satellite is only used when the positioning error level detected by the positioning error level detecting means is equal to or higher than the second determination reference value. A vehicle navigation device comprising: satellite data use control means for recognizing a current position using own vehicle position data recognized by a navigation system.