JPH0682262A - Guidance device for vehicle - Google Patents

Abstract

PURPOSE:To determine whether a GPS is to be utilized according to the condition of traffic jam and to calculate the current position of a vehicle accurately utilizing GPS position measurement coordinates by providing various kinds of means for calculating the condition of the traffic jam. operating the current position, and changing a reference value. CONSTITUTION:The condition of traffic jam is calculated by a traffic jam calculation means 105 based on the road map data in region mesh units which are read. The reference value of the GPS position measurement accuracy which is calculated by a position accuracy calculation means 102 is set according to the calculated condition of traffic jam. The reference value becomes a criterion for determining whether the GPS position measurement coordinates are referred to at the time when calculating the current position of the vehicle using a current position calculation means 103. Since the GPS position measurement accuracy is expressed by the radius of an error circle in reference to the calculated coordinates, a reference value modification means 106 reduces the reference value of accuracy, namely the reference radius of the error circle, when the traffic jam around the vehicle is large and the current position operation means 103 accurately calculates the current position of the vehicle by referring to the accurate GPS position measurement coordinates. Also, when the traffic jam is small, the reference radius of the error circle is increased and the GPS position measurement coordinates are utilized effectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle drive guide device for displaying the present position of a vehicle on a road map and guiding an occupant to a destination.

[0002]

2. Description of the Related Art A drive guide device for a vehicle is known which displays the current position of the vehicle on a road map displayed on a display device and guides an occupant to a destination (for example, Japanese Patent Laid-Open No. Sho-6).
2-98214). In this type of device, the current position of the vehicle is calculated by map matching. That is, the running locus obtained by integrating the running distance and the heading of the vehicle is compared with the road shape of the road map, and if there is a matching road, the current position of the vehicle is set to the position corresponding to the current position on the road. To set. Further, the GPS signal is received to determine the measurement position accuracy (hereinafter referred to as GPS positioning accuracy), and when the GPS positioning accuracy is higher than the reference value, the GPS
The current position of the vehicle is corrected by referring to the positioning coordinates calculated based on the signal.

[0003]

By the way, the GPS positioning accuracy can be expressed in terms of the radius of an error circle centered on the calculated position coordinates. For example, positioning accuracy is 50m
In this case, the GPS positioning coordinates may deviate from the actual position of the vehicle by up to 50 m.

However, in the above-described conventional vehicle drive guide device, since the GPS positioning accuracy is compared with a fixed reference value to determine whether the quality is good or bad, it is determined that the accuracy is good and based on the GPS positioning coordinates. When correcting the current position of the vehicle, the current position of the vehicle may be set on the road different from the road on which the vehicle is actually traveling in an area with high road density around the vehicle. For example, assuming that the reference value of GPS positioning accuracy is 50 m, if the positioning accuracy is 50 m or less, the GPS
Correct the current position by referring to the positioning coordinates. However, when driving in urban areas where the road density around the vehicle is high,
There are many roads within a 50m radius centered around the vehicle,
During map matching, there is a high possibility that a road different from the road actually being traveled may be mistaken for a road currently being traveled.

Further, since the GPS positioning accuracy is compared with a certain reference value to determine its quality, the possibility of misidentification of a traveling road due to map matching is reduced in an area where the road density around the vehicle is low. Regardless, it often happens that the accuracy is determined to be poor and the GPS positioning coordinates cannot be referred to. For example, in the above example, if the positioning accuracy exceeds the reference value of 50 m, the current position is calculated by map matching based on the traveling locus of the vehicle without referring to the GPS positioning coordinates. However, when traveling in the suburbs where the road density around the vehicle is low, there are few roads existing within a radius of 50 m centering on the vehicle, and the possibility of misidentifying the traveling road is reduced during map matching. Regardless of GPS
It often happens that the current position cannot be corrected by using.

An object of the present invention is to use GPS depending on road density.
It is an object of the present invention to provide a vehicle drive guide device that determines whether or not to use a vehicle, and effectively utilizes GPS positioning coordinates to calculate an accurate current position of the vehicle.

[0007]

The present invention will be described with reference to FIG. 1, which is a claim correspondence diagram. According to the present invention, a storage means 100 for storing road map data and a receiving means 101 for receiving a GPS signal are provided. Position accuracy calculating means 102 for calculating the measured position accuracy based on the GPS signal, and when the calculated measured position accuracy is higher than a preset reference value, the current position of the vehicle is calculated by referring to the GPS signal. The present invention is applied to a vehicle drive guide device provided with a current position calculation means 103 and a display means 104 that displays a road map around the vehicle based on road map data and the calculated current position of the vehicle. Then, a road density calculating means 105 for calculating the road density based on the road map data around the vehicle,
A reference value changing unit 106 that changes the reference value of the current position calculating unit 103 according to the calculated road density is provided, thereby achieving the above object.

[0008]

The reference value of the GPS positioning accuracy is changed according to the road density around the vehicle, and when the GPS positioning accuracy is higher than the reference value, the current position of the vehicle is calculated by referring to the GPS signal.
As a result, the higher the road density around the vehicle, the more accurately the GPS signal can be referred to, and the accurate current position of the vehicle can be set on the road map even when the roads are dense.

[0009]

2 and 3 show the construction of a vehicle drive guide device according to one embodiment. This device has a CPU as shown
It is composed of a microcomputer centering on 1. The CPU 1 exchanges data with various devices via the system bus 2 to perform various arithmetic processes. A direction sensor 3 detects the traveling direction of the vehicle, and is connected to the system bus 2 via the amplifier 4, the A / D converter 5 and the I / O controller 6. Reference numeral 7 is a distance sensor that detects the traveling distance of the vehicle, and is connected to the system bus 2 via the I / O controller 6. Reference numeral 8 is a key for inputting various commands and data to the device, which is connected to the system bus 2 via the I / O controller 9. Reference numeral 10 is a voice output speaker, which is connected to the system bus 2 via the sound generator 11 and the I / O controller 9.

Reference numeral 12 is a receiver for receiving GPS signal radio waves (hereinafter referred to as GPS receiver), which is connected to the system bus 2 via an expansion I / O controller 13.
Further, 14 is a receiver equipped with an antenna 15, and receives road traffic information and position information such as traffic congestion, road construction, traffic regulation, etc. from road beacons installed at roads and intersections.

Further, in FIG. 3, reference numeral 16 is a CD-ROM storing road map data, which is an interface SC.
It is connected to the system bus 2 via the SI controller 17. 18 is a VDT (Visual Display)
It is a CRT that functions as a (Terminal), is connected to the system bus 2 via the graphic controller 19, and displays a road map around the current position of the vehicle. Further, the system bus 2 is provided with a V- for image storage of the CRT 18.
RAM 20 and R storing a control program to be described later
OM21, D-RAM22 for temporary storage of data, Chinese character R
An OM 23 and a battery backup RAM 24 that stores information such as the current position when the ignition is turned off are connected.

Although the GPS positioning coordinates and the positioning accuracy are already known, the outline will be described. G sent from satellite
The PS signal includes position information indicating the position of the satellite, time information indicating the correct time, accuracy information indicating the accuracy of the GPS signal itself, and the like. Normally, GPS signal radio waves are received from three or four satellites, and the distance from each satellite is calculated based on the satellite position information and time information included in each signal,
According to the principle of triangulation, the three-dimensional vehicle position, that is, G
PS positioning coordinates are calculated. The accuracy of the calculated GPS positioning coordinates, that is, the positioning accuracy is substantially determined by the accuracy of the GPS signal itself and the positional relationship between the vehicle and each satellite. The accuracy of the former GPS signal itself is indicated by the accuracy information included in the GPS signal. Regarding the positional relationship of the latter satellites, for example, the closer the satellites are to each other and the smaller the elevation angle of each satellite, the worse the accuracy becomes. Therefore, the radius of an error circle centered on the coordinates where the GPS positioning accuracy is calculated (unit:
The conversion table (not shown) for converting the accuracy information and the positional relationship with each satellite into the radius of the error circle is set and stored in the ROM 21. And GPS
Each time the positioning coordinates are calculated, the conversion table is searched to find the radius of the error circle indicating the GPS positioning accuracy.

FIG. 4 shows a GPS signal processing routine.
The CPU 1 executes this subroutine at predetermined time intervals. First, the GPS signal is received by the GPS receiver 12 in step S1, the GPS positioning coordinates are calculated based on the GPS signal in the subsequent step S2, and the D-RAM 22 is operated.
Remember. Note that this calculation method is well known and will not be described. In step S3, the radius of the error circle indicating the GPS positioning accuracy is searched from the conversion table, and the D-RAM 22 is searched.
Remember. When the above process is completed, the process returns to the control program that was being executed before executing this subroutine.

FIG. 5 is a flow chart showing an example of a control program for calculating the current position. The operation of the embodiment will be described with reference to this flow chart. When the ignition key (not shown) of the vehicle is set to the ON position, the vehicle drive guide device is powered on, and the CPU 1 starts executing this control program. In step S11 after the execution is started, the current position of the vehicle, the destination, etc. are initialized. Here, the current position of the vehicle may be the position of the vehicle stored in the backup RAM 24 after the previous run as the initial position, or may be the position input by the occupant operating the key 8. In a succeeding step S12, road map data around the current position of the vehicle is read from the CD-ROM 16 into the D-RAM 22. For road map data, nationwide JIS-X0410
The road map data is read out from the CD-ROM 16 in units of regional meshes. In addition, the road map data is dataized as a set of nodes indicating roads such as intersections and bends, and straight lines connecting the nodes, that is, links, and the position coordinates of each node and each link and the roads. It is stored together with attribute information such as type.

In step S13, the road density is calculated based on the read road map data in units of regional meshes. As described above, since roads are decomposed into nodes and links and converted to data, the density of roads in the area can be known by checking the number of links included in the road map data in the area mesh. In this case, the road density is represented by the number of links per unit area (unit: number / square kilometers). Alternatively, the road density may be obtained by calculating the total length of links included in the road map data in the regional mesh. In that case, the road density is expressed by the total length of links per unit area (unit: kilometers / square kilometers).

Next, in step S14, a reference value of GPS positioning accuracy is set according to the calculated road density. This reference value serves as a criterion for determining whether to refer to GPS positioning coordinates when calculating the current position of the vehicle,
For example, it is set as shown in FIG. 6 according to the road density. As described above, the GPS positioning accuracy is represented by the radius of the error circle centered on the calculated coordinates. Therefore, when the road density around the vehicle is high, the accuracy reference value, that is, the reference radius of the error circle should be reduced. Accurately calculate the current position of the vehicle by referring to highly accurate GPS positioning coordinates. On the other hand, when the road density is low, the accuracy of the current position calculation is less affected, so the reference radius of the error circle is increased to effectively use the GPS positioning coordinates. The reference value of the GPS positioning accuracy with respect to the road density is tabulated and stored in the ROM 21 in advance.

In step S15, the GPS positioning accuracy calculated by the subroutine shown in FIG. 4 is compared with the reference value of the accuracy according to the road density around the vehicle. If the GPS positioning accuracy is higher than the reference value, the operation proceeds to step S16. Otherwise, to step S17. In step S16,
The current position of the vehicle is calculated with reference to the GPS positioning coordinates.

The current position of the vehicle is calculated by the map matching method described above. That is, the traveling locus of the vehicle is obtained based on the traveling distance of the vehicle detected by the distance sensor 7 and the traveling azimuth of the vehicle detected by the azimuth sensor 3, and is compared with the traveling locus by collating with the road map around the vehicle. Search for a road to do. However, the running locus of the vehicle calculated based on the running distance and the traveling azimuth accumulates calculation errors due to detection errors of sensors and the like, and the error increases as the calculation is repeated. Therefore, in order to eliminate the accumulation of such calculation error, the calculation result of the current position is corrected with reference to the GPS positioning coordinates to obtain a more accurate current position.

However, when the present position of the vehicle is calculated with reference to the GPS positioning coordinates, according to the conventional method, only the GPS positioning coordinates with higher accuracy than a certain reference value are used regardless of the road density. In areas with high road density, there is a high possibility that a road that is different from the road that is actually running will be mistaken for a road that is running. Therefore, the GPS positioning coordinates are referred to only when it is determined that the GPS positioning accuracy is equal to or less than the reference value according to the road density and the GPS positioning coordinates are not mistakenly recognized as the road on which the vehicle is traveling. Calculate the current position of the vehicle.

The current position of the vehicle is corrected by the GPS positioning coordinates, for example, as follows. When calculating the traveling locus and the estimated position of the vehicle by integrating the traveling distance and the heading of the vehicle and performing the map matching by collating with the road map around the vehicle, the current position of the vehicle is shown as shown in FIG. When the vehicle mark is out of the error circle centered on the GPS positioning coordinates, or when the vehicle mark is not on the road due to the loss of the road on which the vehicle is traveling, on the road existing within the error circle based on the GPS positioning coordinates. The current position of the vehicle is set in and the vehicle mark is displayed on the road. However, when the estimated position of the vehicle by map matching is within the error circle and is on the road, the correction based on the GPS positioning coordinates is not performed.

On the other hand, if the GPS positioning accuracy is larger than the reference value corresponding to the road density and it is determined that the current position calculation error that misidentifies the road on which the vehicle is running occurs when the GPS positioning coordinates are referred to, then in step S17. Map matching is performed based on the traveling path of the vehicle, and the current position of the vehicle is calculated without referring to GPS positioning coordinates. In step S18, the calculated current position of the vehicle is superimposed on the road map data around the vehicle stored in the D-RAM 22, converted into image data, and displayed on the CRT 18 via the graphic controller 19. In a succeeding step S19, it is determined whether or not the road map itself displayed on the CRT 18 needs to be updated with the movement of the vehicle, and if it needs to be updated, the process returns to the step S12 and the road in the new area mesh unit is updated. Read the map data. If it is not necessary to update the road map, the process returns to step S15 and the calculation of the current position of the vehicle is repeated.

As described above, the reference value of the GPS positioning accuracy is changed according to the road density around the vehicle, and the current position of the vehicle is corrected based on the GPS positioning coordinates when the GPS positioning accuracy is higher than the reference value. Therefore, the accurate current position of the vehicle can be calculated in the area where the roads are dense, and the GPS can be effectively used in the area where the road density is low.

In the above-described embodiment, the road density is calculated from the road map data in the area mesh unit around the vehicle, and the GPS positioning accuracy and the reference value corresponding to the road density are compared to calculate the current position of the vehicle. It was decided whether or not to refer to the GPS positioning coordinates, but the reference value data of the GPS positioning accuracy was stored in advance in the road map data of each regional mesh unit, and the reference value and the GPS positioning accuracy were compared. May be. By doing so, the calculation processing of the road density can be omitted, and the load on the CPU can be reduced.

In the structure of the above embodiment, the CD-RO
M16 is a storage means, GPS receiver 12 is a reception means, CPU1 is a position accuracy calculation means, a current position calculation means,
The road density calculating means and the reference value changing means are connected to the CRT 18
Respectively constitute the display means.

[0025]

As described above, according to the present invention, the reference value of the measurement position accuracy by the GPS signal is changed according to the road density around the vehicle, and the GPS signal is detected when the GPS positioning accuracy is higher than the reference value. Since the current position of the vehicle is calculated with reference to, the accurate current position can be calculated by effectively utilizing GPS.

[Brief description of drawings]

FIG. 1 is a complaint correspondence diagram.

FIG. 2 is a block diagram showing the configuration of an embodiment.

FIG. 3 is a block diagram showing the configuration of an embodiment.

FIG. 4 is a flowchart showing a GPS signal processing routine.

FIG. 5 is a flowchart showing an example of a control program for calculating the current position of the vehicle.

FIG. 6 is a diagram showing a reference value of GPS positioning accuracy with respect to road density.

FIG. 7 is a diagram illustrating correction of the current position of the vehicle based on GPS positioning coordinates.

[Explanation of symbols]

 1 CPU 2 System Bus 3 Direction Sensor 4 Amplifier 5 A / D Converter 6,9 I / O Controller 7 Distance Sensor 8 Key 12 GPS Receiver 13 Extended I / O 14 Receiver 15 Antenna 16 CD-ROM 17 SCSI Controller 18 CRT 19 Graphic Controller 20 V-RAM 21 ROM 22 D-RAM 23 Kanji ROM 24 Backup RAM 100 Storage Means 101 Receiving Means 102 Position Accuracy Calculating Means 103 Current Position Calculating Means 104 Display Means 105 Road Density Calculating Means 106 Reference Value Changing Means

Claims (1)

[Claims] 1. A storage unit for storing road map data, a receiving unit for receiving a GPS signal, a position accuracy calculation unit for calculating a measurement position accuracy based on the GPS signal, and a calculated measurement position accuracy in advance. A current position calculating means for calculating a current position of the vehicle by referring to the GPS signal when the value is higher than a set reference value; and a current position of the vehicle calculated as a road map around the vehicle based on the road map data. In a vehicle drive guide device including a display unit that displays a position, a road density calculation unit that calculates a road density based on road map data around the vehicle, and the current position according to the calculated road density. A drive guide device for a vehicle, comprising: reference value changing means for changing the reference value of the calculating means.