JPH1073442A - Navigation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent erroneous correction due to map matching by making a decision whether the field strength of a radio wave received by a satellite receiving means is higher than a predetermined level. SOLUTION: At first, moving distance and moving direction of a vehicle are received from a self-contained navigator 15 and a surveying data is received from a satellite receiving unit 14. The moving distance and moving direction of the vehicle are accumulated on the previous data of the vehicle in order to determine an estimated position of the vehicle and then a map data in the vicinity of the estimated position is received from an external reader 16. A CPU 11 makes a decision whether the field strength of a received radio wave is lower than a predetermined level. If it is higher than the predetermined level, a decision is made whether the estimated position of the vehicle is within an error range. If it deviates from the error range, the estimated position of the vehicle is corrected to an absolute position and subjected to map matching. If it is within an error range, the estimated position of the vehicle is determined as the position of the vehicle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a navigation device for detecting a position of a vehicle.

[0002]

2. Description of the Related Art A conventional navigation device will be described below.

[0003] Either a device that receives radio waves from a plurality of artificial satellites to obtain positioning data such as the absolute position of a vehicle, or a device that obtains an estimated position of a vehicle from data measured by a self-contained sensor. Or a navigation device that calculates the current position of the vehicle using both of them, corrects the calculated current position of the vehicle on the road in the map data (map matching), and outputs the corrected position to the display device. Have been.

[0004]

In such a conventional navigation device, a correction process called map matching is performed on the calculated vehicle position. However, by performing the map matching, an incorrect display is performed. However, there is a problem that the user may perform the operation. This situation will be specifically described with reference to FIG.

[0007] As shown in FIG. 6 (a), a case is considered in which there is an underground parking lot B which does not exist on the map data and in which radio waves from artificial satellites are cut off. As shown in FIG. 6B, it is assumed that the actual traveling route of the vehicle turns left on the road Ra, enters the underground parking lot B, and reaches the point P. As shown in FIG. 6C, the mark indicating the position of the vehicle should originally be displayed at the point P. However, map matching is performed and the mark is corrected to the point Q on the road R2. There was such a problem.

An object of the present invention is to provide a navigation device that can prevent erroneous correction by map matching.

[0007]

SUMMARY OF THE INVENTION In order to solve this problem, the present invention provides a map reading means for reading predetermined map data from a storage medium storing map data, a detecting means for detecting an operation state of a vehicle, The estimated position calculating means for calculating the estimated position of the vehicle from the output data of the detecting means, and the estimated position of the vehicle calculated by the estimated position calculating means is located on the road with reference to the map data read by the map reading means. A navigation device provided with a map matching means for performing correction so as to determine whether the electric field strength of the radio wave received by the satellite receiving means is equal to or less than a predetermined value. When the determination unit determines that the electric field strength of the radio wave received by the satellite reception unit is equal to or less than a predetermined value, the map matching unit That it was configured and control means for controlling so as not to perform correction.

Thus, a navigation device capable of preventing erroneous correction by map matching can be obtained.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention according to claim 1 of the present invention provides a map reading means for reading predetermined map data from a storage medium storing map data, a detecting means for detecting an operation state of a vehicle, The estimated position calculating means for calculating the estimated position of the vehicle from the output data of the detecting means and the map data read by the map reading means are referred to so that the estimated position of the vehicle calculated by the estimated position calculating means is located on the road. A navigation device comprising a map matching means for correcting the electric field, a satellite receiving means for receiving a radio wave from an artificial satellite, and determining whether or not an electric field intensity of the radio wave received by the satellite receiving means is equal to or less than a predetermined value. When the determining unit determines that the electric field strength of the radio wave received by the satellite receiving unit is equal to or less than a predetermined value, the correction by the map matching unit is performed. When the electric field intensity is equal to or less than a predetermined value, it is determined that the location does not exist in the map data, such as an underground parking lot, and map matching is performed. Absent.

According to a second aspect of the present invention, there is provided a map reading means for reading predetermined map data from a storage medium storing map data, a detecting means for detecting an operation state of a vehicle, and an output data of the detecting means. Estimated position calculating means for calculating the estimated position of the vehicle from the map, and map matching for correcting the estimated position of the vehicle calculated by the estimated position calculating means so as to be located on the road with reference to the map data read by the map reading means. Means for receiving a radio wave from an artificial satellite, the electric field strength of the radio wave received by the satellite receiving means being less than or equal to a predetermined value, and a vehicle detected by the detecting means. Determining means for determining whether or not the speed is equal to or less than a predetermined value; and detecting the electric field intensity of the radio wave received by the satellite receiving means which is equal to or less than the predetermined value, and which is detected by the detecting means. When the determination unit determines that the speed of the vehicle is equal to or lower than the predetermined value, the control unit controls the map matching unit so that the correction is not performed. If the speed of the vehicle is equal to or lower than a predetermined value, it is determined that the location does not exist in the map data, such as an underground parking lot, and map matching is not performed.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 is a functional block diagram of a navigation device according to a first embodiment of the present invention.
In this embodiment, the moving body is described as a vehicle such as an automobile.

In FIG. 1, reference numeral 1 denotes a self-contained sensor unit for detecting a moving distance and a moving direction of a vehicle.
As sensors for detecting the moving distance, there are a wheel speed sensor that detects a pulse signal corresponding to the number of rotations of the wheel, an acceleration sensor that detects the acceleration of the vehicle, and the like. As a sensor for detecting the moving direction, there is a gyro sensor for detecting the angular velocity of the vehicle.

Reference numeral 2 denotes a satellite receiving unit that receives radio waves from artificial satellites and obtains positioning data such as the absolute position of a vehicle. A GPS (Global Positioning S) is a typical example.
ystem), and this embodiment will be described on the premise of GPS.

Reference numeral 3 denotes an estimated position calculation unit that calculates an estimated position of the vehicle from data output from the independent sensor unit 1,
Reference numeral 4 denotes a GPS for correcting the estimated position of the vehicle calculated by the estimated position calculation unit 3 based on the absolute position of the vehicle obtained by the satellite reception unit 2.
It is a correction unit.

Reference numeral 5 denotes a map storage unit in which map data is stored. The map data contains road information. The road information includes intersections and inflection points of roads as feature point (node) data, and the roads are approximated as straight lines connecting the nodes.

Reference numeral 6 denotes a map matching unit that refers to road information near the estimated position of the vehicle and corrects the estimated position of the vehicle so as to be located on the road.

Reference numeral 7 denotes a display unit for displaying the obtained vehicle position on the map data, and reference numeral 8 denotes a control unit for controlling the above-described units.

FIG. 2 is a block diagram showing the configuration of the navigation apparatus according to the first embodiment of the present invention, and shows the hardware configuration of the apparatus shown in FIG.

In FIG. 2, reference numeral 11 denotes a CPU (Central Processing Unit) for executing the operation program in this embodiment,
Reference numeral 12 denotes a ROM (Read Only Memory) storing an operation program executed by the CPU 11, and reference numeral 13 denotes a RAM (Rand) serving as a work area when the CPU 11 executes the operation program.
om Access Memory), 14 is a satellite receiving device for receiving radio waves from artificial satellites, 15 is a self-contained navigation device having a self-contained sensor for detecting a physical quantity of vehicle operation, and 16 is a CD-RO.
An external reading device for reading map data stored in a storage medium such as an M (Compact Disk-Read Only Memory);
A display device 7 displays an image on a display screen such as an LCD (Liquid Crystal Display).

The operation of the navigation device configured as described above will be described below.

FIG. 3 is a flowchart showing the operation of the navigation device according to the first embodiment of the present invention.
2 shows how the operation program stored in the CPU 2 is executed by the CPU 11.

As shown in FIG. 3, first, the self-contained navigation device 1
Then, the moving distance and moving direction of the vehicle are received from step 5 (step 1). The self-contained navigation device 15 integrates data detected by the wheel speed sensor or the acceleration sensor over time (two times in the case of an acceleration sensor) to obtain a moving distance, and integrates data detected by the gyro sensor over time to obtain a moving direction. ing.

The positioning data is received from the satellite receiver 14 (step 2). In the present embodiment, the GPS is used, and the absolute position of the vehicle, the error range, the electric field strength of the radio wave, and the like are received as the positioning data.

The travel distance of the vehicle received in step 1,
The estimated position of the vehicle is calculated by accumulating the moving azimuth with the previous position of the vehicle (step 3).

When the estimated position of the vehicle is determined, map data near the estimated position is received from the external reading device 16 (step 4).

Here, the CPU 11 determines whether or not the electric field strength of the radio wave obtained in step 2 is equal to or less than a predetermined value (step 5). If the value is equal to or more than the predetermined value, it is determined whether the estimated position of the vehicle calculated in step 3 is within the error range obtained in step 2, and if the estimated position of the vehicle is outside the error range. If so, the estimated position of the vehicle is corrected to the absolute position of the vehicle (step 6). In step 6, when the estimated position of the vehicle is within the error range, the estimated position of the vehicle is not corrected.

The estimated position of the vehicle corrected in step 6 is subjected to map matching (step 7). this is,
Referring to the road data read in step 4, a candidate road existing within a predetermined range from the estimated position of the vehicle and having an azimuth difference between the traveling direction of the vehicle and the link direction of the road within a predetermined error. Perform a search. If there are multiple candidate roads, one of the most probable roads is
Choose one. When the candidate road is determined, the estimated position of the vehicle is corrected so as to be located on the candidate road.

On the other hand, if the value is equal to or smaller than the predetermined value in step 5, the estimated position of the vehicle calculated in step 3 is directly determined as the position of the vehicle (step 8).

The estimated position of the vehicle determined in step 7 or 8 is displayed on the display device 17 together with the map data.
(Step 9).

FIG. 4 is a diagram for explaining the operation of the navigation device according to the first embodiment of the present invention. The operation of the flowchart shown in FIG. 3 will be specifically described.

As shown in FIG. 4A, consider a case where a vehicle is trying to enter an underground parking lot B which does not exist in the map data and in which radio waves from GPS satellites are cut off.

The dotted line A in FIG. 4B indicates the course on which the vehicle actually travels. The actual vehicle turns left on the road Ra and proceeds to the underground parking lot B.

As shown in FIG. 4C, if the estimated position of the vehicle in step 3 (see FIG. 3) is the point P, the condition in step 5 (see FIG. 3) is satisfied, and the position of the vehicle is indicated. The mark will be displayed at the point P.

As described above, according to this embodiment, when the electric field strength of the received radio wave is equal to or less than the predetermined value, the vehicle is in a place where radio waves are hard to reach such as an underground parking lot which does not exist in the map data. Since the possibility is high, the correction by the map matching is not performed in such a case.

(Embodiment 2) FIG. 5 is an operation flowchart of a navigation device according to a second embodiment of the present invention. In FIG. 5, steps 11 to 14 correspond to steps 1 to 4 and step 16 in FIG.
Step 19 is the same as Step 6 to Step 9 in FIG.

The flowchart of this embodiment is different from that of the first embodiment in that the CPU 11 determines in step 15 whether the electric field strength is equal to or lower than a predetermined value and the speed of the vehicle is equal to or lower than a predetermined value. The point is to judge.

This is because, for example, when traveling in an underground parking lot, the vehicle travels at a low speed of 20 km / h or less. Therefore, not only the electric field strength of the received radio wave but also the speed of the vehicle are used as judgment data. It is possible to more accurately judge that the place is a place such as an underground parking lot.

The speed of the vehicle in step 15 uses the speed of the vehicle determined by the self-contained navigation device 15.

[0040]

As described above, according to the present invention, map reading means for reading predetermined map data from a storage medium storing map data, detecting means for detecting an operation state of a vehicle, and output of the detecting means Estimated position calculating means for calculating the estimated position of the vehicle from the data, and a map for correcting the estimated position of the vehicle calculated by the estimated position calculating means so as to be located on the road with reference to the map data read by the map reading means. A navigation device including a matching unit, a satellite receiving unit that receives a radio wave from an artificial satellite,
Determining means for determining whether the electric field strength of the radio wave received by the satellite receiving means is equal to or less than a predetermined value, and determining that the electric field strength of the radio wave received by the satellite receiving means is equal to or less than the predetermined value; Is configured to include a control unit that controls so as not to perform the correction by the map matching unit.If the electric field strength is equal to or less than a predetermined value, it is a place that does not exist in the map data such as an underground parking lot. Since the judgment is made and the map matching is not performed, even if the vehicle enters a place such as an underground parking lot that does not exist in the map data, the position of the vehicle can be accurately displayed.

Map reading means for reading predetermined map data from a storage medium storing the map data, detecting means for detecting an operating state of the vehicle, and estimated position calculating means for calculating an estimated position of the vehicle from output data of the detecting means. A navigation device comprising: a map matching unit that corrects the estimated position of the vehicle calculated by the estimated position calculating unit with reference to the map data read by the map reading unit so that the estimated position of the vehicle is located on the road; Satellite receiving means for receiving radio waves from the vehicle, and determining whether the electric field strength of the radio waves received by the satellite receiving means is equal to or less than a predetermined value and whether the speed of the vehicle detected by the detecting means is equal to or less than a predetermined value. Determining that the electric field strength of the radio wave received by the satellite receiving means is equal to or less than a predetermined value, and the speed of the vehicle detected by the detecting means is equal to or less than a predetermined value. When the determination is made by the determination unit, the control unit is configured to perform control so that the correction by the map matching unit is not performed. If there is, it is determined that it is a place that does not exist in the map data such as an underground parking lot, and map matching is not performed, so even if the vehicle enters a place such as an underground parking lot that does not exist in the map data, the position of the vehicle Can be displayed accurately.

[Brief description of the drawings]

FIG. 1 is a functional block diagram of a navigation device according to a first embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a navigation device according to the first embodiment of the present invention.

FIG. 3 is an operation flowchart of the navigation device according to the first embodiment of the present invention.

FIG. 4 is a diagram illustrating the operation of the navigation device according to the first embodiment of the present invention.

FIG. 5 is an operation flowchart of a navigation device according to a second embodiment of the present invention.

FIG. 6 is a diagram illustrating the operation of a conventional navigation device.

[Explanation of symbols]

 Reference Signs List 1 autonomous sensor unit 2 satellite receiving unit 3 estimated position calculating unit 4 GPS correcting unit 5 map storing unit 6 map matching unit 7 display unit 8 controlling unit 11 CPU 12 ROM 13 RAM 14 satellite receiving device 15 self-contained navigation device 16 external reading device 17 Display device

Claims (2)

[Claims] 1. Map reading means for reading predetermined map data from a storage medium storing map data, detecting means for detecting an operation state of a vehicle, and estimating means for calculating an estimated position of the vehicle from output data of the detecting means. A navigation device comprising: a position calculating unit; and a map matching unit that corrects the estimated position of the vehicle calculated by the estimated position calculating unit so as to be located on a road with reference to the map data read by the map reading unit. Satellite receiving means for receiving a radio wave from an artificial satellite; determining means for determining whether or not the electric field strength of the radio wave received by the satellite receiving means is equal to or less than a predetermined value; When the determination unit determines that the electric field strength of the radio wave is equal to or less than a predetermined value, the control is performed so that the correction by the map matching unit is not performed. A navigation device comprising a control unit for controlling the navigation. 2. A map reading means for reading predetermined map data from a storage medium storing map data, a detecting means for detecting an operation state of the vehicle, and an estimating means for calculating an estimated position of the vehicle from output data of the detecting means. A navigation device comprising: a position calculating unit; and a map matching unit that corrects the estimated position of the vehicle calculated by the estimated position calculating unit so as to be located on a road with reference to the map data read by the map reading unit. A satellite receiving means for receiving a radio wave from an artificial satellite; an electric field intensity of the radio wave received by the satellite receiving means being equal to or less than a predetermined value; and a vehicle speed detected by the detecting means being a predetermined value. Determining means for determining whether or not the electric field strength of a radio wave received by the satellite receiving means is equal to or less than a predetermined value, and a vehicle detected by the detecting means. When the determination unit determines that both speeds are equal to or less than a predetermined value,
Control means for controlling so as not to perform correction by the map matching means.