JP2002031536A - Forward direction detection apparatus and method using gps position information and storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a forward direction detection apparatus using GPS position information capable of detecting forward direction even if a vehicle travels slowly or if map matching cannot be achieved. SOLUTION: A GPS sensor 1c outputs position coordinate data on receiving a GPS signal as the vehicle advances (travels). Using the position coordinates of two points which are output from the GPS sensor 1c, the forward direction of the vehicle is computed from a difference between the position coordinates.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heading detection device, a heading detection method and a recording medium using GPS position information.

[0002]

2. Description of the Related Art A function of displaying a road map around a vehicle position, a function of calculating a recommended route from a departure point to a destination,
2. Description of the Related Art There is known a car navigation device having a function of performing route guidance based on a calculated recommended route.
In this car navigation device, it is necessary to detect the current position and traveling direction of the vehicle. For this purpose, for example, a direction sensor for detecting the traveling direction of the vehicle, a vehicle speed sensor for detecting the vehicle speed, a GPS sensor for detecting a GPS signal from a GPS (Global Positioning System) satellite, and the like are provided.

[0003] Inexpensive vibration gyro sensors are most often used as direction sensors for car navigation systems. The vibration gyro sensor is a sensor that detects a rotational angular velocity. In the car navigation device, the displacement of the azimuth is acquired based on the rotational angular velocity detected by the vibration gyro sensor, and the displacement is added to the reference azimuth obtained by the GPS signal and the map matching technology to detect the current heading of the vehicle. Is done.

[0004]

However, for example, when a vehicle enters an indoor multi-story parking lot and runs around the inside, the following problem occurs. Since it is impossible to acquire GPS signals in a multi-story parking lot, GP
The reference azimuth cannot be corrected by the S signal and the map matching technique, and the reference azimuth immediately before entering the multi-story parking lot must be used. Further, since the rotational angular velocity value detected by the vibration gyro sensor has an error, the error is added with time. As a result, if the vehicle exits the multi-story parking garage and travels on the road again, the car navigation device has only vehicle traveling direction data that is significantly different from the actual vehicle traveling direction, and cannot perform proper navigation processing. Problems arise.

On the other hand, some GPS sensors output a traveling direction signal calculated based on a GPS signal.
However, the traveling azimuth signal output from the GPS sensor has a problem that the accuracy of the traveling azimuth signal is low unless the traveling speed of the vehicle is equal to or higher than a predetermined speed based on a predetermined detection principle. Therefore, in a vehicle that runs slowly immediately after coming out of the multi-story parking lot,
This heading signal cannot be used.

An object of the present invention is to use, for example, in a car navigation system, GPS position information capable of detecting a heading even if a vehicle or the like travels slowly or map matching cannot be performed. To provide a traveling direction detecting device, a traveling direction detecting method, and a recording medium.

[0007]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described below with reference to the embodiment shown in FIG. The invention according to claim 1 is applied to a traveling direction detection device that moves as the traveling direction detection target travels and detects the traveling direction of the traveling direction detection target.
GPS position information acquisition means (1c) for acquiring S position information
And a traveling azimuth calculating means (3) for calculating the traveling azimuth of the traveling azimuth detection target using the GPS position information of a plurality of points acquired with the traveling of the traveling azimuth detection target. It is. According to a second aspect of the present invention, in the traveling azimuth calculating device according to the first aspect, the determining means (3) for each acquired GPS position information determines whether or not the GPS position information can be used for calculating the traveling azimuth. In addition,
The traveling azimuth calculating means (3) uses the GP
Only when it is determined that the S position information can be used for calculating the traveling direction, the traveling direction of the traveling direction detection target is computed using the GPS position information. According to the traveling azimuth detecting method of claim 3, the traveling azimuth of the traveling azimuth detection target is acquired by acquiring a plurality of GPS position information with the traveling of the traveling azimuth detection target and using the acquired GPS position information of the plurality of points. Is calculated. The recording medium according to claim 4, wherein a plurality of G's are recorded in accordance with the progress of the traveling direction detection target.
Acquires PS location information, GPS of multiple acquired points
It records a control program for a heading detection device for calculating a heading of a heading detection object using position information.

[0008] In the means and means for solving the above problems, the description is made in correspondence with FIG. 1 of the embodiment for easy understanding, but the present invention is not limited to the embodiment. Absent.

[0009]

FIG. 1 is a block diagram of a car navigation system according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a current position detecting device for detecting the current position (own vehicle position) of a vehicle, for example, a direction sensor 1a for detecting the traveling direction of the vehicle, a vehicle speed sensor 1b for detecting the vehicle speed, and a GPS.
(Global Positioning System) It comprises a GPS sensor (GPS receiver) 1c for detecting GPS signals from satellites.

The azimuth sensor 1a is constituted by a vibration gyro sensor or the like, detects a rotational angular velocity when the vehicle turns, and outputs a corresponding voltage signal. Vehicle speed sensor 1b
Is mounted, for example, on a transmission output shaft of a vehicle, and outputs a pulse according to the vehicle speed. With the combination of the direction sensor 1a and the vehicle speed sensor 1b, the movement of the vehicle can be detected two-dimensionally.

The GPS sensor 1c is a sensor that receives a GPS signal transmitted from a GPS satellite and obtains information on the position of the GPS sensor 1c. The GPS satellites are a plurality of artificial satellites managed by the U.S. Department of Defense, and constantly transmit satellite time data and orbital position data using atomic clocks.
The GPS sensor 1c receives the GPS signal, calculates the distance to the satellite from the difference between the time signals, and measures the current position in the manner of triangulation. When GPS signals are received from three satellites,
Two-dimensional positioning (latitude, longitude) becomes possible. When GPS signals are received from four satellites, three-dimensional positioning (latitude, longitude,
Altitude) is possible. Since these contents are publicly known, the details are omitted. The position information acquired by the GPS sensor 1c is converted into a constant coordinate value and output as own vehicle position information. For example, it is represented using a mesh number when the map is divided into meshes and XY normalized coordinates which are coordinate values obtained by further dividing the map mesh. Sometimes represented by latitude and longitude.

Reference numeral 2 denotes a map database device for storing road map data. The map database device 2 uses a CD-
ROM drive device and CD with road map data recorded
-It is configured by loading the ROM 11. A music CD-ROM or a program storage CD-ROM
When such is loaded, it functions as a CD-ROM reading device. 3 is a control circuit for controlling the entire apparatus,
It consists of a microprocessor and its peripheral circuits. Reference numeral 4 denotes an input device having various switches for inputting a destination of the vehicle and the like. Includes a joystick that directs cursor movement and screen scrolling. The input device 4 may be of a remote control type. Further, a touch panel switch may be provided in the screen.

Reference numeral 5 denotes an image memory for storing image data to be displayed on the display monitor 6. This image data is created from road map drawing data, various graphic data, and the like. The image data stored in the image memory 5 is read out as appropriate and displayed on the display monitor 6. The ROM 7 stores a control program executed by the control device 3 and various data. The RAM 8 is used as a work area.

The car navigation device performs various navigations based on the vehicle position information acquired by the above-described current position detection device 1 and road map data (information) stored in the map database device 2. For example, a road map near the own vehicle position and the own vehicle position are displayed on the display monitor 6, and the driver is guided along the route obtained by the route search.

The GPS sensor 1c outputs a heading signal using a predetermined conventional technique. This heading signal is
This is detected by a conventional technique different from the present invention. Further, the control device 3 performs a known map matching using the position information from the GPS sensor 1c and the road map data of the map database device 2. When a road map is captured by map matching, the traveling direction of the vehicle can be detected based on the road map data. That is, if the current position of the vehicle is corrected assuming that the vehicle is traveling on any of the roads in the road map data by the map matching technology, the traveling direction can be grasped based on the road map data. The control device 3
Depending on the situation, the displacement of the direction obtained by the direction sensor 1a is added based on the direction obtained by any of the above methods,
The current heading of the vehicle, which changes every time, is detected.

However, the traveling direction signal according to the prior art output from the GPS sensor 1c is not accurate unless the speed of the vehicle is higher than a certain speed. This is due to a predetermined detection principle. Therefore, when the vehicle is traveling at a low speed, the traveling direction signal cannot be used. Further, the above-described map matching is not always successful. If the map matching is not successful, the vehicle enters free running in which the position of the own vehicle is detected and displayed based on signals from the direction sensor 1a and the vehicle speed sensor 1b. That is, the vehicle enters a so-called free running state in which the vehicle position mark moves on a road other than the road in the road map.

The car navigation system according to the present embodiment is such that the traveling direction of the vehicle can be reliably detected even when the vehicle is running at low speed and free.

[0018] The background that the traveling azimuth detection according to the present embodiment becomes possible is that on May 2, 2000, the United States issued an SA (Selective Availability,
Selectivity) has been released. Conventionally, a GPS signal is intentionally multiplied by an SA to reduce the accuracy of positional information of the GPS signal. Therefore, GPS
Conventionally, the vehicle position acquired by the sensor 1c has an error of a radius of about 100 m. However, the cancellation of SA for GPS signals in the United States greatly improved the accuracy of GPS signal position information. In the present embodiment, the traveling azimuth of the vehicle is detected using the position information based on the GPS signal with the improved accuracy.

FIG. 2 is a flowchart showing the control for detecting the traveling direction of the vehicle using the position information based on the GPS signal. The routine of this flowchart is executed by the control device 2. For example, the GPS sensor 1c receives a GPS signal from a GPS satellite every second, performs a predetermined operation, and outputs GPS position information every second. The control device 3 executes the following routine every second in synchronization with the output timing of the GPS sensor 1c. Therefore, when this routine is started, the GPS sensor 1
c, one piece of GPS position information is acquired and output.

In step S1, the vehicle speed is calculated based on a signal from the vehicle speed sensor 1b, and it is determined whether or not the vehicle speed is 30 km / H or less. If the vehicle speed is 30 km / H or less, the process proceeds to step S2. If the vehicle speed exceeds 30 Km / H, this routine ends. If the vehicle speed exceeds 30 km / H, the traveling direction signal of the related art output from the GPS sensor 1c can be used as described above, so that it is not necessary to determine the vehicle direction by this routine. The reference value for determining the vehicle speed was 30 km / H.
It is not necessary to limit to this value. An appropriate value may be set by experiments or rules of thumb.

In step S2, the free running distance is 30
It is determined whether it is 0 m or more. If it is determined that the distance is 300 m or more, the process proceeds to step S3. If the distance is less than 300 m, this routine ends. If the vehicle is not running free, it is determined that free running is 0 m, and the routine ends. If the vehicle is not in free running, the vehicle is traveling on the road of the road map data as described above, and thus the traveling direction can be obtained based on the road map data even when the vehicle speed is low.
Although the reference value for determining the free running distance is set to 300 m, it is not necessary to limit to this value. Other values may be used.

In step S3, it is determined whether the SA value is 3 or less. The SA value is an index indicating the accuracy of the position information sent together with the position information from the GPS sensor 1c. Conventionally, the United States uses SA (Select
Before the release of ive Availability), the SA value was, for example, about 7, but after the release of the SA, the SA value became 3 or less. The SA value of 3 or less may be considered to be an error in GPS position information within a radius of about 20 m.
However, this is only a guideline. The conventional error was said to be about 100 m radius. In step S3, SA
If it is determined that the value is 3 or less, the process proceeds to step S4
If it is determined that the number exceeds the limit, this routine is terminated.

In step S4, it is determined whether or not the GPS position information adoption condition is satisfied. The GPS position information adoption conditions include, for example, how many seconds or more continuous three-dimensional positioning by a GPS signal can be performed, whether the number of captured GPS satellites is, for example, four or more, and whether the GPS satellite arrangement condition satisfies a predetermined standard. And so on. That is, in addition to the SA value, the condition is a condition based on information on GPS from which the accuracy and reliability of the position information of the GPS signal can be determined. G
The PS position information adoption condition may be one of the above conditions or a combination thereof (and so on). Further, conditions other than the above may be included.

Note that the SA value in step S3 and the GPS position adoption conditions in step S4 are determined by the individual GPS
This is to determine whether the position information can be adopted. Therefore, it is possible to determine whether or not it can be immediately adopted for each GPS position information. That is, there is no need to acquire a plurality of GPS position information over several seconds and perform a predetermined operation based on the plurality of GPS position information to determine whether or not the individual GPS position information can be used for the first time.

Here, step S4 is omitted and the above SA
Only the value may be used as the GPS position adoption condition. Conversely, the determination of the SA value in step S3 may be omitted and step S3 may be omitted.
The GPS position adoption condition may be determined based on only the determination of No. 4. Other conditions may be employed as long as the accuracy and reliability of each GPS position information can be confirmed. In order to further improve the accuracy, a process of acquiring a plurality of pieces of GPS position information, performing a predetermined calculation, and determining whether the GPS position information can be adopted may be added.

In step S5, the azimuth θgps-n every second is determined based on the GPS position information acquired every second.
Is calculated. In the present embodiment, the GPS position information is GP
Since the XY normalized coordinate value is output from the S sensor 1c every second as an XY normalized coordinate value, the azimuth θgps is calculated from the difference between the coordinates of the currently acquired GPS position information and the coordinates of the previously acquired position information.
-N is detected. For example, it can be detected by angle data with east being 0 degrees. When the GPS position information is output as latitude and longitude values, the azimuth is detected based on the latitude and longitude values.

In step S6, the average value θgps-ave of the current one and the past nine consecutive ten θgps-n
Is calculated. In step S7, ten consecutive θgps
It is determined whether or not the absolute value of the difference between each of −n and the average value θgps-ave is equal to or less than a predetermined threshold value θth1. This is because if there is even one unique value, it is not adopted as data. In step S7, ten consecutive θgps−
If it is determined that the absolute value of the difference between each of n and the average value θgps-ave is equal to or smaller than the predetermined threshold θth1, the process proceeds to step S8, and if the requirement is not satisfied, the process ends.

In step S8, the average value θgps-ave obtained in step S6 is stored in the RAM 8 as the GPS trajectory direction θgps. In step S9, the vehicle direction θ
It is determined whether or not the absolute value of the difference between car and the GPS track azimuth θgps is equal to or greater than a threshold θth2. That is, it is determined whether or not the difference between the GPS track direction θgps obtained above and the currently stored vehicle direction θcar is equal to or greater than a predetermined value θth2. If it is determined that the value is equal to or more than the predetermined value, the process proceeds to step S10, and if it is determined that the value is less than the predetermined value, the process ends.

In step S10, the current vehicle direction θc
ar is updated with the GPS track azimuth θgps obtained based on the GPS position information. The car mark displayed on the display monitor 6 is displayed at a position corresponding to the coordinates of the GPS position information acquired last, and the updated vehicle direction θc
Displayed in the direction based on ar.

As described above, even when the traveling direction signal from the GPS sensor 1c cannot be used according to the prior art when the vehicle is traveling at a low speed, the traveling direction cannot be detected using the road map data because the map cannot be matched. Even in such a case, the traveling direction of the vehicle can be reliably detected.

In the above-described embodiment, an example has been described in which the traveling direction is detected using the GPS position information when the vehicle speed is equal to or lower than a predetermined speed and the free running is equal to or higher than a predetermined distance. It is not necessary to limit to. Always GPS
The traveling direction may be detected using the position information.

Further, in the above-described embodiment, the description has been given of the example of the car navigation device, but the present invention is not limited to this. The present invention can be applied to all types of navigation devices, not limited to those mounted on vehicles. For example, the present invention can be applied to a portable navigation device carried by a person.

Further, in the above-described embodiment, an example of the process in which the control device 3 detects the traveling direction of the vehicle based on the position information output from the GPS sensor 1c has been described, but the present invention is not limited to this. The above-described program may be installed inside the GPS sensor 1c, and the GPS sensor 1c may detect and output the traveling direction of the vehicle based on the GPS position information.

In the above embodiment, the control program executed by the control device 3 has been described as being installed in the ROM 7. However, the present invention is not limited to this. For example, the control program and the installation program may be provided on a recording medium such as the CD-ROM 11 in FIG. In this case, if the map database device 2 is constituted by a DVD drive device or a drive device of another recording medium,
It is also possible to provide it on a corresponding recording medium.

The programs can be provided via a transmission medium such as a communication line represented by the Internet. If the car navigation device can connect to the Internet using a mobile phone or the like, a program can be provided via the Internet.

[0036]

Since the present invention is configured as described above, it has the following effects. Claims 1, 3, and 4
Since the invention of the present invention detects the heading using GPS position information, for example, when applied to a car navigation device, even when the vehicle is running at low speed and the heading signal from the conventional GPS sensor cannot be used, Further, even when the map cannot be matched and the traveling direction cannot be detected using the road map data, the traveling direction of the vehicle can be reliably detected. According to the second aspect of the present invention, it is determined for each GPS position information whether or not the GPS position information can be used for calculating the traveling direction. Therefore, the traveling direction can be detected using highly accurate and reliable position information. Can be. In addition, since the determination is performed for each GPS position information, for example, there is no need to acquire a plurality of GPS position information and perform complicated arithmetic processing, the accuracy and reliability of the GPS position information can be determined in a short time, and the traveling azimuth can be determined. Can be used for arithmetic.

[Brief description of the drawings]

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

FIG. 2 is a flowchart illustrating control for detecting a traveling direction of a vehicle using position information of a GPS signal.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Current location detection apparatus 1a Orientation sensor 1b Vehicle speed sensor 1c GPS sensor 2 Map database device 3 Control circuit 4 Input device 5 Image memory 6 Display monitor 7 ROM 8 RAM

Claims (4)

[Claims] 1. A traveling azimuth detecting device for detecting a traveling azimuth of a traveling azimuth detecting target, the traveling azimuth detecting device detecting the traveling azimuth of the traveling azimuth detecting target. Traveling direction calculating means for calculating the traveling direction of the traveling direction detection target using the GPS position information of a plurality of points acquired in accordance with the traveling of the detection target. . 2. The traveling azimuth calculation device according to claim 1, further comprising: a determination unit configured to determine, for each of the acquired GPS location information, whether the GPS location information can be used for calculating the traveling azimuth. The traveling azimuth calculating means is configured to determine the GP by the determining means.
A traveling direction detection device, wherein the traveling direction of the traveling direction detection target is computed using the GPS position information only when it is determined that the S position information can be used for calculating the traveling direction. 3. A plurality of G's in accordance with the progress of the heading detection object.
A traveling direction detection method, comprising: acquiring PS position information; and calculating a traveling direction of the traveling direction detection target using the acquired GPS position information of the plurality of points. 4. A plurality of G's in accordance with the progress of the heading detection object.
A recording medium recording PS position information, and recording a control program for a traveling azimuth detecting device for calculating the traveling azimuth of the traveling azimuth detection target using the acquired GPS position information of the plurality of points.