JPH0942982A - On-vehicle navigation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately detect and display the position of an own vehicle without errors by using a three axis flux gate sensor and a gyro sensor as an azimuth sensor to calculate the rotating angle of the vehicle by detecting output from either of them for finding the current position of the vehicle. SOLUTION: A three-axis flux gate sensor 3 and gyro sensor 4 are used together as an azimuth sensor. A rotation signal is detected from the sensor 3 during and input to a vehicle position calculation part 7A. When the rotation signal is not detected from the sensor 4, the calculation part 7A judges that a signal caused by a disturbance field is output from the sensor 3 and then the signal from the sensor 3 is cancelled. When both the sensors 3, 4 output similar rotation signals, the calculation part 7A judges that both detect the rotating angle of the vehicle. When rotation signals from both the sensors 3, 4 are different, the disturbance field exists and the rotating angles of both the sensors are not equal, so that the calculation part 7A detects the rotation angle with the output of the sensor 4 and calculates an azimuth.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle-mounted navigation device, and more particularly, to independently (estimate) the position of a vehicle on the map.
The present invention relates to a navigation device that detects by navigation.

[0002]

2. Description of the Related Art An in-vehicle navigation system reads out map data corresponding to the current position of an automobile from a map data storage section such as a CD-ROM, draws a map on the display screen based on the map data, and The current position of the vehicle is fixedly displayed as a vehicle position mark (location cursor) at a certain position on the display screen (for example, the center position of the display screen), and the map is scrolled according to the movement of the vehicle.

Means for detecting the current position of the automobile, which is indispensable in such a vehicle-mounted navigation device, is
Although various means have been put into practical use, they are roughly classified into autonomous (guess) navigation using distance sensors and angle sensors, and GPS (Grobal Positioning System) that receives radio waves from satellites.
It is divided into satellite navigation using a receiver.

In the self-contained navigation, a vehicle speed sensor, a geomagnetic direction sensor, a turning angle sensor and the like are provided on the vehicle to detect the traveling distance and the direction of the vehicle and obtain the vehicle position on the map. The vehicle speed sensor is mainly a pulse sensor that detects the number of revolutions of a wheel or the like within a unit time, and measures and outputs the moving distance. As a geomagnetic direction sensor, a fluxgate sensor in which a primary coil is wound around a ring-shaped core and two coils are wound at orthogonal positions on the core is often used.

The output data of these detecting means are input to the data processing unit, the vehicle position and direction are calculated by the position calculation unit provided in the data processing unit, and the map image drawing unit reads out the area data of the area. The current position of the vehicle is drawn and displayed on the display unit together with the map image.

[0006]

As such a geomagnetic direction sensor, a fluxgate sensor is used, and for example, the traveling direction is defined as the x coordinate and the direction orthogonal thereto is defined as the y coordinate.
In a vehicle-mounted navigation device equipped with a device for momentarily measuring the direction of a vehicle by obtaining geomagnetic components in the x and y directions, when a disturbance magnetic field exists around the vehicle, the disturbance magnetic field does not cause the original direction. An azimuth including an error may be displayed, and in such a case, the vehicle position may be displayed off the road, which causes a problem that accurate navigation cannot be performed. The present invention provides a vehicle-mounted navigation device that solves such a problem.

[0007]

According to the present invention, the above-mentioned problem is solved by calculating the present vehicle position from the output data from the map data storage means storing map data, the distance sensor and the direction sensor provided in the vehicle. In a vehicle-mounted navigation device equipped with a vehicle position calculation means and a map image drawing means for drawing a map image of the vehicle surroundings detected by the vehicle position calculation means together with the vehicle position mark using map data and displaying it on the screen of the display means, The azimuth sensor is composed of two sensors, a triaxial fluxgate sensor and a gyrosensor, and the vehicle position calculating means has a detection output from the triaxial fluxgate sensor of the two sensors, and a detection from the gyrosensor. If there is no output, this output is ignored, and if both sensors have detected outputs, the 3-axis fly When the vehicle rotation angle calculated from the detection output of the X-gate sensor is equal to the vehicle rotation angle calculated from the detection output of the gyro sensor, the vehicle rotation angle calculated from the detection output of the three-axis fluxgate sensor is calculated as follows. On the other hand, if the vehicle rotation angle calculated from the detection output of the three-axis fluxgate sensor and the vehicle rotation angle calculated from the detection output of the gyro sensor are different, the calculation is performed from the detection output of the gyro sensor. It is solved by calculating and displaying the current vehicle position by adopting the vehicle rotation angle.

[0008]

In the vehicle position calculating means which receives the outputs from the two azimuth detecting sensors, the input is only the rotation detecting signal from the three-axis fluxgate sensor, and when there is no input from the gyrosensor, the fluxgate sensor detects the disturbance magnetic field. The input from the triaxial fluxgate sensor is not adopted, because it can be determined that it has been done. When the rotation signals resulting from the detection outputs from the two azimuth detection sensors have the same value, it is determined that the vehicle has rotated, and the output of the three-axis fluxgate sensor is used. On the other hand, when the rotation signal values are different from each other, it is determined that the fluxgate sensor is affected by the disturbance magnetic field, and the detection output of the triaxial fluxgate sensor is ignored and the detection output from the gyro sensor is used. Since the vehicle current position is calculated by the above, it is possible to obtain a navigation device that compensates for the defects of both sensors and that can detect an accurate azimuth without the influence of a disturbance magnetic field.

[0009]

1 is a schematic block diagram of a vehicle-mounted navigator device according to the present invention. In FIG. 1, reference numeral 1 is a CD-ROM (map data storage unit) that constitutes a road map. The map data is composed of (1) road layer, (2) background layer for displaying objects on the map, (3) character layer for displaying municipalities, and the like.

Reference numeral 2 denotes a display device including a CRT or the like, which inputs a video signal and displays a map on a screen together with a vehicle position mark, an intersection guidance image and the like. 3 is a three-axis fluxgate sensor that detects the traveling direction of the vehicle by geomagnetism, 4 is a gyro sensor such as a vibration gyro that detects the traveling direction of the vehicle based on the turning angle of the vehicle, a gas rate gyro, and 5 is a traveling distance It is a vehicle speed sensor.

6 is a map search key, a map scroll key,
The operation unit includes a route search mode key, a set key, a search start key, and the like.

Reference numeral 7 denotes a navigation controller having a microcomputer configuration, which has various navigation functions.
If only the portion related to the present invention is illustrated, 7A is a vehicle for calculating the current position (longitude, latitude) of the vehicle based on each data detected by the fluxgate sensor 3, the gyro sensor 4, and the vehicle speed sensor 5 in the navigation mode. 7B is a position calculation unit, and C is based on the calculated vehicle position data.
A map image drawing unit that draws a map image around the vehicle position together with the vehicle position mark using the map data of the D-ROM 1 and displays the map image on the display device 2.

In the device of the present invention, the direction sensor has three
By using a fluxgate sensor on the shaft and by using this together with a gyrosensor, even if there is a disturbance magnetic field around the vehicle, the disturbance magnetic field will not cause an error. FIG. 2 is an explanatory view of the operation of the triaxial fluxgate sensor used in the vehicle-mounted navigator device of the present invention. In the figure, both sensor A and sensor B are fluxgate sensors, sensor A is arranged to detect geomagnetism in the x-axis and z-axis directions, and sensor B detects geomagnetism in the x-axis and y-axis directions. So that they are arranged so that they are orthogonal to each other.
With this arrangement, both sensors detect the magnetism in the x-axis direction, but only one of them is used as the detection signal. By doing this,
It is possible to detect the geomagnetic components of the x, y and z axes.

The geomagnetism is not horizontal to the ground, but has an angle called the dip angle, which is determined by the latitude. Therefore, when considering the xyz coordinates with the ground plane as the xy plane, the geomagnetic vector has three components of x component, y component, and z component.

On the other hand, considering the case where the x'y'z 'coordinate system is applied to the vehicle, since the vehicle has a roll angle, a pitch angle, and a yaw angle with respect to the coordinate system of the ground, the vehicle may move. Thus, each of these angles changes. Therefore, the geomagnetic vector has the x'component, the y'component, and the z'component, and the respective values change. For this reason, the present invention uses a triaxial fluxgate sensor.

Navigation is carried out by running the vehicle equipped with the device of the present invention having the above-mentioned structure and operating the device. Each sensor input to the vehicle position calculation unit 7A provided in the navigation controller 7 is operated. The operation other than the output processing is the same as the above-mentioned conventional one, and therefore the description thereof will be omitted, and the description will focus on the azimuth measurement which is the subject of the present invention.

While the vehicle is traveling, a rotation signal is detected from the triaxial fluxgate sensor 3 and input to the vehicle position calculation unit 7A, while no rotation signal is detected from the gyro sensor 4 and is not input to the vehicle position calculation unit 7A. In this case, the vehicle position calculation unit 7A determines that the signal due to the disturbance magnetic field is output from the fluxgate sensor, and cancels the output signal of the triaxial fluxgate sensor 3 at this time.

When both the triaxial fluxgate sensor 3 and the gyro sensor 4 output the same rotation signal, the vehicle position calculation unit 7A determines that the rotation of the vehicle has been detected. At this time, the output of the triaxial fluxgate sensor 3 is equal to the geomagnetic vector and the fluxgate sensor 3
The vehicle position calculation unit 7A can calculate the azimuth based on the output.

On the other hand, when the rotation signals of the three-axis fluxgate sensor 3 and the gyro sensor 4 are different, the rotation angles of the two sensors are not equal because of the presence of a disturbance magnetic field. The unit 7A detects the rotation angle from the output of the gyro sensor 4 and calculates the azimuth.

When a vibration type gyro sensor is used as the gyro sensor, drift becomes a problem. The output voltage of the vibration type gyro sensor is ideally zero at rest, but there is a drift of the output voltage due to the characteristics of the piezoelectric element and the characteristics of the electric circuit. However, since this can be ignored for a short time, accurate detection is possible.

[0021]

As described above, according to the present invention, in the vehicle-mounted navigation device having the self-vehicle position detecting means of the self-contained navigation, by using the azimuth detecting sensor in combination with the three-axis fluxgate sensor and the gyro sensor, Since the defects are mutually interpolated and the influence of the disturbance magnetic field is prevented, the detected vehicle current position error is eliminated, and an in-vehicle navigation device in which the accurate position of the vehicle is detected and displayed can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a triaxial fluxgate sensor used in the present invention.

[Explanation of symbols]

 1 CD-ROM (map data storage part) 2 Display device 3 3-axis fluxgate sensor 4 Gyro sensor 5 Vehicle speed sensor 6 Operation part 7 Navigation controller 7A Vehicle position calculation part 7B Map image drawing part

Claims (1)

[Claims] 1. A map data storage means for storing map data, a vehicle position calculation means for calculating a vehicle current position based on output data from a distance sensor and a direction sensor provided in the vehicle, and a vehicle position calculation means. In a vehicle-mounted navigation device equipped with a map image drawing means for drawing a map image around a vehicle together with a vehicle position mark using map data and displaying it on a screen of a display means, the direction sensor comprises a three-axis fluxgate sensor and a gyro sensor. It is composed of two sensors, and the vehicle position calculation means ignores this output when there is a detection output from the triaxial fluxgate sensor among the two sensors and there is no detection output from the gyro sensor. A vehicle calculated from the detection output of the three-axis fluxgate sensor when both have detection output When the rotation angle is equal to the vehicle rotation angle calculated from the detection output of the gyro sensor, the vehicle rotation angle calculated from the detection output of the three-axis fluxgate sensor is adopted, and the vehicle rotation angle of the three-axis fluxgate sensor is adopted. When the vehicle rotation angle calculated from the detection output and the vehicle rotation angle calculated from the detection output of the gyro sensor are different, the vehicle rotation angle calculated from the detection output of the gyro sensor is used to determine the current vehicle position. An in-vehicle navigation device that is calculated and displayed.