JPH0299818A - Apparatus for detecting position of vehicle - Google Patents

Abstract

PURPOSE:To enable precise detection of the present position by providing a magnetization correction amount computing means which determines the amount of a change in an output value of a geomagnetism detecting means due to magnetization of a vehicle from the data of the geomagnetism detecting means, by inputting output values of the two means to an azimuth computing means and by determining the direction of advance of the vehicle thereby. CONSTITUTION:The preceding detected position is set as (X0, Y0). When it is assumed that the direction of advance of a vehicle body turns to be theta in the course of a time T and that a mileage computed from an output value of a mileage detecting means 1 is A, a detected position (X, Y) can be determined from equations X=Acostheta+X0 and Y=Asintheta+Y0. These operations are repeated at every time T and thereby detected position is updated. However, the vehicle body is magnetized by a ferromagnetic field and consequently an output value from a geomagnetism detecting means 2 changes. Then the amount of a change in the output of the means 2 is determined in running in a magnetization correction amount computing means 5, the output of the means 2 is corrected in a azimuth computing means 3 by using said amount, and the new present position is detected in a dead-reckoning computation means 4.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a vehicle position detection device that accurately detects the current position of an automobile or the like in order to display the current position along with a map or notify the vehicle by voice.

Conventional technology FIG. 3 shows a conventional vehicle position detection device.

The structure of this conventional example will be explained below with reference to FIG. 3.

In the figure, 7 is a distance detecting means, 8 is a direction detecting means using a geomagnetic sensor, 9 is a map memory storing map data and the geomagnetic direction on a predetermined straight road, 10 is a control means, and 11 is a display. It is a means.

Next, the operation of the vehicle position detection device will be explained.

The direction of geomagnetism on a predetermined straight road is stored in the map memory 9, and the control means 10 compares the direction of geomagnetism based on the data from the direction detection means 8 with the direction of geomagnetism on the stored straight road. When the difference reaches a predetermined value, the output of the azimuth detection means is corrected based on the geomagnetic direction data in the map memory, and the output of the azimuth detection means is corrected based on the data from the mileage detection means described in 7 above and the error-corrected data from the azimuth detection means. Calculate the current position of. The current position calculated in this way is displayed on the display together with the map (Japanese Patent Application Laid-Open No. 1983-
89300).

Problems to be Solved by the Invention As mentioned above, in the conventional vehicle position detection device, the direction of travel is corrected by storing geomagnetic data for each straight road in the map memory in advance, and calculating the difference between this data and the data from the direction detection means. Since this method is carried out using a geomagnetic field, it may not be possible to correct for changes in the environment due to the increase or decrease of buildings, etc., and it has been difficult to implement because the geomagnetic field is measured over a wide area.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a vehicle position detection device that can improve the accuracy of current position detection.

Means for Solving the Problems A mileage detection means for detecting the distance traveled by a vehicle, a geomagnetism detection means for detecting the traveling direction of the vehicle and the strength of the magnetic field, and geomagnetism due to the magnetization of the vehicle from the data of the geomagnetism detection means. A magnetization correction amount calculation means that calculates the amount of change in the output value of the detection means and corrects the heading calculation; An azimuth calculation means for determining the direction, and an estimation for calculating a new current position based on the travel distance obtained from the previous current position by the travel distance detection means and the azimuth of the vehicle's traveling direction obtained from the azimuth calculation means. It consists of navigation calculation means.

According to the above configuration, the present invention estimates the current position from the geomagnetism detection means and the travel distance detection means, and corrects the center of the circle drawn by the output of the geomagnetism detection means while the vehicle is running, so that the vehicle position can be detected with high accuracy.

Embodiments It is an object of the present invention to provide a vehicle position detection device capable of detecting the current position with high accuracy by correcting the offset of the geomagnetism detection means while the vehicle is running.

The configuration of an embodiment of the present invention will be described below. 1st
In the figure, 1 is a traveling distance detection means, and 2 is a geomagnetism detection means. Reference numeral 3 denotes an azimuth calculating means for determining the traveling direction from the vehicle traveling direction data of the geomagnetism detecting means and the amount of change in the output value of the geomagnetism detecting means. Reference numeral 4 denotes a dead reckoning calculation means for detecting the current position from the outputs of the travel distance detection means and the azimuth calculation means. Reference numeral 5 denotes a magnetization correction amount calculating means for calculating the amount of change in the output value of the earth's magnetic field detecting means due to the magnetization of the vehicle body from the output value of the earth's magnetic field detecting means and correcting the traveling direction calculation by the direction calculating means. 6 is a terminal for outputting the current position data obtained by the dead reckoning calculation means 4.

Next, the operation of the above configuration will be explained.

The azimuth of the traveling direction is determined from the output value of the geomagnetism detection means 2 at regular intervals, and the traveling pressure 1IIt4! The travel distance is determined from the output of the output means 1, and the dead navigation calculation means 4 detects the current position from these values. Now, assume that the previous detected position is (XO, YO). Assuming that the traveling direction of the vehicle body becomes θ during a certain time T and the traveling distance calculated from the output value of the traveling distance detecting means 1 is A, the detected position is determined as follows.

X=Acosθ+X0 Y=AsinO+YO With the above X1 Y as the new detection position, Xo, y respectively
o, and the above calculation is repeated every time T to update the detected position.

However, in reality, the vehicle body is magnetized by a strong magnetic field at a railroad crossing or the like, and the output value from the earth's magnetic field detection means 2 changes, so the detected position determined by the above method deviates from the actual position. Therefore, in the present invention, the amount of change in the output of the geomagnetism detection means 2 is determined in the magnetization correction amount calculation means 5 during traveling, and the output of the geomagnetism detection means 2 is corrected using the amount of change in the output in the direction calculation means 3. The dead reckoning calculation means 4 detects the new current position, and the current position can be determined with high precision.

Vehicle position correction using the above method will be explained using FIG. 2. In FIG. 2, in step 20, the vehicle is turned in advance to obtain the equation of the circle drawn by the output value vX1 vy of the geomagnetism detection means. Here, aN b is the center of the circle, and R is the radius of the circle. Here, the directions from the center as b are arbitrarily divided into equal parts. In step 21, the output values from the travel distance detection means and the geomagnetism detection means are input, and in step 22, the input values and the correction value CX1Cy of the output of the geomagnetism detection means are used to determine the azimuth θ in the travel direction and the travel distance A. The current position is detected as follows using the previously detected current position (XOlYO).

X=AcosO+X0 Y=Asino+YO With the above X and Y as new current positions, xo respectively
, yo. In step 23, the output value Vx+Vy from the geomagnetism detection means is stored in a table. In step 24, the cumulative moving distance d is determined from the moving distance A. In step 25, it is compared whether the cumulative movement distance d is larger than a predetermined movement distance C, and if d≧C, in step 26, V XX within each azimuth range during the movement distance d is compared.
Find the average value xmi and Vymi of VY. In step 27, VxmisVy within each range
Find the equation of a circle with mi as the center and radius R, take any two sets, and find the intersection. Among these intersections (Cx
, Cy), and calculate their average value in step 28. Let's call it the new CXI CV. Then, in step 29, d is set to 0 and the process returns to step 21.

Further, in step 27, the average value (Vxmi) of the output values of the respective geomagnetism detection means.

In step 28, the perpendicular bisector of VYmi) is determined and its average value is determined as new Cx+Cy.

Effects of the Invention As described above, according to the present invention, even if the vehicle body is magnetized, the current position can be detected with high accuracy because the output data of the geomagnetism detection means is automatically corrected.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a vehicle position detecting device according to an embodiment of the present invention, FIG. 2 is a flowchart showing the calculation processing of the means of the same device, and FIG. 3 is a block diagram of a conventional vehicle position detecting device. 1. Travel distance detection means, 2. Geomagnetism detection means, 3.
- Azimuth calculation means, 4. Dead reckoning calculation means, 5. Magnetization correction amount calculation means. Name of agent: Patent attorney Shigetaka Awano Haka1 person -I〇-

Claims (3)

[Claims] (1) A mileage detection means for detecting the distance traveled by the vehicle, a geomagnetism detection means for detecting the traveling direction of the vehicle and the strength of the magnetic field, and an output of the geomagnetism detection means by magnetizing the vehicle from data of the geomagnetism detection means. magnetization correction amount calculation means for determining the amount of change in the value and correcting the heading calculation; and a direction for determining the traveling direction of the vehicle from the vehicle travel direction by the geomagnetism detection means and the output value from the magnetization correction amount calculation means. a calculation means, and a dead reckoning calculation means for calculating a new current position based on the distance obtained from the current position before measurement by the distance detection means and the azimuth in the direction of travel of the vehicle obtained from the azimuth calculation means. A vehicle position detection device comprising: (2) In the magnetization correction amount calculation means, the center and radius of the circle drawn by the output of the geomagnetism detection means are determined from the output data of the geomagnetism detection means when the car is turned in advance, and the direction from the center is arbitrarily divided into equal parts. Then, after each distance traveled, calculate the average strength of the magnetic field within each range, and in the range where data exists, draw a circle with the radius of the circle drawn by the output of the geomagnetism detection means from the average value within that range. 2. The vehicle position according to claim 1, wherein the average value of the intersection points is determined, this is set as the center of the circle drawn by the output of the new geomagnetism detection means, and the correction amount is determined from the difference from the previous center value. Detection device. (3) In the magnetization correction amount calculation means, the center of a circle drawn by the output of the geomagnetism detection means is determined in advance from the output data of the geomagnetism detection means when the car is turned, and the direction from the center is arbitrarily divided into equal parts. Find the average strength of the magnetic field within each range every time you drive a certain distance, select any two sets from the range where the data exists, draw a median line, find this for all sets, and find the intersection point between them. 2. The vehicle position detecting device according to claim 1, wherein the average value of the terrestrial magnetism is determined as the center of the circle drawn by the output of the new geomagnetism detecting means, and the correction amount is determined from the difference from the previous center value.