JPH02134514A - Vehicle-position detector - Google Patents

Abstract

PURPOSE:To make is possible to detect the present position accurately by predicting the present position by a geomagnetism detecting means and a running-distance detecting means, and correcting the center of a circle drawn by the geomagnetism detecting means for every specified running distance in an operating means for magnetization correcting amount. CONSTITUTION:The bearing angle of the advancing direction is obtained from the output value of a geomagnetism detecting means 2 for every specified time. The running distance is obtained based on the output of a running-distance detecting means 1. The present position is detected based on these values in a dead-reckoning-nagivation operating means 4. In reality, however, a vehicle body is magnetized with a ferromagnetic field at a railroad crossing and the like, and the output value from the means 2 is changed. Therefore, the changing amount in output of the means 2 is obtained in a magnetization-correcting- amount operating means 5 during running. The output of the means 2 is corrected by using said changing amount in output in a bearing operating means 3. The new present position is predicted in the means 4. Thus, the present position can be predicted accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a vehicle position detecting device that accurately estimates 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 The configuration of the conventional example will be explained below with reference to FIG. 3.

The direction of geomagnetism on a predetermined straight road is stored in the map memory 33, and the direction detection means 3 is stored in the control means 34.
When the difference between the geomagnetic direction according to the data from 2 and the stored geomagnetic direction on the straight road reaches a predetermined value, the output of the direction detecting means 32 is corrected based on the geomagnetic direction data in the map memory, and the driving starts. The current position of the vehicle is calculated based on the data from the distance detecting means 31 and the error-corrected data from the direction detecting means 32. The current position calculated in this way is displayed on the display means 35 together with the map (for details, see Japanese Patent Application Laid-Open No. 89300/1993).

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-mentioned problems, and an object of the present invention is to provide a vehicle position detection device that can improve the accuracy of current position estimation.

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. magnetization correction amount calculation means for determining the amount of change in the output value of the detection means and correcting the traveling direction calculation; and geomagnetic data when the amount of change in the output value of the geomagnetism detection means is calculated in the magnetization correction amount calculation means. geomagnetic data storage means for storing the information, azimuth calculation means for determining the traveling direction of the vehicle from the traveling direction of the vehicle by the geomagnetic detection means and the output value from the magnetization correction amount calculating means; The vehicle is comprised of a dead reckoning calculation means for calculating a new current position based on the travel distance obtained from the travel distance detection means and the azimuth of the vehicle's traveling direction obtained from the azimuth 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 also stores the output value of the geomagnetism detection means and the geomagnetism data storage means every time a certain distance is traveled in the celadon correction amount calculation means. Since the center of the circle drawn by the output of the geomagnetism detection means is corrected from the average of the output values of the geomagnetism detection means in each azimuth section, the vehicle position can be detected with high accuracy.

Embodiment An object of the present invention is to provide a vehicle position detection device that can estimate 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 dead reckoning calculation means for estimating the current position from the outputs of the travel distance detection means and the azimuth calculation means. Step 5 calculates the amount of change in the output value of the geomagnetism detection means due to the magnetization of the vehicle body from the output value of the geomagnetism detection means and the average of the output values of the geomagnetism detection means in each stored azimuth section, and calculates the amount of change in the output value of the geomagnetism detection means due to the magnetization of the vehicle body, and then calculates the amount of change in the output value of the geomagnetism detection means due to the magnetization of the vehicle body. This is a magnetization correction amount calculation means that corrects the direction calculation. Reference numeral 6 denotes geomagnetism data storage means for storing the average value of the output of the geomagnetism detection means in each azimuth section from which the amount of change in the output value of the geomagnetism detection means was determined. 7 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.

At regular intervals, the azimuth of the traveling direction is determined from the output value of the geomagnetism detection means 2, the travel distance is determined from the output of the travel distance detection means 1, and the current position is detected from these values by the dead reckoning calculation means 4. . Now, the previous detection position is (Xa+
'! s). If 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, then the detected position is determined as follows.

X=Acoso+X- Y=Aslnθ+ylI With the above X1 and Y as new detection positions
V@ and repeats the above calculation 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 in-travel magnetization correction 1 calculation means 5, and the amount of output change is used in the azimuth calculation means 3 to correct the output of the geomagnetism detection means 2. By estimating the new current position in the dead reckoning calculating means 4, the current position can be estimated with high accuracy.

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 and the output value of the geomagnetism detection means V XN V
Find the center CXNCY of the circle drawn by V. Here, the azimuth from the center CX1 Cy is arbitrarily divided into equal parts, and the average value of the output of the geomagnetism detection means in each azimuth section is stored. Step 21
In step 22, input the output values from the travel distance detection means and the geomagnetism detection means, and use the input values and the correction value CXNCY of the output of the geomagnetism detection means to determine the azimuth θ in the travel direction and the travel distance it! Find the IA and find the previous detected current position
(XS, yII) is used to detect the current position as follows.

x = A cos θ +
+ Replace with Yi+. In step 23, the output values Vx and VY from the geomagnetism detection means are 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
The average value VxmL Vymi of N V y is determined, and in the azimuth section where there is no data, the average value of the output of the stored geomagnetism detection means is set as VxmL Vymi. In step 27, VxmL Vym in the interval as follows:
Add each i, find the average, and use this as the new center CXN
Let it be Cy.

Cx=7. ;Vxmi/.

Cy=χ; Vymi/n (n: number of azimuth sections) In step 28, VxmL Vymi of each azimuth section is stored. Then, in step 29, d is set to 0 and the process returns to step 21.

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 the drawing]

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 arithmetic processing of means of the 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 Kurino

Claims (2)

[Claims] (1) Mileage detection means for detecting the mileage of the vehicle;
A geomagnetic detection means for detecting the traveling direction of the vehicle and the strength of the magnetic field; and a magnetization correction that calculates the amount of change in the output value of the geomagnetism detection means due to the magnetization of the vehicle from the data of the geomagnetic detection means and corrects the heading calculation. a geomagnetism data storage means for storing geomagnetism data obtained when the amount of change in the output value of the geomagnetism detection means is determined by the magnetization correction amount calculation means; and a traveling direction of the vehicle according to the geomagnetism detection means. and azimuth calculation means for determining the traveling direction of the vehicle from the output value from the magnetization correction amount calculation means; and the distance obtained from the previous current position by the travel distance detection means and the vehicle direction obtained from the direction calculation means. A vehicle position detection device comprising dead reckoning calculation means for calculating a new current position based on the azimuth of the traveling direction of the vehicle. (2) In the magnetization correction amount calculation means, the center of the 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. Calculating the average output value of the geomagnetism detection means in each azimuth section and storing it in the geomagnetism data storage means,
Then, the average strength of the magnetic field within each azimuth section is calculated every time a certain distance is traveled, and in the azimuth section where there is no output from the geomagnetic field detecting means during the certain distance traveling, the geomagnetism detecting means stored in the geomagnetic data storage means is calculated. 2. The method according to claim 1, wherein the average value of the outputs is used to find the center of a circle drawn by the output of the geomagnetism detection means, and the data of each used azimuth section is newly stored in the geomagnetic data storage means. Vehicle position detection device.