JPH01114711A - Vehicle position detecting device - Google Patents

Abstract

PURPOSE:To conjecture the present position with high accuracy by correcting automatically an output data of an earth magnetism detecting means, even in case of running in a ferromagnetic field. CONSTITUTION:An azimuth in the advance direction is derived from an output value of an earth magnetism detecting means 11 at every prescribed time, a running distance is derived from an output of a running distance detecting means 10, and from these values, the present position is conjectured by a dead-reckoning navigation arithmetic means 13. Also, by repeating the arithmetic operation at every prescribed time, the conjectured position is updated. In this state, if a car body is magnetized by a ferromagnetic field in a railroad crossing, etc., the output value of the means 11 is varied, therefore, the conjectured position is detached from the actual position. Therefore, in an abnormal value deciding means 14, the magnetizing direction is derived by measuring the direction of an abnormal ferromagnetic field from an output of the means 11, and in a magnetic correction quantity arithmetic means 15, the output variation quantity and the variation direction of the means 11 are derived, and in an azimuth arithmetic means 12, the output of the means 11 is corrected by using its output variation quantity and variation direction, by which a new present position can be conjectured with high accuracy by the means 13.

Description

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

Conventional technology FIG. 4 shows a conventional vehicle position detection device.

The configuration of this conventional example will be described below with reference to FIG. 4.

In the figure, 41 is a distance detecting means, 42 is an azimuth detecting means using a geomagnetic sensor, 43 is a map memory in which map data and horizontal components of geomagnetism are stored, 44 is a control means, and 46 is a display means.

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

The horizontal component of the earth's magnetic field on a predetermined straight road is stored in the map memory 43, and the control means 44 determines a predetermined value of the error in the heading direction of the vehicle and the magnitude of the horizontal component of the earth's magnetic field based on the data from the direction detecting means 42. When you reach
The output of the azimuth detection means is corrected based on the geomagnetic horizontal component data in the map memory 43, and the current position of the vehicle is estimated based on the data from the mileage detection means 41 and the error-corrected data from the azimuth detection means 42. The current position estimated in this way is displayed on the display together with the map. (
(Refer to Japanese Unexamined Patent Publication No. 60-89300) 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 the geomagnetic data of each straight road in the map memory in advance. Since the data is measured using the difference between that data and the data from the direction detection means, it may not be possible to correct it due to changes in the environment due to the increase or decrease of buildings, etc., and it may be difficult to implement because geomagnetic measurement covers a wide area. Ta.

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 In order to solve the above-mentioned problems, the present invention provides a traveling distance detecting means for detecting the traveling distance of a vehicle, and a geomagnetic field detecting means for obtaining data on the traveling direction of the vehicle and detecting the strength of the magnetic field. a detection means, an abnormal value determination means for determining an abnormal magnetic field based on the output value of the geomagnetism detection means and determining a direction of change of the abnormal magnetic field;
Magnetization correction amount calculation for calculating the amount of change in the output value of the geomagnetism detection means due to magnetization of the vehicle body from the abnormal magnetic field detection signal from the abnormal value judgment means, the change direction data of the abnormal magnetic field, and the output value of the geomagnetism detection means. and an azimuth calculating means for determining the traveling direction of the vehicle based on the data on the traveling direction of the vehicle by the geomagnetism detecting means and the amount of change in the output value of the geomagnetism detecting means due to magnetization from the magnetization correction amount calculating means; A dead reckoning calculation means for estimating a new current position based on the travel distance obtained from the travel distance detection means from the previous estimated position and the azimuth of the vehicle's traveling direction obtained from the azimuth calculation means. It is.

With the above configuration, the present invention usually estimates the current position from the vehicle-mounted geomagnetism detection means and the mileage detection means, checks whether it is magnetized when an abnormally strong magnetic field is detected, and if it is magnetized, detects the geomagnetism. Since the output value of the means is corrected, the vehicle position can be estimated with high accuracy.

Example The configuration of one embodiment of the present invention will be described below.

In FIG. 1, 1o is a distance detecting means, 11
is a geomagnetic detection means. Reference numeral 12 denotes an azimuth calculating means for determining the traveling direction from the vehicle traveling direction data of the geomagnetism detecting means 11 and the amount of change in the output value of the geomagnetism detecting means 11. 13
is a dead reckoning calculation means for estimating the current position from the outputs of the traveling distance detecting means 1o and the geomagnetism detecting means 11. Reference numeral 14 indicates an abnormal value determining means for determining an abnormality in the output value of the geomagnetic field detecting means 11 and determining the change direction of the abnormal magnetic field. Reference numeral 16 indicates an abnormal magnetic field detection signal from the abnormal value determining means 14, data on the change direction of the abnormal magnetic field, and geomagnetism detection. This is a magnetization correction amount calculation means that calculates the amount of change in the output value of the geomagnetism detection means 11 due to magnetization of the vehicle body from the output value of the means 11, and corrects the traveling direction calculation by the direction calculation means 12. Reference numeral 16 denotes a terminal for outputting the estimated position data obtained by the dead reckoning calculation means 13.

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 11, the travel distance is determined from the output of the travel distance detection means 10, and the current position is estimated from these values by the dead reckoning calculation means 13. . Now, the previous guessed position is (x
o, yo). Assuming that the traveling direction of the vehicle body changes to θ during a certain time T, and the traveling distance calculated from the output value of the traveling distance detecting means 1o is A, the estimated position is determined as follows.

X = A X cos fJ -1-X 0Y=Ax
sin θ ten Y○ With the above x and y as new estimated positions, X○ and YO respectively
The above calculation is repeated every time T to update the estimated 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 geomagnetism detection means 11 changes, so the estimated position determined by the above method deviates from the actual position. Therefore, in the present invention, the abnormal value determining means 14 measures the direction of the abnormal strong magnetic field from the output of the earth's magnetic field detecting means 11 to obtain the magnetization direction, and the magnetizing correction amount calculating means 15 measures the direction of the abnormal strong magnetic field from the output of the earth's magnetic field detecting means 11. The geomagnetism detection means 1 compares the output with the output of the geomagnetism detection means 11 determined in advance.
The direction calculation means 12 calculates the amount and direction of change in the output of 1.
The current position can be accurately estimated by correcting the output of the geomagnetism detection means 11 using the output change amount and change direction, and estimating a new current position in the dead reckoning calculation means 13.

Vehicle position correction using the above method will be explained using FIGS. 2 and 3.

FIG. 2 generally represents the horizontal component of the earth's magnetism by the locus of two mutually orthogonal component output values Vx and Va of the earth's magnetic field detecting means attached to an unmagnetized vehicle.

2o is a trajectory when the vehicle body is turned when no abnormal magnetic field exists. 21 is the output value V! when the earth's magnetic field detecting means detects an abnormal magnetic field caused by a moving object such as a truck. ,
22 is the locus drawn by VA, which is the output value v8 when the earth's magnetic field detecting means detects an abnormally strong magnetic field caused by a railroad crossing. The circle 23 is a predetermined threshold value with the strength of the magnetic field constant.

In general, abnormal magnetic fields caused by fixed objects such as railroad crossings are stronger than abnormal magnetic fields caused by moving objects such as trucks, and can be distinguished by the amount of change in magnetic field strength. They can also be distinguished by the strength of magnetic fields, including geomagnetism. Note that even if the vehicle body is magnetized, the output value of the geomagnetism detection means V! when the vehicle body is turned in a place where there is no abnormal magnetic field! If the coordinates of v8 and Va are translated in parallel so that the center of the circular locus drawn by Va, Va is the origin, it can be handled in the same way as when they are not magnetized.

In FIG. 3, in step 301, the vehicle is turned in advance and the output values of the geomagnetism detecting means are obtained. Here, a and b are the center of the circle, and R is the radius of the circle. In step 302, the output values from the travel distance detection means and the geomagnetism detection means are input, and in step 303, the input values and correction values CX and CY of the output of the geomagnetism detection means are used to determine the azimuth θ in the travel direction and the travel distance. A is found, and the current position is estimated as follows using the previous estimated current position X○, YO.

X=Axcos9+X0 Y=Axsinθ+YO With the above X and Y as new estimated positions, xOlY respectively
Replace with O. In step 304, the moving distance A
Find the cumulative travel distance from . In step 305, it is compared whether the cumulative moving distance is larger than a predetermined moving distance LO,
If L≧LO, then in step 306, the output value V! from the geomagnetism detection means! , Va are stored in the table in order. This table stores the output values of the geomagnetism detection means from a point returned by a predetermined distance C to the current position, and the output data of the geomagnetism detection means before that point is sequentially deleted. In step 307, the traveling distance d from the time when abnormal magnetic field detection was previously determined is determined, and L=O is set.
If the distance d is greater than the predetermined distance C in step 38, step 309 determines the maximum value of each component of the output value of the geomagnetism detection means stored in the table.
Find max, ■ and the minimum values v8, n, and vmin.

max In step 310, the above data is used to determine the variation width M of the magnetic field strength as follows.

””((■max knee vcmin)2+(vymax”
am1n)2) In step 311, it is checked whether the change width is larger than a predetermined threshold Th. If the geomagnetic variation width M is smaller than the predetermined threshold Th, it is determined that no abnormal magnetic field has been detected, and the d is set to 0 in step 316.
Then, the process returns to step 302. If the geomagnetic variation width M is larger than the predetermined threshold Th, it is determined that an abnormal magnetic field has been detected, and in step 312, the a
The one closer to a is called ■work f, and the one that is not closer to a is called V work. Similarly, if the maximum value and minimum value of ■A, which is closer to the above, is ■A6, and the one which is not closer to b is vyl, then the direction of change of the abnormal magnetic field in ■NieVA plane, Φ, is as follows. Seek.

Φ=tan ((Vyl'yf)/(■x6-vxf
)) ((V!, -Vxf)≧(M),!: ki)Φ=y
r+jan ((V, J-V, f)/(V,/V!
0 (when (v!, -v 1) < O) In step 313, the circle equation in step 301 is compared with the current output value of the geomagnetism detection means, and from the current output value, (R-dR) <R1<(R+dR) dR: If the threshold value is satisfied, it is determined that magnetization is not performed, and in step 316, d is set to 0 and the process returns to step 301. If it is not satisfied, it is assumed that magnetization has been achieved, and in step 314, the slope Φ is determined using the current output value of the geomagnetism detection means as the starting point.
The point where the straight line intersects the equation of the circle in step 301 for the first time is determined, and the distances CX and CY from this point of intersection to the current output value of the geomagnetism detection means are determined. Then, in step 316, d is set to 0 and the process returns to step 302.

In addition, in the above embodiment, it was determined whether or not it was an abnormal magnetic field based on the amount of change in the strength of the magnetic field, but the absolute value of the strength of the magnetic field (vx+va2) 1/2 was calculated and a predetermined threshold value was determined. If it is larger than the circle 23 in FIG. 2, it may be determined that it is an abnormal magnetic field.Furthermore, the abnormal magnetic field may be determined by characteristics of the magnetic field change such as the direction of the magnetic field change.

Effects of the Invention As described above, according to the present invention, even if the vehicle body is magnetized by driving in a strong magnetic field such as at a railroad crossing, the current position can be accurately estimated because the output data of the geomagnetism detection means is automatically corrected. can.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a vehicle position detection device in an embodiment of the present invention, FIG. 2 is a locus diagram of the output of the geomagnetism detection means,
FIG. 3 is a flowchart showing the arithmetic processing of the means of the device, and FIG. 4 is a block diagram of a conventional vehicle position detection device. 1o... Mileage detection means, 11...
Geomagnetism detection means, 12...Azimuth calculation means, 13
. . . Dead reckoning calculation means, 14 . . . Abnormal value judgment means, 16 . . . Magnetization correction amount calculation means.

Claims (3)

[Claims] (1) Mileage detection means for detecting the mileage of the vehicle;
A geomagnetism detecting means for detecting the traveling direction of the vehicle and the strength of the magnetic field; an abnormal value determining means for determining an abnormal magnetic field from an output value of the geomagnetism detecting means and determining a change direction of the abnormal magnetic field; Magnetization correction amount calculation means for calculating an amount of change in the output value of the geomagnetism detection means due to magnetization of a vehicle body from an abnormal magnetic field detection signal, change direction data of the abnormal magnetic field, and an output value of the geomagnetism detection means; and a vehicle by the geomagnetism detection means. azimuth calculating means for determining the traveling direction of the vehicle from the traveling direction of the vehicle and the output value from the magnetization correction amount calculating means; and dead reckoning calculation means for estimating a new current position based on the azimuth angle of the vehicle's traveling direction. (2) In the abnormal value determination means, the strength of the magnetic field is determined from the output sample of the geomagnetism detection means, and if the strength of the magnetic field is greater than or equal to a predetermined value, it is determined that it is an abnormal magnetic field, and the output value of the geomagnetism detection means changes. The vehicle position detection device according to claim 1, characterized in that a direction vector is determined. (3) In the magnetization correction amount calculation means, the output value of the geomagnetism detection means when the vehicle is turned is recorded in advance, and after receiving the abnormal magnetic field detection signal from the abnormal value determination means, the output value of the geomagnetism detection means is 2. The vehicle position detecting device according to claim 1, wherein the amount of change in the output value of the geomagnetism detecting means due to magnetization of the vehicle body is determined from the difference between the output value and the recorded output value.