JPS5899714A - Course guiding device for moving body - Google Patents

Abstract

PURPOSE:To acknowledge the timing when the recorrection of offset correction is to be performed appropriately, by monitoring the absolute value of the detected signal of a magnetic azimuth sensor after the correction, and detecting the variation of the absolute value depending on the azimuth. CONSTITUTION:The offset correction and the sensitivity correction of outputs X and Y detected by the magnetic azimuth sensor 1 are performed in a sensor output correcting part 6, and correction data X1 and Y1 are outputted. When the amount of magnetism contained in a body of a vehicle is changed, the offset state is changed, and the locus based on the correction data X1 and Y1 is shifted. Namely, difference is caused in the absolute value (X<1>2+Y<1>2)<1/2> outputted from an absolute value computing part 7, depending on the azimuths. The disagreement between the average value of the absolute values of the correction data and a reference value is detected, and the occurrence of the change in the offset state is warned.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a course guidance device for a moving object, in particular, a course guidance device for a moving object based on the outputs of a magnetic direction sensor and a speed sensor mounted on a moving object such as a passenger car and detecting the direction of the earth's magnetic field. In a course guidance device for a moving object that displays the current position of the moving object on a display, in addition to the function of displaying the current position of the moving object, the absolute value of the azimuth vector signal detected by the magnetic azimuth sensor differs depending on the direction. The present invention relates to a course guidance device for a moving object that has a function to issue a warning when a vehicle is detected.

2. Description of the Related Art Conventionally, it has been considered to detect the direction of travel of a moving object by detecting the direction of earth's magnetism using a magnetic direction sensor that detects the direction of a magnetic field. Then, the current position of the passenger car is extracted based on the output of the magnetic azimuth sensor and speed sensor mounted on a moving body such as a passenger car, and is plotted as a travel trajectory of the passenger car on a display, for example. At the same time, a course guidance device for a mobile object is being developed that maps a road map onto the display and guides the course so that the plot extends along the road on the map. As mentioned above, the basic principle of the course guidance device for a moving object using the magnetic orientation sensor is to know the running direction of the moving object based on the geomagnetic direction detected by the magnetic orientation sensor. ,
The detection signal of the magnetic force position sensor must be accurate azimuth information of the earth's magnetism. However, when the above-mentioned magnetic direction sensor is mounted in a vehicle handle made of iron plates, such as a passenger car, the output of the above-mentioned magnetic direction sensor is affected by the magnetization of the iron plates forming the vehicle. Due to the offset, the accurate direction of the earth's magnetic field cannot be detected. In addition, the shape of the vehicle with steel plate structure (
In general, the width of the vehicle body is small compared to the length in the direction of travel), but due to the problem that there are differences in the ease with which the magnetic field passes due to The detection sensitivity of the magnetic azimuth sensor to the earth's magnetism differs depending on the direction, and therefore the direction of the earth's magnetism cannot be detected accurately. These matters will be specifically explained with reference to FIGS. 1 and 2.

For example, in the magnetic orientation sensor lK shown in FIG. 2 is excited with alternating current so that saturation and unsaturation are repeated. In this state, as shown in the figure, when a magnetic field (in this case, from earth's magnetism) having a magnetic field strength He is applied, voltages VX and VY proportional to the magnetic field strength He are applied to the orthogonal detection coils 4.5. occurs. The generated voltages, ie, the outputs vx and vY of the magnetic orientation sensor 1, are the X-axis and Y-axis components of the geomagnetic vector He, and are given by the following equation, where K is a proportionality constant.

That is, if the magnetic azimuth sensor 1 is rotated 360 degrees with respect to the direction of the earth's magnetism, the trajectory obtained by the outputs Vx and Vy of the magnetic azimuth sensor 1 will be as shown in FIG. 1(B). Vx+Vy = (KHe) = circle 4 given by a-...-@ 0 Therefore, the above magnetic direction sensor 1
The direction of the earth's magnetism, that is, the magnetic north direction, can be determined from the outputs Vx and vY of the It is possible to know the direction in which the moving object is moving.

However, when the above-mentioned magnetic direction sensor l is mounted in a vehicle constructed of iron plates, such as an automobile, residual magnetism (due to magnetization during vehicle assembly) of the iron plates constituting the vehicle , the XLY output of the magnetic orientation sensor 1 is offset to 0, that is, the arrow Hr shown in FIG. The origin 0 of the Y output is displaced to the illustrated point 0'. As a result, the locus of the output (Vx, VY) of the magnetic direction sensor 1 based on the geomagnetic vector He becomes as shown in Figure 2. Therefore, the direction of the geomagnetic vector He is in the direction of arrow 0'P in the figure. Despite this, the azimuth vector obtained by the output of the magnetic azimuth sensor l is the composite vector (vector 0P- shown in FIG. 2) of the residual magnetic vector Hr and the geomagnetic vector He? , it is not possible to detect the exact direction of the earth's magnetic field.

Further, as described above, the magnetic detection sensitivity of the magnetic azimuth center t1 differs depending on the azimuth based on the change in the angle of incidence of the earth's magnetism with respect to the vehicle. In this case, the output locus of the magnetic orientation sensor l is the locus t shown in FIG. 1 or 2,
Alternatively, it will not be a perfect circle like 1t, but will be an ellipse (not shown). Further, although not shown, the influence of the installation position of the magnetic orientation sensor in the vehicle appears as a long elliptical trajectory inclined with respect to the X1Y axes.

Therefore, accurate geomagnetic direction information can be obtained by performing offset correction and sensitivity correction on the output of the magnetic direction sensor 1. However, even if the above correction is made at the start of driving, for example,
For example, the amount of magnetization of the vehicle body may change when the vehicle passes through a railroad crossing or the like using DC power transmission, or the amount of magnetization may change due to gradual demagnetization over time. As described above, when the amount of magnetization of the vehicle body changes, the offset correction performed in the initial state becomes incorrect. Therefore, if the vehicle continues to run without noticing the change in the amount of magnetization, there is a problem that an error will occur in the display of the running trajectory.

The present invention aims to solve the above problems,
Monitor the absolute value of the corrected detection signal of the magnetic orientation sensor, detect fluctuations in the absolute value due to orientation, and issue a warning if the fluctuation value exceeds a predetermined level. It is an object of the present invention to provide a course guidance device for a moving body that can appropriately recognize the timing at which offset correction should be re-corrected and obtain accurate travel locus display. The following description will be given with reference to the drawings. FIG. 3 shows a block diagram of an embodiment of the present invention. The symbol l in the figure corresponds to that in Figure 1, 6 is a senna output correction unit that performs offset correction and sensitivity correction for the output (xSy) of the fusion direction sensor l, and 7 is an absolute value. 8X and 8Y are calculation units that calculate the absolute value of the correction data (X+SY+) output from the sensor output correction unit 6, and 8X and 8Y are absolute value correction units that calculate the absolute value of the correction data (X+SY+) output from the sensor output correction unit 6. one that corrects the correction data X1 and Yl from the sensor output correction section 6;
9 is a speed sensor that outputs a clock signal every unit travel distance of the moving object, for example, every 10 rotations of a wheel;
Reference numeral 10 denotes an integration unit which, in response to the clock signal from the speed sensor 9, operates the absolute value correction units 8X and 8Y.
The outputs X2 and Y! The one that integrates and outputs, ll
13 is a trajectory storage unit that sequentially stores the output of the integration unit 10 and displays the travel trajectory of the moving object on the display 12 based on the stored contents; 13 is a quadrant determination unit that The output of the output correction section 6 (X
14 and 15 are gate circuits, 16 is a distribution circuit section, 17 to 20 are first to fourth shift registers, 21 to 24 are average value calculation units which read out the contents stored in the shift registers 17 to 20 and calculate the average value;
Reference numeral 5 denotes a comparison circuit unit which compares a preset reference value with the contents of the average value calculation unit 21'' and 24 and outputs a warning signal in the case of a discrepancy.0 This invention In FIG. 3 showing one embodiment of the invention, first, the present invention,
The following describes the driving trajectory display function of the vehicle. As described in Chizu in this specification, the output (x, y) detected by the magnetic orientation sensor l is subjected to offset correction and sensitivity correction in the sensor output correction section 6 based on the following formula, and the correction data (X, y) is , Ml) are output. That is, in (3) 2, α is the X offset correction value, and b is the Y
The offset correction value, c#i, is the X sensitivity correction value, and d is the Y sensitivity correction value.

Correction data (X
I, Yt) are subjected to absolute value correction based on the following formula in the absolute value correction units 8X and 8Y based on the absolute value (r) calculated and found in the absolute value calculation unit 7, and the azimuth unit vector X, , Y, is the integration part 1
Sent to 0. At the return, in the integrating section 10, the azimuth unit vectors X and Yt are sequentially integrated in response to the clock signal from the speed sensor 9, and are sequentially stored in the locus storage section 11. Then, the contents of the trajectory memory i11 are read out and displayed as a traveling trajectory on the display I2.

Next, another function of the present invention, that is, a function to immediately warn of the occurrence of a change in the offset state due to a change in the amount of magnetization of the vehicle body will be explained. When the correction in the sensor output correction section 6 is performed correctly, the correction data (Xr, Ys) output from the sensor output correction section 6
The locus is a right circle, for example, as locus L1 in the diagram of FIG. 1(B). Therefore, the above correction data (Xl, Yl
) is approximately constant. However, as stated at the beginning of this specification, when the amount of magnetization of the vehicle body changes, the offset state described in relation to FIG. 2 changes, and the trajectory of the correction data (Xi, Yt > As shown in the trajectory t shown in Figure 2, the origin is shifted from the origin 0 of the X-Y axis.In other words, the above absolute value (2)K depends on the orientation.
Differences arise. In the present invention, focusing on this,
Absolute value of the above correction data X1, Yl ((ca+Y,”)
Average values and reference values for each quadrant 1 to 4 (Figure 1 (B)
) or the one corresponding to the arrow He shown in Figure 2) to warn that a change in the offset state has occurred. explain. As mentioned above, the above correction data l (X
I, Y, > o absolute value < lYt "Yt")
The quadrant determining unit 13 determines in which quadrant the azimuth vector calculated by the absolute value calculating unit 7 and represented by the correction data (XI, y, ) exists. And speed sensor 9
The above absolute value (〆X,”
+Y,”) and the quadrant judgment result are simultaneously sent to the gate circuit 14.
and 15 to the distribution circuit section 16. In the distribution circuit section 16, the absolute value (〆X, "+7θ) is distributed to the first to 40th shift registers 1-7 to 20 based on the quadrant determination result.
The fourth shift registers 17 to 2-0 are predetermined to correspond to the quadrants 9, for example, the first shift register □17 stores the absolute value of the inferior vector within the first quadrant range. , the second shift register 18 stores the absolute value of the azimuth vector within the second quadrant. The above first to fourth shifts/
The plurality of absolute values (m) shifted and stored in the registers 17 to 20, respectively, are sent to the average value calculation units 21 to 2.
4, each average value is calculated. Each of the average values is compared with a reference value having a predetermined threshold value in the comparator circuit section 25, and when a mismatch is detected, a warning signal indicating that the offset correction needs to be re-corrected is output. Then, the warning signal may be used to notify the driver, for example, by operating a warning lamp or a warning buzzer. It goes without saying that when the above-mentioned warning is issued, the above-mentioned offset correction is re-corrected so that an accurate travel trajectory is displayed and the correct course guidance of the moving object is performed. 0 As explained above, according to the present invention, the absolute value of the corrected detection signal of the magnetic force position sensor is constantly monitored, the fluctuation based on the direction of the absolute value is detected, and the fluctuation value is determined to be equal to or higher than a predetermined level. A course for a moving object that makes it possible to appropriately recognize the timing to re-correct the offset correction by issuing a warning immediately when the offset correction occurs, thereby obtaining an accurate driving trajectory display. A guidance device can be provided.

[Brief explanation of drawings]

FIG. 1 (4), 0) is an explanatory diagram for explaining one embodiment of the magnetic orientation sensor used in the present invention, FIG. 2 is an explanatory diagram regarding the offset in the output of the magnetic orientation sensor, and FIG. FIG. 1 shows an overall block diagram of an embodiment of the invention. In the figure, l is a magnetic direction sensor, 6 is a sensor output correction unit, and 7
is an absolute value calculation unit, 8x and 8Y are absolute value correction units, 9 is a speed sensor, 10 is an integration unit, 11 is a trajectory storage unit,
12 is a display, 13 is a quadrant determination unit, 14 and 1
5 is a gate circuit, 16 is a distribution circuit section, 17 to 20 are first to fourth shift registers, 21 to 24 are average value calculation sections, and 25 is a comparison circuit section. Company representative patent attorney Mori 1) ★ (A) CB) Sai 2 Figure

Claims (1)

[Claims] A magnetic direction sensor and a speed sensor are mounted on a moving object, and a display mounted on the moving object and a map displayed in correspondence with the display screen of the display are installed, and the magnetic direction sensor and speed sensor are installed on the moving object. A course guiding device for a moving object is configured to extract the current position of the moving object using a sensor, plot the current position on the display, and correlate it with the map. a sensor output correction section that performs offset correction based on the amount of magnetization of a moving object and sensitivity correction that adjusts the output level on the output of the magnetic orientation sensor that detects a directional component, and outputs correction data; an absolute value calculation section that calculates the absolute value of the correction data output from the output correction section; an absolute value correction section that performs absolute value correction on the correction data based on the output of the absolute value calculation section; and the absolute value and a trajectory storage section that sequentially stores the azimuth information outputted from the correction section using a clock signal outputted from the speed sensor for each predetermined unit traveling distance, and the content of the trajectory storage section is A quadrant determining unit is provided for displaying the current position of the moving body on the display and determining a quadrant in which the azimuth vector represented by the correction data output from the sensor output correcting unit exists, the quadrant determining unit The output of the absolute value calculation unit is distributed based on the contents of the distribution, and the average value calculated for each distributed internal answer is compared with a reference value having a predetermined dark value. A course guidance device for a mobile object 0, characterized in that it is configured to output a warning signal when a discrepancy is detected.