JPH03154816A - Vehicle azimuth arithmetic method - Google Patents

Abstract

PURPOSE:To accurately calculate the azimuth when a vehicle is slanted by calculating the output voltages of an X- and Y-axis coils when the vehicle does not slanting by using the axis coil output voltages of a 1st and a 2nd magnetic azimuth sensor and a table. CONSTITUTION:Cosine values corresponding to the tilt angle of the vehicle is stored in a memory MEM corresponding to the ratio of the X-axis or Y-axis side coil output voltage (x) or (y) of a horizontal magnetic azimuth sensor DSH and the X-axis or Y-axis coil output voltage x' or y' of a slanting magnetic azimuth sensor DSI which is slanted at a specific angle to the DSH in the east-west direction and south-north direction respectively. Then a CPU cosine values from the ratios of the output voltages (x) and (x') and output voltages (y) and (y') by using a table TBL to calculate the X-axis side coil output voltage and Y-axis side coil output voltage of the DSH when the vehicle does not slant, and calculates the displacement of the vehicle by using the X-axis side coil output voltages and Y-axis side coil output voltages. Consequently, the azimuth can accurately be calculated even when the vehicle is slanted on a slope, etc.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a vehicle heading calculation method, and particularly relates to a vehicle heading calculation method that can accurately calculate the heading even when the vehicle is leaning on a slope or the like. 6 <Prior art> Two geomagnetism detection elements (X-axis coil, Y-axis coil) are arranged on the same plane with a phase angle of 90 degrees, and the geomagnetism is detected based on the detection signals of the geomagnetic amount output from these detection elements. 2. Description of the Related Art There are direction measuring devices equipped with detection elements that measure the traveling direction of a vehicle, and are used in automobile navigation systems.

FIG. 4 is an explanatory diagram of such a direction measuring device.

Reference numeral 1 designates a magnetic orientation sensor, which has a toroidal ferrite core 1a and two detection windings (X-axis coil, Y-axis coil) 1b with a phase angle of 90 degrees to each other.

1c, and an excitation winding 1d. A rectangular wave having a frequency f is applied to the excitation winding 1d via an oscillator 2 and an excitation circuit 3.

An excitation current necessary to magnetically saturate the core is applied. In such a state, when earth's magnetism is applied, an imbalance occurs at the magnetic saturation point and the excitation current changes, and based on this change, the detection windings 1b and lc have a width proportional to the strength of the IL field Ho at a frequency of 2f. A pulse voltage is generated. Therefore, these detection winding outputs are filtered through a bandpass filter 4 with a frequency of 2f.
, 5 and rectified by the rectifier 6.7, a voltage expressed by the linear formula % () () (θ is the direction and is a constant) is output,
From Vx and Vy, the orientation θ can be calculated using the following formula (2).

Therefore, the direction calculation section 8 calculates Vx,
Vy is taken in, and the direction O of the vehicle is jointly calculated using equation (2) and output. Incidentally, while rotating the magnetic orientation sensor 1, Vx and Vy are taken in at a predetermined sampling period, and the Vx and Vy are input to the display device 9 as X-axis and Y-axis coordinate values to generate an image and draw it on the CRT. In this case, a circle, which is a Lissajous figure, is drawn.

Figure 5 shows a circle which is a beam serge figure, and a point Pi (i=1, 2, . . .) on the circle is a point whose coordinate values Xi, Yi are the first sampling voltages Vx, Vy. When it faces east, it becomes Xa+ax, when it faces west, it becomes X akin, when it faces north, it becomes Y wax, and when it faces south, it becomes Ymin. Further, the coordinate values (xa, yo) of the center Pc and the radius R are given by the following formula (3) (3) (3). Therefore, voltages Vx and Vy are calculated from X and Y.

<Problem to be solved by the invention> When the magnetic/magnetic force position sensor is horizontal, in other words, when the car is horizontal, the Lissajous figure becomes a perfect circle (
4) The direction of the vehicle can be calculated correctly using the formula.

However, if the vehicle is tilted at a predetermined angle in the north-south direction on a slope, etc., the Lissajous figure will not become a perfect circle, but will be distorted into an ellipse as shown in FIG. Furthermore, when the car tilts in the east-west direction, the Lissajous figure does not become a perfect circle, but becomes distorted into an ellipse as shown in FIG.

If the Lissajous figure is no longer a perfect circle, it becomes impossible to accurately calculate the direction of the vehicle, as shown in FIG. In other words, if the car is not tilted when the car's direction is θ, the 8th
X and Y in the figure are output from each detection winding of the magnetic orientation sensor, and the orientation θ is determined from equation (4). However, when the Lissajous figure becomes a distorted ellipse due to tilting in the north-south direction, X is output from the X-axis coil side, but y is output from the Y-axis coil side.
Since (<Y) is output, the orientation determined by equation (4) becomes θ' (:= tan-'(y/Y)), making it impossible to calculate an accurate orientation.

From the foregoing, it is an object of the present invention to provide a vehicle force position calculation method that can accurately calculate the heading even if the vehicle is tilted.

Means for Solving the Problems> In the present invention, the above problems are solved by a first magnetic azimuth sensor, and a first magnetic azimuth sensor in both east-west and north-south directions.
a second magnetic direction sensor tilted at a predetermined angle, and a first magnetic direction sensor, each tilted at a predetermined angle;
．． A correspondence table between the ratio of each axis coil output voltage of the second magnetic azimuth sensor and a cosine value according to the tilt angle of the vehicle, and the first. means for calculating the X and Y axis side coil output voltages X and Y of the first magnetic azimuth sensor when the vehicle is not tilted using each axis coil output voltage of the second magnetic azimuth sensor and a table;
This is accomplished by calculating the vehicle's heading using x and y.

Effect> X-axis or Y-axis coil output voltage x, y of the first magnetic azimuth sensor and X-axis or Y-axis coil output voltage x1 of the second magnetic azimuth sensor. The cosine value corresponding to the vehicle inclination angle is stored in a table in correspondence with the ratio to yl, and the first
．． Each X-axis side coil output voltage x of the second magnetic orientation sensor,
Find the cosine value cosη using a table from the ratio of x',
The X-axis side coil output voltage X of the first magnetic azimuth sensor when the vehicle is not tilted is calculated by X=x/cosη.

Similarly, the first. From the ratio of each Y-axis side coil output voltage y, y' of the second magnetic orientation sensor, use a table to calculate the cosine value cos
φ is calculated, and the Y-axis coil output voltage Y(-
y/cosφ), and use X and Y to calculate the direction of the vehicle.

<Example> Fig. 1 is a block diagram of a vehicle direction measuring device according to the present invention, and DSH is a first magnetic azimuth sensor (horizontal magnetic azimuth sensor) installed horizontally on the vehicle, and the dotted line in Fig. 4 Corresponds to the part surrounded by. DSI is horizontal magnetic direction sensor DS
A second magnetic azimuth sensor (tilted magnetic azimuth sensor) tilted at a predetermined angle α (for example, 30 degrees) in the east-west and north-south directions with respect to H, MPX is a multiplexer, 5P) i is a sampling and hold circuit, and ADC is analog/digital The converter, CPU is a processor for azimuth calculation, OPP is an operation unit, and MEM is a memory.

The memory MEM stores the X-axis coil output voltage X or Y-axis coil output voltage y of the horizontal magnetic orientation sensor DSH and the X-axis coil output voltage X' or Y-axis coil output voltage y' of the gradient magnetic orientation sensor DSI. (x/x' or y
/y'), a cosine value corresponding to the inclination of the vehicle is stored.

That is, as shown in FIG. 2, the direction of the vehicle is θ,
If the car is tilted φ in the north-south direction, the output voltage y of the Y-axis coil of the horizontal magnetic direction sensor DSH is y=Ym0sinθ” cosφ = Y@CO8φ (5), and the Y-axis coil of the horizontal magnetic direction sensor DSI is The output voltage y' is y' = YmIIsinθ・C08(α±φ)=Y-c
os(α±φ)(6) Therefore, 3/ / 'J' = cosφ/cos (α±φ), so change the inclination angle φ in small increments in the range from O to the maximum inclination angle, and create a table of the relationship between y/y' and cosφ at that time. It is created as a TBL and stored in the memory MEM.

In addition, horizontal magnetic direction sensor DSH1 gradient magnetic direction sensor D
The table placement may be created using the SI X-axis side coil output voltages x and x'.

The processing of the azimuth calculation processor CPU in FIG. 1 will be described below in accordance with the flowchart in FIG. 3.

With the car in a horizontal position, an initial setting command is input to the processor CPU from the operation section opp. After that, the vehicle is rotated to rotate the direction of the horizontal magnetic direction sensor DSH once, and the output voltages X and y on the X-axis and Y-axis coils are sent to the multiplexer MPX, the sampling hold circuit SPH, and the analog/digital converter ADC at a predetermined period. , and the maximum and minimum values of these sampling voltages Xmax,
Xm1n.

Find Y wax, Y win, (3a) to (3c)
The center (X
o , Y o ) are determined and stored in memory (step 101).

...Initial Setting After the initial setting, the azimuth calculation processor CPU calculates the X-axis coil output voltage X and Y-axis coil output voltage y of the horizontal magnetic azimuth sensor DSH, and the X-axis coil output voltage of the gradient magnetic azimuth sensor DSI. The X' and Y-axis side coil output voltages y' are taken in, and voltage ratios X/X' and y/y' are calculated (step 102).

Then, from table TBL, x/x' and "
r! Find the cosine value according to /V' (step 103)
. As a result, if the inclination angle of the vehicle in the east-west direction is η and the inclination angle in the north-south direction is φ, then from the table CO8η, cos
Find φ.

Once each cosine value has been found, the linear formula % formula % (7) Y = y / cosφ---(8) determines the X-axis coil output of the horizontal magnetic direction sensor DSH when the vehicle is not tilted. The voltage X and the Y-axis coil output voltage Y are calculated in step 104), and then the orientation θ is calculated in accordance with equation (4) in step 105), and outputted to, for example, a navigation processor.

<Effects of the Invention> According to the present invention, the voltage of the vehicle is adjusted according to the ratio of the X-axis or Y-axis coil output voltage of the horizontal magnetic azimuth sensor to the X-axis or Y-axis coil output voltage of the gradient magnetic azimuth sensor. Store the cosine value corresponding to the tilt angle in a table, and then
Each X-axis side coil output voltage x, x' of the gradient magnetic orientation sensor
Find the cosine value using a table from the ratio of Since the configuration is configured to calculate the Y-axis coil output voltage Y of the horizontal magnetic azimuth sensor when Can be done.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a direction measuring device according to the present invention. FIG. 2 is an explanatory diagram of the present invention. FIG. 3 is a flowchart of the direction calculation process of the present invention. FIG. 4 is an explanatory diagram of a conventional orientation detection device, and FIG. 5 is an explanatory diagram of the orientation detection principle. FIG. 6 and FIG. 7 are explanatory diagrams of the surge shape when the car is tilted. FIG. 8 is an explanatory diagram of conventional problems. DSH・・Horizontal magnetic direction sensor DSI・・Gradient magnetic direction sensor CPU・・Processor for direction calculation TBL-Moaning table

Claims (1)

[Claims] Find and set the center (X_0, Y_0) of a circle showing the relationship between the X-axis coil side output voltage and the Y-axis coil side output voltage obtained by rotating the direction of the magnetic orientation sensor, X-axis side and Y-axis side coil output voltages X, Y and the setting center of the circle (X_
0, Y_0), in which a second magnetic azimuth sensor is provided which is tilted at a predetermined angle in the east-west and north-south directions with respect to the magnetic azimuth sensor, and the first magnetic azimuth Cosine values corresponding to vehicle inclination angles are stored in a table in correspondence with the ratio of the X-axis or Y-axis coil output voltage of the azimuth sensor to the X-axis or Y-axis coil output voltage of the second magnetic azimuth sensor. Next, use the above table to determine the cosine value from the ratio of the X-axis side coil output voltages x and x' of the first and second magnetic azimuth sensors, and use x and the cosine value to determine whether the vehicle is tilted. Calculate the X-axis coil output voltage X of the first magnetic orientation sensor when Find the cosine value,
y and the cosine value to calculate the Y-axis coil output voltage Y of the first magnetic azimuth sensor when the vehicle is not tilted, and use X and Y to calculate the azimuth of the vehicle. Vehicle orientation calculation method.