JPH0373804A - Azimuth meter for vehicle - Google Patents

Abstract

PURPOSE:To accurately detect the azimuth of a vehicle by correcting the center value of an azimuth circle outputted from an earth magnetism azimuth sensor. CONSTITUTION:The vehicle azimuth meter is constituted of an output circle center value forecasting part 29 for forecasting the center value of an output upper circle based upon the outputs of an output processing circuit 23 and a gyro signal processing circuit 27 both of which use microcomputers for their processing, a switch 28 for electric parts of the vehicle, an output circle center value movement possibility detecting circuit 30 for deciding the movement possibility of the center value of an output circle outputted from the earth magnetism azimuth sensor 21 based upon the possibility of magnetization decided from earth magnetism data obtained from the circuit 23 and the data from the switch 28, a new center value detecting circuit 31 for finding out a center value with a higher accuracy based upon a forecasted center value, and an azimuth detecting part 33 for finding out the azimuth of the vehicle from the found center point and the output of an earth magnetism azimuth sensor 21 which is digitally converted by the circuit 23. Consequently, an always optimum center value can be obtained without executing specific correcting operation, and since the center if moved to the higher accuracy part of the center value, the accuracy of the center value can be improved in accordance with the advance of scanning.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention detects the direction from the output circle center coordinates of the sensor to the coordinates indicated by the output value of the geomagnetic direction sensor as the vehicle direction. The present invention relates to a vehicle compass, and more particularly, to a vehicle compass that corrects the center value of the output direction position of a geomagnetic compass sensor to detect accurate vehicle direction.

(Prior Art) Conventionally, as a device for detecting the direction of a vehicle using a geomagnetic direction sensor, there is one disclosed in, for example, Japanese Patent Laid-Open No. 100812/1983. In this disclosed orientation sensor, a pair of windings are provided in a horizontal orientation and orthogonal to each other, and a geomagnetic component detection voltage can be obtained from these windings in accordance with interlinked geomagnetism. In this direction sensor, when a vehicle travels around in a uniform geomagnetic field, a circle is drawn on the coordinates based on the coordinates indicated by the detected voltage of the winding.

Here, when the vehicle is magnetized, the circle moves, resulting in an error in the running direction of the vehicle.

Therefore, in such a case, the output value of the geomagnetic azimuth sensor is sampled while the vehicle is running in a circle, and the output circle of the geomagnetic azimuth sensor is aligned with the X-axis and Y-axis of the coordinate system as the vehicle turns once. When the outputs of the four intersecting points are obtained, the center value of the output circle is calculated by averaging the sampled output values to correct the detection error of the running direction.

Further, as a method for detecting magnetization of a vehicle, there is a method disclosed in, for example, Japanese Patent Laid-Open No. 59-210317.

This is to detect a malfunction in the orientation system when the absolute value of the geomagnetic field exceeds a reference value.

(Problem to be Solved by the Invention) In the above-described conventional vehicle direction meter, when it detects that the output of the geomagnetic direction sensor is abnormal, it warns the vehicle occupant to make a full circle turn for correction. In order to make corrections when the sensor output is abnormal, it is necessary to make a full turn and perform correction operations every time there is an abnormality in the sensor output.In addition, such correction driving is often impossible; Detection errors increased, often causing the navigation system to become disabled. In addition, even if a correction operation is performed, the center value calculated by the correction operation is used as the center value for calculating the vehicle's direction, so there is a problem that accurate vehicle direction cannot be obtained frequently. .

The present invention has been made in view of the above, and its purpose is to provide a vehicle azimuth that can accurately correct the center value of the output azimuth circle of a geomagnetic azimuth sensor to detect accurate vehicle direction. The objective is to provide a measurement system.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the vehicle azimuth meter of the present invention, as shown in FIG. A geomagnetic sensor 1 that detects the data as data, a vehicle direction change amount detection means 3 that detects the relative angular displacement of the vehicle, a data storage means 5 that stores the detected geomagnetic data and the relative angular change amount, and the data storage means Center value movement possibility determination means 1 for determining the possibility of movement of the center value of the output circle of the geomagnetic azimuth sensor based on the geomagnetic data stored in the geomagnetic data and signals from vehicle electrical equipment switches.
6, distance coefficient setting means 18 for setting a distance coefficient when determining the center value based on the possibility of movement of the center value of the output circle by the center value movement possibility determining means, and a distance coefficient setting means 18 for setting a distance coefficient for determining the center value based on the possibility of movement of the center value of the output circle by the center value movement possibility determining means; an output circle center value prediction means 7 for predicting the output circle center value of the geomagnetic sensor from the geomagnetic data and the amount of relative angle change; a predicted center value storage means for storing the predicted center value; a first provisional center calculation means 11 that calculates a first provisional center value using a group of center values from the time when the stored center value begins to appear at a position away from the current center value for which the orientation is being calculated; a second provisional center calculation means 13 that calculates a second provisional center value using the stored center value group for which the values have been calculated and the latest stored center value; and a second provisional center calculation means 13 that calculates the weights of the first and second provisional center values. Weight calculation means 15
and a distance calculating means 17 for calculating the distance between the current center value and the temporary center value, and determining a center value to be used for calculating vehicle heading using geomagnetic data from the weight, distance and distance coefficient. The gist is that the central value determining means 19 is provided.

(Function) The vehicle direction meter of the present invention predicts and stores a center value from the output of the geomagnetic direction sensor collected while driving, and detects whether the center value has moved significantly from the stored predicted center value. A second temporary center value is set in the vicinity of the first temporary center value and the center value of the current azimuth circle to further improve center value accuracy, and the weight and distance of the first and second temporary center values are set. is calculated, and a distance coefficient is set based on the possibility of movement of the output circle center value of the geomagnetic azimuth sensor using geomagnetic data, etc., and when it is determined that the center value has moved significantly based on the weight, distance, and distance coefficient. , the first provisional center value is set to a new center value and the center value is corrected at high speed while driving, and if there is no center value movement, the predicted center value obtained while driving is used to calculate the center value. The accuracy of the center value is improved by setting the second temporary center value as the new center value, and the center value is always moved to the side with better accuracy regardless of whether or not the center value has moved. Value accuracy can be improved.

(Example) Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 2 is a block diagram showing the configuration of a vehicle compass according to an embodiment of the present invention. The vehicle direction meter shown in the same figure is
a geomagnetic azimuth sensor 21 that detects the geomagnetic direction as geomagnetic data of two mutually orthogonal directional components; an output processing circuit 23 that converts the output of the sensor into a digital signal;
Consists of a rate gyro that detects changes in the vehicle's direction.
a gyro sensor 25 that outputs the turning angular velocity Ω of the vehicle;
A gyro signal processing circuit 27 that integrates the output of the gyro sensor 25 to calculate the amount of change in azimuth, which is the amount of relative angle change of the vehicle, and the output processing circuit 23 and the gyro signal processing circuit 27, which are processed by a microcomputer. two output circle center value prediction units that predict the output azimuth circle center value from the output of the vehicle electrical component switch 28, and the possibility of magnetization determined from geomagnetic data from the output processing circuit 23 and the vehicle electrical component. A geomagnetic direction sensor 21 based on a switch 28 (opening/closing a sunroof, opening/closing a sun visor, etc.)
an output circle center value shift possibility detection circuit 30 that determines the shift possibility of the output circle center value; a new center value calculation unit 31 that calculates a more accurate center value based on the predicted center value; and a direction detecting section 33 that determines the vehicle direction from the center point determined and the output of the geomagnetic direction sensor 21 which is digitally converted by the output processing circuit 23.

As shown in FIG. 3, the geomagnetic direction sensor 21 includes windings 70X perpendicular to each other on an annular permalloy core 60;
70Y is wound.

Further, a winding 80 is wound around the permalloy core 60, and this winding 80 is energized by an excitation power source 90 until just before the permalloy core 60 is saturated, as shown in FIG.

When the geomagnetic direction sensor 21 is placed in a non-magnetic field, the magnetic fluxes φ1 and φ2 passing through the portions S1 and S2 of the permalloy core 60, respectively, have the same magnitude and opposite directions, as shown in FIG.

Therefore, when the magnetic flux interlinking with the winding 70X becomes zero, the detected voltage VW -N-dφ/dt (N is the number of turns) also becomes zero, and similarly the detected amount voltage vy of the winding 70Y also becomes zero.

Furthermore, when the geomagnetic field He is applied perpendicularly to the winding 70X as shown in FIG. A bias is applied to the magnetic flux, and the magnetic flux φ2 becomes asymmetrical as shown in FIG.

Therefore, the detection voltage Vx having the waveform shown in FIG. 7 is applied to the winding 70X.

Further, since the earth's magnetic field He is parallel to the winding 70Y, no voltage vy is generated in the winding 70Y.

When this geomagnetic direction sensor 21 is mounted on a vehicle in a horizontal position as shown in FIG. 8, for example, as shown in FIG. (output value) are obtained respectively.

For the detection voltages Vx and Vy, the value K is the winding constant, and the value B is the earth's magnetic field H.
If it is the horizontal component of e, it is expressed by the following equation (head) and equation (2).

Xx--KBcosθ Second (blind) formula Vy--
KBsInθ Equation (2) Therefore, if the width direction of the vehicle is used as a reference as shown in FIG.
3) Formula % Formula % As understood from the above equations (1) and (2), when the vehicle orbits in the uniform geomagnetic He,
The coordinates indicated by the windings 70X and 70Y (7) detected voltages Vx and Vy draw a circle (the output circle of the geomagnetic direction sensor 21) on the X-Y plane coordinates as shown in Figure 9, and the output circle is It is shown by the formula.

Vx 2+Vy 2= (KB) 2 Equation (4) Thus, the detection voltage Vx of the windings 70X and 70Y.

Since the coordinate defined by vy exists on the output circle, the direction toward that coordinate point (output point) from the center O of the output circle is detected as the running direction of the vehicle.

Here, the vehicle body is magnetized, and as shown in FIG. 10, for example, as shown in FIG.
When interlinked with 0Y, the output circle moves from the broken line position to the solid line position as shown in FIG.

For this reason, the vehicle azimuth meter of this embodiment corrects the center value of the output azimuth circle through the process shown in the flowchart of FIG. 12 in order to always detect accurate vehicle direction.

Next, the operation will be explained with reference to the flowchart shown in FIG.

First, the output circle center value prediction circuit 29
The predicted center value of the output azimuth circle is calculated from the geomagnetic data supplied from the geomagnetic azimuth sensor 21 via the geomagnetic azimuth sensor 21 and the azimuth change amount supplied from the gyro signal processing circuit 27 (step 300). This is, for example, Jitsugan Sho 63-832
It is calculated using the relative angle change method, the least squares method, etc. as described in No. 8 and Utility Model Application No. 63-41579.

This calculation is performed until successful (step 310).

If the calculation is successful, the calculated predicted center value is stored in the memory AA, which is the data memory for calculating the temporary center A, and the memory BB, which is the data memory for calculating the temporary center B (step 320).

The above processing is performed by two output circle center value prediction units.

When the predicted center value calculated as described above is stored in the memories AA and BB, the number of predicted center values stored in the memory AA is 1 due to the action of the new center value calculation unit 31. is checked (step 32).
0). If there is one, return to step 300 and repeat the same operation.

Also, the number of predicted central values stored in memory AA is 2.
If the memory A
Using the n predicted center values Xi and Yl stored in A, center coordinate values Xa and Yb are calculated using the following equations.

Xa - (ΣXi)/n Ya - (ΣY1)/n Then, the weight of the temporary center A is calculated using the following equation (step 360).

σa−([Σ((Xi −Xa) 2 +YI−Ya
)21 /nl'-2)*100/R Weight - 1/σa2 Next, the center value of the temporary center B is calculated using the same calculation as in step 350 using the m predicted center values stored in the memory BB. Calculate (step 370). Then, similar to step 360, the weight of temporary center B is calculated (step 380).

Note that the predicted center value stored in memories AA and BB is cleared in steps 440 and 490 as described later, whereas the predicted center value stored in memory BB is cleared in step 420 when the contents of memory AA are cleared. The difference between the two is how much past data can be carried. The number of stored prediction center value data is n±m.

In addition, as can be seen from the following explanation, temporary center A is used to recognize that the azimuth circle has shifted significantly due to car body magnetization, etc., and temporary center B is used to recognize that the azimuth circle has shifted significantly due to car body magnetization, etc. This is to find a highly accurate center value using the predicted center point from .

The temporary center A is approximately the same coordinate point as the temporary center B when there is no vehicle body magnetization, and in this case, the temporary center A is cleared together with the temporary center calculation memory AA, as will be described later. Further, if the azimuth circle shifts, the center value is immediately moved to the coordinate point indicated by the temporary center A. Furthermore,
When the vehicle body is magnetized, the contents of temporary center A at that time are set as temporary center B.

Compare the weight of the temporary center A calculated as described above with the weight of the current center point (Step 390). If the weight of the temporary center A is large, the center point may be lowered due to magnetization of the vehicle body or the influence of an external magnetic field. This is a case where the value has moved significantly, and step 4
00 onward, and central value Urasa processing is performed at high speed. That is, in step 400, first, the center value currently used for direction calculation is discarded, temporary center IC and A are set as center values for direction calculation, and the weight of temporary center A is set as the center weight for direction calculation.
Then erase the contents of memory BB (step 410).
, transfer the contents of memory AA to memory BB (step 420), and erase the contents of temporary center A in step 4.
30), and also erase the contents of memory AA in step 44.
0), return to step 300.

If the weight of the temporary center A is smaller than the weight of the current center point in step 390, the process proceeds to step 445, where the distance coefficient K is read from the output circle center value movement possibility detection circuit 30.

The calculation of the distance coefficient in the output circle center value movement possibility detection section 30 will be explained with reference to the processing flow shown in FIG. 12.

The process shown in FIG. 12 operates by an interrupt every second,
Determine whether there is a possibility of magnetization (Step 6)
00). The possibility of magnetization can be determined by, for example, Japanese Patent Application No. 62
This is the same as that performed by the magnetization detection processing described in No. 203167, and the explanation thereof will be omitted. In addition,
In this embodiment, this function does not determine magnetization, but merely determines that there is a possibility of magnetization.

If there is no possibility of magnetization as a result of the processing in step 600, the process proceeds to step 605, and the vehicle electrical component switch 2
Check whether 8 is on.

When the vehicle electrical equipment switch 28 is on, the peak value P
Temporarily set A to 800 (which may be changed depending on the electrical equipment), proceed to step 620, and substitute the peak value PA-800 into the formula for the distance coefficient shown in this step to obtain the distance coefficient K.
Calculate. Then, the calculated distance coefficient K is stored in the buffer memory (step 630), and the process ends.

Further, in the check at step 605, if the vehicle electrical component switch 28 is not on, the distance coefficient K is set to 50.
This distance coefficient is set to 610), -50 is stored in the buffer memory, and the process ends.

Further, in the check at step 600, if it is determined that there is a possibility of magnetization and a possibility of movement of the output circle, the process proceeds to step 620, and a distance coefficient K is calculated according to the peak value PA. , the calculated distance coefficient K is stored in the buffer memory (step 630), and the process ends.

When the distance coefficient K is calculated as described above and stored in the buffer memory, it is read into this distance coefficient in step 445, and the process proceeds to step 450.

In step 450, the distance between the center point of the temporary center A and the current center point is calculated using the following equation.

Distance - ((Xa - Proceeds to step 470, where the accuracy of the center value is improved.In other words, in step 470, the current center value is discarded, the center value of temporary center B is used as the center value for calculating the direction, and the weight of temporary center B is set as the center value for direction calculation. Use the weight of the center value for calculation.Then, delete the contents of the temporary center A.Step 4
80), further erase the contents of memory AA in step 49.
0), return to step 300. This step 460-4
The process 90 is performed as a normal process, and is performed for the purpose of improving the accuracy of the center value for calculating the direction.

Further, in step 460, if the distance is greater than the distance factor, nothing is done and the process returns to step 300. In this case, the center value for azimuth calculation is not moved and remains as it was. That is, if the distance is larger in this step 460, the center value has moved, but for a while the weight of the temporary center A is smaller than the weight of the current center point, and after a while from this state, The weight of the tentative center A increases, and steps 390 to 4
This is the case when proceeding to 00. More specifically, step 39
Processing from 0 to 460 is performed when there is a possibility that the center has moved significantly, and is repeated until it is determined whether the center has moved or not. Therefore, the greater the possibility of magnetization, the more
In many cases, the process returns to step 300.

In addition, if the predicted center value becomes inaccurate even though the center value has not moved, the coordinates of the temporary center A will fluctuate and the distance between the centers will increase, but if the predicted center value becomes stable,
The center-to-center distance also becomes smaller, and the process proceeds from step 460 to step 470. In other words, since it is not possible to distinguish between center value movement and fluctuation of the predicted center value, step 46
0 to determine which phenomenon is occurring.

In step 390, if the weight of the temporary center A is larger than the weight of the current center point, this is a case where the center value of the azimuth circle has moved, and this is not limited to the case where the vehicle body is magnetized; for example, Opening/closing of the sunroof, opening/closing of the sun visor, roof carrier, and when a magnetic material is mounted on the carrier are affected by various factors such as the local area and surrounding environment.

[Effects of the Invention] As explained above, according to the present invention, the first temporary center and the second temporary center are set in addition to the current center point, and the weights of the first and second temporary center values and Calculate the distance, set a distance coefficient based on the possibility of movement of the output circle center value of the geomagnetic direction sensor using geomagnetic data, etc., and set the most accurate center value at that time based on the weight, distance, and distance coefficient. As the vehicle is running, it is possible to always obtain the optimal center value at that point without any special correction operations, and the center can be moved to the side with better center value accuracy. , the more the vehicle travels, the more the center value accuracy improves. Furthermore, even if the center value moves due to magnetization of the vehicle body or turning on of a vehicle electrical equipment switch, the center value can be automatically corrected while the vehicle is running by continuing to drive. In addition, by reflecting the possibility of magnetization of the vehicle body, the detection of on-state vehicle electrical equipment switches, etc. in the distance coefficient, it is possible to quickly obtain the correct center value even when the center value moves significantly. Furthermore, since the accuracy of the current center value is known from the confidence interval, the accuracy of the orientation calculated from the output of the geomagnetic orientation sensor is always known.

[Brief explanation of drawings]

FIG. 1 is a diagram corresponding to the claims of the present invention, and FIG. 2 is a block diagram showing the configuration of a vehicle compass according to an embodiment of the present invention.
Figure 3 is an explanatory diagram of the configuration of the geomagnetic orientation sensor, Figure 4 is an explanatory diagram of the excitation characteristics of the geomagnetic orientation sensor, Figure 5 is a diagram showing magnetic flux changes in the permalloy core of the geomagnetic orientation sensor in the absence of a magnetic field, and Figure 6 is Fig. 7 is an explanatory diagram of the detection action of the geomagnetic direction sensor; Fig. 8 is an explanatory diagram of the vehicle running direction; Fig. 9 is an explanatory diagram of the output circle;
The figure is an explanatory diagram showing a state in which a magnetic field other than geomagnetism is applied to the geomagnetic direction sensor, Figure 11 is an explanatory diagram showing the movement of the output circle due to vehicle body magnetization, and Figure 12 is an explanatory diagram of the vehicle compass shown in Figure 2. FIG. 13 is a flowchart showing the operation of the output circle center value shift possibility detection circuit used in the vehicle compass shown in FIG. 2. 21... Geomagnetic direction sensor 23... Output processing circuit 25... Gyro sensor 27... Gyro signal processing circuit 28... Vehicle electrical equipment switch 29... Output circle center value prediction unit 30... Output circle center value movement possibility detection unit 31...new center value calculation unit 33...direction detection unit

Claims (1)

[Claims] A geomagnetic sensor that detects the geomagnetic direction as geomagnetic data of two direction components orthogonal to each other, a vehicle direction change amount detection means that detects the relative angular displacement of the vehicle, and stores the detected geomagnetic data and the relative angular change amount. a data storage means, and a center value movement possibility determination for determining the possibility of movement of the center value of the output circle of the geomagnetic azimuth sensor based on the geomagnetic data stored in the data storage means and a signal from a vehicle electrical component switch. means, distance coefficient setting means for setting a distance coefficient when determining a center value based on the possibility of movement of the center value of the output circle by the center value movement possibility determining means; output circle center value prediction means for predicting the output circle center value of the geomagnetic sensor from the geomagnetic data and the amount of relative angle change; predicted center value storage means for storing the predicted center value; a first provisional center calculation means for calculating a first provisional center value using a group of center values after the stored center value begins to appear at a position away from the current center value being calculated; and a first provisional center calculation means for calculating the current center value. second provisional center calculation means for calculating a second temporary center value using the stored center value group and the latest storage center value; and weight calculation means for calculating weights of the first and second temporary center values. a distance calculation means for calculating the distance between the current center value and the tentative center value; and a center for determining the center value used to calculate the vehicle heading using geomagnetic data from the weight, distance and distance coefficient. A vehicle compass comprising: a value determining means.