JPH0548090Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Field of Application The present invention relates to the improvement of a compass for automobiles, and particularly relates to a technique for preventing the compass from being disturbed when passing through a predetermined disturbance magnetic field area such as a railroad crossing of a train.

Background of the Invention In recent years, devices have been developed that are installed in automobiles and detect direction by detecting geomagnetism, such as magnetic compasses that directly display the direction of magnetic north, and navigator devices that display the driving position of self-propelled vehicles by processing direction signals. It is used for various purposes.

One such technique is disclosed in Japanese Patent Laid-Open Publication No. 55212/1980.

This conventional technology relates to a magnetic compass in which a device is mounted on a running vehicle to detect the earth's magnetism and display the direction of the vehicle using a lamp or the like.

Problems to be Solved by the Present Invention The above-mentioned conventional compass is based on geomagnetic detection, so it is inexpensive and relatively accurate, but it has the fatal drawback of being susceptible to disturbance magnetic fields. Ta.

That is, there are various structures that generate magnetic fields, such as electric train tracks and DC substations, along the roads on which automobiles travel, which have an effect on the geomagnetism detection device. Therefore, when a car is running in such a disturbance magnetic field, it cannot function as a compass.

Means for Solving the Problems The present invention focuses on the fact that the geomagnetism detection device of a car is affected by disturbance magnetic fields caused by the above-mentioned buildings along the road, etc., only within a certain predetermined area. The accuracy decreases when the vehicle is traveling, making it unsuitable as a direction sensor for long-distance travel, but it is configured as follows to detect direction using a steering angle sensor that is unaffected by disturbance magnetic fields.

That is, a geomagnetic azimuth detection means that detects the azimuth by measuring geomagnetism, a steering angle azimuth detection means that detects the azimuth based on the product of the steering angle of the steering wheel and the travel distance, and a road network to which identification flags indicating disturbance magnetic field areas are added in advance. It has a map storage means for storing data, and a control unit that performs calculation processing of a route based on azimuth data, travel distance data, and road network data, and also has a control unit that performs route calculation processing based on azimuth data, travel distance data, and road network data, and passes through a predetermined disturbance magnetic field area based on an identification flag indicating the disturbance magnetic field area. An object of the present invention is to solve the problems of conventional techniques by means of an automobile azimuth meter comprising: a display means having a switching section for switching the input side of azimuth data to the steering angle azimuth detection means side when determining the azimuth direction; That is.

Function The automobile compass of the present invention having the above configuration functions as follows.

In other words, the display means calculates a route based on the azimuth data, travel distance data, and road network data, and also determines passing through a disturbance magnetic field area based on the identification flag added to the road network data, and while passing through the disturbance magnetic field area, the steering angle azimuth is The detection means obtains azimuth data, and after passing, the geomagnetic azimuth detection means obtains azimuth data again, thereby avoiding the influence of the disturbance magnetic field in advance.

Embodiments A preferred embodiment of the present invention will be described with reference to the accompanying drawings.

In FIG. 1, 1 is a geomagnetic sensor, 2 is a geomagnetic azimuth calculating section, and both constitute geomagnetic azimuth detecting means.

Further, 3 is a steering angle sensor, 4 is a distance sensor, and 5 is a steering angle azimuth calculating section, and a combination of these constitutes a steering angle azimuth detecting means.

Incidentally, the steering angle sensor 3 is a sensor that converts a steering angle from a steering wheel of an automobile into an electrical signal, and is used for various purposes. For example, sensors in so-called safety drive guides, which use a microcomputer to judge the steering wheel operation pattern when a driver is fatigued and issue an alarm, and devices that control the suspension based on the steering wheel operation speed and the vehicle's running speed. It is used as.

In the preferred embodiment of the present invention, the above-mentioned steering angle sensor 3 is also used.

Further, the distance sensor 4 is a sensor that outputs a pulse signal according to the rotation speed of the tire, for example,
The steering angle and azimuth calculation section 5 detects the azimuth based on the product of the steering angle data from the steering angle sensor 3 and the traveling distance data from the distance sensor 4.

Further, 6 is a map storage section, 7 is a control section, 8 is a display section, 9 is a switching section, and 10 is an error correction section, which constitute display means.

Here, the map memory unit 6 stores road network data as a digital signal of a predetermined number of bits,
The map storage unit 6 outputs the road network data in response to an access signal from the control unit 7.
A suitable means for this is, for example, a compact disc (DC) player.

Further, the control unit 7 displays the traveling direction of the self-propelled vehicle, a road map, etc. on the display unit 8 based on the road network data from the map storage unit 6 and the azimuth data from the geomagnetic azimuth calculation unit 2 or the steering angle azimuth calculation unit 5. It is to be displayed. Further, an identification flag indicating a disturbance magnetic field area is added in advance to the road network data, and the control unit 7 detects this identification flag and controls the switching unit 9 to switch the connection relationship of the switching unit 9.

Furthermore, the control section 7 outputs the difference between the azimuth data from the geomagnetic azimuth calculation section 2 and the azimuth data from the steering angle azimuth calculation section 5 before and after the switching control of the switching section 9 to the error correction section 10. .

The switching section 9 switches the connection relationship between the geomagnetism side terminal 9a and the steering angle side terminal 9b in response to a control signal from the control section 7, and is composed of an analog switch or the like.

Further, the error correction section 10 corrects the geomagnetic direction data based on the error data from the control section 7.

Next, the operation will be explained in detail with reference to FIGS. 2 and 3.

Assume now that a car is traveling through points P1 to P8 on the road network shown in FIG. In Figure 3, A is a road, B is a train line, and C is a road.
The range is the disturbance magnetic field area caused by the train line B, the P3 point and the P6 point are the switching points of the switching section 9, and the P2, P4, P5, and P7 points are the points before and after the switching. Further, θ1 [degrees] and θ2 [degrees] indicate magnetic azimuth angles, and α1 [degrees] and α2 [degrees] indicate steering angle azimuth angles.

The operation of the control section 7 will be explained below with reference to the flowchart shown in FIG.

First, in step 101, the switching unit 9 is switched to the geomagnetic side terminal 9a, the geomagnetic direction data is read, and the process proceeds to step 102. In step 102, the switching section 9
When the switching point is judged and the identification flag indicating the disturbance magnetic field area added to the road network data is detected, that is, when the judgment is YES, the process advances to step 103 and NO is selected.
If so, proceed to step 112.

In step 103, the steering angle side terminal 9b of the switching section 9
The magnetic azimuth angle θ1 [degrees] immediately before switching to is memorized at point P2, and the process proceeds to step 104. In step 104, P3
At this point, the switching unit 9 is switched to the steering angle side terminal 9b and the process proceeds to step 105.

In step 105, the steering angle side terminal 9b of the switching unit 9 is
The steering angle azimuth α1 [degrees] immediately after the change to is stored at point P4, and the process proceeds to step 106.

In step 106, the steering angle azimuth data is read from the steering angle azimuth calculating section 5, and the process proceeds to step 107. In step 107, the switching point of the switching unit 9 is determined, and if it is determined to avoid the disturbance magnetic field area based on the road network data, that is, if the determination is YES, step 108 is performed.
If NO, return to step 106.

In step 108, the geomagnetic side terminal 9 of the switching unit 9
The steering angle azimuth angle α2 [degrees] immediately before switching to a is memorized at point P5, and the process proceeds to step 109.

In step 109, the switching section 9 is switched to the geomagnetism side terminal 9a at point P6, and the process proceeds to step 110.

In step 110, the geomagnetic side terminal 9 of the switching unit 9
The geomagnetic azimuth angle θ2 [degrees] immediately after switching to a is memorized at point P7, and the process proceeds to step 111.

In step 111, each azimuth angle θ1, α1, α2, θ2 [degrees] stored in steps 103 to 110 is
The error Δθ [degrees] before and after switching of the switching unit 9 is determined by the value of
is calculated based on the formula Δθ=(θ2−θ1)−(α2−α1), and the process proceeds to step 112.

In step 112, the geomagnetic azimuth data is corrected based on the error value Δθ [degrees] obtained in step 111 or the omnidirectional data of the geomagnetic azimuth data.
Return to 101.

As described above, the operation of the preferred embodiment of the present invention described in detail with the flowchart shown in steps 101 to 112 maintains the normal function of the compass while passing through a predetermined disturbance magnetic field area.

The geomagnetic azimuth calculation section 2, steering angle azimuth calculation section 5, control section 7, switching section 9, and error correction section 10 in the preferred embodiment of the present invention can be configured as a microcomputer program. In addition, the display section 8
The map may be displayed on a CRT display, an EL display, etc., or a compass display showing the magnetic north direction using segments may be displayed on a fluorescent display tube, liquid crystal display, etc.

Effects of the present invention As explained in detail above, the present invention uses the steering angle azimuth detection means when detecting passage through a predetermined disturbance magnetic field area using the identification flag indicating the disturbance magnetic field area added in advance to road network data. Its structural feature lies in the fact that it obtains azimuth data.

Therefore, the influence of the disturbance magnetic field on the geomagnetic direction detecting means can be avoided in advance, and there is an excellent effect that the normal function of the inexpensive and highly accurate direction meter can be maintained.

[Brief explanation of the drawing]

FIG. 1 is an electrical block diagram showing a preferred embodiment of the present invention. FIG. 2 is a flowchart illustrating the operation of the preferred embodiment of the present invention. Third
The figure is an explanatory diagram showing a road network for explaining the operation of the preferred embodiment of the present invention. 1... Geomagnetic sensor, 2... Geomagnetic direction calculation unit, 3... Rudder angle sensor, 4... Distance sensor, 5...
. . . Rudder angle azimuth calculation section, 6 . . . Map storage section, 7 . . . Control section, 8 . . . Display section, 9 .

Claims (1)

[Scope of Claim for Utility Model Registration] Geomagnetic direction detection means for detecting direction by measuring geomagnetism, steering angle direction detection means for detecting direction by the product of the steering angle of the steering wheel and travel distance, and an identification flag indicating a disturbance magnetic field area. a map storage means for storing road network data added in advance; a control unit for calculating a route based on the direction data, travel distance data, and road network data; a display means having a switching section that switches the input side of the azimuth data to the steering angle azimuth detection means side when determining passage through a disturbance magnetic field area;