JPS59228110A - Vehicle mounted geomagnetism sensor - Google Patents

Abstract

PURPOSE:To perform accurate correction, by providing the second geomagnetism sensor, which corrects the output of a geomagnetism sensor, which is provided at an ordinary position, at a place where the effect of magnetization from a railroad crossing is strong. CONSTITUTION:A geomagnetism sensor 3 is provided at a part D of the body of a vehicle, e.g., a roof, where the effect of the magnetization from a railroad crossing is small. With this sensor as the first geomagnetism sensor, geomagnetism is measured. A second geomagnetism sensor 4 is provided at a part of the body, where the effect of the magnetization from the railroad crossing is strong, e.g., a floor 1a of the body and the like. Based on the detected outputs of the geomagnetism sensors 3 and 4, the amount of the magnetization of the body is obtained based on the difference, and the detected output of the first geomagnetism sensor 3 is corrected.

Description

[Detailed description of the invention] The present invention relates to a vehicle-mounted geomagnetic sensor.

An on-vehicle geomagnetic sensor is installed in a vehicle and is used, for example, as a direction sensor for measuring the traveling direction of a vehicle by detecting geomagnetism. For example, a Toroidalco ← type fluxgate type sensor is used as a magnetic q sensor.

By the way, conventional vehicles such as automobiles have a characteristic that when they cross a railroad crossing, the vehicle floor etc. are magnetized by the magnetic field generated by power transmission lines, and this is generally referred to as railroad crossing magnetization. Therefore, when arranging a geomagnetic sensor on a vehicle body, consideration must be given to ensuring that the geomagnetic sensor is sensitive only to geomagnetism and is not affected by vehicle body magnetization such as the above-mentioned railroad crossing magnetization.

As an example of a conventional method for eliminating the influence of the above-mentioned car body magnetization, for example, the car body magnetization is regarded as one magnet, and the difference in the output of two geomagnetic sensors (both of which are placed close to each other on the body of the vehicle) is proposed a method for estimating and correcting the amount of magnetization.In other words, as shown in FIG.
1, the magnitudes of the vectors M, , M, related to the magnetic field at the respective positions of the geomagnetic sensors 22 and 23 arranged by a predetermined support structure are different. Therefore, the vehicle body magnetization, that is, the amount of magnetism of the magnet 21, is estimated based on the difference between the geomagnetic sensors M, , M, and the output of a predetermined geomagnetic sensor is corrected to obtain the original detection signal output generated only by the geomagnetism. That is.

According to such conventional methods, installation of the geomagnetic sensors 22 and 23 inevitably requires a large space, and on the other hand, it is not possible to sufficiently detect differences in the output of each sensor, and conversely, differences in the output of each sensor cannot be sufficiently detected. There was a drawback that errors occurred.

In view of the above-mentioned problems, the present inventors have created the present invention in order to effectively solve the problems.

The purpose of the present invention is to effectively correct the detection output of an on-vehicle geomagnetic sensor used for a vehicle compass, etc., to eliminate the influence of vehicle body magnetization, and to detect only the original geomagnetism. , its feature is that it is a second type of geomagnetic sensor different from ordinary geomagnetic sensors.
geomagnetic sensors are installed in locations that are strongly affected by vehicle body magnetization,
The vehicle body magnetization amount is estimated based on the difference between the outputs of the two geomagnetic sensors, and the detected output of the normal geomagnetic sensor is corrected.

An embodiment of the present invention will be described below based on the accompanying drawings.

FIG. 1 is a diagram showing a mounting location of an on-vehicle geomagnetic sensor according to the present invention in a vehicle.

As shown in FIG. 1, in a vehicle 1 to which level crossing magnetization is applied, the vehicle body floor 1a is mainly magnetized, and it can be considered that the magnet 2 exists on the vehicle body floor 1a. This magnet 2 generates a magnetic field A in the car body 1, and as is clear from the distribution of this magnetic field, the magnetic field is strongest at the car body floor 1a (the magnetic field is weaker in other parts of the car body).

Conventionally, the above-mentioned in-vehicle geomagnetic sensor is generally installed in parts of the car body where the influence of railroad crossing magnetization is small, such as the bonnet center (NB), near the driving instrument nozzle (C),
It was placed on the roof.

In this embodiment, as an example, a geomagnetic sensor 3 is disposed on the roof, and is used as a first geomagnetic sensor to detect geomagnetism and to be used as a known compass sensor.

In the present invention, a second geomagnetic sensor 4 is further provided, and this geomagnetic sensor 4 is disposed in a portion of the vehicle body that is largely affected by magnetization at a railroad crossing, such as the vehicle floor 1a. Then, based on the detection outputs of the geomagnetic sensors 3 and 4, it is possible to estimate the car body magnetization due to the level crossing magnetization as the difference between them. The detection output of the first geomagnetic sensor 3 is corrected so that only the original geomagnetism can be detected, which is then used for subsequent signal processing and measurement.

(Two geomagnetic sensors 3 and 4 are prepared, and one is placed in a place where the influence of railroad crossing magnetization is small, and the other one is placed in a place where the influence is large, so they are placed in separate places. This eliminates the need for a support structure between the sensors as in the past, and has the advantage that the installation space for each sensor is small.Also, since the difference in output between the geomagnetic sensors 3 and 4 can be made large, The degree of influence from external disturbances is small;
The above correction can be effectively performed.

As is clear from the above explanation, according to the present invention, the second geomagnetic sensor for correcting the output of the geomagnetic sensor disposed at the normal position is disposed at a location where the influence of railroad crossing magnetization is strong. , the output difference between the two geomagnetic sensors can be large, and accurate correction can be performed. Furthermore, since the two geomagnetic sensors can be installed separately, there is no need for a support structure between the sensors, resulting in less installation space.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a state in which a vehicle-mounted geomagnetic sensor according to the present invention is being inspected, and FIG. 2 is a diagram for explaining problems with the vehicle-mounted geomagnetic sensor. In the drawing, 1 and 20 are vehicles, 2 and 21 are virtual magnets magnetized by railroad crossings, and 3, 4, 22, and 23 are geomagnetic sensors.

Claims (1)

[Claims] In a vehicle such as a car that is equipped with an electronic device such as a compass that uses a geomagnetic sensor, the geomagnetic sensor described above is installed in a location where the influence of vehicle body magnetization is weak, and another geomagnetic sensor is installed in a location where the influence of vehicle body magnetization is strong. The amount of magnetization of the vehicle body is determined by the respective outputs of the geomagnetic sensor and the other geomagnetic sensor which are separately installed, and the output of the geomagnetic sensor is corrected based on the amount of magnetism of the vehicle body to eliminate the influence of the magnetism of the vehicle body. This is an in-vehicle geomagnetic sensor.