JPH0553209B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a hybrid navigation system including a radio navigation system and a geomagnetic sensor, and more particularly to a hybrid navigation system equipped with a vehicle body magnetization correction function for the geomagnetic sensor.

[Technical background of the invention and its problems]

Generally, when a vehicle is running, magnetization occurs in the vehicle body. Therefore, in the case of a vehicle equipped with a navigation device using a geomagnetic sensor, there is a problem in that the magnetization of the vehicle body affects the geomagnetic sensor, making accurate positioning impossible. Therefore, a vehicle body magnetization correction technique has been disclosed in Japanese Patent Application Laid-Open No. 58-48811 regarding vehicle body magnetization correction for a geomagnetic sensor. This conventional vehicle body magnetization correction technique makes the vehicle make a circular turn, detects the center coordinates of the geomagnetic sensor output, and eliminates the influence of the vehicle body magnetization.

However, in the case of such conventional car body magnetization correction technology, correction cannot be performed unless the car body orientation data is sampled for one turn, and in order to sample data for one turn during normal driving, it is necessary to start sampling. It was expected that a considerable amount of time and distance would be required from the time the sampling was completed to the completion of the sampling, and there was a problem that the state of magnetization of the vehicle body would change during sampling, making it impossible to perform correct correction. In addition, correction using circular turning data is
In order to reduce correction value errors due to disturbances, data outside the normally expected data range is deleted, so there is a problem that correction may not be possible if a large change occurs in the car body magnetization. Ta.

[Purpose of the invention]

The present invention has been made in view of such conventional problems, and uses a radio navigation calculation unit to determine the heading direction of the vehicle, and uses this heading heading to correct the vehicle body magnetization of the geomagnetic sensor. Another object of the present invention is to provide a hybrid navigation device that can accurately indicate the direction of travel.

[Structure of the invention]

As shown in FIG. 1, this invention includes a radio navigation calculation unit that receives navigation radio waves and calculates the position of the vehicle, a geomagnetic sensor unit that detects magnetic fields, and a distance sensor unit that detects the distance traveled by the vehicle. and a relative position calculation section that calculates the relative position of the vehicle, the vehicle's traveling direction determined from the vehicle position calculated by the radio navigation calculation section and the direction determined by the geomagnetic sensor section. The present invention is characterized by comprising a magnetization correction calculation section that calculates the amount of vehicle body magnetization from the magnetic field and the magnitude of the horizontal component of the magnetic field determined in advance, and sends this amount of vehicle body magnetization to the relative position calculation section. The gist is hybrid navigation equipment.

[Embodiments of the invention]

Hereinafter, embodiments of the present invention will be explained in detail based on the drawings. FIG. 2 shows an embodiment of this invention.
a geomagnetic sensor 1 that converts the horizontal component of geomagnetism into two voltages, X and Y, depending on the vehicle direction; a distance sensor 2 that generates a signal every time the vehicle moves a certain distance;
The vehicle is equipped with a relative position calculation circuit 3 that determines the traveling direction from the X and Y data from the geomagnetic sensor 1 and calculates the relative position of the vehicle based on this traveling direction and distance data from the distance sensor 2. It also receives radio waves from GPS satellites and calculates the vehicle's absolute position.
The amount of magnetization of the vehicle body is calculated based on the GPS position calculation circuit 4, the traveling direction data from the GPS position calculation circuit 4, the magnetic data from the geomagnetic sensor 1, and the preset magnitude of the horizontal component of the geomagnetic field. , a magnetization correction calculation circuit 5 which supplies the relative position calculation circuit 3.

The operation of the hybrid navigation system having the above configuration will be explained next. The geomagnetic sensor 1 consists of a magnetic field vector detector having a ring core,
The geomagnetic field is divided into voltages in the X and Y directions and output depending on the direction of the vehicle. Therefore, when the vehicle makes one turn, the X and Y voltages draw a circle as shown in FIG. This circle center point Q=(X ₀ , Y ₀ ) is shifted from the reference point O when the vehicle body is magnetized. Then, the traveling direction of the vehicle is determined by the vector when the output of the geomagnetic sensor 1 is P ₁ = (X ₁ , Y ₁ ).
Each θ ₁ formed by QP ₁ and the Y axis becomes.

The relative position calculation circuit 3 calculates a vector QP ₁ representing this heading, and multiplies it by the distance signal from the distance sensor 2 to determine the relative position. -Step 11
−13.

However, if the amount of magnetization of the vehicle body changes and the center point shifts to Q', the output from the same geomagnetic sensor 1
Even if P ₁ = (X ₁ , Y ₁ ), the traveling direction of the vehicle will be θ ₁ '. Therefore, it is necessary to always detect the correct center point coordinates and to correct any deviations in the center point coordinates.

On the other hand, the GPS position calculation circuit 4 receives radio waves from GPS satellites and performs absolute position measurement. However, in positioning using the GPS position calculation circuit 4, if there is an obstruction between the vehicle and the satellite, satellite radio waves cannot be received and positioning becomes impossible. for that,
When positioning by GPS navigation is impossible, positioning must be interpolated by a geomagnetic sensor, and the geomagnetic sensor 1 is used together with the GPS position calculation circuit 4.

In the GPS position calculation circuit 4, the positioning accuracy is high and the positioning calculation interval can be shortened, so that the vehicle's traveling direction θ _A
Calculate – Steps 14 and 15.

The magnetization correction calculation circuit 5 takes in the magnetic field data output P _A = (X _A , Y _A ) from the geomagnetic sensor 1 (steps 12, 18), and at the same time receives the heading data θ _A from the GPS position calculation circuit 4. Import (step
16, 19), calculate the heading straight line _lA as shown in Figure 5. Furthermore, this magnetization correction calculation circuit 5 includes:
The magnitude of the magnetic field due to geomagnetism is fixed in advance (approximately
300mG), so the magnitude of the magnetic field is given, and the magnetic field P _A on the positioning line l _A = (X _A , Y _A )
Find a point Q = (X ₀ , Y ₀ ) that is 300 mG away from the point, and set this point as the center point coordinates - Step 20.
twenty one.

Information on the center point coordinates Q=(X ₀ , Y ₀ ) obtained in the magnetization correction calculation circuit 5 in this manner is given to the relative position calculation circuit 3.

The relative position calculation circuit 3 uses the center point coordinates 9 to calculate the magnetic field voltage Q given from the geomagnetic sensor 1.
= (X, Y), a vector QP→ is obtained, and this traveling direction vector QP→ is multiplied by the distance signal from the distance sensor 2 to obtain the relative position.

Note that this correction calculation based on the vehicle body magnetization can be performed periodically while the vehicle is running.

In this case, if the heading of the vehicle changes while traveling from point A to point A', the output of the geomagnetic sensor 1 will also change, and if it seems that accurate correction cannot be made, the vehicle's steering angle sensor etc. It is also possible to use this method to determine whether or not the vehicle is traveling in a straight line, and if the vehicle is not traveling in a straight line, no correction is performed.

In addition, in the case of the above embodiment, as the radio navigation calculation section
Although the GPS position calculation circuit 4 is used, the present invention is not limited to this, and other radio navigation calculation devices such as LORAN and Omega may of course be used. Furthermore, the radius of the output circle of geomagnetic sensor 1 is
The value is 300mG, but this varies slightly in each region of the earth, and the horizontal component of the geomagnetic field differs greatly between the north pole and the equator, so choose a value that suits the region where the vehicle will be used. There is a need to.

〔Effect of the invention〕

This invention calculates the coordinates of the center point of the magnetic field output from the traveling direction of the vehicle determined by the radio navigation calculation unit, the output voltage of the geomagnetic sensor at that time, and the magnitude of the horizontal component of the magnetic field due to geomagnetism, and performs vehicle body magnetization correction. It is something. Therefore, there is no need to actually make one turn of the vehicle or wait until the vehicle has made one turn in order to find the coordinates of the center point of the output voltage of the geomagnetic sensor as in the past, and the vehicle body magnetization can be corrected in a short time using less data. It has the advantage that it can be done. Furthermore, even if there is a sudden change in the amount of vehicle body magnetization over time, the amount of correction of vehicle body magnetization can be easily changed.

[Brief explanation of the drawing]

Fig. 1 is a diagram corresponding to the claims of the present invention, Fig. 2 is a circuit block diagram of an embodiment of the invention, Fig. 3 is a diagram showing the influence of vehicle body magnetization on the geomagnetic sensor.
FIG. 4 is a diagram explaining the operation of determining the traveling direction by the GPS position calculation circuit, FIG. 5 is a diagram explaining the operation of determining the center point coordinates by the magnetization correction calculation circuit of the above embodiment, and FIG. This is a flowchart explaining the operation. 1...Geomagnetic sensor, 2...Distance sensor, 3...Relative position calculation circuit, 4...GPS position calculation circuit, 5...Magnetization correction calculation circuit.

Claims (1)

[Claims] 1. A radio navigation calculation unit that receives navigation radio waves and calculates the vehicle position, a geomagnetic sensor unit that detects magnetic fields, a distance sensor unit that detects the distance traveled by the vehicle, and calculates the relative position of the vehicle. The hybrid navigation device has a relative position calculation section that calculates the vehicle's traveling direction determined from the vehicle position calculated by the radio navigation calculation section, a magnetic field determined by the geomagnetic sensor section, and a predetermined magnetic field. 1. A hybrid navigation device comprising: a magnetization correction calculation unit that calculates a vehicle body magnetization amount from the magnitude of a horizontal component and sends the vehicle body magnetization amount to a relative position calculation unit.