JPH0643896B2 - Vehicle heading measurement method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [1] Field of Industrial Application The present invention relates to a vehicle traveling direction measuring method using a geomagnetic direction sensor. According to the present invention, it is possible to calculate the bearing measurement error of the sensor due to the magnetization of the vehicle itself and to correct the detected data to know the correct bearing, so that the vehicle that is rushed for the purpose of freight transportation, emergency or maintenance, etc. The general passenger car can be operated efficiently.

[2] Prior art An in-vehicle geomagnetic direction sensor is provided in a vehicle and is used as a sensor such as an azimuth meter that measures the traveling direction of a vehicle or the like by detecting the geomagnetism. The flat gate type is known.

By the way, a conventional vehicle such as an automobile has a characteristic that a vehicle body floor is magnetized by a magnetic field generated by a power transmission line when it crosses a railroad crossing, which is generally called railroad crossing magnetization.

Therefore, when arranging the geomagnetic sensor on the vehicle body, it must be taken into consideration that the geomagnetic sensor is sensitive only to the geomagnetic field and is not affected by the vehicle body magnetization such as the above-mentioned crossing magnetization.

As a conventional method of eliminating the influence of the magnetization of the vehicle body, for example, as disclosed in JP-A-59-228110 and JP-A-60-4806, a magnetized chassis is used as one magnet. Considered, at least 2 placed close to each other on top of the body
A method has been proposed in which the amount of magnetization is estimated and corrected based on the output difference of each geomagnetic sensor. That is, as shown in FIG. 2, if the vehicle body magnetization is considered as a virtual magnet (22) generated in the chassis (21a) of the vehicle (21), a geomagnetic sensor (23) arranged by a predetermined support structure. , (24), the magnitudes of the magnetic fields MG ₁ and MG ₂ are different. Therefore, the vehicle body is magnetized based on the difference between the geomagnetic sensors (23) and (24), that is, the amount of magnetism of the magnet (22) is estimated, and the output of a predetermined geomagnetic sensor is corrected to determine only the geomagnetism. It is intended to obtain the original detection signal output that occurs.

[3] Problems of the prior art According to the conventional method, calculation must be performed assuming the magnitude of the geomagnetism, and fluctuations in the magnitude of the geomagnetism depending on the measurement point cause the azimuth measurement error. There was a serious drawback. In view of the above problems, the inventor of the present invention has made the present invention to effectively solve the problems.

(4) Means for Solving Problems The object of the present invention is to effectively correct the detection output of a vehicle-mounted geomagnetic sensor used for a vehicle compass and the like to provide a vehicle body (11), (11
The purpose is to eliminate the influence of magnetization on a) and to detect only the output due to the original geomagnetism, which is characterized by a geomagnetic sensor (13) different from the normal geomagnetic sensor (14). The effect of magnetization is arranged at a location in the stronger magnetic field MG ₁ of MG ₁ and MG ₂ , and first at time t, the direction of magnetization of the vehicle body is calculated based on the difference between the outputs of both geomagnetic sensors, Next, the magnitude of vehicle body magnetization is calculated from the output of both geomagnetic sensors at a certain time (Δt) and the output of both geomagnetic sensors at time t, and from the above results, the detection output of the normal geomagnetic sensor is calculated. It was corrected and the original direction was detected.

Details will be described below with reference to FIG.

The first sensor (13) is mounted directly below the roof at l ₁ and is in a strong magnetic field MG ₁ due to the magnetization of the chassis (11a).
The second sensor (14) is in the magnetic field MG ₂ due to magnetization weaker than MG ₁ , where l ₂ is greater than l _{1 at} the position l ₂ from the roof.

FIG. 3 illustrates the flux gate type geomagnetic direction sensor, and FIG. 4 illustrates the state of the direction error due to magnetization of the vehicle body. In FIG. 3, the toroidal core (31) has an exciting circuit (32),
Outputs from the mutually orthogonal output windings (33) and (34)
Vx and Vy are taken out. Next, the circle (42) shown by the solid line in FIG. 4 shows the detection output when the vehicle rotates 360 degrees in a state where a magnetic field other than the earth's magnetism is superimposed, and the dotted line (41)
The output (31) corresponding to the true azimuth is the center α,
Then, the azimuth error occurs by the deviation amount G. In other words, the azimuth angle is detected as θ ′ assuming that the vehicle is facing the point B, but the true azimuth angle is θ, and the actual azimuth is at the point A, and the angle is the azimuth error.

Letting Vx ₁ and Vy ₁ be the outputs extracted from the mutually orthogonal output windings of the first sensor and Vx ₂ and Vy ₂ be the outputs of the second sensor, their output vectors are represented by the following equations.

Here, θ is the vehicle rotation angle, α is the azimuth deviation angle due to vehicle magnetization, and G ₁ and G ₂ are the magnitudes of the magnetic fields MG ₁ and MG ₂ at the first and second sensors, respectively. ) And K are sensor output coil constants, and B is the horizontal component of the earth's magnetism.

Equations (5) and (6) are obtained from the above equation.

Vx ₁ −Vx ₂ ＝ (G ₁ −G ₂ ) cosα …… (5) Vy ₁ −Vy ₂ ＝ (G ₁ −G ₂ ) sinα …… (6) Therefore, The α in the equation (7) represents the direction of car body magnetization.

Now that the direction of magnetization is unknown, the magnitude of magnetization is next calculated.

The output of the first sensor at a certain time t is Vx ₁ (t),
Let Vy ₁ (t), the vehicle rotation angle be θx (t) time (t + △ t), and the output of the first sensor be Vx ₁ (t + △ t) and Vy ₁ (t + △ t). The formula is obtained.

Vx ₁ (t) = KB cos θ (t) + G ₁ cos α …… (8) Vy ₁ (t) = KB sin θ (t) + G ₁ sin α …… (9) Vx ₁ (t + △ t) = a KB cos (θ ( t) + △ θ) + G ₁ cosα (10) Vy ₁ (t + △ t) = aKBsin (θ (t) + △ θ) + G ₁ sinα (11) △ θ: Time t to time (t + △ t) The change amount a of the vehicle rotation angle during the period is a coefficient representing the intensity of the geomagnetism, and is obtained as follows.

Equations (10) and (11) are Vx ₁ (t + △ t) = aKB {cosθ (t) cos △ θ -sinθ (t) sin △ θ} + G ₁ cosα ...... (b) Vy ₁ (t + △ t) = a KB {sin θ (t) cos △ θ + con θ (t) sin △ θ} + G ₁ sin α …… (b) From equations (8) and (9), KBcosθ (t) = Vx ₁ (t ) -G ₁ cos α …… (c) KB sin θ (t) = Vy ₁ (t) -G ₁ sin α …… (d) (c) and (d) are assigned to (a) and rearranged, Substituting (c) and (d) into (b) and rearranging, Substituting Eq. (12) into Eq. (13) and rearranging, Ia ² + Ja + L = 0 …… (14) where J = Vx ₁ (t + △ t) (-sinαcos △ θ-cosαsin △ θ) + sin α (Vy ₁ (t) sin △ θ-Vx ₁ (t) cos △ θ) -Vy ₁ (t + △ t) (sin αsin △ θ-cos _α cos △ θ) -cos _α (-Vy ₁ (t) cos △ θ-Vx ₁ (t) sin △ θ) = -Vx ₁ (t + △ t) (sin αcos △ θ + cos αsin △ θ) + Vy ₁ (t) (sin αsin △ θ + cos αcos △ θ) + Vx ₁ (t ) (sinαsin △ θ + sinαcos △ θ) -Vy ₁ (t + △ t) (sinαsin △ θ-cosαcos △ θ) = -Vx ₁ (t + △ t) sin (α + △ θ) + Vy ₁ (t) cos (α- △ θ) -Vx ₁ (t) sin (α- △ θ) + Vx ₁ (t + △ t) cos (α + △ θ) …… (15) I ＝ Vy ₁ (t) sin △ θ- Vx ₁ (t) cos △ θ) (-sin αcos △ θ -cos αsin △ θ) + (Vy ₁ (t) cos △ θ + Vx ₁ (t) sin △ θ) ・ (sin αsin △ θ-cos αcos △ θ) = -Vy ₁ (t) cos α sin ² △ θ + Vx ₁ (t) sin αcos ² △ θ -Vy ₁ (t) cos αcos ² △ θ + Vx ₁ (t) sin αsin ² △ θ = Vx ₁ (t) sin α-Vy ₁ (t) cosα …… (16) L = Vx ₁ (t + △ t) sinα-Vy1 (t + △ t) cosα …… (17) From equation (14) Since G1 and α are obtained from the above, the vehicle direction θ at time t
(t) is Vehicle direction θ (t + △ t) at time (t + △ t) is The amount of displacement G ₂ can be obtained in exactly the same way.

(6) Examples Examples (1), (2) and (3) of the present invention are summarized in the following table.

[7] Effects of the Invention In the present invention, a plurality of geomagnetic direction sensors are arranged at a plurality of positions where the influence of vehicle body magnetization is different, and the deviation angle α (detection of the magnetization Direction), and the deviation amount (magnitude of magnetization) G is calculated from the sensor output at a certain time (t) and the time (Δt) after that, and α and G are used. Since the output of the geomagnetic sensor is corrected, accurate vehicle azimuth data without the influence of vehicle body magnetization can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration for carrying out the measuring method of the present invention. FIG. 2 is a diagram for explaining a conventional measuring method. FIG. 3 is a diagram showing the configuration of the flux gate type geomagnetic sensor. FIG. 4 is a diagram showing a state of a heading error due to magnetization of the vehicle body. 11: Vehicle 11a: Chassis 12: Magnet 13: First sensor 14: Second sensor 21: Vehicle 21a: Chassis 22: Magnet 23, 24: Geomagnetic sensor 31: Toroidal core 32: Magnetic resistance winding 33, 34: Output Coil 41: Output vector related to true direction 42: Output vector related to measurement direction

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-60-4806 (JP, A) JP-A-59-44614 (JP, A) JP-A-58-115376 (JP, A)

Claims (3)

[Claims] 1. A method of measuring a traveling direction of a vehicle by a geomagnetic direction sensor, wherein the geomagnetic direction sensor is arranged at each of a plurality of positions having different magnetic field strengths due to magnetization of the vehicle body. The outputs induced by the geomagnetism and the vehicle body magnetization are measured at the time (t) and the time (t + Δt) respectively to calculate the deviation angle α and the deviation amount G due to the vehicle body magnetization. Based on the above, a vehicle traveling azimuth measuring method is characterized in that the vehicle rotation angle θ (t) at time (t) is obtained by the following equation and used as the traveling azimuth of the vehicle. Here, Vx and Vy are the outputs of the geomagnetic sensor placed in the position where the magnetic field due to the magnetization of the vehicle body is strong. 2. A geomagnetic sensor arranged on a vehicle comprises a first sensor arranged at a position strongly influenced by body magnetization and a second sensor arranged at a position weakly influenced by body magnetization. Then, the outputs Vx ₁ and Vy _{1 of the first} sensor and the outputs Vx ₂ and Vy _{2 of} the second sensor are measured at time (t) and (t + Δt), and from the values, The vehicle advancing direction measuring method according to claim 1, wherein the deviation angle (α) and the deviation amount (G) due to vehicle body magnetization are calculated. Here, a is a coefficient that expresses the intensity of the geomagnetism, and Δθ is the amount of change in the vehicle rotation angle during time Δt. 3. The vehicle rotation angle (θ) is detected by measuring the wheel speed.
The vehicle traveling direction measuring method according to the above paragraphs and 2.