JPH0531086B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a moving object direction detection device used, for example, as a direction meter used in a car or a vehicle-mounted travel trajectory display device. .

[Prior Art] Conventionally, there has been a device of this type that utilizes a geomagnetic sensor that outputs geomagnetic components in the longitudinal and lateral directions of a vehicle body.

[Problem to be solved by the invention] This geomagnetic sensor can always know the absolute direction, but when passing a railroad crossing, bridge, etc., or when a magnetized truck or the like is driving nearby, the geomagnetic sensor can detect disturbance magnetic fields. It has the disadvantage that it is easily influenced and causes errors in the detected direction.

This invention was made to eliminate the above-mentioned drawbacks, and even if there is a disturbance other than the geomagnetic field while driving on a road with relatively little angular variation, such as a straight line or a gentle curve close to a straight line. It is an object of the present invention to obtain a mobile body orientation detection device that can provide a true orientation output.

[Means for Solving the Problems] A mobile object orientation detection device according to the present invention includes a geomagnetic orientation detection means, and a first calculation means for calculating a variation in the moving direction of the mobile object within a predetermined time from the detected value. and an angular velocity azimuth detection means, a second calculation means for calculating a variation in the moving direction of the moving body within a predetermined time from the detected value, and a calculation value of the first calculation means is larger than the first reference value. And if the calculated value of the second calculating means is smaller than the second reference value, the second value is added to the detected value of the geomagnetic direction detecting means at the time before each variation, which is the first and second calculated values, occurs.
and output means for outputting a value obtained by adding the calculated values of the calculating means.

[Operation] In the present invention, when the calculated value of the first calculating means is larger than the first reference value and the calculated value of the second calculating means is smaller than the second reference value, the output means outputs the first and second values. A value obtained by adding the calculated value of the second calculating means to the detected value of the geomagnetic direction detecting means at the time before each variation occurs, which is the second calculated value, is output, and this value is displayed as the heading direction. It is something.

[Embodiment] Fig. 1 is a block circuit diagram showing the basic configuration of the present invention, and 1 is _a means (hereinafter referred to as
(referred to as "geomagnetic direction detecting means"), 2 is a first calculating means which calculates a variation Δθ _M (ΔT) in the moving direction of the moving body from the direction of the earth's magnetism during a minute time ΔT. 3
is the first comparison means, and the variation Δθ _M (ΔT) is the reference value M
Outputs a signal only when the value is greater than 4 is a means for detecting the moving direction of the moving body from the angular velocity applied to the moving body (hereinafter referred to as angular velocity direction detection means); 5 is a second calculating means, which detects the moving direction of the moving body from the angular velocity during the minute time ΔT; Detect the variation in direction Δθ _A (ΔT). 6 is the second comparison means, where the variation Δθ _A
A signal is output only when (ΔT) is smaller than the reference value A. Therefore, when this output is present, it can be seen that the moving object is traveling in a straight line or a gentle curve close to a straight line. 7 is a discrimination means, the first,
A signal is output when signals are input from both the second comparison means 3 and 6. 8 is an addition calculation means which, when a signal is input from the discrimination means 7, calculates the traveling direction α of the moving body at time t ₁ before detecting both variations.
(see Figure 3) is added with the variation Δθ _A (ΔT), and when no signal is input from the discriminating means 7, the variation Δθ _M
Add (ΔT). In addition, below, the first and second
The comparing means, the discriminating means, and the addition calculation means will be collectively referred to as the output means. Reference numeral 9 denotes a display device that displays the heading direction input from the addition calculation means 8.

FIG. 2 is a block circuit diagram of an embodiment embodying the configuration of FIG. 1, in which 11 and 14 are A/D converters;
12 is an angular velocity sensor, 13 is an integrator, 15 is a microcomputer, and the microcomputer 15
2, 3, 6, 7 and 8 in FIG. 1 are configured by software, and FIGS. 7 and 8 are flowcharts for the microcomputer 15.

Next, the operation of this embodiment will be explained.

The moving direction θ _M (t) of the moving body detected from the direction of earth's magnetism by the detection means 1 is converted into digital data by the A/D converter 11 and input to the microcomputer 15 .

The angular velocity sensor 12 generates an output voltage proportional to the angular velocity, which is positive when the traveling direction of the moving body rotates clockwise, and negative when the traveling direction of the moving body rotates counterclockwise. The integrator 13 integrates the output of the angular velocity sensor 12 to generate an angular output θ _A (t). A/D converter 14 converts this output signal into a digital signal.

FIG. 3 shows a diagram in which the own vehicle V is traveling on a road having an inclination α with respect to the east-west direction, and the traveling direction at time t ₁ is α.

In the figure, own vehicle V is at time t ₁ and time (t ₁ +
ΔT), and when another magnetic vehicle _{K approaches at V(t 1 + ΔT} ), the detection means 1 detects the disturbance magnetic field K. Under _the influence _of That is, the fourth
As shown in the figure, the output θ _M (t ₁ +ΔT) of the detection means 1
is represented by the composite magnetic output H of the earth's magnetism E{θ _M (t ₁ )} and the disturbance magnetism K (θ _N ).

FIG. 5 is a diagram showing the output signal θ _A (t ₁ ) of the integrator 13 when the moving body V in FIG. 3 moves straight from the position V (t ₁ ) to the position V (t ₁ +ΔT), Figure 6 also shows the direction signal θ _M (t) output from the detection means 1.
FIG.

Next, the operation of the microcomputer 15 will be explained using the flowcharts shown in FIGS. 7 and 8.

The microcomputer 15 performs steps 20 and 21.
Then, read θ _M (t ₁ ) and θ _A (t ₁ ) at time (t ₁ ), and after ΔT seconds, that is, at time (t ₁ +
Read θ _M (t ₁ + ΔT) and θ _A (t ₁ + ΔT) at ΔT).

Next, in steps 22 and 23, the variations Δθ _M (ΔT) and Δθ _A (ΔT) for ΔT seconds are calculated, respectively.

That is, for example, as shown in FIG.
is traveling in a straight line on a road with an inclination α relative to the east-west direction, the axis t ₁ passes through V (t ₁ ), and at this time there is no influence from another magnetic vehicle K, and the time (t ₁ +
ΔT), it is assumed that another magnetic vehicle K is passing nearby. The vector diagram at this time is θ _M at time (t ₁ ) as shown in Figure 4.
(t ₁ ), X(t ₁ )=|E|cos θ, Y(t ₁ )=|E|
sin θ, θ _A (t ₁ ) = α _, and at time ( _{t 1} + ΔT), under the influence of the magnetic disturbance K, ₁ +ΔT)=|E|sinθ+|K|sinθ _N θ _A (t ₁ +ΔT)=α. However, θ _N indicates the direction of the disturbance magnetic field K.

Also, the variation after ΔT seconds is Δθ _M (ΔT) = tan ^-1 [|E|sinθ+|K|sinθ _N /|E|cosθ+|K|
cosθ _N ]−α Δθ _A (ΔT)=0.

By the way, when the car is traveling almost straight,
If the variation Δθ _M (ΔT) is large, this value does not output the true orientation. However, at this time, the angular velocity sensor 12 is completely unaffected even if another magnetically charged vehicle K passes nearby, and θ _A (t ₁ +
ΔT)−θ _A (t ₁ )≒0. In other words, the variation in traveling direction during time ΔT is the variation Δθ _A (ΔT)≒
0, so when the variation Δθ _M (ΔT) is large and the variation Δθ _A (ΔT) is small, the variation Δθ _A
It is better to use (ΔT) as the correct azimuth variation. That is, the first reference value M (for example, 5°) is set for the variation Δθ _M (ΔT) of the geomagnetic direction detection means 1, and the variation Δθ _A of the angular velocity sensor 12 is set.
A second reference value A (for example, 1°) is set for (ΔT), and the output traveling direction is switched in accordance with fluctuations in these reference values M and A.

That is, in step 24 it is determined that Δθ _A (ΔT)<A, and in step 25 it is determined that Δθ _M (ΔT)>M. If both are YES, in step 26,
In step 28, the result obtained by adding Δθ _A (ΔT) to the output θ _M (t ₁ ) before the output of the variation Δθ _M (ΔT) is output as a heading signal.

Otherwise, in step 27, the variation Δθ _M
(ΔT) is the geomagnetic direction detection means 1 before the occurrence of variation.
The signal added to the output θ _M (t ₁ ) is outputted as a heading signal and displayed on the display device 9.

As described above, in this embodiment, when the moving object is traveling on a road with no or relatively few angle changes, such as a straight line or a curve close to a straight line,
When the variation Δθ _A (ΔT) in the moving direction of the moving object determined by the angular velocity direction detection means 4 is smaller than the reference value A, the variation Δθ _M (ΔT) in the moving direction of the moving object measured by the geomagnetic direction detection means 1 due to disturbance magnetism. becomes larger than the reference value M, each variation Δθ _A (ΔT) and Δθ _M (ΔT)
By adding the variation Δθ _A (ΔT) detected by the angular velocity direction detection means 4 to the detected value θ _M (t ₁ ) of the geomagnetic direction detection means 1 at a time before the occurrence of the magnetic disturbance (time t ₁ ), the disturbance magnetic field is calculated. Accurate heading with little influence can be determined.

The reason why the vehicle is targeted during driving with relatively few changes in angle is as follows. In other words, when driving with many angle changes, the variation Δθ _M
(ΔT) and Δθ _A (ΔT) both have large values,
During such driving, there is an influence of magnetic disturbance, and Δθ _M
This is because even if (ΔT) becomes a large value, it is not known whether this is due to disturbance magnetism or due to running with many angle changes. However, by comparing Δθ _A (ΔT) at this time, it seems to be possible to determine to some extent whether it is due to disturbance magnetism or due to driving with many angle changes.In general, the angular velocity direction detection means 4 is an angular velocity sensor such as a gyro device. Since the angle is determined by integrating the value of , accurate Δθ _A (t) and Δθ _A (ΔT) cannot be obtained due to vibrations caused by the running of the moving body. Therefore, in the device of this invention,
Even if there is a disturbance magnetic field while driving with many changes in angle, the traveling direction of the moving body is uniformly determined only by the output of the geomagnetic direction detection means 1, and only when traveling with few changes in angle, the output of the angular velocity direction detection means 4 is used. The direction of travel is determined by taking this into account. By the way, on general roads, there are many more parts where angle changes are small than parts where angle changes are large, such as turns, so if accurate azimuth calculation can be performed on parts where angle changes are small as in this example, it will actually be easier to calculate the direction. This means that accurate direction calculations can be made in most parts of the road network, which is sufficient for practical use.

[Effects of the Invention] As described above, according to the present invention, the first calculated value is larger than the first reference value by the output means, and the calculated value of the second calculation means is smaller than the second reference value. In this case, a value obtained by adding the calculated value of the second calculating means to the detected value of the geomagnetic direction detecting means at the time before each variation, which is the first and second calculated value, is generated is output, so that the comparison This is effective because accurate heading can be obtained while driving with few changes in target angle.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the overall configuration of an embodiment of the invention, FIG. 2 is a block diagram showing an embodiment of the invention, and FIG. 3 is an explanatory diagram illustrating the state of a geomagnetic sensor subjected to disturbance. Figure 4 is a vector diagram for the state shown in Figure 3, Figure 5 is a graph showing the integrator output when traveling straight, and Figure 6 is a graph showing the geomagnetic field when a magnetic disturbance occurs when traveling straight. A graph showing the calculated azimuth signal, FIG. 7, is a flowchart of the same embodiment. 1... Means for detecting the traveling direction of a moving object from the direction of geomagnetism, 2... First calculation means, 3... First
comparison means, 4... means for detecting the traveling direction of the moving body from the angular velocity, 5... second calculation means, 6...
Second comparison means, 7... Discrimination means, 8... Addition calculation means, 9... Display device, θ _M (t)... Traveling direction of the moving object calculated from the geomagnetic field at time t,
Δθ _M (ΔT)... Variation in the moving direction of the moving body calculated from the geomagnetism during ΔT, M... First reference value,
Δθ _A (ΔT)... Variation in the moving direction of the moving body calculated from the angular velocity during ΔT, A... Second reference value. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1 geomagnetic azimuth detection means for detecting the traveling direction of the moving object from the direction of the earth's magnetism; a first calculating means for calculating a variation in the traveling direction of the mobile object within a predetermined time from the detection value of the geomagnetic azimuth detection means; and angular velocity. angular velocity azimuth detecting means for detecting the traveling direction of the moving body from the angular velocity azimuth detecting means; second calculating means for calculating a variation in the traveling direction of the movable body within the predetermined time from the detected value of the angular velocity azimuth detecting means; When the calculated value of the calculating means is larger than the first reference value and the calculated value of the second calculating means is smaller than the second reference value, each variation that is the first and second calculated values occurs. A mobile body orientation detection device comprising an output means for outputting a value obtained by adding a calculated value of the second calculation means to a detected value of the geomagnetic orientation detection means at a time before the movement.