JPH0816236A - Magnetic field induction cable and vehicle position detector using the cable - Google Patents

Abstract

PURPOSE:To obtain a detection range more than the width of a vehicle while maintaining high detection accuracy at the time of detecting the lateral displacement of the vehicle by detecting a magnetic field induced from a magnetic field induction cable by right and left magnetic field sensors. CONSTITUTION:This magnetic field induction cable 100 is laid zigzag so as to be alternately offset by D/2 on the right and left sides of a target induction line (shown by an alternate long and sort dash line) in each prescribed distance L. The value D is an optional distance satisfying D<W (W is a mounting distance between right and left magnetic field sensors mounted on a vehicle). Based upon the intensity VR, VL of magnetic fields detected by the right and left sensors, Z=(VL-VR)/(VL+VR) is calculated and Zc=Za+Zb, i.e., the sum Zc of Za at a point (a) of the cable 100 and Zb at a point (b), is calculated. Since the Zc corresponds to lateral deflection variable X at the rate of 1 to 1 in an X section [-(W+D)/2, (W+D)/2], the variable X can be determined.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle position detecting device, and more particularly to a lateral displacement of a vehicle by detecting an induction magnetic field generated by a magnetic field induction cable laid on a road surface with left and right magnetic field sensors provided on the vehicle. It relates to a detecting device.

[0002]

2. Description of the Related Art Conventionally, there is known a guidance system in which steering of a vehicle is controlled by a guidance line laid on a road surface so that the vehicle travels along a predetermined route. For example, Japanese Patent Publication Sho 5
In the moving body control device of the 4-1996 gazette, the structure which controls steering of a vehicle is disclosed by detecting the magnetic field induction cable laid on the road surface with a magnetic field sensor on either side. The principle of vehicle steering control using such a magnetic field induction cable will be described below with reference to FIGS. 9 to 13. Figure 9
As shown in, the induction cable 10 laid on the road surface
When an alternating current IsinωT is applied to 0, a concentric induction magnetic field is generated on the vertical surface of the induction cable 100. When the magnetic field sensor 10 is arranged in this induction magnetic field, an induction voltage e proportional to the horizontal magnetic field strength is generated at both ends of the coil.
That is,

[Equation 1] Here, n is the number of turns of the coil, s is the cross-sectional area of the coil, and μ _{0 is the} vacuum permeability. The lateral excursion X and the maximum value E of the induced voltage e when the height H is constant are

[Equation 2] Becomes Note that K = nsωμ ₀ I. FIG. 10 shows the relationship between the lateral displacement X and the maximum value E. That is, the maximum induced voltage is generated when the magnetic field sensor 10 comes directly above the induction cable 100.

On the other hand, as shown in FIG. 11, when the magnetic field sensors 10a and 10b are mounted on the left and right sides of the vehicle at a height H and a distance W from the induction cable 100, a deviation from the vehicle center to the induction cable 100 is obtained. The maximum values VR and VL of the induced voltage e of the magnetic field sensors on the left and right of the position X show changes as shown in FIG. That is, the maximum value VR of the right sensor 10a is at a position where the lateral displacement X is -W / 2 (that is, the vehicle is displaced to the left by W / 2 and the right magnetic field sensor 10a is located directly above the induction cable 100). The maximum value VL of the left magnetic field sensor 10b is obtained at a position where the lateral displacement X is W / 2 (that is, the vehicle is displaced to the right by W / 2 with respect to the induction cable 100). 10b is the induction cable 1
It is obtained when you come directly above 00). Therefore, a composite magnetic field characteristic of the detected magnetic field strength VR of the right magnetic field sensor 10a and the detected magnetic field strength VL of the left magnetic field sensor 10b.

## EQU3 ## Z = (VL-VR) / (VL + VR) shows the characteristic as shown in FIG. In the relationship shown in FIG. 13, the lateral displacement X and the combined magnetic field characteristic Z are in the section [-w /
2, w / 2] indicates that there is a one-to-one correspondence. Therefore, by calculating the combined magnetic field Z from the magnetic field strengths detected by the left and right magnetic field sensors 10a and 10b,
The position where the vehicle is present with respect to the guide cable 100, that is, the lateral deviation X with respect to the guide cable 100 is uniquely obtained.

[0004]

However, in the conventional vehicle position detecting device using the magnetic field guiding cable, the range in which the lateral deviation can be uniquely obtained from the detected magnetic field strength is ± W / 2. It is a range. Therefore, when the vehicle is run along the guide cable 100, it is necessary to perform steering control so that the lateral deviation thereof is ± W / 2 or less. There is a problem that the vehicle deviates, and as a result, an accurate vehicle position cannot be detected and steering control becomes impossible.

To increase the detection range, it is sufficient to increase W. However, since the left and right magnetic field sensors cannot be mounted over the vehicle width, W cannot increase over the vehicle width. Further, as W is increased, the magnetic field guiding cable 100
The magnetic field strength becomes weaker as the distance from the distance increases, and there is a problem that the detection accuracy is deteriorated due to the influence of noise.

The present invention has been made in view of the above problems of the prior art, and provides a vehicle position detecting device having a detection range equal to or larger than the vehicle width while maintaining high detection accuracy, and a magnetic field induction cable used for the same. To provide.

[0007]

In order to achieve the above object, the magnetic field guiding cable according to claim 1 is a magnetic field guiding cable which is laid on a road surface and detects the position of a vehicle by using the induced magnetic field. It is characterized in that it is laid on the road surface by offsetting a predetermined amount alternately with respect to the target guide line at a predetermined distance.

In order to achieve the above object, a vehicle position detecting device according to a second aspect is a vehicle position detecting device using the magnetic field guiding cable according to the first aspect, wherein the left offset of the magnetic field guiding cable is used. Portion and a pair of magnetic field detecting means provided at a predetermined position of the vehicle for detecting the induced magnetic field generated in the right offset portion, and the first combined magnetic field characteristic is calculated based on the induced magnetic fields detected by the pair of magnetic field detecting means. First synthetic magnetic field calculation means, second synthetic magnetic field calculation means for calculating a second synthetic magnetic field characteristic by the sum of the synthetic magnetic field characteristic of the right offset portion and the first synthetic magnetic field characteristic of the left offset portion, and the second synthetic magnetic field in advance Storage means for storing the relationship between the characteristic and the lateral deviation amount from the target guide line of the vehicle; and the second combined magnetic field characteristic and the lateral deviation amount from the target guide line of the vehicle stored in the storage means. Based on engagement, and having a lateral deviation amount calculating means for determining the lateral deviation amount corresponding to the second resultant magnetic field characteristics the calculated.

Further, in order to achieve the above object, a vehicle position detecting device according to a third aspect of the present invention is the vehicle position detecting device according to the second aspect, wherein the target guiding line of the magnetic field guiding cable is further provided. A second magnetic field detecting means for detecting an induction magnetic field generated in a vertical portion is included, and the timing of detecting the induction magnetic field generated in the left offset portion and the right offset portion of the magnetic field induction cable is determined by the target induction of the magnetic field induction cable. It is characterized in that it is determined based on the detection timing of the induced magnetic field generated in the portion substantially perpendicular to the line.

[0010]

The magnetic field guiding cable according to the first aspect of the invention is not laid straight along the target guiding line like the conventional magnetic field guiding cable, but is alternately left and right at a predetermined distance with respect to the target guiding line. It is laid in zigzag with a fixed offset. As a result, the detection range is expanded by the offset amount, and since the mounting distance of the sensor is the same as the conventional one, the accuracy is not deteriorated.

In the vehicle position detecting device according to the second aspect, the vehicle position is detected by using the induction magnetic field generated from the magnetic field induction cable according to the first aspect. That is, the pair of left and right magnetic field detecting means detects the induced magnetic field generated at the left and right offset portions of the magnetic field guiding cable, and the combined magnetic field of the detected induced magnetic fields is calculated. Then, the second combined magnetic field is calculated from the sum of the combined magnetic field of the right offset part and the combined magnetic field of the left offset part. As for the relationship between the second combined magnetic field characteristic and the lateral displacement of the vehicle, a region where the lateral displacement is one-to-one expands by a lateral offset as will be described later, so that lateral displacement that could not be detected in the past can be reliably detected. can do.

According to another aspect of the vehicle position detecting apparatus of the present invention, not only the left and right offset portions of the magnetic field guiding cable but also the guide magnetic field of a portion substantially perpendicular to the target guide line is used. Is to detect. The composite magnetic field characteristics described above are calculated from the induced magnetic fields of the left and right offset portions. However, by detecting the strength of the induced magnetic field of the portions substantially perpendicular to the target guide line, the detection timing of the induced magnetic fields of these left and right offset portions can be determined. Can be accurately determined.

The principle of detecting the vehicle lateral deviation of the present invention will be easily understood by referring to the following embodiments.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a magnetic field guiding cable of the present invention and a vehicle position detecting device using the same will be described below with reference to the drawings.

First Embodiment FIG. 1 shows the laid state of the magnetic field induction cable in this embodiment. The magnetic field guiding cable 100 is laid in a zigzag pattern by alternately offsetting it by D / 2 for each predetermined distance L with respect to the target guiding line (one-dot chain line in the figure).
Note that D is the left and right magnetic field sensors 10 mounted on the vehicle.
For the mounting distance W of a and 10b,

## EQU00004 ## An arbitrary distance that satisfies D <W. An alternating current is passed through the magnetic field induction cable 100.

FIG. 2 shows such a magnetic field induction cable 1
00 shows the state of the magnetic field strength at point a (right offset portion) and point b (left offset portion) in FIG. 1 when a vehicle equipped with left and right magnetic field sensors 10a and 10b travels. . Note that Za and Zb are each a
Based on the detected magnetic field strength VR of the right magnetic field sensor 10a and the detected magnetic field strength VL of the left magnetic field sensor 10b at point b.

## EQU00005 ## The left and right combined magnetic field characteristics (first combined magnetic field characteristics) obtained by Z = (VL-VR) / (VL + VR). Since point a is offset by D / 2 to the right from the target guide line, Za shows a characteristic obtained by shifting the combined magnetic field characteristic Z shown in FIG. 13 to the left by D / 2, while point b is the target. Since it is offset to the left by D / 2 from the guide line, Zb shows the characteristic that the combined magnetic field characteristic Z shown in FIG. 13 is shifted to the right by D / 2.

Then, a combined magnetic field characteristic (second combined magnetic field characteristic) obtained by adding these Za and Zb

## EQU6 ## Zc = Za + Zb is shown in FIG. The horizontal axis represents the lateral displacement amount X, and the vertical axis represents Zc. Section [-(W + D) / 2, (W + D) /
2] monotonically increases, X = (W + D) / 2 reaches a maximum, X =
A characteristic is that the minimum is − (W + D) / 2, and the value is 0 when X = 0. Therefore, the interval [-(W + D) / 2, (W + D) /
In 2], Zc and lateral displacement X have a one-to-one correspondence, and if the combined magnetic field characteristic Zc is known, the lateral displacement amount X can be uniquely determined. Since the width of the section [-(W + D) / 2, (W + D) / 2], that is, the detection width of the vehicle lateral deviation is W + D,
The detection width is increased by D as compared with the conventional device.

The vehicle position detecting principle of the present embodiment is as described above, and FIG. 5 shows a specific configuration of the vehicle position detecting device of the present embodiment. A right magnetic field sensor 10a and a left magnetic field sensor 10b are provided on the left and right sides of the vehicle with a space of W therebetween, and output the detected magnetic field strengths (induced voltages) VR and VL to the arithmetic unit CPU12. The CPU 12 calculates Za and Zb from these detection signals VR and VL, and further calculates the combined magnetic field characteristic Zc. On the other hand, FIG.
The relationship between the combined magnetic field characteristic Zc and the lateral displacement amount X shown in FIG.
The lateral displacement amount X corresponding to the combined magnetic field characteristic Zc calculated by accessing the is read and output as a control signal to the steering actuator or the like. Hereinafter, the operation of this embodiment will be described in more detail with reference to the processing flowcharts shown in FIGS. 6, 7, and 8.

First, in FIG. 6, the CPU 12 reads the value C of a wheel pulse counter (not shown) (S10).
1), the traveling distance is calculated by multiplying the counter value C and the traveling distance d per pulse. And this mileage is L
It is determined whether or not (the length of the left and right offset portions in FIG. 1) is exceeded (S102), and if L is exceeded, the counter value is reset (S103), and the detection signal from the right magnetic field sensor 10a is detected. The detection signal VL from the VR and the left magnetic field sensor 10b is read (S104, S105).
Then, based on these detection signals, the CPU 12

## EQU00007 ## The left and right combined magnetic field characteristics are calculated by Z = (VL-VR) / (VL + VR) (S106). This combined magnetic field characteristic is the combined magnetic field characteristic Z of the right offset portion.
Either a or the combined magnetic field characteristic Zb of the left offset portion.

After Z is calculated, the value of the flag f1 is checked (S107). If f1 = 0 is not satisfied, the vehicle is positioned at the right offset portion (point a in FIG. 1), and the calculated Z is Za. = Z (S108), flag f1
Is set to 0 (S109). On the other hand, the flag f1 is 0
If it is, the Z calculated that the vehicle is located at the left offset portion (point b in FIG. 1) is set to Zb = Z (S110), and the flag f1 is set to 1 (S11).
1). Thus, every time the vehicle runs L, the value of the flag f1 is alternately set to 0 and 1, and Za and Zb are calculated. In addition, even if only L is traveled in the initial stage, it is Za or Zb.
Since only one of the above is calculated, in this case S10
When 9 is completed, the process returns to S101 again. Then, after Za and Zb are calculated, the CPU 12 uses them to synthesize the combined magnetic field characteristics.

## EQU8 ## Zc = Za + Zb is calculated (S112), the memory 14 is accessed, and the corresponding lateral displacement amount X is read from the map (S113). As a result, the lateral displacement amount of the vehicle can be accurately detected within the detection range W + D.

Further, since the detection range is expanded from the conventional W to W + D, the vehicle can be controlled at a speed higher than the conventional speed even on the road where the vehicle has conventionally been required to decelerate so as not to leave the road. Is possible.

Second Embodiment In the above-mentioned first embodiment, the length of the offset portion of the magnetic field guiding cable is fixed to L, and the detection timing is determined by whether the traveling distance of the vehicle exceeds L. Instead of calculating the traveling distance of the vehicle from the wheel pulse and determining whether or not the vehicle has traveled L as described above, the magnetic field guiding cable 10
It is also possible to determine the detection timing of Za and Zb by detecting the induction magnetic field generated in the portion substantially perpendicular to the target induction line of 0. FIG. 4 illustrates the principle of this detection timing. As shown in FIG. 4A, in addition to the right magnetic field sensor 10a and the left magnetic field sensor 10b,
A magnetic field sensor 11 is provided to detect an induction magnetic field generated in a portion of the magnetic field induction cable 100 substantially perpendicular to the target induction line. The induction magnetic field generated in a portion of the magnetic field induction cable 100 that is substantially perpendicular to the target induction line has a magnetic field distribution as shown in FIG. 4B, and as shown in FIG.
Has a maximum value when is located right above the magnetic field induction cable (that is, when it crosses the magnetic field induction cable). Therefore, Za and Zb can be detected using the timing when the magnetic field strength detected by the magnetic field sensor 11 becomes maximum.

FIG. 7 and FIG. 8 show a processing flow chart of the vehicle position detection in this case. FIG. 7 is almost the same as the process flowchart of FIG. 6 except for the process of determining the magnetic field measurement timing (S201). FIG. 8 shows the details of the determination processing of the magnetic field measurement timing. First, the maximum value MAX is reset to 0 (S301), and the CPU 12 reads the magnetic field strength Vc detected by the magnetic field sensor 11 (S302). Then, the value of the flag f2 is checked (S303).

When the flag f2 is set to 0, the detected magnetic field strength Vc and the maximum value MAX are compared (S304). If Vc exceeds MAX, Vc is updated as a new MAX (S305), and the magnitude comparison between 0.9MAX and Vc is performed. When Vc is 0.9 MAX or less, it is determined that the detected magnetic field strength has changed from MAX to 0.9 MAX or less, that is, the induction magnetic field cable is crossed, and the value of the flag f2 is set from 0 to 1 ( S307), L is calculated and the count value C is reset (S308, S30).
9).

When it is determined in S303 that the value of the flag f2 is not 0, it is next determined whether or not f2 is 2 (S310). When f2 is 1, the magnitude comparison between the detected magnetic field strength Vc and the predetermined threshold value TH1 is further performed (S313). The threshold TH1 is shown in FIG.
As shown in (C), the vehicle travels approximately at the center position of the right or left offset portion, and the magnetic field induction cable 10
It is a threshold value for discriminating a position where the induced magnetic field strength generated in a portion of 0 which is substantially perpendicular to the target guide line becomes almost 0.
When the detected magnetic field strength Vc is less than or equal to the threshold value TH1, it is determined that the vehicle is traveling at the substantially central position of the right or left offset portion, and the flag f2 is set from 1 to 2 (S314). On the other hand, if the value of the flag f2 is 2 in S310, then the detected magnetic field strength Vc is compared with a predetermined threshold value TH2 (S311).
The threshold value TH2 is a threshold value for determining whether or not the vehicle is located in the vicinity of a portion of the magnetic field guiding cable 100 substantially perpendicular to the target guiding line as shown in FIG. 4 (C). If the detected magnetic field strength Vc is greater than TH2, it is determined that the vehicle is traveling in the vicinity of a portion of the magnetic field guiding cable 100 that is substantially perpendicular to the target guiding line, and the flag f2 is set from 2 to 0 (S312). ). In this way, by setting the value of the flag f2 based on the detected magnetic field strength Vc, it is possible to determine which position the vehicle is traveling with respect to the magnetic field guiding cable, and the value of the flag f2 is 1 When, that is, when passing through the portion of the magnetic field guiding cable 100 that is substantially perpendicular to the target guiding line, reading of VR and VL is started, Z is calculated, and Za and Zb can be obtained alternately.

Since the detection timing is determined by the magnitude of the magnetic field strength Vc in the second embodiment, the length L of the offset portion of the magnetic field guiding cable 100 can be variable instead of being fixed. Therefore, the length of the right offset portion and the length of the left offset portion can be changed, and D <
Various lengths can be used under W conditions.

By changing the pitch of the left and right offset portions between a straight road and a curved road, it is possible to give the magnetic field guiding cable itself the shape information of the road surface. As a result, the vehicle can recognize from the change in the cycle of the detected magnetic field strength Vc that the vehicle is currently traveling on a curved road or will travel on a curved road, and decelerates to control the vehicle to leave the traveling road. Can be effectively prevented.

The embodiment of the present invention has been described above.
It should be added that the present embodiment includes the following embodiments in addition to the technical matters described in the claims.

(1) The magnetic field guiding cable according to claim 1, wherein the length of the offset portion is determined according to the curvature of the road surface.

[0030]

As described above, according to the magnetic field guiding cable and the vehicle position detecting device of the first to third aspects, high detection accuracy can be achieved when detecting the lateral displacement amount of the vehicle using the magnetic field strength. It is possible to obtain a detection range that is equal to or larger than the vehicle width while maintaining it.

In particular, according to the vehicle position detecting device of the third aspect, since the detection timing is determined by the strength of the induction magnetic field generated in the portion of the magnetic field induction cable substantially perpendicular to the target induction line, the offset of the induction magnetic field cable. By changing the pitch of the portion according to the curvature of the road surface or the like, it becomes possible to accurately grasp not only the lateral displacement amount but also the condition of the road surface. This has the effect of making it easier to control the traveling of the vehicle.

[Brief description of drawings]

FIG. 1 is a plan view showing a laid state of a magnetic field induction cable according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a first combined magnetic field characteristic of the example of the present invention.

FIG. 3 is an explanatory diagram of a second combined magnetic field characteristic according to the embodiment of this invention.

FIG. 4 is an explanatory diagram of detection timing according to the embodiment of this invention.

FIG. 5 is a configuration diagram of an embodiment of the present invention.

FIG. 6 is a processing flowchart of an embodiment of the present invention.

FIG. 7 is a processing flowchart of another embodiment of the present invention.

FIG. 8 is a processing flowchart of another embodiment of the present invention.

FIG. 9 is an explanatory diagram of a conventional device.

FIG. 10 is a diagram illustrating a magnetic field strength of a conventional device.

FIG. 11 is a configuration diagram of a conventional device.

FIG. 12 is a diagram illustrating a magnetic field strength of a conventional device.

FIG. 13 is an explanatory diagram of a composite magnetic field characteristic of the conventional device.

[Explanation of symbols]

 10, 11 Magnetic field sensor 12 CPU 14 Memory 100 Magnetic field induction cable

Claims (3)

[Claims] 1. A magnetic field guiding cable which is laid on a road surface and detects the position of a vehicle by using the induced magnetic field, the magnetic field guiding cable being laid on the road surface by offsetting a predetermined amount for each predetermined distance alternately with respect to a target guide line. The magnetic field induction cable characterized in that. 2. A vehicle position detecting device using the magnetic field guiding cable according to claim 1, wherein the vehicle position detecting device is provided at a predetermined position of a vehicle for detecting a guiding magnetic field generated at a left offset portion and a right offset portion of the magnetic field guiding cable. A pair of magnetic field detecting means, a first composite magnetic field calculating means for calculating a first composite magnetic field characteristic based on the induced magnetic field detected by the pair of magnetic field detecting means, and a composite magnetic field characteristic and a left offset of the right offset portion. Second combined magnetic field calculation means for calculating the second combined magnetic field characteristic by summing the first combined magnetic field characteristics of the parts, and the relationship between the second combined magnetic field characteristic and the lateral deviation amount from the target guide line of the vehicle is stored in advance. A lateral displacement corresponding to the calculated second combined magnetic field characteristic based on a relationship between the storage means and the second combined magnetic field characteristic stored in the storage means and the lateral deviation amount from the target guide line of the vehicle. amount Vehicle position detecting apparatus comprising: the lateral displacement amount calculation means determining the. 3. The vehicle position detecting device according to claim 2, further comprising second magnetic field detecting means for detecting an induced magnetic field generated in a portion of the magnetic field guiding cable substantially perpendicular to the target guiding line,
The timing of detecting the induced magnetic field generated in the left offset portion and the right offset portion of the magnetic field guiding cable is determined based on the detection timing of the induced magnetic field generated in the portion of the magnetic field guiding cable substantially perpendicular to the target guiding line. A vehicle position detecting device characterized by the above.