JPH03162614A - Vehicle azimuth detector - Google Patents

Abstract

PURPOSE:To find the center point of a present vehicle azimuth accurate at all times by detecting the displacement variation of the vehicle according to the detection data of driven wheel speed sensors and an earth magnetism sensor and also detecting variation in the azimuth of the vehicle according to the detection data of the driven wheel speed sensor. CONSTITUTION:The vehicle azimuth detecting device 1 is constituted centering a control part 2 consisting of a microcomputer. The earth magnetism sensor 3, the driven wheel speed sensors 4a and 4b which detect the speed of the right and left driven wheels, and a storage part 5 such as a floppy disk where various data are stored are connected to the control part 2. The voltage value of the sensor 3 is inputted to the control part 2 to find the current vehicle azimuth. Center point processing is carried out according to the detection data of the sensors 4a and 4b to find the center point in the current vehicle azimuth. Then the current vehicle position, etc., is displayed on a map on the screen 7a of a navigation system 8 according to the current vehicle azimuth detected by the device 1 and a traveling distance, etc., detected by the sensors 4a and 4b.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to the improvement of a vehicle direction detection device used in a vehicle navigation system, etc., and more specifically, the present invention relates to the improvement of a vehicle direction detection device used in a vehicle navigation system, etc. This article relates to a vehicle orientation detection device that can accurately determine the center point. [Prior Art] Fig. 6 is a graph showing an ideal X-Y output voltage trajectory of the geomagnetic sensor mounted on the vehicle when the vehicle rotates once. Generally, the center point C(x.Y) of the current vehicle orientation is determined as the center of the intersection of the above trajectory and the reference voltage Y=Yo-X-Xo. That is, each of the above intersection points is (xl, xk)
(y+, y2), the above center point C(x, y) is C(x.y) = (( Xl + X2 )/2, (
y+ + V2 )/2 ) ・=(indicated by +1.

Conventional vehicle orientation devices memorize the detection data of the geomagnetic sensor and obtain the output voltage locus each time the vehicle turns while the vehicle is running. FIG. 7 shows an example of an actual output voltage trajectory stored in the vehicle direction detection device.

[Problem to be solved by the invention]

In the conventional vehicle direction detection device, as mentioned above, the detection data from the geomagnetic sensor is stored as is, so as shown in Fig. 7, the output voltage trajectory is affected by "disturbances such as JX.Y" due to various factors. For example, the above-mentioned "disturbance" X in the output voltage trajectory appears when the vehicle passes through a place where radio waves are strongly emitted. Furthermore, the above-mentioned "disturbance" Y appears, for example, when an oncoming vehicle approaches from a distance. Therefore, the center point C I (x, y) of the current vehicle direction determined based on the output voltage trajectory may include the above-mentioned "disturbance", and in this case, the center point C I (x, y) is accurately This resulted in an error in the direction detected by the geomagnetic sensor. Therefore, it is an object of the present invention to provide a vehicle direction detection device that can always accurately determine the center point of the current vehicle direction of a geomagnetic sensor. [Means for Solving the Problems] In order to achieve the above object, the present invention provides a vehicle orientation detection device that uses detection data from a geomagnetic sensor to determine the center point of the current vehicle orientation. a trailing wheel speed sensor that detects; and a first azimuth change detection means that detects a change in the azimuth of the vehicle based on detection data of the geomagnetic sensor;
A second azimuth change detection means detects a azimuth change of the vehicle based on the detection data of the trailing wheel speed sensor, and a azimuth change difference between the first azimuth change detection means and the second azimuth change detection means is within a predetermined range. an azimuth change difference determining means for determining whether the output value of the geomagnetic sensor is within a predetermined range; and an output value determining means for determining whether the output value of the geomagnetic sensor is within a predetermined range; When it is determined that the output value of the geomagnetic sensor is within the predetermined range and the output value determining means determines that the output value of the geomagnetic sensor is within the predetermined range, the center point is determined using the detection data of the geomagnetic sensor, and The detection adopted last time when the orientation change difference determining means determines that the orientation change difference is not within the predetermined range, or when the output value determining means determines that the output value of the geomagnetic sensor is not within the predetermined range. The present invention is configured as a vehicle direction detection device characterized by comprising a center point calculation means for calculating the center point of the current vehicle direction using data. [Operation] Since this vehicle orientation detection device is configured as described above, for example, if there is no disturbance in the detection data of the geomagnetic sensor or the disturbance is small, the orientation change difference discriminating means detects the first
The difference in azimuth change between the azimuth change detection means and the second azimuth change detection means falls within a predetermined range. Furthermore, since the output value of the geomagnetic sensor determined by the output value determining means is within a predetermined range, the center point calculation means uses the detection data of the geomagnetic sensor to determine the center point of the current vehicle heading. The detection data of the geomagnetic sensor is greatly disturbed when the vehicle passes by a large magnetic field or passes over railroad tracks. For example, in the former case, the azimuth change difference determining means may determine that the azimuth change difference between the first azimuth change detection means and the second azimuth change detection means exceeds a predetermined range. In the latter case, the output value determining means may determine that the output value of the geomagnetic sensor is not within the predetermined range.
In any of these cases, the detected data of the geomagnetic sensor that is disturbed cannot be adopted, so the center point calculation means uses the previously adopted detected data of the geomagnetic sensor to find the center point of the current vehicle heading. Therefore, only the undisturbed detection data of the geomagnetic sensor is used to find the center point of the current vehicle direction.
The concentric points are exact. [Examples] Examples embodying the present invention will be described below with reference to the accompanying drawings to provide an understanding of the present invention. On the other hand, the following examples are examples embodying the present invention, and are not intended to limit the technical scope of the present invention. FIG. 1 is a Bronnoch diagram showing the use of a vehicle orientation pupil detection device according to an embodiment of the present invention in a vehicle navigation system; FIG. 2 is a flowchart showing center point detection processing of the vehicle orientation detection device; Fig. 3 is an explanatory graph showing an example of the output value of the geomagnetic sensor of the same vehicle direction detection device, Fig. 4 is an explanatory graph showing a predetermined range of the output value of the same geomagnetic sensor, and Fig. 5 fa1, (bl is the geomagnetic sensor, respectively) It is an explanatory graph showing another example of the output value of the sensor. The vehicle direction detection device 1 shown in FIG. 1 is mounted on a vehicle having two left and right driven wheels (not shown). The control unit 2 is mainly composed of a control unit 2 consisting of a microcomputer CPU, etc., and the control unit 2 includes a geomagnetic sensor 3 that detects geomagnetism, a trailing wheel speed sensor 41 (and 4b),
Furthermore, a storage unit 5 such as a floppy disk for storing various data is connected. The voltage value of the geomagnetic sensor 3 is input to the control 9+12, and the current vehicle direction is determined. Further, based on the detection data of the following wheel speed sensors 4m and 4h, the control unit 2 determines the speed difference of the trailing wheels, etc., and determines a change in the current vehicle heading. The above-mentioned geomagnetic sensor 3, secondary speed sensor 4a. Center point detection processing described later based on the detection data of 4b? The center point of the vehicle's current orientation is determined. This vehicle direction detection device 1 is further connected to the control unit 2, an input unit 6 such as a handwriting tablet left for various input operations, and a display NI7 made of a CRT for displaying map information etc. on a screen 71. , used as a vehicle navigation system 8. The current vehicle direction detected by the vehicle direction detection device 1 and the trailing wheel speed sensor 4■. Screen 7. of the navigation system 8 is displayed based on the mileage etc. detected by 4b.
The current vehicle position etc. is displayed on the map. Next, the second [! Regarding the center point detection processing procedure of this vehicle direction detection device 1, step S1. S2,
I will explain in order. When the navigation system 8 is activated and the vehicle equipped with the navigation system 8 turns, the current vehicle direction θ1 is detected by the geomagnetic sensor 3 (Sl).
, the difference from the previously detected vehicle orientation (vehicle orientation change Δθ1
) is determined (s2) The means for realizing the function of detecting the azimuth change Δθ1 of the vehicle based on the detection data of the geomagnetic sensor 3 described above is an example of the first azimuth change detection means.
At this time, the speed difference between the right and left driven wheels is calculated based on the detection data of the driven wheel speed sensors (right, left) 41, ah (S3).
Furthermore, based on this speed difference, a change in the vehicle direction Δθ2 before and after the turn is determined (S4). An example of the second azimuth change detection means is a means for realizing the function of detecting the azimuth change Δθ of the vehicle based on the detection data of the following wheel speed sensors 4, 4, described above. Then, the process of determining whether the detection data of the geomagnetic sensor 3 detected in step S1 contains "disturbances" such as X and Y shown in FIG. 7 is performed as described below. That is, the detection azimuth change Δθ of the geomagnetic sensor 3 obtained in S2, and the detection azimuth change Δθ of the trailing wheel speed sensors 4a, ah.
It is determined whether the azimuth change difference 1Δθ1−Δθ21 with respect to θ is within a predetermined range (S5)? For example, as shown in Figure 3, the above Δθ is included in the detection data of the geomagnetic sensor.
If a "disturbance" Y occurs such that the difference in azimuth change between 1 and Δθ2 is not within a predetermined range, the detection data of the geomagnetic sensor 3 is not stored in the storage unit 5 (S6), and the previously stored detection data is Data cannot be rewritten. That is, as will be described later, in this case, the center point of the current vehicle direction is determined using the detection data of the previously employed geomagnetic sensor. Direction change difference determination is a means for realizing the function of determining whether the difference in direction change between the detected direction change Δθ1 of the geomagnetic sensor 3 and the detected direction change Δθ2 of the trailing wheel speed sensors 41, 4& is within a predetermined range. This is an example of a method. When the azimuth change difference 1Δθ1−Δθ21 is within a predetermined range, the detected azimuth change difference Δθ of the geomagnetic sensor 3 and the following wheel speed sensor 4■. When the detected azimuth changes △θ, and 4+, respectively coincide with each other by chance as shown in FIG. The disturbance X in Figure 5+al corresponds to the disturbance X in Figure 7, and the disturbance Y in Figure 7 corresponds to the disturbance x,.'y2 or Y shown in Figure 5(a). , may occur singly or in combination.Here, it is determined whether the voltage output value of the geomagnetic sensor 3 is within a predetermined range (between α and β) shown in the diagonal ijI section of Fig. 4. (S7). If the voltage output value of the geomagnetic sensor 3 described above is within the predetermined range (α
~β) is an example of an output value determining means. At this time, Fig. 5+a
1. (As shown in bl, the voltage output value (for example, P, P2) of the geomagnetic sensor 3 is outside the predetermined range (outside the α above)
In this case, the detection data of the geomagnetic sensor 3 is not stored in the storage unit 5, and the previously stored detection data is not rewritten. That is, as will be described later, in this case, the center point of the current vehicle direction is determined using the detection data of the previously employed geomagnetic sensor. On the other hand, the voltage output value of the geomagnetic sensor 3 is within a predetermined range (α ~
β), the state is not as shown in Fig. 3 above, and the voltage output value is included in the shaded area in Fig. 4 above, so the voltage output value is used to find the center point of the current vehicle direction. The detection data of the geomagnetic sensor 3 is stored in the storage unit 5 (S8), and the previously stored detection data is rewritten as the detection data of the geomagnetic sensor 3. Therefore, the detection data stored in the storage unit 5 becomes data that does not include the disturbances JY+ shown in FIG. 3 and the disturbances X...Y2 shown in FIG. 5 ta+, (bl).
Based on the detection data stored in the storage unit 5, the (1)
) can be used to find the center point of the current vehicle heading. Therefore, this stopping point for the current vehicle orientation can always be accurately determined. Also, the current vehicle direction of the geomagnetic sensor 3 determined using this center point as a reference is naturally accurate. When it is determined that the voltage output value of the geomagnetic sensor 3 described above is within a predetermined range (between α and β), using the detection data of the geomagnetic sensor 3, it is determined that the voltage output value of the geomagnetic sensor 3 is not within the predetermined range (between α and β). An example of a center point calculation means is a means for realizing the function of determining the center point of the current vehicle heading using the previously adopted detection data when the judgment is made. Note that the vehicle having two left and right driven wheels is primarily a 2WD vehicle, but also includes a 4WD vehicle that can be driven by switching to 2WD. [Effects of the Invention] According to the present invention, in the vehicle direction detection device for determining the center point of the current vehicle direction using detection data of a geomagnetic sensor,
a driven wheel speed sensor that detects the speed of each of the driven wheels; a first azimuth change detection means that detects a change in the orientation of the vehicle based on the detection data of the geomagnetic sensor; a second azimuth change detection means for detecting a azimuth change; the first azimuth change detection means and the second azimuth change detection means;
azimuth change difference determining means for determining whether the azimuth change difference with the azimuth change detecting means is within a predetermined range; and output value determining means for determining whether the output value of the geomagnetic sensor is within the predetermined range. When the orientation change difference determining means determines that the orientation change difference is within the predetermined range, and the output value determining means determines that the output value of the geomagnetic sensor is within the predetermined range, the geomagnetic sensor The center point is determined using the detected data of A vehicle heading detection device is provided, comprising: center point calculating means for determining the center point of the current vehicle heading using previously adopted detection data when it is determined that the vehicle heading is not within the range. Therefore, the center point of the current vehicle direction of the geomagnetic sensor can always be accurately determined.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing how a vehicle orientation detection device according to an embodiment of the present invention is used in a vehicle navigation system, FIG. 2 is a flowchart showing center point detection processing of the vehicle orientation detection device, and FIG. The figure shows the vehicle's orientation detection device II+! ! FIG. 4 is an explanatory graph showing an example of the output value of the magnetic sensor; FIG. 5 is an explanatory graph showing a predetermined range of the output value of the geomagnetic sensor; FIG. 6 is an explanatory graph showing an ideal x-y output voltage trajectory of a geomagnetic sensor. FIG. 7 is an explanatory graph showing an example of an actual output voltage trajectory stored in a conventional vehicle direction detection device. It is a graph. [Explanation of symbols] l...Vehicle direction detection device 2...Control unit 3...Geomagnetic sensor 4, 4, etc....Following wheel speed sensor 5...Storage unit

Claims (1)

[Scope of Claims] 1. A vehicle direction detection device that determines the center point of the current vehicle direction using detection data of a geomagnetic sensor, comprising: a driven wheel speed sensor that detects the speed of two driven wheels; and a detection of the geomagnetic sensor. a first azimuth change detection means for detecting a change in the azimuth of the vehicle based on data; a second azimuth change detection means for detecting a change in the azimuth of the vehicle based on the detection data of the trailing wheel speed sensor; and the first azimuth change detection means. azimuth change difference determining means for determining whether a difference in azimuth change between the means and the second azimuth change detection means is within a predetermined range; and an output for determining whether an output value of the geomagnetic sensor is within a predetermined range. The value determination means and the orientation change difference determination means determine that the orientation change difference is within the predetermined range, and the output value determination means determines that the output value of the geomagnetic sensor is within the predetermined range. When the center point is determined using the detection data of the geomagnetic sensor, the orientation change difference determining means determines that the orientation change difference is not within the predetermined range, or the output value determining means determines that the orientation change difference of the geomagnetic sensor is not within the predetermined range. A vehicle direction detection device comprising: center point calculation means for calculating the center point of the current vehicle direction using previously adopted detection data when it is determined that the output value is not within the predetermined range. .