JPH045334B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vehicle-mounted orientation detector, and more specifically, when a vehicle is traveling, it measures the absolute orientation and relative orientation of the vehicle, and calculates the orientation included in each measurement location. The present invention relates to a vehicle-mounted orientation detector configured to obtain a true orientation by performing signal processing to remove errors.

BACKGROUND ART In recent years, direction detectors have become popular because they are installed in automobiles to provide the driver with direction information regarding the direction in which the vehicle is traveling. This direction detector is a conventional vehicle-mounted direction sensor that is particularly useful for avoiding congested traffic points or determining the shortest distance to a destination. Examples of the detector include a magnetic condenser, a gas rate sensor, and the like. However, if an attempt is made to detect the orientation using a magnetic compass, for example, if the vehicle body itself is magnetized, accurate orientation detection becomes impossible. Additionally, when a vehicle equipped with this magnetic compass travels on a road along train tracks, the error contained in the detected direction signal becomes extremely large due to the magnetic field caused by the overhead wires or the current flowing through the tracks. There are drawbacks. As a result, accurate orientation cannot be measured, and the original function cannot be achieved, resulting in unnecessary confusion.

On the other hand, the latter gas rate sensor requires a considerable amount of time to reach a stable state from the initial state after the power is turned on, and during that time, if you try to detect the direction using the output signal of the sensor, it will be in an unstable state. Second, the reliability of the direction detection results is poor. That is, before the vehicle starts running, it must remain in a standby state for a considerable period of time, resulting in a lack of quick response. In addition, this gas rate sensor is expensive, and has been exposed to disadvantages such as a significant impediment to its widespread use due to economic reasons.

The present invention has been made to solve the various inconveniences mentioned above, and measures the overall direction and relative direction of the vehicle using a magnetic compass and a tachometer attached to the rear wheels of the vehicle. To provide an on-vehicle orientation detector that can overcome measurement errors included in each measured value and ensure the true orientation of the vehicle by processing these signals. With the goal.

In order to achieve the above object, the present invention provides a first azimuth measuring means that is mounted on a vehicle and senses geomagnetism to detect the absolute azimuth of the vehicle's traveling direction; or a second azimuth measuring means for detecting the relative azimuth in the traveling direction of the vehicle in accordance with the rotational angular velocity, and a measurement error included in the output signals of the first encirclement measuring means and the second encirclement measuring means is removed. means for detecting the true direction of the vehicle; the means for detecting the true direction of the vehicle includes a relative direction calculator connected to the output side of a set of rotation detectors constituting the second direction measuring means; , an error occurrence period detector connected to the output side of the relative azimuth calculating unit and receiving the output of the magnetic dialect meter constituting the first azimuth measuring means, and a magnetic It is characterized by comprising an azimuth meter and a variable time constant integrator that removes an error signal included in the output of the relative azimuth calculator.

Next, preferred embodiments of the vehicle-mounted orientation detector according to the present invention will be described in detail with reference to the accompanying drawings.

In FIG. 1, reference numeral 10 indicates a first rotation detector, and reference numeral 12 indicates a second rotation detector. These rotation detectors 10, 12 are
As shown in FIG. 2, these devices are attached to the rotating shafts of the left rear wheel and the right rear wheel of a vehicle 13 in which this device is mounted, respectively, via gears or the like. In this case, the output sides of the first rotation detector 10 and the second rotation detector 12 are connected to a relative orientation calculator 14, and the output side of the relative orientation calculator 14 is connected to one input of the error occurrence detector 16. Connected to the terminal. On the other hand, of the vehicle 13,
For example, the output side of the magnetic compass 18 mounted on the roof is connected to the other input terminal of the error occurrence period detector 16, and is further connected to one input terminal of the variable magnetic constant integrator 20. The output side of the error occurrence period detector 16 is connected to the other input terminal of the variable magnetic constant integrator 20.

The vehicle-mounted orientation detector according to the present invention is basically constructed as described above, and its operation and effects will be explained next.

Therefore, in the above configuration, first, when the vehicle 13 is traveling straight, the respective rotational speeds of the rear wheels 22 and 24 are the same, and therefore the relative orientation calculator 1
There is no output signal from 4. On the other hand, when the wheels turn right or left, the relative azimuth calculator 14 detects the deviation between the rotation angles of the first rotation detector 10 and the second rotation detector 12. Therefore, when the vehicle 13 changes its traveling direction, one wheel relatively rotates more than the other wheel. That is, as shown in FIG. 3, the traveling direction of the vehicle 13 is θ.
If only the rear wheel 24 is changed, the rear wheel 24 is changed from the rear wheel 22.
The vehicle will travel an additional distance l. Therefore, if the rotational speed at which the rear wheel 24 rotates extra than the rear wheel 22 at that time is Δn, and the radius of the rear wheels 22 and 24 is p, the following equation holds true. That is, Δn=l/dπp (1) Therefore, if the distance between the rear wheels 22 and 24 is r, θ is calculated by the following equation.

θ=rl=2πp×rΔn...(2) In this case, the radius p of the rear wheels 22, 24, and
Since the separation distance r between these rear wheels 22 and 24 is a known number specific to the vehicle type, if the left Δn of the rotational speed of the rear wheels 22 and 24 is detected, the change θ in the traveling direction of the vehicle 13 can be detected. Desired. That is, the difference Δn between the rotational speeds of the rear wheels 22 and 24 is thus:
The relative orientation calculator 14 calculates the relative orientation based on the output signals of the first rotation detector 10 and the second rotation detector 12.

On the other hand, an output signal from a magnetic compass 18 that detects absolute orientation in response to earth's magnetism is introduced into a variable magnetic constant integrator 20. Therefore, it is assumed that the output signal related to the absolute orientation of the magnetic compass 18 is θ _AB , and in this case, the output signal θ _AB of the magnetic compass 18 generates the waveform shown in FIG. 4A. That is, the vehicle continues to travel straight, the vehicle is displaced in a predetermined direction (the rising portion of waveform diagram A), and the vehicle is further maintained in a straight forward state. During this time, the point indicated by reference numeral a is, for example, the vehicle 13 traveling on a road extending along the train tracks, and as a result, an azimuth error caused by disturbance of the magnetic field caused by the current flowing in the overhead wire. This is the waveform related to On the other hand, as shown in FIG. 4B, if the vehicle 13 moves straight and as a result, the rotation speeds of the first rotation detector 10 and the second rotation detector 12 are the same, the relative orientation calculator 14 It shows a flat waveform as shown in . However, when the direction of travel is switched, the output of one of the rotation detectors increases, so the waveform rises, and as the vehicle continues to travel straight, the waveform becomes flat again. In FIG. 4B, reference numeral b indicates a waveform portion in which an azimuth error occurs due to reasons such as one of the rear wheels 22, 24 of the vehicle idling.

Therefore, if we consider the waveforms a and b related to the azimuth error, the azimuth error indicated by these waveforms is usually
Since each occurs independently, waveform a and waveform b
It becomes possible to detect the period during which the orientation error occurs by determining the distance between the two directions. The error occurrence period detector 16 receives the output signal θ _AB of the magnetic azimuth meter 18 at one input terminal, and receives the output signal θ _RL of the relative azimuth calculator 14 at the other input terminal.
It becomes possible to detect the error occurrence period by capturing waveform a and waveform b, respectively. This error occurrence period detection signal is introduced into the variable magnetic constant integrator 20. Therefore, the output signal θ _AB from the magnetic compass 18 is introduced into the variable magnetic constant integrator 20 . Therefore, in this variable magnetic constant integrator 20, when an output signal from the error occurrence period detector 16 exists, the time constant is increased in accordance with the output signal from the error occurrence period detector 16. It becomes possible to remove errors. That is, since the absolute azimuth signal θ _AB of the magnetic azimuth meter 18 and the relative azimuth θ _RL of the relative azimuth calculator 14 are both introduced into the error period detector 16, the difference signal θ _AB −θ _RL (see FIG. (See C)
An error occurrence period signal T _e (see FIG. 4D) is detected from . The error occurrence period detector 16 obtains a rectangular waveform absolute value signal from the waveform shown in FIG. 4C.

Therefore, in the variable time constant integrator 20, when such a signal from the error occurrence period detector 16 is not introduced, that is, when no azimuth error occurs, the time constant of the integrator 20 is small. The absolute azimuth signal θ _AB is output as is.
On the other hand, while an azimuth error occurs, that is, when a rectangular waveform is introduced from the error occurrence period detector 16 to the variable time constant integrator 20 as shown in FIG. The variable constant integrator 20 is selected to have a large time constant, and as a result, the absolute azimuth θ _T becomes variable with a variable time constant while the azimuth error signals represented by a and b shown in FIG. 4A and B are removed. It is output from the integrator 20 (see FIG. 4E).

The output signal θ _T from which the measurement error has been removed in the manner described above is displayed on, for example, a display (not shown) and is visually recognized by the driving vehicle as a direction signal.

According to the present invention, as described above, the traveling direction of a vehicle is measured using the absolute bearing and the relative direction, and the true traveling direction of the traveling vehicle is detected by removing measurement errors included in each bearing signal. It is configured to do so. Therefore, it is not only possible to confirm the vehicle's direction extremely accurately compared to the case of using a conventional magnetic direction meter, but also it is possible to confirm the direction of the vehicle much more accurately than when using a conventional magnetic direction meter. It does not cause any inconvenience such as having to wait for a certain period of time to run. Furthermore, for example,
If a relatively inexpensive rotary encoder or the like is used as the rotation detector, there is no need to use an expensive device such as a gas rate sensor, and there is an advantage that the entire device can be manufactured at a low cost.

Although the present invention has been described above with reference to a preferred embodiment, the present invention is not limited to this embodiment. It goes without saying that various improvements and changes in design can be made without departing from the gist of the present invention, such as obtaining the same effect even if the present invention is used.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a vehicle-mounted orientation detector according to the present invention, FIG.
A schematic explanatory diagram showing a state in which one rear wheel is displaced relative to the other rear wheel as the vehicle shown in the figure is displaced in the traveling direction. Figure 4 shows the output waveforms of the components shown in Figure 1. FIG. 10, 12... Rotation detector, 13... Vehicle, 1
4...Relative orientation calculator, 16...Error occurrence period detector, 18...Magnetic direction meter, 20...Variable time constant integrator.

Claims (1)

[Claims] 1. A first azimuth measuring means mounted on a vehicle that senses geomagnetism and detects the absolute azimuth of the vehicle's traveling direction; a second direction measuring means for detecting the relative direction of the vehicle; and a means for detecting the true direction of the vehicle by removing measurement errors included in the output signals of the first direction measuring means and the second direction measuring means. , the means for detecting the true direction of the vehicle includes a relative azimuth calculator connected to the output side of a set of rotation detectors constituting the second azimuth measuring means, and a relative azimuth calculator connected to the output side of the relative azimuth calculator. Moreover, the first
An error occurrence period detector which receives the output of the magnetic compass which constitutes the direction measuring means, and an error signal included in the outputs of the magnetic compass and the relative direction calculator by changing a time constant according to the output of the error occurrence period detector. An in-vehicle orientation detector comprising: a variable time constant integrator.