JP2000019238A - Navigation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make maintainable high accuracy by automatically selecting position information by the Decca system in the case where the Decca system stores a range measurement position accuracy higher than that in the GPS system, and the measurement position by the GPS system exists within the range. SOLUTION: A Decca effective memory 13 stores a range (Decca effective range) where position accuracy being measured by a Decca device 3 in advance is higher than that being measured by a GPS device 2. The GPS device 2 measures its own ship position by the GPS system, and inputs position information according to the GPS system from the GPS device 2 to a switchover control part 11. The switchover control part 11 judges whether the present position of its own ship is in the Decca effective range being stored into the Decca effective memory 13 or not. When the present position of its own ship is within the Decca effective range, the output of the Decca device 3 is selected. Otherwise, the output of the GPS device 2 is selected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention is used as a navigation device for a ship. The present invention relates to an apparatus for automatically setting a current position used for an autopilot. The present invention relates to a technique for automatically selecting an optimal navigation device according to a position measurement area.

[0002]

2. Description of the Related Art As a navigation device conventionally used on ships, a GPS (Global Positioning System) system, N
NSS (Navy Navigation Satellite System), Decca (Decca Navigator System), Omega, LORAN (Long Range Navigation), and Inertial Navigation (INS) are known. Table 1 shows the specifications of these navigation systems.

[0003]

[Table 1] Among them, GPS systems and decker systems are mentioned as navigation systems with high accuracy. Specifically, while the accuracy of other navigation devices (NNSS system, Omega system, Loran system, inertial navigation system) has an error of 100 m or more, GPS
The system has an error of about 10 m, and the decker system has an accuracy of an average of several tens of errors.

[0004] Since the GPS system measures the position according to radio waves from 24 satellites in orbiting the earth, almost the same accuracy can be maintained regardless of the use area. On the other hand, the decker system measures the position according to radio waves of 70 to 130 kHz band from the master station and the slave station provided on the ground, so the accuracy difference between the use areas is large, and the GPS method is used in the area where the best accuracy can be exhibited. Higher accuracy (error number m) can be ensured.

The area where the decker method can be used with high accuracy is
This is a range where the terrestrial waves from the master station and the slave station of the decker system effectively reach, and the error increases when the distance from the master station and the slave station increases and the spatial wave is received together with the terrestrial wave. Generally, a range from the main station to about 450 km is considered to be a high-accuracy range (hereinafter, referred to as a decker effective range).

When a ship is in a special terrain, such as in a narrow bay surrounded by high mountains, terrestrial waves from a decker-type master station and a slave station are difficult to arrive, or
In some cases, an obstacle such as a radio wave reflected on land forming a multipath may occur. In such a case, the GPS system may be more advantageous even when the master and slave stations of the decker system are nearby.

FIG. 8 shows the state of mounting of navigation devices in a conventional ship. The ship is equipped with a plurality of navigation systems, such as a GPS system, a decker system, an inertial navigation (INS) system, and the like, and switches between them according to the experience of a navigator. For example, the decker method is used in an area where the decker method can exhibit the best accuracy, and the GPS method is used in other areas. Further, if an external radio wave cannot be received due to some kind of obstacle, the system switches to an inertial navigation system which is a self-contained navigation system.

[0008]

As described above, in order to switch between and use a plurality of types of navigation devices mounted on one ship, the operator must have excellent experience, and complicated operations involved in the switching are required. Is also required.

[0009] Further, when an operator who is unfamiliar with the operation erroneously performs the switching operation, a situation may occur in which the accuracy that should be obtained can not be obtained.

Generally, in an area where the decker system is effective, it is convenient to use fixedly the output information of the decker system as the position information given to the automatic ship navigation device, but the position information at which the decker system operates with high precision is convenient. In order to switch between the decker system and the GPS system according to the position information obtained in advance, it is necessary to constantly check the position and frequently switch.

In addition, when the radio wave reception state of the decker system fluctuates, such as when traveling in a bay, fixing the output information of the decker system may lower the precision of maneuvering of the ship, so that frequent operations may be performed. In some cases, it is necessary to switch between the deck output and the GPS output.

It is an object of the present invention to provide an automatic steering apparatus capable of automatically switching output information from a plurality of types of navigation apparatuses. An object of the present invention is to provide a navigation device and an automatic steering device that can automatically maintain high accuracy. An object of the present invention is to provide a navigation device that can improve navigation safety. SUMMARY OF THE INVENTION An object of the present invention is to provide a navigation device in which a navigator or a steering wheel is not bothered by a switching operation of an automatic steering device.

[0013]

According to the present invention, the effective range of the decker, which is the range in which the decker system operates with high precision, is stored in a memory in advance, and the decker system is switched to the decker system within the effective range of the decker, and the outside of the effective range of the decker is switched. Therefore, switching to the GPS system is the most important feature.

That is, the present invention relates to a navigation device, which is equipped with both a decker system and a GPS system, wherein the form of position information obtained from each of the two systems is set in common, and one of the position information is selected. This is a navigation device to be supplied to the autopilot. The features of the present invention include:
A memory in which a range in which the position accuracy measured by the decker method is higher than the position accuracy measured by the GPS method is stored in advance, and whether or not the position measured by the GPS method is within the range is determined. And a means for automatically selecting the output position information of the decker method.

As described above, the effective range of the decker is stored in the memory in advance, and the position information measured by the GPS method is compared with the position information stored in the memory to determine whether or not the own ship is in the effective range of the decker. Can be automatically determined and switched. Since the master and slave stations of the decker system are fixedly installed on the ground, it is easy to obtain information on the effective range of the decker for the entire area on the earth.

In the above range, the positions of the master station and the slave station of the decker system are A and B, respectively, and a point on a parabola drawn by a point where the phase difference between the two radio waves coming from A and B is equal is P. When the angle at which the parabola intersects the straight line AP or the straight line BP is 90 ° ± α, it is preferable that α <30 °.

Further, there is provided means for monitoring fluctuations in the S / N or reception level of radio waves arriving from the master station and the slave station of the decker system, respectively. A unit may be provided for prohibiting the selection of the decker system when there is a level fluctuation exceeding a predetermined level. Thus, even if the S / N ratio is degraded or the fading increases due to the condition of the ionosphere or the topography, the system is automatically switched to the GPS system even within the effective range of the decker. Therefore, a highly reliable navigation device can be configured.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION

[0019]

(First Embodiment) The structure of the first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram of the first embodiment of the present invention.

The present invention relates to a navigation device, which comprises a decker device 3.
And the GPS device 2 are provided together, and the form of the position information obtained from each of the two devices is set in common,
The navigation device selects one of the position information and supplies it to the autopilot device 4.

Here, the feature of the present invention is that a decker effective range memory 13 in which a range in which the position accuracy measured by the decker device 3 is higher than the position accuracy measured by the GPS device 2 is previously stored; A switching control unit 11 as means for judging whether or not the position measured by step 2 is within the range and automatically selecting the output position information of the decker device 3 when within the range. is there.

FIG. 2 is a diagram for explaining the effective range of the decker. In the range, the positions of the master station and the slave station of the decker system are A and B, respectively, and two radio waves arriving from the A and B are used. When a point on a parabola drawn by a point having the same phase difference is P, and an angle at which this parabola intersects the straight line AP or the straight line BP is 90 ° ± α, α <30 °
Is defined as the range. In the example of FIG. 2, the angle at which the straight line AP intersects with the parabola is 75 ° (= 90 ° −15 °), and the angle at which the straight line BP intersects with the parabola is 84 ° (= 9).
0 ° -6 °). This is 90 °
It is included in the range of ± α.

Next, the operation of the first embodiment of the present invention will be described with reference to FIG. FIG. 3 is a flowchart showing the operation of the switching control unit 11 according to the first embodiment of the present invention. GPS device 2
Measures the position by the GPS method. First, the switching control unit 11 inputs position information according to the GPS method from the GPS device 2 (S1). Subsequently, reference is made to the position information stored in the decker effective range memory 13 (S
2). As a result, it is determined whether or not the current position of the own ship is within the effective range of the decker (S3). Here, if the position of the own ship is within the decker effective range, the output of the decker device 3 is selected (S4). If the position of the own ship is outside the effective range of the decker, the output of the GPS device 2 is selected (S
5).

Thus, if the position of the own ship is within the effective range of the decker, the decker device 3 can be automatically selected, and if the position of the own ship is outside the effective range of the decker, the GPS device 2 can be automatically selected.

(Second Embodiment) A second embodiment of the present invention will be described with reference to FIGS. FIG. 4 is a block diagram of the second embodiment of the present invention. FIG. 5 is a flowchart showing the operation of the switching control unit 11 according to the second embodiment of the present invention.
In the second embodiment of the present invention, a measuring unit 14 is provided.
4 receives the radio waves of the master and slave stations of the decker system,
The S / N is measured. This allows
Even when the own ship is within the effective range of the decker, it is possible to automatically detect that the S / N has deteriorated and switch to the GPS device 2.

For example, when the ship is navigating in a narrow bay, the radio waves of the decker system (70 to 130 kHz) may be interrupted depending on the coastal terrain. At this time, when the arriving radio wave is weakened and the S / N is deteriorated, it is possible to automatically switch to the GPS device 2.

As shown in FIG. 5, the GPS device 2
The position is measured by the S method. Switching control unit 11
First, position information is input from the GPS device 2 by the GPS method (S11). Subsequently, the position information stored in the decker effective range memory 13 is referred to (S12).
As a result, it is determined whether the current position of the own ship is within the effective range of the decker (S13). Further, the switching control unit 11 activates the measurement unit 14 to receive radio waves arriving from the master station and the slave station of the decker system (S14),
N is measured (S15). As a result, if the S / N is equal to or greater than the threshold (S16), the decker device 3 is selected (S1).
7). Also, if the S / N is less than the threshold even within the decker effective range (S16), the GPS device 2 is selected (S16).
18).

(Third Embodiment) A third embodiment of the present invention will be described with reference to FIGS. The configuration of the third embodiment of the present invention is the same as the configuration of the second embodiment of the present invention shown in FIG.
FIG. 6 is a flowchart showing the operation of the switching control unit according to the third embodiment of the present invention. In the second embodiment of the present invention, the measuring unit 14
Measured the S / N of the radio waves arriving from the master station and the slave station. In the third embodiment of the present invention, the measuring unit 14 measures the fluctuation (fading) of the reception level of the radio waves arriving from the master station and the slave station. It is characterized by. Thereby, even when the own ship is within the effective range of the decker, it is possible to automatically detect that the fluctuation of the reception level has increased and switch to the GPS device 2.

As one of the conditions for maintaining the high accuracy of the decker system, it is important that only the terrestrial waves are received and the spatial waves reflected by the ionosphere are not received. That is, since the transmission distance is different between the terrestrial wave and the space wave, a phase difference is generated. And the accuracy is degraded.

In general, radio waves of the decker system (70 to 130
kHz), since the spatial wave is not received because the range relatively close to the transmission source corresponds to the skip zone of the spatial wave.
Can be a Decca effective range. However, even in a range close to the source of the radio wave, the radio wave may be reflected by the ionosphere depending on the state of the ionosphere, and may arrive together with the ground wave.
Under such circumstances, the accuracy of the decker method is degraded.

Since the spatial wave is a radio wave reflected on the ionosphere, which changes every moment, its reception level also changes every moment. Therefore, by measuring the amount of fluctuation (fading) of the reception level, it is possible to estimate the mixing of spatial waves. As a result, the accuracy of the decker system is predicted to degrade,
It is possible to automatically switch to the GPS system even within the effective range of the decker.

When the ship is navigating in a narrow bay, some radio waves may be blocked by coastal terrain,
Although fading may occur by forming a multipath or the like, the accuracy of the decker system also deteriorates in such a case. Also in this case, the switching control based on the fading measurement shown in the third embodiment of the present invention is effective.

The operation of the third embodiment of the present invention will be described with reference to FIG. FIG. 6 is a flowchart showing the operation of the switching control unit 11 according to the third embodiment of the present invention. First, GPS device 2
, Position information is input by the GPS method (S21).
Subsequently, the position information stored in the decker effective range memory 13 is referred to (S22). As a result, it is determined whether the current position of the own ship is within the effective range of the decker (S23). Further, the switching control unit 11 activates the measuring unit 14 to receive the radio waves arriving from the master station and the slave station of the decker system (S24), and measures the fading thereof (S24).
25). As a result, if the amount of fading is equal to or less than the threshold (S26), the decker device 3 is selected (S27). If the fading amount is larger than the threshold value even within the effective range of the decker (S26), the GPS device 2 is selected (S28).

(Fourth Embodiment) A fourth embodiment of the present invention will be described with reference to FIGS. The configuration of the fourth embodiment of the present invention is the same as the configuration of the second embodiment of the present invention shown in FIG.
FIG. 7 is a flowchart showing the operation of the switching control unit 11 according to the fourth embodiment of the present invention. As shown in the second embodiment of the present invention, the fourth embodiment of the present invention receives the radio waves of the master and slave stations of the decker system, measures the S / N ratio thereof, As shown, the radio waves of the master and slave stations of the decker system are received, their fading is measured, and it is determined whether or not to select the GPS device 2 even if the S / N and fading are within the effective range of the decker. It is characterized by doing.

The operation of the fourth embodiment of the present invention will be described with reference to FIG. First, position information is input from the GPS device 2 by the GPS method (S31). Subsequently, reference is made to the position information stored in the decker effective range memory 13 (S3).
2). As a result, it is determined whether or not the current position of the own ship is within the effective range of the decker (S33). If the position of the ship is within the effective range of the decker, the switching control unit 11 further activates the measuring unit 14 to receive radio waves arriving from the master station and the slave station of the decker system (S34), /
N is measured (S35). As a result, if the S / N is equal to or more than the threshold (S36), the fading is measured (S36).
37). As a result, if the amount of fading is equal to or less than the threshold (S38), the decker 3 is selected (S39). If it is outside the decker effective range (S33), the GPS device 2 is selected. However, even if it is within the decker effective range, the S / N is less than the threshold (S36), or the amount of fading is larger than the threshold. If (S38), the GPS device 2 is selected (S40).

In this way, the radio wave of the decker system is measured for both S / N and fading, and the output of the GPS device 2 or the decker device 3 is selected according to the result. By comparison, the GPS device 2 or the decker device 3 can be selected with higher accuracy.

[0037]

As described above, according to the present invention,
An automatic steering device capable of automatically switching output information from a plurality of types of navigation devices can be realized. Further, the present invention can realize a navigation device and an automatic steering device that can automatically maintain high accuracy. Further, the present invention provides
It is possible to improve the navigation safety and to realize a navigation device in which the navigator or the driver does not have to be bothered by the switching operation of the automatic steering device.

[Brief description of the drawings]

FIG. 1 is a block diagram of a device according to a first embodiment of the present invention.

FIG. 2 is a diagram for explaining a decker effective position.

FIG. 3 is a flowchart illustrating an operation of a switching control unit according to the first embodiment of the present invention.

FIG. 4 is a block diagram of a device according to a second embodiment of the present invention.

FIG. 5 is a flowchart illustrating an operation of a switching control unit according to a second embodiment of the present invention.

FIG. 6 is a flowchart illustrating an operation of a switching control unit according to a third embodiment of the present invention.

FIG. 7 is a flowchart illustrating an operation of a switching control unit according to a fourth embodiment of the present invention.

FIG. 8 is a diagram showing a mounting state of a navigation device in a conventional ship.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 switching device 2 GPS device 3 decker device 4 autopilot device 5 INS device 6 position correction unit 10 switching unit 11 switching control unit 12 position comparison unit 13 decker effective range memory 14 measurement unit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (reference) // G05D 1/00 G05D 1/00 A

Claims (3)

[Claims] 1. A navigation device equipped with both a decker system and a GPS system, wherein the form of position information obtained from each of the two systems is set in common, and one of the position information is selected and supplied to an automatic pilot device. A memory storing in advance a range in which the position accuracy measured by the decker method is higher than the position accuracy measured by the GPS method, and determining whether or not the position measured by the GPS method is within the range. Means for automatically selecting the output position information of the decker system when it is within the navigation apparatus. 2. A means for monitoring S / N of radio waves arriving from a master station and a slave station of a decker system, respectively.
2. The navigation system according to claim 1, further comprising means for prohibiting the selection of the decker system when the S / N is lower than a predetermined value. 3. A means for monitoring fluctuations in reception levels of radio waves arriving from a master station and a slave station of a decker system, respectively, when the degree of the fluctuations is equal to or more than a predetermined value,
2. The navigation device according to claim 1, further comprising means for inhibiting selection of a decker system.