JP2000180191A - Navigator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a navigator which prevents an increase of position correction errors by a multipath by detecting reflection by an obstacle when receiving signals of a GPS satellite. SOLUTION: A position-estimating means 3 calculates an estimated position of a machine with use of a move distance and an angular shift amount. A distance-calculating means 5 calculates a distance between a position of the machine and a position of a receive satellite. A multipath-detecting means 6 compares a signal propagation time of a GPS signal and the distance calculated by the distance-calculating means 5, detects a multipath and controls not to correct the position according to a GPS when the multipath is detected. An increase of position correction errors is accordingly prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a navigation device for detecting a position of a self-vehicle using a sensor for detecting a signal and a speed and an angular displacement from a satellite and a map database, and more particularly to a navigation device for detecting a position correction error due to multipath. It is configured to prevent an increase.

[0002]

2. Description of the Related Art A conventional navigation device detects a position of the navigation device using a distance sensor, a direction sensor, a map database, a satellite positioning system (GPS), or the like. As shown in FIG. 4, the conventional device calculates the relative movement distance and the amount of angular displacement by accumulating the movement distance obtained from the distance sensor 201 and the amount of angular displacement obtained from the azimuth sensor 202, respectively. The position of the own device is calculated by performing a map matching process using the database 203 (see, for example, JP-A-5-346328). Further, when the accumulated error due to the relative positioning becomes large or when the initial position is set, the position of the own device is corrected using the satellite positioning system 204 (GPS) or the like.

[0003]

The positioning accuracy of a normal GPS is about 30 meters on average, but in a place where obstacles such as high-rise buildings are dense, propagation delay occurs due to reflection of the obstacles. An error larger than usual may occur. In such a case, the conventional navigation device has a problem that a position correction error due to GPS increases.

If the number of receivable satellites becomes less than three due to an obstacle, the position cannot be corrected by GPS, and the accumulated error of relative positioning accumulates, and the positioning accuracy is reduced. .

The present invention has been made in order to solve the above problems.
A navigation device capable of detecting an obstacle of a GPS signal and preventing erroneous position correction by comparing a distance from a position of the own device estimated by relative positioning to a receiving satellite and a propagation time of a signal from the satellite. In addition, it calculates the multiple candidate positions by relative positioning and map matching, compares the azimuth and elevation angle of the satellite for each candidate position with the position and height of the surrounding obstacle and actually To provide a navigation device capable of calculating its own position without being affected by obstacle reflection by determining whether or not a receiving satellite is receivable at that position and receiving less than three satellites. Aim.

[0006]

[MEANS FOR SOLVING THE PROBLEMS] GPS by obstacle reflection
In order to prevent an increase in the position correction error, the navigation device of the present invention has the following configuration. The position estimating means accumulates the moving distance obtained from the distance sensor and the angular displacement obtained from the azimuth sensor to relatively estimate the position of the own device. The satellite distance calculating means calculates the distance between the position of the receiving satellite obtained from the GPS receiver and the position of the own device estimated by the position estimating means. In the multipath detection means,
Obstacle reflection is detected by comparing the propagation time of the signal measured by the GPS receiver with respect to the satellite being received and the distance from the estimated position of the own device to the satellite calculated by the satellite distance calculation means. By performing the position correction using the GPS only when the obstacle reflection is not detected, it is possible to prevent the position correction error from increasing.

The satellite azimuth calculating means calculates the azimuth and elevation of the receiving satellite with respect to the own position calculated by the position estimating means. The multipath detecting means compares the azimuth and elevation of the receiving satellite calculated by the satellite azimuth calculating means with the position and height of an obstacle around the estimated position obtained from the map database, and determines whether the GPS transmission signal can be directly reached. The obstacle reflection is detected by the determination. When the obstacle reflection is detected, the position correction by the GPS is not performed, thereby preventing the position correction from becoming large.

The navigation apparatus of the present invention has the following configuration in order to calculate its own position even when receiving less than three satellites. The candidate position calculation means calculates a candidate position of the own device using the moving distance obtained from the distance sensor and the angular displacement obtained from the azimuth sensor. The position calculating means compares the azimuth and elevation of the receiving satellite with respect to each candidate position calculated by the satellite azimuth calculating means and the position and height of the surrounding obstacle obtained from the map database,
By selecting a candidate to which the transmitted signal can directly reach, it is possible to determine the position without being affected by multipath and by receiving less than three satellites.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is directed to a distance sensor for detecting a moving distance, an azimuth sensor for detecting an angular displacement, a moving distance obtained by the distance sensor, and the azimuth sensor. Position estimating means for relatively calculating the position of the own device using the amount of angular displacement obtained by the above, a GPS receiver for measuring the position of the receiving satellite of the satellite positioning system and the propagation time of the transmitted signal, and the GPS Satellite distance calculating means for calculating a distance from a position of a receiving satellite obtained from a receiver to a position of the own apparatus calculated by the position estimating means; a propagation time of a signal obtained from the GPS receiver and the satellite distance calculating means Multipath detection means for comparing the distance from the estimated position calculated by the satellite to the satellite to detect obstacle reflection of the satellite signal. The sensor measures the amount of angular displacement, the position estimating means calculates its own position relatively using the moving distance obtained by the distance sensor and the amount of angular displacement obtained by the azimuth sensor, and the GPS receiver uses the satellite positioning system. Measuring the position of the receiving satellite and the propagation time of the transmitted signal,
The satellite distance calculating means calculates the distance from the position of the receiving satellite obtained by the GPS receiver to the position of the own apparatus estimated by the position estimating means, and the multipath detecting means calculates G
The obstacle reflection of the satellite signal is detected by comparing the propagation time of the signal obtained from the PS receiver with the distance from the estimated position calculated by the satellite distance calculation means to the satellite.

According to a second aspect of the present invention, in addition to the configuration according to the first aspect, a map database storing road information and a position and a height of a building, and the position estimating means calculates the position. Satellite azimuth calculating means for calculating the azimuth and elevation of the receiving satellite with respect to the own position using the own position and the satellite position measured by the GPS receiver, and the positions of surrounding buildings obtained from the map database; Multipath detection means for detecting the obstacle reflection of the satellite by comparing the height and the azimuth and elevation of the receiving satellite calculated by the satellite azimuth calculation means is provided, and the map database includes road information, road information, and building information. The position and height are stored, and the satellite azimuth calculating means uses the estimated position of the own device calculated by the position estimating means and the satellite position obtained by the GPS receiver to determine the own position. The multipath detecting means compares the azimuth and elevation of the receiving satellite calculated by the satellite azimuth calculating means with the position and height of the obstacle stored in the map database and calculates the satellite signal. Of obstacle reflection is detected.

According to a third aspect of the present invention, in addition to the configuration of the second aspect, a moving distance obtained from the distance sensor, an angular displacement obtained from the azimuth sensor, and obtained from the map database. Position candidate calculating means for calculating a candidate position from road information, and calculating the azimuth and elevation of the satellite with respect to its own position using each candidate position calculated by the candidate position calculating means and the position of the satellite obtained by the GPS receiver Satellite azimuth calculating means, and a candidate position for determining the position of the own apparatus from a plurality of candidates by comparing the azimuth and elevation angle calculated by the satellite azimuth calculating means with the height of the building around the candidate point stored in the map database. The candidate position calculating means includes a moving distance obtained from a distance sensor, an angular displacement obtained from an azimuth sensor, and a map database. One or more candidate positions are calculated using the road information obtained, and the satellite azimuth calculating means uses the candidate position calculated by the candidate position calculating means and the satellite elevation obtained by the GPS receiver to determine the elevation angle of the satellite with respect to each candidate position. The azimuth is calculated, and the candidate position determining means determines the position from a plurality of candidates by comparing the azimuth and elevation calculated by the satellite azimuth calculating means with the height of the building around the candidate position stored in the map database.

An embodiment of the present invention will be described below with reference to FIGS. 1 to 3 and FIGS. 5 to 7.

(First Embodiment) FIG. 1 is a navigation apparatus showing a configuration of a first embodiment of the present invention. The navigation device shown in FIG.
Azimuth sensor 2, position estimating means 3 for estimating the position of the own device from the moving distance and the amount of angular displacement, GPS receiver 4 for measuring the position of a GPS satellite and the signal propagation time of the satellite, and position estimating means 3. Distance calculating means 5 for calculating the distance from the calculated own position to the position of the satellite obtained by the GPS receiver 4
A multipath detecting means 6 for detecting a multipath by comparing the distance from the estimated position of the own device calculated by the distance calculating means 5 to the satellite and the signal propagation time to each satellite obtained by the GPS receiver 4; It is composed of

Next, the operation of the above embodiment will be described with reference to FIG.
Description will be made with reference to (a) and (b). FIG. 5A is an explanatory diagram of the operation of the navigation device when multipath does not occur. The GPS satellites 101, 102, and 103 can receive signals at the estimated position 120 without signal reflection at an obstacle. At this time, the distance from the self-estimated estimated position calculated by the satellite distance detecting means 5 to the satellite i is ri, the signal propagation time of the satellite i obtained from the GPS receiver is Δti, the speed of light is c, the GPS
Assuming that the clock error of the receiver is tu, the following equation (1) holds for the GPS satellites 101, 102, and 103 in FIG. ri = c (Δti−tu) (1) where i is a satellite number set to 101, 102, 103.

Here, the clock error tu of the GPS receiver is represented by each G
The values are the same for PS satellites. Therefore, equation (1)
Holds, the following equation (2) also holds. ri−cΔti = rj−Δtj (2) where i and j are satellite numbers and i ≠ j.

On the other hand, FIG. 5B is a diagram for explaining the operation of the navigation apparatus when the transmission signal of the GPS satellite 101 is reflected by the obstacle 112 and reaches the position of the navigation apparatus. At this time, equation (1) does not hold for the GPS satellite 101.
Therefore, when Ts is set as a threshold value, the multipath detecting means 6 determines that obstacle reflection has occurred when the following equation (3) is satisfied. max ｛ri−cΔti｝ −min ｛rj−Δtj｝> Ts (3) where i and j are satellite numbers and i ≠ j.

When the multipath detecting means 6 detects an obstacle reflection, the position is not corrected by the GPS, or the position is corrected by using a satellite combination that does not satisfy the equation (3). The threshold value Ts can be determined according to the target positioning accuracy.

According to the first embodiment of the present invention, by adopting such a structure, when the own aircraft is located in a place adjacent to a high-rise building, the GPS of the GPS caused by the reflection of obstacles of the signal is used. It is possible to prevent the position correction error from increasing.

In the above description, the case where the position is estimated using the distance sensor 1 and the direction sensor 2 has been described. However, road information in a map database may be used for position estimation, or other sensors may be used. Absent. Also, the case where the number of received GPS satellites is two or more has been described. By calculating the clock error of the GPS receiver using a statistical method, multipath can be detected even when the number of received satellites is one. You may.

(Second Embodiment) FIG. 2 is a navigation device showing a configuration of a second embodiment of the present invention. In the navigation device shown in FIG. 2, in addition to the configuration of the navigation device shown in FIG. 1, the azimuth and elevation of the receiving satellite are determined from the position of the GPS satellite obtained by the GPS receiver 4 with respect to the own position estimated by the position estimating means 3. , And a map database 8 in which road information and the position and height of obstacles are stored. The multipath detecting means 6 calculates the reception satellites calculated by the satellite azimuth calculating means 7. Obstacle reflection is detected by comparing the position and orientation with the position and height of the obstacle obtained from the map database 8.

Next, the operation of the above embodiment will be described with reference to FIG. FIG. 6 shows the position estimated by the position estimation procedure.
FIG. 4 is an explanatory diagram of an operation when a transmission signal of a satellite 201 cannot be directly received in 220. GPS satellites 201, 202,
203 indicates a satellite 220 at a position 220 estimated by the position estimating means 3.
It is possible to directly receive the signals of 2,203. Satellite 20
When one transmission signal passes through the transmission path 2-a, the transmission signal is cut off by the obstacle 211, so that the signal cannot be directly received. However, when the signal of the satellite 201 passes through the transmission path 2-b, it can reach the estimated position 220 by reflecting off the obstacle 212.

In this case, the multipath detecting means 6 compares the satellite position and azimuth calculated by the satellite azimuth calculating means 7 with the positions and heights of obstacles around the position of the own device, and determines the satellite position and the own position. If an obstacle exists on the connecting line segment, it is determined that a multipath has been detected. If a multipath is detected, the position is not corrected by the GPS, or the position is corrected by a satellite combination to which a satellite transmission signal can directly reach.

According to the second embodiment of the present invention, by adopting such a configuration, even when the own aircraft exists in a place adjacent to a high-rise building, the GPS of the GPS caused by the reflection of obstacles of the signal is used. It is possible to prevent the position correction error from increasing.

(Third Embodiment) FIG. 3 is a navigation device showing a configuration of a third embodiment of the present invention. In the navigation device shown in FIG. 3, in addition to the configuration of FIG. 2, one or more units are used by using the travel distance obtained from the distance sensor 1, the angular displacement obtained from the azimuth sensor 2, and the road information stored in the map database 8. Candidate position calculating means 9 for calculating the position candidate of the own device, and comparing each candidate position obtained by the satellite direction calculating means 7 with the position and the direction of the satellite and the position and height of the obstacle stored in the map database 8. And a position determining means 10 for determining the position of the own device.

Next, the operation of the above embodiment will be described with reference to FIG. FIG. 7 is an explanatory diagram of the operation when two own position candidates are created by the received satellite position candidate calculating means 9 when the number of received satellites is two. GPS satellite 30
In 1 and 302, the position candidate calculating means 9 calculates two own position candidates 320 and 321 based on the moving distance obtained from the distance sensor 1 and the angular displacement obtained from the direction sensor 2. Although the number of satellite receptions at both the candidate positions 320 and 321 is two, at the candidate position 321 the signal is reflected on the obstacle 311 and received on the transmission path 3-b. The satellite azimuth calculating means 7 calculates the azimuth and elevation of the receiving satellite with respect to each candidate position, and the position candidate deciding means 9 compares the azimuth and elevation of the satellite with the position and azimuth of the obstacle obtained from the map database 8, and By determining whether or not a signal can be directly received at the candidate position, the candidate position of the own device is determined.

According to the third embodiment of the present invention, by adopting such a configuration, it is possible to determine its own position without being affected by multipath even in a place where high-rise buildings are densely packed. Become. Further, even when the number of received satellites is less than three, the candidate position can be determined.

In the above embodiment, the distance sensor 1
Although the position candidates are calculated using the azimuth sensor 2 and the map database 8, other relative positioning means (for example, a gyro sensor, an acceleration sensor, etc.) may be used for calculating the position candidates.

[0028]

As described above, according to the present invention, the satellite distance calculating means calculates the distance from the position of the satellite obtained from the GPS receiver to the estimated position of the own apparatus calculated by the position estimating means, and performs multipath calculation. The detecting means compares the signal propagation time of the receiving satellite obtained from the GPS receiver with the distance from the satellite position calculated by the satellite distance calculating means to the own position estimation position, and performs position correction by GPS when detecting multipath. Since there is no configuration, there is an effect of preventing a position correction error from increasing due to signal reflection from an obstacle.

Further, a map database and satellite azimuth calculating means are added to the above configuration, the satellite azimuth calculating means calculates the azimuth and elevation of the receiving satellite with respect to the estimated position obtained from the position estimating means, and the multipath calculating means calculates the satellite azimuth. When the multipath is detected by comparing the azimuth and elevation of the receiving satellite calculated by the calculating means with the position and height of the obstacle around the estimated position obtained from the map database, the position is not corrected by GPS when multipath is detected. This has the effect that the position correction error can be prevented from increasing due to the signal reflection from the obstacle.

Further, a position candidate calculating unit and a position candidate determining unit are added to the above configuration, and the position candidate calculating unit calculates a position candidate using the distance obtained from the distance sensor and the angular displacement obtained from the direction sensor. The satellite azimuth calculating means calculates the azimuth and elevation of the receiving satellite with respect to the candidate position, and the position candidate deciding means calculates the azimuth and elevation of the receiving satellite calculated by the satellite azimuth calculating means and the position and height of the obstacle obtained from the map database. Since the configuration is such that the position candidates are determined by comparison, the position candidates can be determined without being affected by the signal reflection of the obstacle, and the position candidates can be determined even when three or less satellites are received. It has the effect that it becomes possible.

[Brief description of the drawings]

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

FIG. 2 is a block diagram showing a configuration of a navigation device according to a second embodiment of the present invention;

FIG. 3 is a block diagram showing a configuration of a navigation device according to a third embodiment of the present invention;

FIG. 4 is a block diagram illustrating a configuration of a conventional navigation device;

FIG. 5 (a) is an explanatory diagram of an operation of the navigation device according to the first embodiment of the present invention when no obstacle reflection of a signal occurs, and FIG. 5 (b) navigation according to the first embodiment of the present invention. Operation explanatory diagram when obstacle reflection of a signal in the device occurs,

FIG. 6 is an operation explanatory diagram of the navigation device according to the second embodiment of the present invention;

FIG. 7 is an explanatory diagram of an operation in the navigation device according to the third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Distance sensor 2 Direction sensor 3 Position estimation means 4 GPS receiver 5 Satellite distance calculation means 6 Multipath detection means 7 Satellite direction calculation means 8 Map database 9 Candidate position calculation means 10 Own device position determination means

Claims (3)

[Claims] 1. A distance sensor for detecting a moving distance, an azimuth sensor for detecting an angular displacement amount, and a position of the own device using a moving distance obtained by the distance sensor and an angular displacement amount obtained by the azimuth sensor. Position estimating means for relatively calculating, a GPS receiver for measuring a position of a receiving satellite of the satellite positioning system and a propagation time of a transmitted signal,
Satellite distance calculating means for calculating a distance from a position of a receiving satellite obtained by a PS receiver to a position of the own apparatus estimated by the position estimating means; a propagation time of a signal obtained from the GPS receiver and calculating the satellite distance A navigation device including a multipath detecting means for detecting obstacle reflection of a satellite signal by comparing a distance from an estimated position calculated by the means to the satellite. 2. A map database in which road information and a position and a height of a building are stored, and a position of a receiving satellite calculated from a satellite position measured by the GPS receiver with respect to a position of the own device calculated by the position estimating means. Satellite azimuth calculating means for calculating the azimuth and the elevation angle, and comparing the height of the surrounding building obtained from the map database and the azimuth and the elevation angle of the receiving satellite calculated by the satellite azimuth calculation means, to obtain the reflection of the obstacle reflection of the satellite. 2. A multi-path detecting means for performing detection.
A navigation device as described. 3. A position candidate calculating means for calculating one or more candidate positions from a moving distance obtained from the distance sensor, an angular displacement obtained from the azimuth sensor, and road information obtained from the map database; Satellite azimuth calculation means for calculating the azimuth and elevation of the satellite for each candidate position calculated by the position calculation means; and azimuth / elevation calculated by the satellite azimuth calculation means and around the candidate points stored in the map database. 3. The navigation apparatus according to claim 2, further comprising candidate position determining means for determining a position when the number of candidates is two or more by comparing the height of the building.