JP4357357B2 - GPS satellite positioning device, positioning method, and navigation device using the same - Google Patents

Description

  The present invention relates to a GPS positioning device for positioning a GPS satellite by receiving a GPS signal from the GPS satellite, and more particularly to setting a positioning range of the GPS satellite.

  The GPS (Global Positioning System) is a system that measures the distance to a satellite by receiving radio waves from a plurality of satellites orbiting the earth and detects the position by a triangular intersection method. Such a position detection system is used in navigation devices and navigation systems such as vehicles, ships, and airplanes that are moving objects.

  In order to perform position detection by GPS, it is necessary to receive radio waves or GPS signals from at least three or more GPS satellites. If three GPS satellites are used, a two-dimensional position (latitude, longitude) can be detected, and if there are four or more, a three-dimensional position (longitude, latitude, altitude) should be detected. Can do.

  In order to improve the position detection accuracy, it is preferable to receive a direct wave from a GPS satellite. However, direct waves from GPS satellites cannot always be received, such as when the elevation angle of GPS satellites is small, or when traveling in urban areas where there are many obstacles such as high-rise buildings. As a result, a signal having a poor state containing a large amount of signal may be received, and as a result, the position accuracy may deteriorate.

  In view of these problems, Patent Document 1 stores the position and height of a main building in map data, determines whether or not a building exists on a line connecting a vehicle and a GPS satellite, and If there is a building, the signal from the satellite is excluded from the positioning target because it is considered to be affected by multipath. On the other hand, when there are four or more satellites having no building on the line, the vehicle position is detected using the positioning results of these satellites.

  Further, Patent Document 2 discloses performing positioning calculation only with a signal from a GPS satellite having a high elevation angle. According to Patent Document 2, the navigation device includes an elevation angle setting means for a user to set an arbitrary elevation angle, and the current state of the mobile object is determined only by radio signals from GPS satellites that are equal to or higher than the elevation angle set by the elevation angle setting means. Positioning calculation is performed.

JP-A-10-253371 JP-A-6-281721

  However, conventional GPS positioning has the following problems. If a GPS receiver can receive signals from at least four GPS satellites, it can perform three-dimensional position detection. However, recent GPS receivers increase the number of channels, and from all observable GPS satellites. The so-called all-in-view method, which uses the above signals for positioning, has become the mainstream. In the case of the all-in-view method, if the radio wave conditions from all GPS satellites are good, the positioning accuracy, that is, the position detection accuracy is improved. On the other hand, if any one GPS signal is bad, the position detection accuracy is deteriorated. Resulting in.

  FIG. 11 is a diagram schematically showing the arrangement of GPS satellites, and FIG. 12 is a table showing the numbers, SNR (S / N ratio), azimuth angle, elevation angle, and reception status of GPS satellites arranged there. It is. In the example shown in the figure, there are six GPS satellite numbers that can be measured: 7, 8, 11, 20, 28, 31. Of these, the SNR of the satellite number 20 is 29 “dB”, and positioning is performed. It cannot be said that it should be a satellite. This is because if such a weak signal with poor radio wave condition is used for positioning, the pseudo distance to the GPS satellite tends to increase, and as a result, the accuracy of the vehicle position deteriorates.

  In general, since a signal with a poor SNR is considered to be affected by multipath due to a building or the like, it can be excluded from a positioning target by the method shown in Patent Document 1. However, in Patent Document 1, it is necessary to store the position and height of the main building in advance, and there is a building on the line connecting the vehicle and the GPS satellite every time the vehicle and the GPS satellite move. It is necessary to determine whether or not, and a certain processing time is required for the calculation. On the other hand, an expensive processing device is required to realize high speed, and the cost is increased.

  Similarly, a signal with a poor SNR is considered to have a low elevation angle of the GPS satellite, and can be excluded from the positioning target by the method shown in Patent Document 2. However, even if the elevation angle value is high, there is a signal with a poor SNR, and it cannot be said that the elevation angle value and the SNR are necessarily in a unique relationship. Therefore, the method of Patent Document 2 does not solve the above problem. It is insufficient. Furthermore, the method of Patent Document 2 always narrows down the positioning range, so that there is a drawback that good positioning cannot be performed due to the positioning of GPS satellites and shielding objects such as surrounding high-rise buildings.

  The present invention solves the above-described conventional problems, and limits the positioning range of the GPS satellite while minimizing the deterioration of positioning accuracy, and uses the GPS satellite positioning method, positioning apparatus, and the same. An object of the present invention is to provide a navigation apparatus.

  A positioning device according to the present invention detects a position of a moving body from a receiving means for receiving a GPS signal from a GPS satellite, a positioning means for positioning a GPS satellite based on the received GPS signal, and a positioning result by the positioning means. Position detection means, discrimination means for discriminating GPS satellites whose positioning should be prohibited from GPS satellites positioned by the positioning means, and elevation angle information and azimuth angle regarding the GPS satellites whose positioning should be prohibited by the discrimination means Storage means for storing information corresponding to the position of the moving body, and a positioning prohibition range is set based on the elevation angle information and azimuth angle information stored in the storage means, and GPS satellites within the set positioning prohibition range are positioned. And positioning control means for controlling the positioning means so as to be excluded from the target.

  A navigation device according to the present invention includes a positioning device having the above-described features, map data storage means for storing map data, a display, and map data from the map data storage means based on the position of the moving body detected by the positioning device. And a display control means for superimposing the position of the moving body on the map data and displaying them on the display.

  Further, according to the present invention, a positioning method for positioning a GPS satellite by receiving a GPS signal from the GPS satellite determines a GPS satellite whose positioning should be prohibited from the GPS satellites that are positioned based on the reception level of the GPS signal. A step, a step of storing elevation angle information and azimuth angle information relating to the determined GPS satellite in association with the position of the moving body, and a positioning prohibition range is set and set based on the stored elevation angle information and azimuth angle information. And the step of controlling the positioning of the GPS satellites so as to exclude the GPS satellites within the positioning prohibited range from the positioning target.

  According to the positioning device and the positioning method of the present invention, a GPS satellite that should be prohibited from positioning is determined from the positioning GPS satellites, and the elevation angle information and the azimuth angle information regarding the GPS satellite are associated with the position of the moving object. The positioning prohibited range is set based on the stored elevation angle information and azimuth angle information, and GPS satellites within this positioning prohibited range are excluded from positioning targets, so that the deterioration of positioning accuracy of GPS satellites is minimized. Thus, the position detection accuracy can be improved. Further, since the positioning prohibition range is set based on the azimuth angle information and the elevation angle information stored in the storage means, the processing time can be shortened and high-speed positioning control according to the moving speed of the moving body can be realized. Furthermore, also in the navigation apparatus according to the present invention, the vehicle position mark can be accurately drawn on the map screen on the display.

  The positioning device according to the present invention is preferably implemented in a navigation device for a moving body such as a vehicle or a ship equipped with a GPS receiver. Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram showing a configuration of a GPS receiver according to an embodiment of the present invention. In the figure, a GPS receiver 1 measures the distance to a GPS satellite based on an RF receiver 12 that receives a GPS signal from a GPS satellite via an antenna 10 and a GPS signal received by the RF receiver 12. The positioning calculation unit 14, the position detection unit 16 that detects the position of the moving body based on the positioning result measured by the positioning calculation unit 14, and the positioning calculation result and the position detection result are received from the positioning calculation unit 14 and the position detection unit 16, The controller 18 includes a control unit 18 that controls reading and writing to the storage device 24 and controls the positioning calculation unit 14 based on information from the storage device 24, and a storage device 24 that stores orbit information of GPS satellites.

  The GPS signal emitted from the GPS satellite includes almanac data including orbit information related to the GPS satellite, ephemeris data including accurate orbit information of each satellite and time information when the signal is emitted, and these are encoded in a predetermined format. Has been. The RF receiver 12 decodes the received GPS signal and outputs it to the positioning calculator 14.

  The positioning calculation unit 14 measures the distance of the GPS satellite based on the decoded GPS signal. The measured data is supplied to the position detector 16 where the current position of the moving body is detected.

  The control unit 18 includes a discrimination control unit 20 and a positioning control unit 22. The discrimination control unit 20 discriminates whether or not there is a GPS satellite that should be prohibited from positioning (hereinafter referred to as a positioning prohibited satellite) among the GPS satellites measured by the positioning calculation unit 14. When it is determined that there is a positioning-prohibited satellite, the elevation angle and azimuth angle related to the GPS satellite are stored in the storage device 24. In this embodiment, when the GPS signal reception level is a predetermined value, for example, 30 dB or less, it is determined that the satellite is a positioning prohibited satellite. For example, taking FIG. 12 as an example, since satellite number 20 is 29 dB, this is determined to be a positioning prohibited satellite. Note that satellites determined as positioning prohibited satellites are also excluded from positioning targets.

  FIG. 2 shows an example of storing the azimuth and elevation angles of GPS satellites in the storage device 24. If it is determined that the satellite is a positioning-prohibited satellite, the determination control unit 20 has an azimuth angle F (F1, F2... Fn) and an elevation angle G related to the GPS satellite at a certain time interval T (T1, T2... Tn). (G1, G2,... Gn) are stored in the storage device 24. Information on these azimuth angle F and elevation angle G is stored in correspondence with the position M (latitude, longitude) of the moving object detected by the position detector 16.

  The positioning control unit 22 sets a positioning prohibition range based on the information on the azimuth angle F and the elevation angle G stored in the storage device 24, and the positioning calculation unit 14 so as to exclude GPS satellites existing in this range from positioning. To control.

  The storage device 24 is preferably composed of a readable / writable semiconductor memory, a hard disk, or the like, and the controller 18 controls the reading / writing thereof.

  Next, the operation of the GPS receiver of this embodiment will be described with reference to the flowchart of FIG. A signal from the GPS satellite is received by the RF receiver 12, and positioning calculation unit 14 starts positioning of the GPS satellite. The discrimination control unit 20 checks whether or not a signal with an SNR of 30 dB or less is included in the signal level of the GPS signal that is a positioning target in the positioning calculation unit 14 (step S101).

  When a signal of 30 dB or less is included, the determination control unit 20 determines that the GPS satellite of the signal is a positioning prohibited satellite (step S102). At the same time, the positioning control unit 22 controls the positioning calculation unit 14 so as to prohibit or exclude positioning of GPS satellites that are determined to be positioning-prohibited satellites. There may be a plurality of positioning-prohibited satellites, but preferably, positioning of at least four GPS satellites is possible in order to enable three-dimensional position detection. If the number of positioning-prohibited satellites is set to be less than 4 by using multiple positioning-prohibited satellites, a satellite having a poor SNR is preferentially prohibited from among the multiple positioning-prohibited satellites, so that 4 satellites remain. To.

  The positioning calculation unit 14 does not perform positioning of GPS satellites determined to be positioning prohibited, but receives orbit information about the GPS satellites from the RF receiving unit 12. Then, the discrimination control unit 20 stores the azimuth angle and elevation angle related to the positioning prohibited satellite in the storage device 24 (step S103). Further, the discrimination control unit 20 stores the position M of the moving body detected by the position detection unit 16 in the storage device 24 in association with the azimuth angle and elevation angle of the satellite (step S104).

  For example, in the arrangement of the GPS satellites shown in FIG. 4, when the satellite number 20 is determined as a positioning-prohibited satellite, the azimuth angle F and elevation angle G with respect to the satellite number 20 together with the position M of the mobile object are shown in FIG. Remembered.

  When a predetermined time t has elapsed since the storage in the storage device 24 (step S105), the discrimination control unit 20 determines whether the SNR of the positioning prohibited satellite is greater than 30 dB or the positioning prohibited satellite can be positioned. Is determined (step S106). If the SNR is 30 dB or less, the azimuth angle F, the elevation angle G, and the position M are continuously stored in the storage device 24 (steps S103 and S104). At this time, the time T stored in the storage device 24 has passed a fixed time t from the previous time.

  On the other hand, when the SNR becomes larger than 30 dB or when the signal cannot be measured, the positioning prohibition is canceled and the storage of the azimuth and elevation angles related to the positioning prohibited satellite is ended (step S107). . When there are other positioning-prohibited satellites, the processing from step S103 is repeated, and when there are no positioning-prohibited satellites, the position storage of the moving body is terminated (steps S108 and S109).

  Next, the positioning operation when the moving body moves again in the vicinity of the position (point) stored in the storage device 24 will be described with reference to the flowchart of FIG. The position is detected by the position detector 16 in accordance with the movement of the moving body (step S201). The positioning control unit 22 compares the position detected by the position detection unit 16 (hereinafter referred to as detection position D) with the position stored in the storage device 24 (hereinafter referred to as storage position M). Then, it is determined whether or not it is in the vicinity of the storage position M (step S202). For example, as shown in FIG. 6, the X and Y coordinates of the storage position M are (Mx, My), the X and Y coordinates of the detection position D are (Dx, Dy), and within the distance of the radius R of the storage position M. If there is a detection position D, it is determined to be the periphery, and if it is outside the distance of the radius R, it is determined not to be the periphery.

（σｇ：仰角の範囲考慮値、σｆ：方位角の範囲考慮値） When there is a detection position D around the storage position M, the positioning control unit 22 reads the azimuth angle F and elevation angle G corresponding to the storage position M from the storage device 24 (step S203), and positioning using the detection position D as a reference. A prohibited range is set (step S204). For example, the azimuth angle at the storage position Mp is Fp, the elevation angle is Gp, and the azimuth angle Fdp and elevation angle Gdp at the detection position Dp are set as follows.

(Σg: Elevation angle range consideration value, σf: Azimuth angle range consideration value)

  σg and σf have a certain range in elevation angle and azimuth. This is because it is necessary to consider this because the detection position D always changes when the moving body moves. In particular, since the change in the detection position D has a large effect on the azimuth angle, ± σp is set around Fp. Further, the magnitude of σg and σf is assumed to be 30 dB or less if the signal is from a GPS satellite within a certain range, assuming that the moving body is stationary in addition to the speed of the moving body. Consideration is also taken into account.

  For example, if the GPS satellite number 20 shown in FIG. 4 is determined to be a positioning-prohibited satellite, a positioning-prohibited range as shown in FIG. 7 is set when the mobile body moves around the storage position M. .

  The positioning control unit 22 notifies the positioning calculation unit 14 of the positioning prohibited range, that is, the information of the expressions (1) and (2) (step S205). In response to the positioning prohibition range, the positioning calculation unit 14 excludes GPS signals included in the positioning prohibition range from positioning from the signal received from the RF reception unit 12 (step S206). And the positioning result of the positioning calculation part 14 is supplied to the position detection part 16, and the present position of a moving body is detected there.

  When the detection position D is moved away from the vicinity of the storage position M due to the movement of the moving body (step S207), the positioning control unit 22 instructs the positioning calculation unit 14 to cancel the positioning prohibited range (step S208). ). Further, the positioning control unit 22 determines whether or not the detection position D of the moving body is around the other storage position M, and when it comes to the periphery of the other storage position M, the above step The processing from S203 is performed (step S209).

  As a result, positioning-prohibited satellites that adversely affect positioning calculations are detected during GPS positioning, and the positioning-prohibited range is set based on this, so noise such as multipath signals can be removed and positioning accuracy can be improved. It is. In addition, by determining the positioning range of the GPS satellites according to the position of the moving body (vehicle), it is not necessary to detect GPS satellites that adversely affect the positioning calculation when moving the same position again. It leads to shortening of processing time.

  In the first embodiment, the positioning-prohibited satellite is discriminated using the criterion that the SNR of the received signal is 30 dB. However, the discriminating method is not limited to this. For example, a GPS satellite having the worst SNR among GPS signals received by the RF receiver 12 can be set as a positioning prohibited satellite.

  Alternatively, a GPS signal history may be stored, a signal having a large variation or dispersion in the SNR of the received signal may be monitored, and this satellite may be a positioning prohibited satellite. FIG. 8 is a graph showing the fluctuations of SNRs of received signals accumulated for a certain period (T1 to T5) for satellites A and B. The SNR fluctuation is checked, and the GPS satellite having the largest fluctuation value (Vmax) can be determined as a positioning prohibited satellite. Alternatively, when the fluctuation value (Vmax) is greater than or equal to a predetermined value, the GPS satellite may be a positioning prohibited satellite.

  Furthermore, in the first embodiment, when a positioning-prohibited satellite is determined, the azimuth angle and elevation angle of the satellite are sampled at regular intervals. However, the present invention is not limited to this. For example, the azimuth angle and the elevation angle may be sampled every time the moving body moves a certain distance from the position information of the moving body detected by the position detection unit 16. That is, you may make it memorize | store an azimuth and an elevation angle so as to correspond to the movement locus | trajectory of a mobile body.

  Next, a second embodiment of the present invention will be described. In the second embodiment, the GPS receiver 1 according to the first embodiment is applied to an in-vehicle navigation device, and this configuration is shown in FIG. The in-vehicle navigation device 100 includes a GPS receiver 1 according to the first embodiment, a self-contained navigation sensor 110 including a vehicle speed sensor, a gyro sensor, and the like, an operation input unit 120 that inputs an instruction from a user, and the Internet. For example, a communication control unit 130 for acquiring map data and traffic information from a server, a storage unit 140 for storing map data and the like necessary for navigation, and an audio output for outputting audio from the speaker 152 The unit 150 includes a display control unit 160 for drawing a map or the like on the display 162, and a navigation control unit 170 for controlling each of these units.

  The navigation control unit 170 reads out map data corresponding to the vehicle position from the storage unit 140 based on the position detection result from the position detection unit 16 of the GPS receiver 1 and causes the display 162 to display the map data. At the same time, a mark indicating the position of the vehicle is drawn on the map screen of the display.

  By applying the GPS receiver according to the first embodiment to a navigation device, for example, as shown in FIG. 9, when a positioning-prohibited satellite is determined, the azimuth angle and elevation angle for the satellite are determined for each intersection ( (C1, C2, C3, C4...) May be stored. When the host vehicle 200 travels again on the same route, the positioning prohibition range can be set based on the azimuth angle and elevation angle stored for each intersection. Furthermore, when the search route R to the destination is determined, a positioning prohibition range based on the azimuth angle and the elevation angle at the intersection on the route may be set in advance.

  In addition to intersections, azimuths and elevations are sampled on a specific route at regular distances or at regular intervals of latitude and longitude, or sampled at specific targets or municipal boundaries. It is also possible. Further, when the vehicle is traveling on an expressway, the azimuth angle and elevation angle of the positioning prohibited satellite may be stored for each service area or interchange by referring to the map data.

  Thereby, in the area where the host vehicle once traveled, the positioning prohibition range is set, so that the positioning accuracy can be improved and the processing for that can be performed in a short time. This is particularly effective when the vehicle moves at a high speed such as an expressway.

  By applying the GPS receiver of this embodiment to the navigation device, GPS satellites with poor radio wave conditions that are affected by multipaths are excluded from positioning targets, and errors in positioning accuracy by the GPS receiver are minimized. can do. As a result, the vehicle position can be accurately displayed on the map screen, and the route guidance can be performed more accurately.

  The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific embodiments, and various modifications can be made within the scope of the gist of the present invention described in the claims. Deformation / change is possible.

  In the above-described embodiment, an example in which the GPS receiver is applied to an in-vehicle navigation device has been described. However, the present invention is not limited to this and can be applied to a navigation device such as a ship or an aircraft.

  The GPS satellite positioning device according to the present invention is preferably widely used in a GPS receiver, a navigation device using the GPS receiver, a navigation system, an electronic device having a navigation function, and the like.

It is a block diagram which shows the internal structure of the GPS receiver which concerns on 1st Example of this invention. It is a storage example of a storage device. It is a flowchart explaining operation | movement of the GPS receiver which concerns on a 1st Example. It is a figure which shows a positioning prohibition satellite in arrangement | positioning of a GPS satellite. It is a flowchart explaining the positioning operation | movement when a moving body moves the position vicinity memorize | stored in the memory | storage device. It is a figure which shows the example of determination of whether it is the periphery of a memory | storage location. It is a figure which shows the example of a setting of a positioning prohibition range. It is a figure which shows the fluctuation | variation of SNR of a GPS satellite. It is a block diagram which shows the structure of the navigation apparatus to which the GPS receiver of a 1st Example is applied. It is a figure explaining the positioning example in a navigation apparatus. It is an arrangement plan of GPS satellites. It is a table | surface which shows the reception state of the signal from the GPS satellite shown in FIG.

Explanation of symbols

1: GPS receiver 10: Antenna 12: RF receiver 14: Positioning calculation unit 16: Position detection unit 18: Control unit 20: Discrimination control unit 22: Positioning control unit 24: Storage device 100: Navigation device 170: Navigation control unit

Claims (12)

A positioning device mounted on a moving body,
Receiving means for receiving GPS signals from GPS satellites;
Positioning means for positioning a GPS satellite based on the received GPS signal;
Position detecting means for detecting the position of the moving body from the positioning result by the positioning means;
When the number of GPS satellites that can be measured by the positioning means exceeds a certain level, if the GPS satellites that can be positioned satisfy a certain condition, the GPS satellite that satisfies the certain condition is determined as a GPS satellite that should be prohibited from positioning. Discriminating means to perform,
Storage means for storing elevation angle information and azimuth angle information related to GPS satellites determined to be positioning prohibited by the determination means in association with the position of the moving body;
The detected position of the moving body detected by the position detecting means and the storage position of the moving body stored in the storage means are compared, and when the detected position is within a certain range of the storage position, the elevation angle information stored in the storage means A positioning control means for setting a positioning prohibition range based on the azimuth angle information and controlling the positioning means so as to exclude GPS satellites within the set positioning prohibition range from positioning targets;
A positioning device having The positioning device according to claim 1, wherein the determining means selects a GPS signal having the lowest reception level from a plurality of GPS signals, and determines this as a GPS satellite that should be prohibited from positioning. The positioning device according to claim 1, wherein the determining means determines that a GPS signal having a reception level equal to or lower than a predetermined value is a GPS satellite whose positioning is prohibited. The positioning device according to claim 1, wherein the determining means determines that the GPS signal reception level variance or fluctuation is the largest as a GPS satellite that should be prohibited from positioning. The positioning device according to claim 1, wherein the determining unit determines that a GPS satellite whose reception level dispersion or fluctuation is equal to or greater than a predetermined value is a GPS satellite whose positioning is prohibited. The positioning device according to claim 1, wherein the storage unit stores elevation angle information and azimuth information of GPS satellites whose positioning should be prohibited at regular intervals. The positioning device according to claim 1, wherein the storage unit stores elevation angle information and azimuth information of GPS satellites whose positioning should be prohibited every time the moving body moves a certain distance. The positioning device according to claim 1, wherein the positioning prohibited range is a three-dimensional space defined by an azimuth angle range and an elevation angle range with reference to the detection position of the moving body. A positioning device according to any one of claims 1 to 8 ,
Map data storage means for storing map data;
Display,
Display control means for reading out map data from the map data storage means based on the position of the moving body detected in the positioning device, and overlaying the position of the moving body on the map data, and displaying them on the display;
A navigation device. A positioning method for positioning a GPS satellite by receiving a GPS signal from a GPS satellite using a positioning device mounted on a moving body ,
If others positioning GPS satellites is more constant in the positioning device, when the positioning GPS satellites satisfy certain conditions, as a GPS satellite should be prohibited positioning the GPS satellites which satisfies the predetermined condition A step of determining;
Storing elevation angle information and azimuth angle information relating to GPS satellites determined to be prohibited from positioning in correspondence with the detection position of the moving object;
Compare the detected position of the moving object with the stored position of the moving object, and set the positioning prohibition range based on the stored elevation angle information and azimuth angle information when the detected position is within a certain range of the stored position. Controlling the positioning of the GPS satellites so as to exclude the GPS satellites within the set positioning prohibited range from the positioning target;
A positioning method having The positioning method according to claim 10 , wherein the determining step selects a GPS signal having the lowest reception level from a plurality of GPS signals, and determines this as a GPS satellite that should be prohibited from positioning . The positioning method according to claim 10, wherein the determining step determines that the GPS signal reception level is equal to or lower than a predetermined value as a GPS satellite whose positioning is prohibited .

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