JP2003149318A - Navigation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a large error to be generated in a navigation device even when radio waves from artificial satellites are received by a multi-path propagation. SOLUTION: CPU 91 calculates autonomous navigation data and GPS navigation data (S100-S120). If a combination of GPS satellites used in the calculation of the GPS navigation data is identical to the combination used in the previous calculation, differences of present location, moving direction, and moving velocity of an own automobile between the autonomous navigation data and the GPS navigation data are respectively calculated to check each difference is within a range of the predetermined values (S130-S190). When any of the differences exceeds the predetermined value, it is prohibited to correct the autonomous navigation data according to the GPS navigation data (No: S150, S170, S190). The navigation data is determined by performing map matching processing on the uncorrected autonomous navigation data, and a CRT controller 8 is instructed to display the navigation data (S210 and S220).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a navigation device mounted on a moving body and calculating the position, moving direction, moving speed, etc. of the moving body.

[0002]

2. Description of the Related Art Conventionally, the current position, moving direction, moving speed, etc. of the own vehicle have been calculated, and the current position, moving route, etc. of the own vehicle are displayed together with a map on a display installed in the driver's seat. Then, a navigation device for guiding the driver to the destination has been developed.

Generally, a navigation device detects a moving direction and a moving speed of the own vehicle by using a speed sensor, a direction sensor and the like mounted on the own vehicle, and detects the moving direction and the moving speed of the own vehicle from the moving direction and the moving speed. The so-called autonomous navigation has been widely used in which the moving distance is calculated and the current position of the vehicle is grasped based on these detected values and calculated values and map data stored in advance in the navigation device. However, since autonomous navigation calculates the next current position starting from the current position of the vehicle that was calculated last time, the moving direction and movement detected using the sensor may change due to the characteristics of the sensor itself, disturbances that act on the vehicle, etc. If an error occurs between the speed and the actual moving direction or moving speed of the own vehicle, the error between the current position of the own vehicle calculated by the navigation device and the actual current position of the own vehicle is accumulated. There was a problem that it would end up.

Therefore, with the generalization of surveys using radio waves (hereinafter referred to as "GPS radio waves") transmitted from GPS (Global Positioning System) satellites arranged on a predetermined orbit of the earth, GPS satellites Is used to calculate the current position, moving direction, and moving speed of the vehicle.
GPS navigation has come to be used in navigation devices.

A navigation device using GPS navigation stores orbital data of all GPS satellites, and can always grasp the coordinates of all GPS satellites. For this reason, three or four GPS radio waves are selected from the GPS radio waves received from a plurality of GPS satellites, and a signal superimposed on the selected GPS radio waves (hereinafter referred to as "GPS
Signal. ) Is used to calculate the distance (pseudo distance) from each source GPS satellite to the own vehicle, and the coordinates of the own vehicle can be calculated by triangulation. Then, the navigation device using GPS navigation calculates the current position, moving direction, and moving speed of the own vehicle based on the calculated coordinate data. However, in addition to the method of calculating the moving speed and the moving direction of the own vehicle based on the coordinate data, the frequency shift due to the Doppler effect generated in the received GPS radio wave is measured, and based on this, the vehicle A method of calculating the moving speed and the moving direction is also used.

Unlike the autonomous navigation, the GPS navigation does not use the previous current position of the own vehicle as a reference and measures the coordinates of the own vehicle at any time, and therefore has the advantage that no error is accumulated.
However, a navigation device using GPS navigation cannot receive GPS radio waves in a place where radio waves from the outside are blocked, such as in a tunnel. There was a problem that the position, moving direction, and moving speed could not be grasped.

Therefore, in recent years, a so-called hybrid navigation device has been developed which uses both autonomous navigation and GPS navigation. The hybrid type navigation device uses the GPS at a place where GPS radio waves can be received.
Based on the current position, moving direction, and moving speed (hereinafter referred to as "GPS data") of the vehicle calculated by navigation, the current position, moving direction, and moving speed of the vehicle detected or calculated by autonomous navigation (hereinafter, “Autonomous navigation data”) is corrected, while in a place where GPS radio waves cannot be received, the current position, moving direction, and moving speed of the vehicle are calculated using only autonomous navigation.

For this reason, it becomes possible to calculate the current position, moving direction, and moving speed of the vehicle even if GPS radio waves cannot be received in addition to the accumulation of errors.

[0009]

However, as shown in FIG. 3, in a city where tall buildings and the like are lined up, GPS radio waves transmitted from GPS satellites do not reach the receiving antenna of the navigation device directly, but are self-contained. There is a case where so-called multipath propagation occurs in which the light reaches a receiving antenna after being reflected by a building or the like existing around the vehicle. In this case, in the above-mentioned hybrid type navigation device, the autonomous navigation data is corrected based on the GPS data affected by the multipath propagation, so that the driver is provided with information having a large error. was there.

That is, when multipath propagation occurs, G
Since the propagation distance of the radio wave received from the PS satellite is longer than in the normal time when the multipath propagation does not occur, a large error occurs in the GPS data calculated using the GPS radio wave in which the multipath propagation has occurred. Of. In particular, when the frequency deviation occurring in the received GPS radio wave is measured to calculate the moving speed and the moving direction of the vehicle, for example, the GPS radio wave transmitted from the rear of the vehicle is multi-path. When the vehicle is received from the front of the vehicle due to path propagation, the received GPS radio wave has a frequency shift opposite to the original frequency deviation, which may cause an error in the moving speed and the moving direction of the vehicle. there were.

Therefore, in order to solve the above-mentioned problems, it is an object of the present invention to provide a navigation device which does not generate a large error even when receiving the radio waves of an artificial satellite which propagates multipath. .

[0012]

A navigation device according to claim 1, which is an invention for achieving the above object,
The direction detecting means detects the moving direction of the moving body, and the speed detecting means detects the moving speed of the moving body. Then, the position calculating means calculates the position of the moving body based on the inputs from the direction detecting means and the speed detecting means. In addition, the satellite radio wave receiving means receives radio waves transmitted from a plurality of artificial satellites,
The positioning data calculation means calculates the positioning data of the mobile body based on the signal superimposed on the radio wave received by the satellite radio wave reception means. Then, the correcting means, based on the positioning data calculated by the positioning data calculating means, the moving direction of the moving body detected by the direction detecting means, the moving speed of the moving body detected by the speed detecting means, and the movement calculated by the position calculating means. At least one of the body positions is corrected.

However, at least one of the moving direction of the moving body detected by the direction detecting means, the moving speed of the moving body detected by the speed detecting means, and the position of the moving body calculated by the position calculating means, and the positioning data. On the basis of the positioning data calculated by the calculating means, the multipath propagation determining means determines that the radio wave received by the satellite radio wave receiving means is a multipath propagated radio wave, and the correction inhibiting means,
The correction by the correction means is prohibited.

Therefore, according to the navigation device of the present invention, when the multipath propagation determination means determines that the radio wave received from the artificial satellite is the radio wave propagated by the multipath, the moving direction of the moving body detected by the direction detection means. Also, since the moving speed of the moving body detected by the speed detecting means and the position of the moving body calculated by the position calculating means are not corrected, a large error is generated even when receiving the radio waves of the multipath-propagated artificial satellite. Never.

When the positioning data includes at least the position of the moving body, the multipath propagation determining means is
As in the navigation device according to claim 2, when the difference between the position of the mobile body calculated by the position calculating means and the position of the mobile body included in the positioning data is larger than a preset threshold value, A first radio wave received by the satellite radio wave reception means is determined to be a multipath-propagated radio wave
It is desirable to have the determination means of.

That is, when the radio wave from the artificial satellite propagates in multiple paths, the propagation path of the radio wave from the artificial satellite to the moving body becomes longer than the normal propagation path in which the multipath does not propagate. The position of the moving body
If the difference from the position of the moving body included in the positioning data is larger than the difference that can occur at normal times, it can be determined that the satellite radio wave reception means has received the radio waves propagated by multipath.

Therefore, if the multipath propagation determination means is configured as in the navigation device according to the second aspect, it is determined whether the radio waves from the artificial satellite received by the satellite radio wave reception means are multipath propagated radio waves. It can be easily determined. When the positioning data includes at least the moving direction of the moving body, the multipath propagation means
As in the navigation device according to claim 3, when the azimuth difference between the moving azimuth detected by the azimuth detecting means and the moving azimuth included in the positioning data is larger than a preset azimuth difference threshold, satellite radio wave reception is performed. Second determining that the radio wave received by the means is a multipath-propagated radio wave
It is desirable to have the determination means of.

If the propagation path of the radio wave becomes longer than the normal time due to the multipath propagation, if the positioning data calculation means calculates the moving direction of the moving body based on the length of the propagation path of the received radio wave, the calculation is performed. The azimuth difference between the moving azimuth of the moving body detected by the azimuth detecting means and the moving azimuth of the moving body included in the positioning data is also larger than the azimuth difference that can occur in normal times.

When the positioning data calculating means calculates the moving direction of the moving body by measuring the frequency deviation generated in the received electric wave, for example, the electric wave transmitted from the rear of the moving body. However, if it is received from the front of the moving body due to multipath propagation, the received radio wave will have a frequency shift opposite to the original one, so the movement of the moving body detected by the azimuth detection main means will be detected. The azimuth difference between the azimuth and the moving azimuth of the moving body calculated by the positioning data calculation means is larger than the azimuth difference that can occur during normal times.

Therefore, if the multipath propagation means is configured as in the navigation device according to the third aspect, it is easy to determine whether the radio waves from the artificial satellite received by the satellite radio wave reception means are multipath propagated radio waves. Can be determined. Further, when the positioning data includes at least the moving speed of the moving body, the multi-path propagating means includes the moving speed detected by the speed detecting means and the positioning data as in the navigation device according to claim 4. Third determining means for determining that the radio wave received by the satellite radio wave receiving means is a multipath-propagated radio wave when the speed difference from the included moving speed is larger than a preset speed difference threshold value. It is desirable to have

That is, as in the case of the navigation device according to the third aspect, even if the positioning data calculating means calculates the moving speed of the moving body based on the length of the propagation path of the received radio wave, the positioning data calculating means receives the moving signal. Even if the moving speed of the moving body is calculated based on the frequency deviation generated in the radio wave, the speed difference between the moving speed of the moving body and the moving speed of the moving body detected by the speed detecting means is larger than the speed difference that can occur at normal times. growing.

Therefore, if the multipath propagation determination means is configured as in the navigation device according to the fourth aspect, it is determined whether the radio waves from the artificial satellite received by the satellite radio wave reception means are multipath propagated radio waves. It can be easily determined. It should be noted that in the navigation device according to claim 5, the combination specifying means is an artificial source which is a transmission source of radio waves used for calculation of positioning data based on a signal superimposed on the radio waves received by the satellite radio wave receiving means. Identify satellite combinations. Then, when the combination specified by the combination specifying means is a combination different from the previous time calculated by the positioning data calculating means, the judgment prohibiting means prohibits the judgment by the multipath propagation judging means.

That is, according to the navigation device of the present invention, the multipath propagation determining means receives the radio wave from the artificial satellite based on the deviation of the positioning data caused by the combination of the artificial satellites used for calculating the positioning data. It is possible to prevent erroneous determination that the radio wave is a multipath-propagating radio wave.

The radio waves received from a plurality of artificial satellites are the same as those of the navigation device according to claim 6.
It is desirable to use radio waves transmitted from PS satellites.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration block diagram of a navigation device according to the present invention. As shown in FIG. 1, the navigation device 1 according to the present embodiment includes a VICS receiver 2 that receives road traffic information transmitted from a traffic information center.
A GPS receiver 3 for receiving GPS radio waves, a vehicle speed sensor 4 for detecting the moving speed of the own vehicle, a direction sensor 5 for detecting the moving direction of the own vehicle, and map data such as topography and road shape are stored. Map memory 6 and the navigation device 1
An operation interface (for example, a key switch) 7 for inputting destination position information and commands, and a CRT controller 8 for performing screen display processing on a display (not shown) equipped in the navigation device 1.
And the current position, moving direction, moving speed (hereinafter, referred to as “navigation data”) of the own vehicle, and the like are calculated based on the input from each unit configuring the navigation device 1, and the calculation result is sent to the CRT controller 8. It is composed of an arithmetic unit 9 for outputting.

The arithmetic unit 9 is a CPU 91 for calculating navigation data and controlling each unit of the navigation device 1.
And a ROM 92 that stores the program executed by the CPU 91 and the data transferred from the CPU 91 and each unit of the navigation device 1 and supplies the program and data to the CPU 91 and each unit of the navigation device 1 as necessary. The RAM 93 includes an input / output circuit 94 that mediates between the arithmetic unit 9 and each unit of the navigation device 1.

Here, the CPU 91 is adapted to select four GPS radio waves out of a plurality of GPS radio waves received by the GPS receiver 3 and calculate GPS navigation data using the selected GPS radio waves. However, the current position of the own vehicle is calculated based on the coordinates of the own vehicle obtained by triangulation from the pseudo distance between the GPS satellite, which is the transmission source of each GPS radio wave, and the own vehicle. And the moving speed are set to be calculated based on the frequency shift occurring in the selected GPS radio wave. In addition, an identification signal indicating which GPS satellite is the transmission source of the GPS radio wave is inserted in the GPS signal superimposed on the GPS radio wave, and the CPU 91 detects the GPS radio wave received based on the identification signal. Recognize each sender. And RO
Since M92 stores the orbital data of all GPS satellites, the CPU 91 grasps the coordinates of each GPS satellite based on the orbital data, and forms the largest distance from each other when viewed from the own vehicle. The GPS radio waves transmitted from the four GPS satellites are set to be used for GPS navigation data calculation.

Hereinafter, the CPU 91 of the navigation device 1
The flow of the navigation data calculation process carried out by will be described in detail with reference to the flowchart shown in FIG. However, when the navigation device 1 is activated, the CPU 91 immediately calculates the current position of the vehicle using GPS radio waves and sets the calculated current position as the first starting point in the autonomous navigation (initialization setting). The flowchart of FIG. 2 shows the flow of processing after initialization setting.

As shown in FIG. 2, when the initialization setting is completed, the CPU 91 first calculates the autonomous navigation data based on the inputs from the vehicle speed sensor 4 and the direction sensor 5 (S100). Then, when the calculation of the autonomous navigation data is completed, the CPU 91 confirms whether the GPS receiver 3 receives GPS radio waves (S110). Here, when it is confirmed that the GPS receiver 3 has received the GPS radio wave, the CPU 9
1 calculates GPS navigation data (S120).

When the calculation of GPS navigation data is completed, C
PU91 is the GP used for the previous GPS navigation data calculation.
All the GPs used for the GPS navigation data calculation this time by reading the identification signal inserted in the S signal from the RAM 93.
Compared with the identification signal inserted in the S signal, this GP
The combination of GPS satellites used to calculate S navigation data is
It is confirmed whether the combination is the same as the combination of GPS satellites used for the previous GPS navigation data calculation (S130).

When it is confirmed that the combination is the same, the CPU 91 calculates the difference between the current position of the own vehicle in the autonomous navigation data and the current position of the own vehicle in the GPS navigation data (S140). Then, if the absolute value of the difference between the current positions is smaller than a predetermined value (200 m in the present embodiment) (Yes: S150), the CPU 91 causes the moving direction of the own vehicle in the autonomous navigation data and the own vehicle in the GPS navigation data. The azimuth difference from the moving azimuth is calculated (S160).

Here, if the absolute value of the azimuth difference is also smaller than the predetermined value (45 degrees in the embodiment) (Yes: S17).
0), the CPU 91 further calculates the speed difference between the moving speed in the autonomous navigation data and the moving speed in the GPS navigation data (S180). If the absolute value of the speed difference is also smaller than the predetermined value (180 km / h in the present embodiment) (Yes: S190), the CPU 91 determines that the received GPS radio wave is not multipath-propagated, and G
The autonomous navigation data is corrected based on the PS navigation data (S200).

When the correction of the autonomous navigation data is completed, the CP
U91 reads the map data stored in the map memory 6 into the CPU 91, and performs map matching processing on the autonomous navigation data to determine the navigation data (S210). Then, the determined navigation data is output to the CRT controller 8 and an instruction is issued to display the current position of the own vehicle, the moving route, etc. on the display together with the map (S220).

If it is confirmed in S110 that the GPS receiver 3 is not receiving GPS radio waves,
The CPU 91 immediately shifts the processing to S210 and S220, determines the navigation data by performing map matching processing on the autonomous navigation data which is not corrected based on the GPS navigation data, and outputs the determined navigation data to the CRT controller 8. Then, an instruction is given to display the current position of the vehicle, the moving route, etc. on the display together with the map.

Further, in S130, the combination of the GPS satellites used for the current GPS data calculation and the previous GP
When the combination of GPS satellites used for calculating the S navigation data is different, the CPU 91 immediately executes the process.
The process proceeds to 200 to S220, and the execution of the multipath propagation determination processing (S140 to S190) is prohibited.

Further, in S150, 170 and 190,
If any one of the current position difference, the bearing difference, and the speed difference exceeds the predetermined value, the CPU 91 determines that the multipath-propagated GPS radio wave has been received, and immediately executes the process.
The process proceeds to 210 and S220, and the correction of the autonomous navigation data based on the GPS navigation data affected by the multipath propagation is prohibited.

Through the above processing, the navigation device 1
Calculates navigation data, detects multipath propagation, and when multipath propagation is detected, GP
The correction process of autonomous navigation data based on S navigation data is prohibited. Therefore, the navigation device 1 can provide the driver with highly accurate information such as the current position without generating a large error even when receiving the GPS radio waves propagated by multipath.

Further, since the multipath propagation is determined by verifying all the differences between the current position, the moving direction, and the moving speed in the autonomous navigation data and the GPS navigation data, the accuracy of multipath propagation detection is high. Further, when the combination of GPS satellites used for calculating the GPS navigation data is switched, execution of the determination processing of multipath propagation is prohibited. Therefore, the GPS navigation data generated when the combination of GPS satellites is switched and It is possible to prevent erroneous determination that an error from the autonomous navigation data is due to occurrence of multipath propagation.

In this embodiment, the azimuth sensor 5
Corresponds to the direction detecting means of the present invention, and the vehicle speed sensor 4 is
The GPS receiver 3 corresponds to the satellite radio wave receiving means of the invention, which corresponds to the speed detecting means of the invention. Further, S100 in the CPU 91 corresponds to the position calculating means of the present invention, and S1
20 corresponds to the positioning data calculation means of the present invention, and S20
0 corresponds to the correction means of the present invention.

Then, S140 to S190 correspond to the multipath propagation determining means and the correction inhibiting means of the present invention.
However, S140 and S150 correspond to the first determining means of the present invention, S160 and S170 correspond to the second determining means of the present invention, and S180 and S190 correspond to the third determining means of the present invention.

Further, S130 corresponds to the combination specifying means and the judgment prohibiting means of the present invention. Although the embodiments of the present invention have been described above, it is needless to say that the present invention is not limited to the above embodiments and can take various forms within the technical scope of the present invention. .

For example, in the above-described embodiment, the moving speed and moving direction of the own vehicle in the navigation data are calculated by measuring the frequency deviation generated in the received GPS radio wave. Similarly, the moving speed and the moving direction of the own vehicle may be calculated from the coordinates of the own vehicle obtained by using the pseudo distance.

In the above embodiment, four GPS radio waves are used to calculate the GPS navigation data, but if it is sufficient to calculate the current position of the vehicle in two dimensions,
GPS navigation data may be calculated using three GPS radio waves. Further, in the above-described embodiment, the present invention is applied to a navigation device mounted on a vehicle. However, among other moving bodies such as an aircraft and a ship, those that may move in a place where multipath propagation occurs. You may apply to the navigation apparatus mounted.

[Brief description of drawings]

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

FIG. 2 is a flowchart showing the flow of navigation data calculation processing performed by the CPU of the navigation device according to the present invention.

FIG. 3 is an explanatory diagram showing an outline of multipath propagation that occurs in a city.

[Explanation of symbols]

1 ... Navigation device, 2 ... VICS receiver, 3
... GPS receiver, 4 ... Vehicle speed sensor, 5 ... Direction sensor, 6 ... Map memory, 7 ... Operation interface,
8 ... CRT controller, 9 ... arithmetic unit, 91 ... C
PU, 92 ... ROM, 93 ... RAM, 94 ... Input / output circuit.

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Claims (6)

[Claims] 1. An azimuth detecting means mounted on a mobile body for detecting a moving azimuth of the mobile body, a speed detecting means for detecting a moving speed of the mobile body, and a radio wave transmitted from a plurality of artificial satellites. Satellite radio wave receiving means, position calculating means for calculating the position of the moving body based on inputs from the azimuth detecting means, and the speed detecting means, and the radio wave received by the satellite radio wave receiving means. The positioning data calculation means for calculating the positioning data of the moving body based on the signal, and the moving direction of the moving body detected by the direction detecting means based on the positioning data calculated by the positioning data calculation means, Correction means for correcting at least one of the moving speed of the moving body detected by the speed detecting means and the position of the moving body calculated by the position calculating means, In navigation devices, the moving speed of the azimuth movement direction detection means detects the moving object, and the movable body where the velocity detecting means detects,
Based on at least one of the positions of the mobile body calculated by the position calculation means and the positioning data calculated by the positioning data calculation means, the radio wave received by the satellite radio wave reception means is multipath-passed. A multipath propagation determining means for determining whether or not the radio wave has been propagated, and the multipath propagation determining means is a radio wave that has undergone multipath propagation of the radio wave received by the satellite radio wave receiving means. A navigation device comprising: a correction prohibiting unit that prohibits the correction by the correcting unit when determined. 2. The positioning data calculated by the positioning data calculation means includes at least the position of the mobile body, and the multipath propagation determination means includes the position of the mobile body calculated by the position calculation means, When the position difference from the position of the moving body included in the positioning data is larger than a preset threshold value, the radio waves received by the satellite radio wave receiving means are multipath-propagated radio waves. The navigation device according to claim 1, further comprising a first determining unit that determines that there is. 3. The positioning data calculated by the positioning data calculating means includes at least the moving direction of the moving body, and the multipath propagation determining means determines the moving direction detected by the direction detecting means and the positioning. When the azimuth difference from the moving azimuth included in the data is larger than a preset azimuth difference threshold value, the radio wave received by the satellite radio wave receiving means is determined to be a radio wave that has been multipath propagated. The navigation device according to claim 1 or 2, further comprising two determining means. 4. The positioning data calculated by the positioning data calculating means includes at least the moving speed of the moving body, and the multipath propagation determining means determines the moving speed detected by the speed detecting means and the positioning. When the speed difference from the moving speed included in the data is larger than a preset speed difference threshold, it is determined that the radio wave received by the satellite radio wave receiving means is a radio wave that has been multipath propagated. The navigation device according to any one of claims 1 to 3, further comprising: a determination unit according to claim 3. 5. A combination of artificial satellites that are the transmission sources of the radio waves used for the calculation of the positioning data by the positioning data calculation means is specified based on the signal superimposed on the radio waves received by the satellite radio wave reception means. The combination specifying means and the combination specified by the combination specifying means,
5. A determination prohibition unit that prohibits the determination by the multipath propagation determination unit when different from the previous calculation by the positioning data calculation unit, is provided. Or the described navigation device. 6. The navigation device according to claim 1, wherein the radio wave received by the satellite radio wave receiving means is a radio wave transmitted from a GPS satellite.