JPH0334035B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention is a GPS (Global Positioning System) suitable for use in automobiles that drive in urban areas or mountainous areas.
System) Concerning navigation transmission values.

(Prior Art) In general, GPS navigation equipment simultaneously selects three or more satellites to measure the user's position.In general, in order to obtain the highest measurement accuracy, GPS navigation equipment uses GDOP (or A GPS navigation device is known in which a combination of satellites that minimizes the horizontal accuracy divergence (HDOP) is selected.

(Problem to be solved by the invention) However, for example, some of the satellites selected for the minimum GDOP include satellites with low elevation angles, so if there is a dependence on shielding in areas such as urban areas or mountains,
Each time such a blockage existed, it became impossible to receive signals from the satellite, which caused GPS navigation equipment on the ground to lose track of the satellite.

(Means for Solving the Problems) The present invention provides that when a car equipped with a GPS navigation device travels in urban areas or mountainous areas, signals from selected satellites are detected when the signals from the satellites selected for positioning the car's driving position are detected when the car is traveling in urban areas or mountains. In order to avoid frequent loss of reception, the satellite selection unit itself determines the combination of satellites that can be used for positioning, depending on whether you are driving in a suburban area with few obstacles or in a mountainous or urban area with many obstacles. The aim is to provide a GPS navigation device with functions.

(Embodiment) FIG. 1 is a configuration diagram showing an embodiment of the device of the present invention, in which 1 is a satellite signal receiving antenna, 2 is a receiving section 3
is an arithmetic processing unit, 4 is a control unit, 5 is a map terrain information storage unit, 6 is a position display operation unit, 7 is a satellite selection unit,
8 is an estimated position calculation unit, 9 is a magnetic compass, and 10
is a distance meter.

Before explaining the operation based on FIG. 1, an overview of the satellite selection means, which is important in the present invention, will be described.

That is, how to select a satellite when a car is traveling in a suburban area with few obstacles can be determined by the following items.

Select the satellite combination with the minimum GDOP.

Data is received from the map terrain information storage unit 5, and it is confirmed from this data that there is no possibility that the satellite selected will be unreceivable due to obstructions such as high mountains.

In addition, when selecting a satellite when a car is traveling in a mountainous area or an urban area where there are many obstructions, emphasis is placed on the following items.

() The elevation angle of the satellite as seen from the user is high.

() The direction of the satellite is the direction of travel of the car or
Select the satellite in the opposite direction.

() Exclude satellites that are often unreceivable while driving from satellite selection.

If all of (), (), and () are adopted as conditions for satellite selection, it is possible to cover continuous positioning of the self-positioning position to a fairly satisfactory degree.
There is no practical problem even if only the two conditions () and () are met.

The map terrain information storage unit is divided into suburban areas and urban areas, and in the suburban areas, the location of mountains,
Height is memorized. This allows the car to
When selecting satellites while driving in a suburban area,
If there is a satellite that cannot be received due to the height of the mountain, that satellite can be excluded from satellite selection.

The satellite selection unit 7 also receives data from the map terrain information storage unit, determines whether the car is traveling in the suburbs or in the city, and selects either the suburban satellite selection method or the urban satellite selection method. and determine the satellite for positioning. In the urban area satellite selection method, satellites with a low possibility of becoming unreceivable due to obstructions are selected as positioning satellites. In this way, the GPS navigation device allows continuous positioning as much as possible. Next, the operation of the GPS navigation device when a car drives in a city area will be explained.

FIG. 2 is a diagram for explaining the present invention; specifically, it is a diagram for explaining how a vehicle follows the route of the vehicle travel path 11 when driving in a city area.

In the illustrated example, at time t ₀ the car 17
I was traveling north, but at this time, there were 5 lights in the sky.
There are two satellites, and the satellite arrangement is as follows. The numbers in parentheses indicate the reception status.

Satellite 12...elevation angle 10 degrees, azimuth 135 degrees (unreceivable) Satellite 13...elevation angle 30 degrees, azimuth 180 degrees (receivable) Satellite 14...elevation angle 60 degrees, azimuth 270 degrees (receivable) Satellite 15...elevation angle 20 degrees, azimuth 315 degrees (receivable) Satellite 16...elevation angle 10° Azimuth 0° (receivable) Satellite 12 and satellite 15 are now unreceivable due to the shield 18. GPS navigation device is
If the direction data from the magnetic compass 9 that detects the direction of travel of the vehicle 17 and the mileage data from the distance meter 10 that detects the number of rotations of the wheels are input, even if positioning is not performed in this case,
The estimated location and direction of travel of the vehicle can be determined.

First, the operation will be explained based on FIG.
When the user's initial position, date, and time are input to the position display operation unit 6, the GPS navigation device starts positioning operation. The user's initial position data input into the position display operation unit 6 is sent to the control unit 4. At this time,
The control unit 4 sends the user's initial position data to the satellite selection unit 7 and instructs it to select a satellite. The satellite selection unit 7 refers to the data in the map terrain information storage unit 5 and determines which of the suburban satellite selection means and the urban satellite selection means is appropriate based on the current user initial position. Thereafter, a combination of satellites is determined using one of the means, and the combination of satellites is notified to the control unit 4. Thereby, the control unit 4 instructs the receiving unit 2 to receive the selected satellite.
Upon receiving this command, the receiving unit 2 demodulates the satellite signal sent from the antenna 1 and measures the pseudo range of the satellite. And, this receiving section 2 is
Satellite navigation message data and satellite pseudo data are sent to the arithmetic processing section 3. The arithmetic processing unit 3 establishes the following commonly known navigation equation based on these data and determines the user position.

_{Navigation equation Xu = G} ^-1 _{[ AuS − ρ ] _ _} , UY, UZ: User position in XYZ earth-fixed coordinate system BU: User clock offset e _ij : Unit vector formed by satellite i and user position
XYZ component Au = r ₁ 0 0 00 r ₂ 0 00 0 r ₃ 00 0 0 r ₄ r _i = (e _i1 e _i2 e _i3 1) S = [R ₁₁ R ₁₂ , R ₁₃ B ₁ R ₂₁ R ₂₂ R ₂₃ B ₂ R ₃₁ R ₃₂ R ₃₃ B ₃ R ₄₁ R ₄₂ R
₄₃ B ₄ ] ^T ρ = [ρ ₁ ρ ₂ ρ ₃ ρ ₄ ] ^T R ^ij : XYZ component of the XYZ earth-fixed coordinate system of satellite i b _i : Satellite clock offset of satellite i ρ _i : Pseudorange of satellite i This The obtained user position result is sent to the position display operation section 6. The device display operation section 6 displays the easer position results. The arithmetic processing unit 3 also sends the user position result to the satellite selection unit 7. The satellite selection section 7 is commanded by the control section 4 to select a satellite at regular intervals, selects a receiving satellite, and notifies the control section 4 of the combination of satellites to be used for positioning. Upon receiving this, the control section 4 instructs the receiving section 2 to receive the selected satellite. The receiving unit 2 executes this command, and then notifies the control unit 4 whether or not the selected satellite can be received. If there is a satellite selected for positioning that cannot be received by the receiver 2, the controller 4 instructs the satellite selector 7 to select the satellite again. Therefore, the satellite selection section 7 selects satellites excluding the satellites that could not be received.

The satellite selection unit 7 can then notify the control unit 4 of the newly selected combination of satellites. Then, the control unit 4 instructs the arithmetic processing unit 3 to use the new satellite combination for positioning,
The GPS navigation device will be able to continue positioning.
Furthermore, when the GPS navigation device is not performing positioning, or when positioning is temporarily disabled, the estimated position calculation unit 8 uses the azimuth data from the magnetic azimuth meter 9 that detects the traveling direction of the vehicle, and the azimuth data of the wheels. The estimated position of the user is calculated by receiving the distance traveled from the distance meter 10 that detects the number of revolutions. Thereafter, this result is sent to the satellite selection section 7 arithmetic processing section 3. The satellite selection unit 7 and the arithmetic processing unit 3 use the sent data as an estimated position of the user.

In the example of FIG. 2, first, satellite selection is performed at time _T0 . Here, since the elevation angle of the satellite seen from the user described in the urban area satellite selection method is high, the satellite 1
4. Also, by selecting a satellite whose orientation is in the direction of travel of the car or in the opposite direction, satellite 1
3. Select satellite 16. Furthermore, by selecting a satellite 12 that is expected to have a low value of GDOP from the remaining satellites 12 and 15, it is possible to improve the accuracy of continuous positioning.

When starting 3D positioning, receive the angular satellite,
Data demodulation and pseudorange measurements are performed, but the satellite signal is blocked by buildings and cannot be received by the satellite. Therefore, instead of satellite 12, satellite 15 is selected again. However, satellite 15 is also unreceivable due to the influence of buildings. Therefore, there are three satellites that can be received: satellite 13, satellite 14, and satellite 16, and two-dimensional positioning is started. Thereafter, two-dimensional positioning is continued using three satellites, satellite 13, satellite 14, and satellite 16, but it is assumed that satellite 15 becomes able to receive data at time _t1 . Then, at time t ₂ , satellite 1
3 can no longer be received due to the influence of a building. At this time, the orientation of the satellite 15 is opposite to the direction in which the vehicle is traveling, and this satellite 15 is newly selected as a positioning satellite. Then, satellite 14, satellite 1
5. You will be able to receive 3 satellites, 16 satellites.
Positioning becomes possible again.

(Effects of the Invention) As explained above, the present invention uses map information of the area where the car is scheduled to travel, and selects a satellite according to the topography of the area where the car is traveling, thereby receiving satellite radio waves without interruption. This allows continuous position measurement even in areas with many obstructions.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the apparatus of the present invention, and FIG. 2 is a diagram for explaining the present invention. DESCRIPTION OF SYMBOLS 1... Antenna, 2... Receiving section, 3... Arithmetic processing section, 4... Control section, 5... Map terrain information storage section, 6... Position display operation section, 7... Satellite selection section,
8...Estimated position calculation unit, 9...Magnetic compass, 10
... Distance meter, 11 ... Car driving route, 12,1
3, 14, 15 and 16...satellite, 17...car, 18...shielding object.

Claims (1)

[Claims] 1 In the GPS navigation device installed in a car,
A map topographic information storage unit that stores map topographic information of the area in which the car is scheduled to travel, distinguishing it into a suburban area and an urban area; It has a satellite selection means, and as a satellite selection means in an urban area, at least the first condition for an area where a car is running in a city is that the elevation angle of the satellite as seen from the car is high, and the second condition is the azimuth of the satellite. and a satellite selection unit that determines a combination of satellites by selecting satellites located in the traveling direction of the vehicle or in a direction opposite to the traveling direction, so as to perform continuous positioning of the traveling position of the vehicle. GPS navigation device.