JPH06100645B2 - GPS navigation device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a GPS (Global Positioning System) navigation device suitable for being used by being mounted on a vehicle that runs in an urban area or a mountain area.

(Prior Art) Generally, a GPS navigation device selects three or more satellites at the same time to perform positioning of a user position. In general, there is known a GPS navigation device in which a combination of satellites that minimizes GDOP (or HDOP indicating horizontal accuracy divergence) showing geometrical accuracy divergence is selected in order to maximize positioning accuracy.

(Problems to be solved by the invention) However, since satellites with a low elevation angle are included in the satellites selected by the minimum GDOP, for example, if there is a shield in an area such as an urban area or mountains, the shield will be Each time it was present, it was unable to receive signals from the satellite, and the GPS navigation device on the ground could not be located.

The present invention prevents the signal from the satellite selected for positioning the traveling position of the vehicle when the vehicle equipped with the GPS navigation device travels in a city area or a mountain area from being often unreceivable due to the obstacle. In addition, the GPS navigation device is designed so that the satellite selection unit itself has a function of deciding a combination of satellites that can be positioned when traveling in a suburb with few shields and in a mountainous area or an urban area with many shields. Is to provide.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention stores map topography information of a planned area where a vehicle travels so that a suburb area and a city area can be identified. An information storage unit,
Based on the map terrain information from this map terrain information storage unit, it is determined whether the vehicle is traveling in the suburbs or in the city,
A satellite selecting means for performing suburban satellite selection or urban satellite selection is provided, and when the urban satellite selection is performed, the elevation angle is higher than a certain value as the first condition, and the satellite azimuth is the second condition. And a satellite selection unit that determines a satellite combination by selecting a satellite in the traveling direction of the vehicle or in the vicinity of the opposite direction to the traveling direction of the vehicle and by selecting a satellite in the vicinity of a direction orthogonal to the traveling direction of the vehicle. hand,
It is a GPS navigation device that measures the position of a vehicle.

(Embodiment) FIG. 1 is a block diagram showing an embodiment of the device of the present invention. 1 is an antenna for receiving satellite signals, 2 is a receiving section, 3 is an arithmetic processing section, 4 is a control section, and 5 is a map topography. An 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 rangefinder.

Before explaining the operation based on FIG. 1, an outline of satellite selecting means important in the present invention will be described.

In other words, how to select the satellites when the vehicle runs in the suburbs where there are few shields is to first select the satellite combination with the smallest GDOP.

In addition, how to select a satellite when a vehicle travels in a mountainous area or an urban area with many shields should focus on the following items.

I) For the satellite with the highest elevation angle seen from the user, the elevation angle must be higher than the set value.

II) Select a satellite whose direction is near the direction of travel of the vehicle or in the opposite direction, and at the same time, select a satellite which is near the direction orthogonal to the direction of travel of the vehicle.

If I) and II) are prioritized conditions for satellite selection, for example, when an intersection is reached, the radio waves of the satellite in the orthogonal direction can be received, and continuous positioning of the self-positioning position that is quite satisfactory can be covered.

In the map topographic information storage unit, the suburb area and the urban area can be discriminated from each other.
Height is recorded. As a result, when the vehicle selects a satellite while traveling in the suburbs, if there is a satellite that cannot be received due to the position and height of the mountain, the satellite can be excluded from the satellite selection.

In addition, the satellite selection unit 7 receives data from the map topographical information storage unit 5 and determines whether the vehicle is traveling in the suburbs or in the city, and selects the satellite selection method for the suburbs or the satellite selection for the city areas. Select the method and determine the satellite for positioning. In the satellite selection method for urban areas, a satellite that is unlikely to be unreceivable due to an obstacle, that is, the satellite with the highest elevation angle and the elevation angle higher than a certain value is selected as the positioning satellite.
For satellites that are likely to be unreceivable due to the obstacle, that is, satellites with a low elevation angle, satellites near the traveling direction of the vehicle and satellites near the orthogonal direction to the traveling direction of the vehicle are selected. If these satellites can receive, good HDOP will be obtained. For example, when coming to an intersection, radio waves from satellites in the orthogonal direction can be received. In this way, the GPS navigation device makes continuous positioning possible. In the embodiment, the operation of the GPS navigation device when the automobile runs in the city will be described.

FIG. 2 is a diagram for explaining the present invention, and specifically, a diagram for explaining how an automobile follows the route of the automobile traveling path 11 when traveling in an urban area.

In the illustrated example, the automobile 17 is traveling in the north direction at time t ₀ , but at this time, there are five satellites in the sky, and the satellite arrangement is as follows. () Shows the reception status.

Satellite 12… Elevation angle 10 ° Azimuth 90 ° (Unable to receive) Satellite 13… Elevation angle 30 ° Azimuth 180 ° (Receivable) Satellite 14… Elevation angle 60 ° Azimuth 270 ° (Receivable) Satellite 15… Elevation angle 20 ° Azimuth 315 ° (Receivable) Impossible) Satellite 16 ... Elevation angle 10 ° Azimuth 0 ° (Receivable) Here, the satellites 12 and 15 cannot be received due to the shield 18. When the GPS navigation device inputs the azimuth data from the magnetic azimuth meter 9 that detects the traveling direction of the automobile 17 and the traveling distance data from the range finder 10 that detects the number of rotations of the wheels, positioning is performed in this case. Even if it does not exist, the estimated position and traveling direction of the car can be obtained.

First, the operation will be described with reference to FIG. The GPS navigation device starts the positioning operation when the user's initial position, date, and time are input to the position display operation unit 6. The user's initial position data input to 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 the satellite selection unit 7 to perform satellite selection. The satellite selection unit 7 refers to the data of the map topographical information storage unit 5 and determines which of the suburban satellite selection unit and the city satellite selection unit is appropriate from the current user initial position. After that, the combination of satellites is determined by either one of the means, and the control unit 4 is notified of the combination of satellites. As a result, the control unit 4 instructs the receiving unit 2 to receive the selected satellite. Receiving this command, the receiving unit 2 data-demodulates the satellite signal sent from the antenna 1 and measures the pseudo range of the satellite. Then, the receiving unit 2 sends the navigation message data of the satellite and the pseudo range data of the satellite to the arithmetic processing unit 3. Based on these data, the arithmetic processing unit 3 formulates the following well-known navigation equation that is usually well known, and obtains the user position. Navigation equation UX, UY, UZ: XYZ User position in fixed earth coordinate system Bu: User clock offset eij: XYZ component of unit vector formed by satellite i and user position 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 Rij: XYZ of satellite i XYZ component of earth fixed coordinate system Bi: Satellite clock offset of satellite i ρi: Pseudo distance of satellite i The user position result is sent to the position display operation unit 6. The position display operation unit 6 displays the user position result. The arithmetic processing unit 3 also sends the user position result to the satellite selecting unit 7. The satellite selection unit 7 is instructed by the control unit 4 to perform satellite selection at regular time intervals, and in response to this, satellite selection is performed and the control unit 4 is informed of the combination of satellites used for positioning. Receiving this, the control unit 4 instructs the receiving unit 2 to receive the selected satellite. Receiver 2
Executes this command, and then informs the control unit 4 whether or not each selected satellite has been able to receive.
If there is a satellite selected for positioning that the receiving unit 2 could not receive, the control unit 4 instructs the satellite selecting unit 7 to perform satellite selection again. So the satellite selector 7
Will select satellites other than those that could not be received.

Then, the satellite selection unit 7 can inform 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, and the GPS navigation device can continue positioning. In addition, when the GPS navigation device does not perform positioning, or when positioning cannot be performed temporarily, the estimated position calculation unit 8 uses the magnetic azimuth meter 9 that detects the traveling direction of the vehicle.
The user's estimated position is calculated by receiving the azimuth data from and the mileage data from the range finder 10 that detects the rotation speed of the wheels. After that, this result is sent to the satellite selection unit 7 and the arithmetic processing unit 3. The satellite selection unit 7 and the arithmetic processing unit 3 use the sent data as the estimated position of the user.

In the example of FIG. 2, first, the satellite state is performed at time t ₀ . Here, I) as described in the satellite selection method for urban areas, the elevation angle of the satellite seen from the user is higher than a certain value, and the elevation angle is the maximum. By selecting satellites in the opposite direction,
13, Select 16 satellites. In addition, the positioning accuracy can be improved by selecting the satellites 12 near the direction orthogonal to the traveling direction of the automobile.

When three-dimensional positioning is started, each satellite is received, data demodulation and pseudo range measurement are performed, but the satellite 12 is incapable of reception because the satellite signal is shielded by the shield 18. Therefore, instead of satellite 12, satellite 15 is selected again. However, the satellite 15 cannot be received due to the influence of the shield 18.
Therefore, the receivable satellites are three satellites, namely satellite 13, satellite 14, and satellite 16, and two-dimensional positioning is started. Then satellite 13, satellite 1
Two-dimensional positioning by three satellites of four satellites 16 is continued, but satellite 12, satellite 1 near the direction orthogonal to the traveling direction of the car
Strive to capture 5. Suppose a car arrives at an intersection at time t ₁ . At this time, the satellite 12 becomes receivable, and the GPS navigation device becomes capable of three-dimensional positioning by the satellite 12, satellite 13, satellite 14, and satellite 16. Also, the HDOP at this time should be better than before. At this time, if the error of the previous positioning position is large, the previous positioning position can be corrected. Immediately thereafter, the satellite 12 becomes unreceivable and the two-dimensional positioning is continued again. Next, in FIG. 3, the vehicle changes its traveling direction and travels in the east direction, and satellite selection is performed again at time t ₂ immediately after that. Here, from the priority conditions of I) and II), satellite 1
2, Satellite 14 and Satellite 15 are selected. Also, the satellite 13 is selected so that the HDOP is good. At this point, all satellites can be received and three-dimensional positioning is performed. Then the time
At t ₃ , satellite 13 becomes unreceivable due to shield 18,
Positioning is switched to a combination of 12, satellite 14, satellite 15, and satellite 16. In this way, three-dimensional positioning can be continued.

(Effect of the Invention) As described above, according to the present invention, satellite radio waves are received without interruption by selecting a satellite corresponding to the terrain of the traveling region using the map terrain information of the planned traveling region of the automobile. Therefore, it is possible to continuously measure the position even in an area with many shields.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the device of the present invention, and FIG.
3 and 4 are diagrams for explaining the present invention. 1 ... antenna, 2 ... reception section, 3 ... arithmetic processing section, 4 ... control section, 5 ... map topographic information storage section, 6 ... position display operation section, 7
...... Satellite selector, 8 …… Estimated position calculator, 9 …… Magnetic compass, 10 …… Distance meter, 11 …… Vehicles, 12, 13, 14, 15 and 16… Satellite, 17 …… Vehicle , 18 …… Shield

Claims (1)

[Claims] 1. A GPS navigation device mounted on an automobile,
A map terrain information storage unit that stores map terrain information of a planned region where the vehicle will travel so that it can be discriminated between a suburb area and an urban area, and a car travels in the suburbs based on the map terrain information from the map terrain information storage unit. It has a satellite selecting means for determining whether the vehicle is traveling in the middle or in the city and selecting the satellite for the suburbs or the satellite for the city. When the satellite for the city is selected, the elevation angle is higher than a certain value as the first condition. And the second condition is to select a satellite whose satellite direction is in the traveling direction of the vehicle or in the direction opposite to the traveling direction of the vehicle and to select a satellite in the vicinity of the direction orthogonal to the traveling direction of the vehicle. A GPS navigation device characterized by comprising a satellite selection unit for determining a combination and performing positioning of a vehicle traveling position.