JPH0781870B2 - GPS navigation system for automobiles - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a GPS navigation device for an automobile, and more particularly, to a GPS mounted on an automobile for measuring the position of the automobile.
In the receiver, the estimated position calculated by the output data from the dead reckoning sensor along with the position measured by GPS
The present invention relates to a GPS navigation device for an automobile, which can be calibrated based on a measurement position by GPS.

[Prior Art] For users who move every moment such as ships and aircraft,
In order to confirm or determine the user's current position, running speed, etc. by sending radio waves from multiple artificial satellites, GPS has been used in recent years.
The usefulness of navigation devices is receiving attention. This GPS navigation device has the following features.

It can be used continuously all over the world.

Position and velocity measurement accuracy is extremely high.

There are no restrictions on users.

If the GPS navigation device has the above features, the GPS
The objects using navigation devices should be not limited to ships and aircraft, but also automobiles. In particular,
If it can be used for avoiding traffic congestion in urban areas, checking its current position in a short period of time, and finding a detour to the destination, it is possible to obtain great time and economic effects.

Generally, GPS navigation devices utilize three or more satellites.
Each of these artificial satellites is equipped with a high-precision atomic clock or the like, but on the other hand, such an expensive clock device is not provided on the receiving side. Therefore, a clock offset appears in the time information on the receiving side. Therefore, the receiving side receives the radio waves from the artificial satellites at the same time, and calculates the position of the receiving point from the pseudo range data including the clock offset of the receiver between each satellite and the receiving point and the position data of each receiving satellite. it's shown.

However, as is well known, in urban areas, mountainous areas, or in tunnels, a certain number of radio waves from satellites belonging to GPS may be blocked by a shield from reaching the vehicle. May be difficult to confirm the current location. For example, when a vehicle is equipped with a GPS receiver and the vehicle travels, if the vehicle enters a tunnel from the road, reception of radio waves from the satellite is interrupted, and GPS positioning becomes impossible. For this reason, the dead reckoning sensor that detects the traveling direction and speed is installed in the car, and the dead reckoning sensor estimates the car based on the output data from the dead reckoning sensor based on the measurement position at the time when the reception of satellite radio waves was interrupted. The position was calculated and displayed on the display.

[Problems to be solved by the invention]

However, as described above, when the reception of radio waves is interrupted and positioning by GPS becomes impossible, the position measured by GPS is uniquely used at the time of interruption of reception of satellite radio waves and the output data from the dead reckoning sensor is used to There is the following problem in the method of calculating the estimated position of. That is, the positioning accuracy index DOP (Dilution of Precision) at the time of reception interruption
When positioning is performed using measured data when the value is bad or when the reception level immediately before the interruption of the reception of satellite radio waves deteriorates, the actual position of the vehicle may differ greatly. When dead reckoning is performed from this position as a starting point, there is a drawback that a track at an estimated position different from the track of the actual vehicle is displayed.

The present invention has been made in view of the above points, and eliminates the above problems, when the DOP (Dilution of Precision) value of the positioning accuracy index at the time of interruption of reception of radio waves from a satellite is bad, or reception of satellite radio waves. An object of the present invention is to provide a GPS navigation device for an automobile capable of displaying the current position of the automobile with high accuracy even when the reception level immediately before the interruption deteriorates.

[Means for solving problems]

In order to solve the above problems, the present invention is provided with an estimated position calculation unit having a function of calculating an estimated position of an automobile based on output data from a dead reckoning sensor that detects a traveling direction and speed of the automobile, and is installed in the automobile. The receiver that detects the data required for positioning and the reception level of the received satellite signal from the satellite radio waves received by the GPS antenna, and the current position, date, time, and selection of the vehicle based on the positioning data sent from the receiver. Receiving position calculation unit having a function to calculate the DOP value indicating the positioning accuracy index of the plurality of satellites, the reception level sent from the receiving unit and the positioning data and DOP value sent from the receiving position calculation unit Based on the estimated position from the position calculator and the time data from the real-time clock, the conditions are that the DOP value is below a certain value, the reception level is above a certain value, and a certain time The function to determine whether to calibrate the estimated position using the GPS measurement position, based on whether the difference between the estimated distance between each measurement position of and the measurement distance between each measurement position by GPS is within a certain value. A GPS navigation device for automobiles was constructed with the position calibration judgment unit.

[Action]

By configuring the GPS navigation device for automobiles as described above, when positioning by GPS becomes impossible due to interruption of reception of radio waves from the satellites that compose GPS, the reception level and reception sent from the receiving unit Based on the positioning data and DOP value sent from the position calculation unit, the estimated position from the estimated position calculation unit, and the time data from the real-time clock, the condition is that the DOP value is below a certain value and the reception level is above a certain value, and is constant. Estimated distance between each measurement position and GP
The positioning position is positioned with high accuracy depending on whether the difference between the measurement distance between each measurement position by S is within a certain value.
Since the estimated position is calculated from the traveling direction and speed of the own vehicle as the starting point calibrated by the measured position by GPS, it is possible to display the current position of the vehicle with high accuracy even when the satellite radio wave is interrupted.

〔Example〕

 An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the system configuration of an automobile GPS navigation device according to the present invention. In the figure, 10 is a car, and the car 10 has an antenna 11 for receiving radio waves transmitted from a GPS satellite (not shown), a direction sensor 12, and a rangefinder 13
And are provided. The output side of the antenna 11 is connected to the reception section 14, and the output sides of the azimuth sensor 12 and the range finder 13 are connected to the estimated position calculation section 19. One output terminal of the reception unit 14 is connected to the input terminal of the reception position calculation unit 15, and the other output terminal is connected to the input terminal of the position calibration determination unit 17. One output terminal of the reception position calculation unit 15 is connected to the input terminal of the real-time clock 16, and the other output terminal is the estimated position calculation unit 19, the position calibration determination unit 17, and the data switching unit 18.
And are connected to each input terminal. Real time clock 16
The output terminal of is connected to one input terminal of the position calibration determination unit 17. One output terminal of the position calibration determination section 17 is connected to the input terminal of the estimated position calculation section 19, and the other output terminal is connected to the input terminal of the data switching section 18. The output terminal of the estimated position calculation unit 19 is connected to the input terminal of the position calibration determination unit 17 and the input terminal of the data switching unit 18. The output terminal of the data switching unit 18 is connected to the display unit 20.

In the vehicle GPS navigation device configured as described above,
A GPS satellite (not shown) sends a navigation signal on the transmitted radio waves. The GPS satellite transmission radio wave carrying the navigation signal is captured by the antenna 11 and sent to the receiving unit 14. The receiving unit 14 demodulates satellite navigation data from the captured satellite radio waves and measures pseudo range data from the reception point to the satellites, and sends the data to the reception position calculation unit 15 and also the reception level of the received satellite radio waves. The measurement is performed, and this data is sent to the position calibration determination unit 17. The reception position calculation unit 15 is a reception unit.
Based on the satellite navigation data from 14 and the satellite position calculated from this data and the pseudo-range data from the receiving point to the satellite, calculate the receiving position and accurate time and DOP value which is the positioning accuracy index, and calculate the receiving position. The DOP value is sent to the position calibration judgment unit 17 and the data switching unit 18, and the time is set by the real time clock.
The real time clock 16 is provided to calibrate 16. On the other hand, in the estimated position calculation unit 19, when the GPS navigation device for this vehicle is started, the azimuth sensor 12 and the range finder are based on the current position of the vehicle 10 acquired from a map or the like input using an operation unit (not shown). The estimated position of the automobile 10 is calculated based on the data from 13 and sent to the position calibration determination unit 17 and the data switching unit 18. The position calibration determination unit 17,
Reception level data from the reception unit 14, DOP value and positioning data from the reception position calculation unit 15, estimated position data from the estimated position calculation unit 19, and a real-time clock 16
Based on the time data from, it has a function to judge whether the position measured by GPS is located with high accuracy by comparing with the "guess position calibration condition" below, and if the judgment condition is met, position calibration is performed. The signal is sent to the estimated position calculation unit 19. In the estimated position calculation unit 19, when this position calibration signal is sent, the estimated position is calibrated to the measurement position by GPS sent from the reception position calculation unit 15, and thereafter the calibrated position is used as a base point. The direction 12 installed in the car 10
And the estimated position is calculated based on the data from the rangefinder 13. As a result, the estimated position is calibrated only when the measured position accuracy by GPS is good. Therefore, the estimated position with high accuracy can be displayed even when the positioning of the satellite is interrupted.

“Estimated position calibration conditions” The positioning accuracy index DOP value must be below a certain value (the smaller the DOP value, the better the positioning accuracy).

The satellite radio reception level must be above a certain level.

The difference between the estimated distance between each estimated position at fixed time intervals and the measured distance between each measured position by GPS must be within a certain value.

In the above, the present invention has been described with reference to a preferred embodiment in the above embodiment, but the present invention is not limited to the above embodiment, within the scope not departing from the gist of the present invention.
It goes without saying that various improvements and design changes are possible.

〔The invention's effect〕

As described above, according to the present invention, when positioning by GPS is disabled due to interruption of reception of radio waves from satellites constituting GPS, various data from the estimated position calculation unit are used and During good reception of
The estimated position is highly accurately positioned according to the DOP value, reception level, and other conditions.The estimated position is calculated based on the starting point that is calibrated at the measured position by GPS. The excellent effect that the position can be displayed is obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing the system configuration of an automobile GPS navigation device according to the present invention. In the figure, 11 ... Antenna, 12 ... Direction sensor, 13 ... Distance meter, 14 ... Reception unit, 15 ... Reception position calculation unit, 16 ... Real-time clock, 17 ... Position calibration determination unit, 18 ... … Data switching section, 19 …… Estimated position calculation section, 20 …… Display section.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Noboru Yamaoka No. 1 1-1 Shimorenjaku, Mitaka City, Tokyo Japan Radio Co., Ltd. (72) Inventor Yasuyuki Uekusa 2 Takaracho, Kanagawa-ku, Yokohama, Kanagawa Nissan Motor Co., Ltd. (72) Inventor Hisao Kishi 2 Takaracho, Kanagawa-ku, Yokohama, Kanagawa Nissan Motor Co., Ltd. (72) Hideo Takai 2 Takaracho, Kanagawa-ku, Yokohama, Kanagawa Nissan Motor Co., Ltd. (56) References 62-98214 (JP, A) JP 61-138113 (JP, A) JP 61-90069 (JP, A)

Claims (1)

[Claims] Claims: 1. An estimated position calculation unit having a function of calculating an estimated position of a vehicle based on output data from a dead reckoning sensor for detecting a traveling direction and speed of the vehicle, and a GPS antenna installed in the vehicle. A receiver that detects the data necessary for positioning and the reception level of the received satellite signal from the satellite radio waves, and the current position and date and time of the vehicle and a plurality of selected satellites based on the positioning data sent from the receiver. A reception position calculation unit having a function of calculating a DOP value indicating the positioning accuracy index, a reception level transmitted from the reception unit, positioning data and a DOP value transmitted from the reception position calculation unit, and the estimated position calculation unit. As a condition, the DOP value is less than a certain value, the reception level is more than a certain value, and each measurement is performed every certain time from the estimated position from the Position calibration that has a function to determine whether or not to calibrate the estimated position using the GPS measurement position depending on whether the difference between the estimated distance between positions and the measurement distance between each measurement position by GPS is within a certain value. A GPS navigation device for an automobile, comprising: a determination unit.