JPS61138114A - Gps navigation system - Google Patents

Abstract

PURPOSE:To make an accurate position display by calculating the current position on the basis of pseudo range data from a receivable signal, position data from a GPS receiver, and an estimated position from a specific computing element when the number of receivable satellites is >=3. CONSTITUTION:The GPS receiver 1 detects satellite position data and pseudo range data from the radio wave of the GPS satellite which is acquired by the antenna 6 of an automobile 5 and when the number of receivable satellites is >=3, the computing element 3 calculates the reception position from both data and the result is displayed on a display device 4. When there area <3 receivable satellites, a computing element 2 calculates the estimated position on the basis of azimuth data from a magnetic azimuth meter 7, run range data from a range finder 8, and measurement position data from the computing element 3 right before a break of reception to output the result to the computing element 3, which detects the reception position on the basis of the respective data, thereby displaying the reception position on the display device 4.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a GPS navigation system for an automobile, particularly by processing the estimated current position of the automobile and reception data of currently receivable satellite radio waves.

The present invention relates to a GPS navigation device that continuously displays a position with good accuracy even when it is impossible to simultaneously receive radio waves from three or more satellites.

(Prior art) A GPS positioning device usually receives three or more satellites at the same time, and receives pseudorange data including the time offset of the receiver between each satellite and the receiving point, and the position data of each receiving satellite. It is configured to calculate and display the position of a point.

(Problems to be Solved by the Invention) However, there is a drawback that positioning cannot be performed when the number of receiving satellites is less than three due to the influence of shielding objects such as buildings in urban areas. In addition, as a solution to this problem, it is possible to display the estimated position using direction data and distance data from a compass and rangefinder while positioning is not possible, but the estimated position will accumulate position errors over time. Therefore, continuous position display is possible, but the two-position measurement error increases.2. In particular, when the unreceivable period becomes long, the increase is extremely unsuitable for practical use.

(Means for Solving the Problems) In order to solve these drawbacks, the present invention aims to solve the problem that the reception of satellite radio waves is frequently interrupted due to the influence of shielding objects in urban areas. If reception is not possible, artificially calculate the reception data of the satellites that are currently receivable from the direction data and distance data from the direction meter and distance meter, and the reception data immediately before reception interruption.

To provide a GPS navigation device which enables continuous positioning without interruption using a total of three pieces of received data, and also enables positioning with better accuracy than an estimated position calculated from azimuth data and distance data during positioning interruptions. The purpose is to

(Embodiment) Fig. 1 is a block diagram of an embodiment of the present invention, and ■ is a G
PS receiver, 2 is estimated position calculator.

3 is a receiving position calculator, 4 is a position indicator, 5 is a car, 6
is a GPS receiver antenna, 7 is a magnetic compass, and 8 is a distance meter.

The outputs of the GPS receiver 1 and the estimated position calculator 2 are input to a received position calculator 3, and the output of the calculator 3 is fed back to the position indicator 4 and the estimated position calculator 2. .

Figure 2 shows the satellite radio wave reception situation (7) and the positioning error curve (a), and the period during which satellites 1, 2, and 3 can be received in the satellite radio wave reception situation (7) is shown in figure (a). are shown as solid lines, and periods in which reception is not possible are shown as dotted lines. As shown in Figure (A2), the satellite position error during the unreceivable period increases over time.

As can be seen from the positioning error curve (A) of these three satellites, the average value of the positioning error according to the present invention is shown in Figure 2 (
The positioning error curve in b) is shown in a line graph (solid line), showing that it is much improved compared to the conventional method (dotted line).

FIG. 3 shows how a car receives radio waves from three satellites and performs positioning while the car is driving. At time t1, satellites 1, 2 .
3 radio waves are received and positioning is possible, but at 1 time t2
In this case, reception of radio waves from the satellite 3 is interrupted due to the shielding object 9, so positioning is impossible using the conventional positioning method. However, in the present invention, FIG. 4 shows that positioning is possible by calculating a pseudo distance between the satellite 3 and the estimated position.

That is, FIG. 4 shows the position measurement according to the present invention at time t2, and satellite 1 is centered on satellites 1 and 2.3 at time 1 and 2.
．． The measurement position 10 is the center of a triangle surrounded by three circles whose radii are the measured distance between the satellite 2 and the reception position and the calculated distance between the estimated position of the satellite 3 and the satellite 3.

(for production) Next, these operations will be explained with reference to the drawings.

The radio waves from the GPS satellite are the GPS of car 5 shown in Figure 1.
It is captured by the receiver antenna 6 and sent to the GPS receiver 1. The GPS receiver 1 amplifies and demodulates the GPS signal to detect satellite position data and pseudorange data. In this case, if the number of receivable satellites is three or more, the reception position calculator 3 calculates the reception position from the satellite position data and pseudorange data from the CPS receiver 1.

The result is displayed on the position display 4 as a numerical value or as a track. However, while the car 5 is driving in a city area, etc., the radio waves from the three satellites cannot be received at the same time due to a shield 9 such as a building (Figs. 3 and 4), and the satellite radio waves shown in Fig. 2 (7) cannot be received simultaneously. When receiving radio waves from one or two satellites intermittently, the target position calculator 2 operates to calculate the direction data from the magnetic compass 7, the mileage data from the distance meter 8, and The estimated position at time t2 is calculated using the measured position data of the car at time t1 immediately before the reception of radio waves from the satellite 3 in FIG. As a result, the reception position calculation unit 3 determines the position of the satellite 1 at time t2 from the GPS receiver 1 as shown in FIG. The reception of the satellite 3 is performed using the received data of the satellite 2, that is, the pseudorange data and satellite position data, the calculated value of the pseudorange data between the satellite 3 and the estimated position at time t2, and the satellite position data of the satellite 3 at time t2. Even if the signal is interrupted, the reception position at time t2 can be calculated and displayed numerically on the 1-position display 4 or as a track on a map.

On the other hand, the reception position calculator 3 also outputs the measured position data immediately before the interruption of reception to the estimated position calculator 2.

It is used to calculate the estimated position of the computing unit 2. However, as mentioned above, as shown in the positioning error graph in Figure 2, the period from time t1 to time t2, when it is impossible to receive three or more satellite radio waves, is determined by the magnetic compass. When an estimated position is calculated using azimuth data, distance data from a rangefinder, and received position data at time t, the positioning error increases over time, as shown by the estimated position error in Figure 2. . However, when the reception position is calculated using the method according to the present invention, the positioning error is reduced compared to the estimated position error, as shown by the positioning error according to the present invention in FIG. 2(A).

Furthermore, since it does not increase with the passage of time, it has the advantage that even if there is a shield 9, there is no problem.

(Effects of the Invention) As is clear from the above description, 1) the Q industrial vehicle of the present invention is equipped with a GPS receiver, and when used in urban areas, Continuous positioning is impossible with a GPS receiver, and even if continuous positioning is possible using the magnetic compass direction data and the distance data from the distance meter, it is not possible to perform continuous positioning with good positioning accuracy. Although it is not expected, the above azimuth data.

In addition to the distance data, by using the received data immediately before the interruption of reception to calculate the received data in a pseudo manner, it is possible to accurately measure the position even when the number of received satellites is less than three.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment of the present invention;
71 shows the reception status of satellite radio waves, (A) shows the positioning error curve, Fig. 3 is an explanatory diagram of a car receiving radio waves from a satellite, and Fig. 4 shows the case of receiving radio waves from a satellite according to the present invention. FIG. 1....GPS receiver, 2. ... Estimated position calculator,
3゜...reception position calculator, 4. ...Position indicator, 5
．．・・Automobile, 6.・・GPS receiver antenna, 7,
...magnetic compass, 8. ...Distance meter, 9. ...shielding object, 10. ···Measurement position.

Claims (1)

[Claims] A GPS receiver that receives radio waves from a GPS satellite and outputs position data of the GPS satellite and pseudo distance data between the GPS satellite and the vehicle, and the GPS receiver becomes unable to receive satellite radio waves. an estimated position calculator that calculates the current estimated position of the car using the direction data from the magnetic compass that detects the direction of travel of the car and the mileage data from the distance meter, starting from the received position calculated immediately before; , GPS if the number of receivable satellites is 3 or more
The position is calculated using the satellite position data and pseudorange data from the receiver, and if there are fewer than three satellites that can be received due to the influence of obstructions such as buildings, the current car position data from the estimated position calculator is calculated. The current position of the car is calculated using the estimated position of the satellite, the satellite position data of the satellites that have been used for position measurement from the GPS receiver, and the pseudorange data obtained by receiving unobstructed satellite signals. and a position display unit that displays the positioning results from the reception position calculation unit as a numerical display or a track on a map. GPS navigation device.