JPS61167813A - Gps navigation system - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

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 GFS 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. Devices are known that are 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, although continuous position display is possible, the single position measurement error increases, and especially when the unreceivable period becomes long, this increase is significantly 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, pseudo positioning can be performed from the direction data and distance data from the direction meter and rangefinder, as well as the data received immediately before the reception interruption, and the direction data and distance data are obtained even after the positioning interruption. An object of the present invention is to provide a GPS navigation device that enables positioning with better accuracy than the estimated position calculated by.

(Embodiment) FIG. 1 is a block diagram of an embodiment of the present invention.
A PS receiver, 2 a pseudolite position calculator, 3 a reception position calculator, 4 a position indicator, 5 a car, 6 a GPS receiver antenna, 7 a magnetic compass, and 8 a distance meter.

FIGS. 2(a) and 2(b) respectively show the satellite signal reception situation and the positioning error curve (in other words, the positioning error curve). In part (a) of ia) of the same figure, among the reception status of satellite radio waves, periods in which satellites 1, 2, and 3 are receivable are shown by solid lines, and periods in which they are unreceivable are shown by dotted lines. The satellite position error during the unreceivable period is increasing as time passes, as shown in (a) of FIG. Based on the position error curves of these three satellites, the average value of position measurement errors according to the present invention is determined by the second
The positioning error curve shown in FIG. 6) is shown as a line graph represented by a solid line.

FIG. 3 is a diagram for explaining the present invention, and shows how a car receives radio waves from three satellites and performs positioning while the car is traveling (numeral 11 indicates the road the car is traveling on). When the position of the car 91 is at time t1, radio waves from satellites 1, 2, and 3 can be received and positioning is possible, but the position of the car 92 is at time t.
2, the reception of radio waves from the satellite 3 is interrupted by the shield 10, so positioning is impossible using the conventional positioning method.

However, positioning becomes possible by calculating the position of the pseudosatellite 3 shown by the dotted line in the figure for explaining the present invention.

FIG. 4 is a diagram for explaining position measurement of a vehicle according to the present invention at time t2. In other words, the pseudo distances between each of the satellites 1 and 2 and the reception position of the car 92 and the estimated positions of the pseudosatellite 3 and the car 93 are calculated with each of the satellites 1 and 2 and the pseudosatellite 3 as centers at time t2. The measurement position is the center of a triangle surrounded by three circles with radius equal to the distance. The pseudo distance between the pseudo satellite 3 and the estimated position 93 is the distance between the satellite 3 and the car 91 measured at time t1.
is equivalent to the pseudo distance between the positions of

(Operation) Next, the operation of the GPS navigation device configured as shown in FIG. 1 will be explained with reference to these drawings. - Radio waves from the GPS satellites are captured by the GPS 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.

If the number of receivable satellites is 3 or more, receive position calculator 3
calculates the reception position from the satellite position data and pseudorange data from the GPS receiver l.

The result is displayed on the position display 4 as a numerical value or as a track. However, if a car is unable to receive signals in urban areas and receives radio waves from one or two satellites intermittently, as shown in the satellite radio reception situation shown in Figure 2, the pseudo satellite position calculator 2 uses the magnetic compass 7 to The reception position calculator 3 calculates the pseudosatellite position at time t2 using the azimuth data of , the distance data from the distance meter 8, and the satellite position data at time t1 immediately before the interruption of radio wave reception of the satellite 3 shown in FIG. is satellite 1. at time t2 from GPS receiver 1 as shown in FIG. Using the received data of satellite 2, that is, the pseudorange data and satellite position data, the pseudorange data of satellite 3 at time t1, and the pseudolite data of satellite 3 at time t2, even if the reception of satellite 3 is interrupted, the time t
The reception position at 2 can be calculated and displayed numerically on the 9 position display 4 or as a track on a map.

Although Figures 3 and 4 show the case where the radio waves of Satellite 3 are blocked, it is also possible to measure the position of the car even if the radio waves of Satellite 2 and Satellite 3 are blocked at the same time. That is clear.

As shown in the positioning error grave graph in Figure 2, from time t1 to t2 when it is impossible to receive three or more satellite radio waves.
If the estimated position is calculated using the direction data from the magnetic compass, the distance data from the distance meter, and the received position data at time t1 during the period of , the positioning error will be as shown by the estimated position error in Figure 2. increases over time.

However, if the received position 92 of the car is calculated as described above, the positioning error is reduced compared to the conventional estimated position error, as shown in Figure 2, and it hardly increases over time. It's not easy.

(Effects of the Invention) As is clear from the above description, the present invention has the advantage that when a GPS receiver is mounted on a car and used in an urban area where there are many shielding objects such as buildings, Therefore, continuous position measurement is not possible, and even if continuous position measurement is possible using the estimated position based on the direction data from the magnetic compass and the distance data from the distance meter, good positioning accuracy cannot be expected. data.

By calculating pseudosatellite position data using satellite position data immediately before reception interruption in addition to distance data, accurate position measurement is possible even when the number of received satellites is one or two.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG.
) is the reception status of satellite radio waves, (b) is the positioning error curve, Fig. 3 is an explanatory diagram of a car receiving radio waves from a satellite, and Fig. 4 is the case of receiving radio waves from a satellite according to the present invention. FIG. 1....GPS receiver, 2. ...Pseudo satellite position calculator. 3.... Reception position calculator, 4... Position indicator, 5.
...Car, 6. ...GPS receiver antenna, 7
．． ...magnetic compass, 8. ...Distance meter, 9. ...shielding object, 10. ···Measurement position. Figure 1 Figure 20 (a) -+[18藺M2Figure (b) -1◆Special

Claims (1)

[Claims] A GPS receiver that receives radio waves from GPS satellites and outputs position data of the GPS satellites and pseudorange data between the GPS satellites and the vehicle, and a GPS receiver that receives radio waves from three or more satellites simultaneously due to obstructions. Based on the satellite position data received just before reception became impossible, the distance meter detects the direction data from the magnetic compass and the rotation speed of the wheels, which detects the direction of travel of the car at that time. a pseudolite position calculator that outputs pseudolite position data that can be received in a pseudo manner at the time using at least distance data from the GPS receiver, pseudorange data from the GPS receiver, satellite position data, and the pseudolite position calculation unit; When the number of receivable satellites is three or more, the position is calculated using pseudorange data and satellite position data, and when the number of receivable satellites is less than three. It consists of a receiving position calculator that calculates the position by also using pseudosatellite position data when there is no pseudosatellite, and a position indicator that displays the positioning results from the receiving position calculator as a numerical display or a track on a map. A GPS navigation device characterized in that it measures the operating position of a vehicle continuously without interruption.