JPS63109381A - Data processing method of gps receiving apparatus - Google Patents

Abstract

PURPOSE:To detect the more accurate present place of a vehicle, by calculating the average value of a predetermined number of the output data outputted from a global positioning satellite system (GPS) receiving apparatus during the stop of the vehicle. CONSTITUTION:CPU 7 judges whether a vehicle is stopped at first and, when the vehicle is stopped, judges whether the GPS data (data) outputted from a GPS receiving apparatus is effective. When the data is judged to be ineffective, processing is finished without performing anything and, when said data is judged to be effective, it is judged whether a predetermined number of data are inputted from the apparatus 4 during the stop of the vehicle. When a predetermined number of data are inputted, the average value of said data is calculated and the standard deviation thereof is simultaneously calculated to judge whether the standard deviation is within a predetermined value. When said standard deviation is within the predetermined value, the average value is stored in RAM 9 as the present place data of the vehicle. A distance error is calculated at each time when the vehicle runs over a definite distance and the position of the vehicle on a road is detected from the position previously detected on the basis of map data and set to the present place of the vehicle to always accurately confirm the present place of the vehicles.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to the Global Positioning Satellite System (GlobalPositioning Satellite System).
GPS that outputs the vehicle's current location data based on the GPS (hereinafter abbreviated as GPS)
The present invention relates to a method for processing received data by a receiving device.

Background Art In recent years, in-vehicle navigation devices have been researched and developed that guide a vehicle to a predetermined destination by storing map information in a memory, reading the map information from the memory, and displaying the map information along with the vehicle's current location on a display device. has been done.

Such a navigation device requires a detection means for detecting the current location of the vehicle, and as this detection means, for example, the above-mentioned GPS is used.

This system is said to be able to measure the current position of a vehicle with a maximum accuracy of about 20 meters by receiving radio waves emitted from multiple artificial satellites.

However, the measurement accuracy of such a system varies depending on the position of the satellite, satellite perturbation, ionospheric conditions, etc., so if the data received by the GPS receiver is used as is, it will not be possible to obtain the desired measurement accuracy. Moreover, since the current location of the vehicle while it is running changes from moment to moment, it is desirable to be able to accurately detect the current location of the vehicle in response to these changes.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned points, and provides data for a GPS receiving device that enables more accurate current location detection of a vehicle by increasing the reliability of current location data obtained by the GPS receiving device. The purpose is to provide a processing method.

The data processing method of the GPS receiver according to the present invention calculates the average value of a predetermined number of output data output from the GPS receiver while the vehicle is stopped, and when the standard deviation of this average value is within a predetermined value, The data is valid data and is characterized by being used as current location data of the vehicle.

Example Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a block diagram showing the configuration of an in-vehicle navigation device to which a data processing method for a GPS receiving device according to the present invention is applied. In the figure, 1 is a geomagnetic sensor for outputting vehicle orientation data based on geomagnetism (earth's magnetic field), 2 is an angular velocity sensor for detecting the angular velocity of the vehicle, and 3 is a geomagnetic sensor for detecting the distance traveled by the vehicle. A mileage sensor 4 is a GPS receiving device for detecting the current location of the vehicle from latitude and longitude information, and the outputs of these sensors (devices) are supplied to the system controller 5.

The system controller 5 is connected to an interface 6 that manually converts the outputs of the sensors (devices) 1 to 4 and performs A/D (analog/digital) conversion, etc., and processes various image data that are sequentially sent from the interface 6. A CPU (central processing circuit) 7 that calculates the amount of movement of the vehicle, etc. based on the output data of each sensor (device) 1 to 4.
and a ROM (read-only) in which various processing programs and other necessary information for the CPU 7 are written in advance.
Memory) 8, RAM (Random Access Memory) 9 in which information necessary for executing programs is written and read, and so-called CD-ROMs, IC cards, etc., which are digitized (numerical). A recording medium 10 on which map information has been recorded, and a V-RAM (Vi
Graphic data such as a map sent from the CPU 7 is drawn in the graphic memory 11 and is stored as an image in the graphics memory 11.
It is composed of a graphic controller 13 that controls display on a display 12 such as an RT. The input device 14 consists of a keyboard or the like, and various commands and the like are issued to the system controller 5 by the user's keystrokes.

Next, the basic procedure executed by the CPU 7 will be explained according to the flowchart shown in FIG.

The CPU 7 first initializes the program to execute it (step S1), and then determines whether the current location of the vehicle has been set (step S2). If the current location has not been set, a current location setting routine is executed (step S3), for example, the current location is manually set using the keys on the input device 14. Next, the mileage is set to zero (step S4), and it is then determined whether there is any key input from the input device 14 (step S5).

If there is no key personnel available, a map of the area around the current location is displayed on the display 12, and the current location of the vehicle and its direction are displayed on this map using, for example, a vehicle mark, and when the vehicle moves, the map scrolls as the vehicle moves. Furthermore, when the vehicle position is likely to exceed the range of the map data currently on the graphic memory 11, the necessary map data is read out from the recording medium 10 and displayed on the display 12 (step S6).

If there is key human power, the current location is reset (step S7) and sensor correction (step S8) according to the input data.
, destination setting (step S9), and map enlargement/reduction (step 510).

Further, the CPU 7 constantly calculates the direction of the vehicle based on the output data of the geomagnetic sensor 1 and the angular velocity sensor 2 at regular time intervals, as shown in FIG. 3, by interrupt processing using a timer (step S11.512).

By the way, GPS is a system that determines the current location of a vehicle as an absolute position (latitude and longitude) on the earth by receiving information from a device made up of satellites. As mentioned earlier, this system is said to be able to measure the current position of the vehicle with a maximum accuracy of about 20 meters;
It varies depending on the satellite position, satellite perturbation, ionospheric conditions, etc.

The principle of detecting the current location of a vehicle using GPS will be briefly explained below.

As schematically shown in Fig. 4, the GPS uses a plurality of antennas A1 to A4 distributed at appropriate intervals on the earth E.
It is composed of a plurality of satellites 81 to S4 and a user P, and each satellite 81 to S4 is controlled by a control station C via antennas A1 to A4. In addition, each satellite S1 to S4 has a receiver that receives signals from antennas A1 to A4, and a transmitter that emits various information signals to user P. Each is equipped with a transmitter that receives a signal.

Here, if there is a clock that is completely synchronized at the transmitting point and receiving point of radio waves, and the transmitted signal is controlled by that clock, then if you measure the timing at the receiving point, you can measure the propagation time of the radio wave between the transmitting and receiving points. By multiplying it by the speed of light, the distance between the transmitting and receiving points can be determined. Now, there are three satellites St l in the field of view (receivable area) of user P.
S2, sa, each satellite S1+ 82
Assume that the satellites S1 and S3 are transmitting ranging signals using clocks that are synchronized with each other, and that the positions of the satellites S1 and S2+S3 at the time of reception are accurately determined. By measuring the reception time of these signals at the reception point P, each satellite SI
+s2. The distance between s3 and receiving point 2 is calculated, and user P
The position of can be determined as the intersection of three spherical surfaces centered on each satellite Sl r S2 r S3.

However, in reality, it is difficult to completely synchronize the clocks at the transmitting point and the receiving point, and errors occur due to delays in the received signals. In addition, in this system, measurement accuracy fluctuates, including distance measurement errors due to the position errors of the satellites 81 to S4, the state of the ionosphere, etc. Therefore, the signals emitted from the satellites 81 to S4 to the user The deterioration coefficient (Geometrical Dilution
Of Precision (hereinafter abbreviated as GDOP) data is included.

The table below shows an example of the types and magnitudes of distance measurement errors that have been published, and by simply multiplying these numbers by GDP, you can calculate what will happen if the user actually uses this system. It is now possible to calculate position detection accuracy.

Table: Types and magnitudes of distance measurement errors of user devices Therefore, in the present invention, in order to further increase the reliability of the received data of this GPS receiving device 4, the vehicle is stopped in relation to the received data of the GPS receiving device 4. This makes it easier to perform statistical processing by performing necessary data processing within the data.

Next, the GPS according to the present invention executed by the CPU 7
The procedure of the method of processing received data by the receiving device 4 will be explained according to the flowchart of FIG.

First, the CPU 7 determines whether the vehicle is stopped (step 521). If it has stopped, it is determined whether the data output from the GPS receiver 4 (hereinafter referred to as GPS data) is valid (step 522). This determination is made using the GDOP (deterioration coefficient) of the GPS data. This GDOP is a coefficient representing an increase in measurement error determined by a geometric function between the satellite used and the vehicle when measuring the current location.

If it is determined in step S22 that the GPS data is invalid, the process is completed without performing any operations; if it is determined that the GPS data is valid, the count value of the data counter is first zeroed out (step 823), and then GPS while the vehicle is stopped
It is determined whether a predetermined number of GPS data have been input from the receiving device 4 (steps 824, 825). predetermined number of G
Once the PS data has been input, the average value and standard deviation of these data are determined (step 526);
It is determined whether the standard deviation is within a predetermined value of 65 (step 527). If the standard deviation is within the predetermined value of 65, the average value is stored in the RAM 9 as the vehicle's current location data (step 528), and used for subsequent calculations of the current location.

Furthermore, at this time, current location recognition processing that is executed based on map data is also performed.

In this current location recognition process, the distance error caused by the detection error of the mileage sensor 3, the digitization error of the map data, etc. is corrected by the above-mentioned fixed distance from the previously detected position based on the map data every time the vehicle travels a certain distance. By detecting a position on a distant road and using this detected position as the current location, processing is performed to always accurately recognize the current location of the vehicle. A specific method for processing current location recognition has already been proposed by the present applicant in Japanese Patent Application No. 156883/1983.

As described above, by performing the necessary processing on the GPS data to obtain current location data while the vehicle is stopped, the current location of the vehicle can be accurately determined from this current location data.

As described in detail, according to the present invention, while the vehicle is stopped,
The average value of a predetermined number of output data output from the GPS receiver is calculated, and when the standard deviation of this average value is within a predetermined value, this data is considered valid data and is used as the vehicle's current location data. Since the reliability of the current location data obtained by the device can be increased, the current location of the vehicle can be detected more accurately.

[Brief Description of the Drawings] Fig. 1 is a block diagram showing the configuration of an in-vehicle navigation device to which the data processing method of a GPS receiving device according to the present invention is applied, and Figs. 2 and 3 are executed by the CPH in Fig. 1. Fig. 4 is a flowchart showing the basic procedure of the GPS.
The figure is a flowchart showing the procedure of the data processing method of the GPS receiver according to the present invention, which is executed by the CPU in FIG. Explanation of symbols of main parts 1... Geomagnetic sensor 2. Old... Angular velocity sensor 4... GPS receiver

Claims (1)

[Claims] A data processing method for a GPS receiver mounted on a vehicle and outputting current location data of the vehicle based on the global positioning satellite system, the method comprising:
The method is characterized in that the average value of a predetermined number of output data output from the receiving device is determined, and when the standard deviation of this average value is within a predetermined value, this data is considered valid data and used as the current location data of the vehicle. A data processing method for a GPS receiving device.