JPS63187176A - 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 navigation system using GPS satellite signals, and particularly relates to a system suitable for displaying driving routes on a map for automobiles. .

[Conventional technology]

As methods for measuring self-position W in an on-vehicle navigation system, integral navigation, satellite navigation, or a combination of both are known. Of these, G is one of the satellite navigation systems.
P S (Global PositioningSy
ste+n (Worldwide Positioning System) requires the setting of an initial position in order to perform positioning.
11 rGPS receiver development and positioning experiment results.” However, the settings were such that the latitude and longitude were entered directly as numerical values, and no consideration was given to simplifying this.

[Problem that the invention seeks to solve]

In the above-mentioned conventional technology, the initial position must be input using numerical values such as latitude and longitude, and no consideration is given to general users who cannot easily know the latitude and longitude of their own position.

An object of the present invention is to provide a method for automating the initial position setting of a GPS receiver in an on-vehicle navigation system that uses a direction sensor and a self-positioning sensor using a GPS receiver.

[Means for solving problems]

The above purpose is to always store the current position that can be calculated from the output value of the azimuth sensor included in the in-vehicle navigation system and the current vehicle speed.

This is achieved by using the above current position coordinates as the initial position when the GPS receiver starts positioning.

be done.

[Effect]

The amount of movement relative to the starting point is determined from the absolute direction determined by the direction sensor and the current vehicle speed determined by the vehicle speed sensor, and the current position coordinates are determined. These position coordinates are always stored, and when the GPS receiver is powered on, the stored coordinate values are read and used as the initial position coordinates for positioning calculations. Once the positioning calculation has started, the positioning calculation can be performed continuously by using the positioning result of each time as the next initial position. Therefore, the initial position setting of the GPS receiver can be automatically performed as described above.

〔Example〕

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

FIG. 1 shows a system configuration diagram of an embodiment of the present invention, a
Satellite signals transmitted from PS satellites 10A to 10C and received by antenna 1 such as a helical antenna are
The spectrum is despread by the S receiver 2, and the orbital data of the satellites is reproduced. At the same time, pseudo distances between each satellite and the user (in this case, a car) are calculated, and positioning calculations are performed.

On the other hand, the direction sensor 3 detects the direction of the earth's magnetic field and outputs the direction in which the own vehicle is traveling.

Further, the ROM 7 stores a navigation trajectory calculation program, a display program, etc.

It is loaded into the RAM 6 and executed by the CPU 5.

Further, map information is stored in a CD (compact disc) ROM 8, and the self-position calculated by the CPU 5 and the above-mentioned map information are displayed in a superimposed manner on the display unit 9, thereby displaying the travel trajectory. Note that the display section 9 may be a CRT, a plasma display, or the like.

The current position is calculated using the heading direction of the vehicle measured by the direction sensor 3 and the vehicle speed measured by the speedometer 12. G
6 13 is a backup memory that uses both the PS positioning results and the current position from the direction sensor, and functions as a non-volatile RAM that can retain data even after the system power is turned off. The position coordinates are written when it is turned off.

It functions to hold it, and the whole is connected by a bus 11.

The keyboard 4 is for various data input operations,
An example of the arrangement of the keyboard surface is shown in FIG. The keyboard has number keys 1000, cursor movement *-fool,
It consists of a QPS operation key 1002, an initial position change key 1003, and a map page switching key 1004.

The numerical keys 1000 are composed of numbers 0 to 9, a decimal point, degrees 2 minutes 2 seconds, and a carriage return key. The cursor movement key 10o1 is of a type that allows up/down, left/right movement using separate keys, but it may of course be of a type such as a joystick.

Next, the operation of this embodiment will be explained. Note that when performing positioning using such a GPS receiver, as mentioned above, an initial position for positioning calculation is required, but C/
In a receiver using an A code (Coarsa/Acquisition code), it is sufficient to set the initial position within a range of about 100B.

First, Figure 3 shows the process that starts when the power switch of the navigation system is turned on. If the switch is turned on now, the position (stop position) when the switch was turned off last time is backed up by process 20. Read from memory 13. In process 21, the read position is displayed on the map displayed on the display unit 9.

The display method may be a blinking cross-shaped cursor, etc.

By the way, if this position needs to be changed, that is,
If you moved by ferry or car train after turning the main switch to 0Ffl last time.

A change is necessary, and at this time, an input indicating that the change is necessary is inputted from the change key 1003 of the keyboard 4. Then, only the steps that need to be changed are processed from process 22 to process 2.
Pass through 3. In this process 23, the cursor movement key 1001 of the keyboard 4 is operated to set the current self-position.

In process 24, it is determined whether or not there is an input operation to activate the GPS receiver. If the surrounding situation seems unsuitable for GPS reception, such as in an area with a lot of buildings in a tunnel, perform an input operation that will not activate the GPS. If the aps key 1002 for operating the GPS has been input, the process proceeds to step 258, and the power of the GPS is turned on. Afterwards,
The degree of certainty of the current position determined from the direction sensor 3 and vehicle speedometer 12.

The longitude is used as the calculation period position for GPS positioning.

Once the initial position has been determined in this manner, positioning is performed using GPS according to the processing details shown in FIG.

First, in process 40, when the number of visible satellites is insufficient, that is, less than two, the process proceeds to process 44, in which visible satellites at the current time and position are selected.

A message such as "Insufficient number of visible satellites" is output on the display unit 9 and the process ends.

On the other hand, if the selected satellites are different from the previously selected combination of satellites, the combination of satellites must be changed. In this case, process 4
Proceed to step 1 and collect data only for the satellites for which there is no satellite orbit data necessary for positioning calculations among the newly selected satellite combinations. If there is no change in the selected ms, process 42.
Proceed to.

In process 42, positioning calculation is performed using the satellite orbit data and pseudo distance values between the user and each satellite, process 43.
Then, the positioning result obtained in step 42 is updated as the initial position for the next positioning calculation. Above processing 40-44
Positioning calculations are performed periodically.

Note that after the initial position setting in process 23 is performed.

If the GPS is not operated, the series of processes shown in FIG. 3 ends. However, if you want to start the GPS after a while after starting a run, press the GPS key 10 on the keyboard 4.
Press 02. Then, the interrupt input shown in FIG. 3 occurs, processing starts from step 25, and the GPS operates.

FIG. 5 shows a processing flow diagram of the navigation system using the direction sensor 3 and the vehicle speed meter 12.

First, in process 30, the vehicle speed is read from the vehicle speedometer 12, and the voltage from the direction sensor 3 is taken in at that timing. The direction of the own army is calculated from the taken-in voltage, and the amount of movement determined from the relationship with the vehicle speed is calculated in process 32. In process 33, the previous reference point plus the amount of movement is set as the current position,
This value is updated and stored as a new reference point.

Furthermore, an embodiment in which a gyro is used instead of the orientation sensor in the above embodiment can also be easily realized.

Therefore, according to this embodiment, the initial position setting is automatically obtained and the operation is simplified.

Note that FIG. 6 and subsequent figures are also examples of a navigation system, and this system will be described below.

As described above, the GPS system requires input of an initial position when the power switch is turned on to start operation, that is, at a cold start.

The initial position can be input by manually inputting latitude, longitude, etc., as described in, for example, IEICE technical research report 5ANE84-11 rGPS receiver development and positioning experiment results. was. However, in everyday life, these numbers are not familiar to us and are usually not written on road maps. Therefore, inputting information was not only tedious but also sometimes impossible. Note that such a situation is particularly likely to occur when traveling by ferry or the like.

Therefore, in the example explained below in Figure 6, we focus on the fact that FM broadcast radio waves have a relatively high frequency and therefore have difficulty reaching long distances, and calculate the location based on the frequency of the FM broadcast station with a high reception level. heading, which gives the initial position.

For this purpose, an FM receiver is installed, its tuner is controlled to scan the band, and the frequency of the received signal that is above a predetermined level is detected. The corresponding ellipse-1 broadcast station is selected, its location is read out, and this is set as the initial location.

First, Figure 6 shows the entire system (3PS
The receiver 2 performs position calculation (positioning) by receiving satellite signals through the antenna 1 , and the positioning output is transferred to the control circuit 53 . In applications such as automobiles, data transfer often does not require high speed, so serial transmission is advantageous because it requires fewer signal lines. The configuration of the GPS receiver 2 is detailed in, for example, Japanese Unexamined Patent Publication No. 58-88676.

The control circuit 53 displays a map on a cathode ray tube (CRT) 57, sends and receives data to and from the GPS receiver 2, and controls FM radio No. 55.
Exchanging data with and receiving data.

It is convenient for the FM radio No. 55 to be an electronically controlled tuner called an electronic tuner. That is, the electronic tuner type has a search mode, and by pressing a switch, it searches for a tuning position where reception is possible and stops. Therefore, the control circuit 53 is designed to issue a search command. Furthermore, there is a device that digitally displays the tuning frequency, and the frequency information is taken out to the outside and inputted to the control circuit 53 so that one frequency can be known. Antenna 54 is for FM radio. , 58 are speakers.

When position information is sent from the GPS receiver 2, the control circuit 53 displays the current position superimposed on the map on the CRT 57. If the current position falls outside the displayed map, new map data is read from the external storage device 56 and displayed. As the external storage bag W156, a large capacity bag such as a cassette tape or a compact disc is convenient.

The initial location search using FM Radio No. 55 is performed by the user,
This is done when it is determined that initialization is necessary after moving on a ferry board, etc., and when the stored data of the previous location information is erased. In the latter case, it is automatically started on the hardware.

In the former case, the user presses the switch 59 to notify the navigator device and start.

A detailed explanation of the control circuit 53 will be given using FIG.
The PU 70 operates based on a clock obtained from a crystal oscillator
An input/output board (I10) that reads the output of the power failure detection circuit 77 to check the power failure history of the backup power supply of AM75.
76, interface circuit with external memory 56 (I/
F)79. A serial communication circuit (SIO) 71 for exchanging data with the GPS receiver 2, a ROM 72 for storing frequency and position data, and a circuit 1073 for exchanging data with the FM radio No. 55. A display circuit 78 is connected to display a map on the CRT 57 and display the current position.

The CPU 70 operates according to programs stored in the ROM 74. From GPS receiver 2, 5IO71
Variable information such as location data sent via RA
Stored in M75. The RAM 75 has power backup, retains the information even when the system is powered off, and reuses it the next time it operates. The backup power supply circuit is implemented as shown in the figure.

During normal operation, power is supplied to RAM75 via diode D1.
At the same time, the battery BAT is charged via the resistor R. On the other hand, during non-operation, diode D2 is connected from battery BAT.
The data is supplied to the RAM 75 through the RAM 75.

A non-operating battery BAT is monitored by a power outage detection circuit 77, and when the voltage drops below a certain level, it is stored in an internal flip-flop and read out through I1076 when the CPU 70 starts next time.

The I/F 79 is an external memory 5 that stores map data.
Data requests from the CPU 70 are transmitted to the external memory 56 through the I/F 79, and read data is also transmitted to the CPU 70 through the I/F 79. The read map data relating to the current position is transferred to the display circuit 78, and the other data is transferred to the RAM 75.The data transferred to the 0 display circuit 78 is displayed on the CRT 57.

11073 is for exchanging the 55th FM radio control information and frequency information.

The CPU 70 sends a search command to a signal line 730 as necessary.
give against. The respective frequencies are input as parallel signals via a signal line 731.

Note that when tuning is completed, data of a certain frequency exists on the signal line 731, and the CPU 70 reads that data and searches the frequency position correspondence table (map) stored in the ROM 72 to determine the position. You can know. Note that detailed operations will be explained later using a flowchart.

FIG. 8 is a flowchart explaining the operation of the GPS receiver 2. When the power is turned on, first, initialization is performed at a, and the sensitivity 1 frequency of the receiving section and the like are set to appropriate values. Next, satellite signal acquisition is performed in b.

Satellite signals are subject to frequency shifts due to the Doppler effect.
Frequency control is performed to absorb this deviation.

When satellite acquisition is completed, orbit data is collected at C and waits for collection completion. Orbit data is sent superimposed on a signal wave. When the collection of trajectory data is completed, positioning calculation becomes possible and is executed at d, and the result is transferred to the control circuit 53 at e. In the positioning calculation, as described above, coarse accuracy is sufficient, but it is necessary to provide an initial position, and in a normal start, the previous data stored in the battery backup memory inside the APS receiver 2 is used. However, if there is no battery backup memory, data may be sent from the control circuit 53 in initialization a.

When it is necessary to change the initial position, data is sent from the control circuit 53 and an interrupt is generated. In this interrupt processing, firstly, f receives the initial position data, rewrites the stack memory so that it processes the return address of one interrupt in 1g, and returns. And the return address of 1g because it takes a certain amount of time to collect orbital data.

If reception has already occurred and data collection is complete,
It may also be the address of d.

FIG. 9 is a flowchart of the control circuit 53.

When the power is turned on, initialization is performed at A. At B, the power outage history of the inactive backup power source is examined. If there is no power outage history, go to H and use GPS receiver 2.
Wait for data from B, and if there is data, display the current position on the map at the factory, and repeat this process.
If it is determined that there is a power outage history, initial position data will be acquired assuming that the position data was destroyed during non-operation. First, at C, the 55th FM radio is instructed to perform a tuner scan. In D.

Wait for the tuner scan to stop. Stopping can be determined by monitoring the frequency and seeing that the frequency does not change for a certain period of time or more. At E, the position of the station of that frequency is checked from the table stored in the ROM 72. If there is no corresponding station at F, repeat from C.
If there is a corresponding station, it is sent to the GPS receiver 55 in G. The above is a case where the memory contents have been destroyed, but if the user decides that the previous data is inappropriate after traveling by ferry etc.
The user presses the switch 59 to generate an interrupt. When a 0 interrupt occurs, the return address is set to C at J and the process returns. After that, the position is found using the method described above.

If we take Japan as an example, there are at least one FM broadcast station for each base.
Accuracy of about 1100k is sufficient. Note that scanning does not necessarily select the nearest station, but since FM radio waves have a high frequency and have a short range compared to medium waves and short waves, this is not a problem.

Further, it is not necessary to provide an FM radio especially for this device, and the radio installed in the car can be used as is or after being modified.

Therefore, according to the examples explained in FIGS. 6 to 9, it is possible to automatically or semi-automatically provide the necessary initial position information to the GPS receiver using the FM broadcast station. The user is freed from tedious operations.

〔Effect of the invention〕

According to the present invention, in an in-vehicle navigator system equipped with a self-positioning sensor that uses both an azimuth sensor and a GPS receiver, the current position is determined from the navigation using the azimuth sensor, and this value is used as the initial value required for GPS positioning. If used as position coordinates, the initial position setting of the GPS receiver can be automated.

[Brief explanation of the drawing]

Fig. 1 is a system configuration diagram showing one embodiment of the present invention;
The diagrams are explanatory diagrams of the keyboard, Figures 3, 4, and 5.
6 is a system configuration diagram showing another example of the navigation system, FIG. 7 is a block diagram of a control circuit, and FIGS. 8 and 9 are flowcharts for explaining the operation. . DESCRIPTION OF SYMBOLS 1... Antenna, 2... GPS receiver, 3... Orientation sensor, 4... Keyboard, 5... CPU, 6...
・・RAM, 7-ROM, 8-CD ROM, 9...
Display section, IOA~10C...GPS satellite, 11...
・Bus, 12...Vehicle speed and t+ figure are 6 figures high] figure is also 8 figures

Claims (1)

[Claims] 1. In a navigation system in which the current position is determined by a combination of absolute position data detected using a GPS satellite signal and relative position data calculated from the direction and distance traveled of a moving object, the current position is calculated sequentially. a non-volatile data holding means for storing the final value of the current position data;
A navigation system characterized in that the data read from the data holding means is set as initial value data necessary for calculating the absolute position data when powering up the system. 2. The navigation system according to claim 1, wherein the navigation system is configured such that the direction of the mobile object is detected by a geomagnetic direction sensor.