Data processing: vehicles – navigation – and relative location – Navigation – Employing position determining equipment
Reexamination Certificate
2000-03-10
2002-01-01
Louis-Jacques, Jacques H. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Navigation
Employing position determining equipment
C701S207000, C701S208000, C701S117000, C340S988000, C340S990000, C340S995190
Reexamination Certificate
active
06336075
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a car navigation system, and more particularly, to an apparatus and method for guiding a vehicle which is capable of accurately detecting a position of a vehicle moving on a road regardless of a location or an environment of the road, so that the current position of the vehicle, its advancing direction and a remaining distance to its destination can be informed to a driver through a voice guidance and a graphic display, thereby guiding the vehicle accurately and steadily to an intended destination.
2. Description of the Background Art
In general, a car navigation system is characterized in that positions of roads and facilities on a map are digitized and stored in a memory, and history of current position information on a vehicle is periodically analyzed by using satellites and maps with the roads of the map stored in the memory, thereby guiding the vehicle steadily to the destination within the shortest time.
In most car navigation systems, there is expressed only a simple operation for shortest path selection from an arbitrary starting position to a destination, which does not give the driver any current traffic condition
Recently, there has been proposed a method of guiding a car navigation system in which traffic information is received by a data file to thereby search a shortest path for guidance. This method employs a global positioning system (GPS).
The GPS system in use for the traffic information collection system is a space-based satellite radio navigation system developed by the U.S. Department of Defense which includes an intentional error in transmission in order to prevent a military use by other countries.
According to this system, by receiving radio signal transmitted from at least three or four satellites among many GPS satellites having an atomic frequency in the orbit, a distance to the satellites is obtained from the radio time of the radio signals, for which a speed measurement is available by using the Doppler effect of a three-dimensional or two-dimensional lateral position and the radio waves.
As aforementioned, the global positioning system (GPS) was initially developed for military use, as it was confirmed to have a high utility value for civil vehicle means, the satellite started a service for civil use, by transmitting radio signals for measurement which contains the range error.
By applying the global positioning system to the car navigation system, information on a vehicle operation, such as a distance to the destination and the time required, can be obtained.
Typically, the error in the distance signal received from the GPS satellite is approximately in the range of 100 m to 2 km.
FIGS. 1 and 2
show an apparatus for guiding a vehicle using the conventional global positioning system.
The apparatus for guiding a vehicle of the conventional art includes a plurality of GPS satellites
20
placed in a orbit for transmitting a GPS signal including position information and time information on a vehicle; and a GPS receiver
10
mounted in the vehicle for receiving the GPS signals including the position and time information from the plurality of GPS satellites
20
, detecting a current position of the moving vehicle by using the GPS signals, and guiding the vehicle to its destination.
As shown in
FIG. 2
, the GPS receiver
10
includes an antenna
100
for receiving the GPS signal including the position and time information of the vehicle from the plurality of satellites
20
; a frequency down converter
101
for frequency down converting the plurality of GPS signals each in the different range of a few GHz(substantially 1-8 GHz) as received to baseband signals; a GPS tuner
102
for extracting only a GPS signal corresponding to the current position of the vehicle from the frequency down converted baseband signals; a position operation unit
103
for computing an absolute coordinate of a latitude, a longitude, an altitude, and a standard time with the extracted GPS signal and outputting current position information on the vehicle; a compact disk player
106
having a disk ROM storing digitized positions of roads and facilities of a map; an operating panel
107
for inputting a position of a starting position or a destination; a CPU
105
for analyzing history of position information transmitted periodically from the position operation unit
103
to correct a position measurement error, and mapping the current position of the vehicle to each road on the map as stored in the disk ROM of the compact disk player
106
; and a monitor
104
for displaying drive guide information outputted from the CPU
105
on a screen until it reaches a destination designated by the operating panel
107
.
FIG. 3
is a flow chart of the process of the method for guiding a vehicle in which the GPS signal transmitted from the GPS satellites
20
is received, by which the current position of the vehicle is computed, and the computed current position of the vehicle is mapped onto the road of the map stored in the disk ROM of the compact disk player
106
, thereby guiding the vehicle to its destination through the shortest path.
The operation of the apparatus for guiding a vehicle using the global positioning system in accordance with the conventional art will now be described with reference to FIG.
3
.
When the car navigation system adapting the global positioning system is started to be operated, the CPU
105
actuates the compact disk player
106
. Accordingly, the compact disk player
106
loads the map stored in the disk ROM as digitized and displays it on the screen of the monitor
104
through the CPU
105
.
When positions of the roads and the facilities of the map is displayed on the screen of the monitor
104
, a driver inputs a desired destination through the operating panel
107
(step S
10
).
At this time, the plurality of GPS satellites
20
placed in the orbit, that is, the
24
GPS satellites, transmits the GPS radio waves including the position and time information of the vehicle.
The GPS radio waves transmitted from the plurality of satellites
20
are received by the GPS receiver
10
mounted in the vehicle as shown in FIG.
1
.
As shown in
FIGS. 1 and 2
, the GPS receiver
10
mounted in the vehicle receives the radio waves from at least three or four GPS satellites
20
(preferably three GPS satellites) among the plurality of GPS satellites
20
through a radio wave receiver such as the antenna
100
, and supplies them to the frequency down converter
101
.
The frequency down converter
101
frequency down converts the received GPS radio waves of a few GHz to baseband signals and supplies the same to the GPS tuner
102
.
The GPS tuner
102
extracts only a corresponding baseband signal that is the most suitable to its position among the baseband signals for each GPS signal inputted through the frequency down converter
101
.
The position operation unit
103
computes the current position of a vehicle, that is, a latitude, a longitude, an altitude and the standard time, on the basis of respective baseband signals inputted through the GPS tuner
102
, and provides it to the CPU
105
(to be described later).
As is known, the GPS signal is a signal transmitted from the plurality of GPS satellites
20
having time information. Arrival time taken for the radio waves to reach the vehicle from the respective GPS satellite
20
is different to each other due to the difference of the distance from each GPS satellite to the vehicle.
By comparing the GPS signal arrival time from each GPS satellite pre-set over a reference coordinate corresponding to a specific position and a GPS signal arrival time from each GPS satellite received at a position of a specific position, an absolute coordinate value of the current specific vehicle can be obtained.
Accordingly, the CPU
105
reads out the current position information on the vehicle which was arithmetically operated by the position operation unit
103
and map-matches it with the road on the map as stored in the disk ROM of the compact di
Jin Seo-Yong
Kim Dong-Joon
Ko Joong-Hyup
Park Jong-Hun
Sin Young-Dal
Jacobson & Holman PLLC
Louis-Jacques Jacques H.
ROTIS Inc.
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