AUTOMOBILE NAVIGATING SYSTEMS.
AUTOMOBILE NAVIGATING SYSTEMS.
Modern automobile navigating systems are intended
For effective planning and performance of trips. Navigating
The system defines and gives out to the driver current co-ordinates
The car on a district map, chooses an optimum route to
The set purpose, helps the driver to follow this route.
The general data Mechanical prototypes of navigating systems
Have appeared in the USA in 1910 when cars have begun
To be made in considerable quantities, and roads yet were not
Are marked. For example, in navigating system Chadwick Road Guide
The metal disk with apertures rotated to sinhron th with the passed
By.
Apertures marked crossroads on a route. To paths on
Disk springs nestled special molotochki. At hit
molotochka in an aperture the device published a call, and special
rychazhok with the coded symbol specified to the driver, what
It is necessary to execute action. However accuracy and reliability of the such
Navigating systems were low, them have ceased to use
After standardization of traffic signs in the twenties and marking
Roads.
In 60th years the automobile companies have started to show again
Interest to navigating systems. In 1987 Toyota their beginnings
To establish on serial models as an option. In 1994 in the USA,
To Europe, Japan already it has been sold more than 500 thousand devices.
The first navigating systems were applied only to indication
Estimated time of arrival in destination and distance to
It was used also by gauges of an azimuth and speed of rotation of wheels.
Later databases from the cartographical have started to be used
Possibility to define current co-ordinates has appeared the information,
The car on a district map. For this purpose there are some methods.
Functions and structure of navigating system the System can
To carry out navigating notation, to define position
The car on a district map on a configuration of a passed way,
To define absolute co-ordinates by means of satellite system
GPS (Global Positioning System - "global positioning
System "). By means of navigating notation define
Relative position of the car and movement direction on
The information received from gauges of speed of rotation of wheels and
Azimuth.
Configuration of a site of the passed way, received with the help
Navigating notation, it is compared to a configuration of roads,
Plotted. Having defined road on which moves
The car, system finds also its current co-ordinates. More
Exact definition of co-ordinates of the car on a map is made with
Help GPS on width and a longitude. It is considered, that for practical
Is more whole to know enough co-ordinate of the car to within
The size of half of quarter, that is 100 metres.
The automobile navigating system should have in the
Structure gauges of the passed way and a movement direction. The gauge
The passed way is this or that design electronic
odometra, the information in which arrives from gauges of speed
Rotations of wheels ABS. Odometram a number of the regular is inherent
Errors which are necessary for correcting:
- The difference in diameters of the new and worn out tyre cover gives
Error in definition of the passed distance to 3 %;
- At the expense of increase in diameter of a tyre cover from centrifugal force on
Each 40 km/h of speed of the car an error in definition
The passed distance increases by 0,1-0,7 %;
- Change of pressure in tyres on 10 psi (689 kpa) increases
Error on 0,25-1,1 %.
Gauges of a direction For definition of a direction of movement
The car the azimuth gauge, gauges of speed are usually used
Rotations of wheels, gyroscopes.
The azimuth gauge uses a magnetic field of the Earth and represents
Itself the ring core from ferromagnetika on which are reeled up
Winding of excitation and it is perpendicular each other two days off
Windings. The sinusoidal is enclosed to an excitation winding
Pressure. In the absence of an external magnetic field in days off
Windings it is directed EDS vzaimoinduktsii, also sinusoidal, with
Zero average value. In the presence of the constant external
Magnetic field intensity N (a magnetic field of the Earth)
There is a distortion of the sinusoidal form of a magnetic stream in
The core at the expense of imposing of a constant component and pressure
Target windings.
If the external magnetic field is directed under corner Q to a winding
H average values of pressure in target windings will be defined
So:
Vx = kHcosQ, Vy = kHsinQ, where k - factor
Proportionality.
From here Q=arctg (Vy/Vx), that is a direction of movement of the car
It is defined. Modern gauges of an azimuth are issued in
Integrated execution. For definition of a direction of movement
The car gauges of speed of rotation of forward wheels are used,
Applied and for ABS. The corner of turn of the car is defined on
Differences of the ways which are passed at turn left and right wheels.
At gyroscope use angular speed is defined
The car on turn also it is integrated for corner definition
Turn. In navigating systems various types are used
Gyroscopes, for example the gas.
Navigating notation Navigating notation is a method
Definitions of co-ordinates of moving object (the car, the plane,
Vessel etc.) in relation to a starting point. The sum is used
Vectors of the passed distances, the information on directions
Arrives from the gauge of an azimuth or the gauge of speed of rotation of wheels.
The direction of movement of the car is usually defined on
To the geomagnetic gauge of an azimuth (compass). The car case
It is executed from metal and other magnetic materials and it is capable
To be magnetised by external fields (for example, in a magnetic field,
Created by electric locomotive electric motors on the railway
Moving, etc.). In this case there is a regular
Error in definition of a direction of movement of the car.
Parasitic an error in definition of a direction of movement
The car. The parasitic magnetic field is compensated
Additional magnets near to a compass.
The magnetic field also is deformed in tunnels, on the metal
Bridges, at movement along lorry convoys. Application of gauges
Speeds of rotation of wheels along with a compass often solves this
Problem. Gauges of speed of rotation of wheels are tolerant to the such
To distortions, in practice gauges of an azimuth and speed of rotation of wheels
Supplement each other at definition of a direction of movement
The car.
Navigating notation gives low accuracy of definition
Current co-ordinates of object. For the car it is necessary
To correct the co-ordinates defined by a method of the navigating
Notations each 10-15 kilometres. Fortunately, cars usually
Move on roads which are plotted.
Electronic maps In some navigating systems
The cartographical information is stored on-line and passed
On the car on a radio channel, but in most cases
The navigating system assumes presence of necessary base
Data onboard the car.
CD-ROM is used for storage cartographical and road
Information for comparison of configurations of roads and a passed way,
Search of an optimum route, conclusion of a district map to the display.
The considerable capacity of CD (to 600 Mb) allows to do it.
The cartographical information or electronic maps exist in
Two basic formats: matrix and vector. In the matrix
Format (pixel) the correspond to each element of a map
Values of Cartesian co-ordinates X-Y. Matrix maps demand much
Places in memory of the computer or on a data carrier also are inconvenient
For mathematical operations at a lining and tracking for
Route.
In a vector format of road of street are represented
Sequences of pieces of the straight lines described analytically,
Crossings - sites. Sites identify in co-ordinates - a longitude
And width. If road (street) not a straight line, in a break point also
The site is located. Thus, roads (street) of any configuration
Are approximated by a set of vectors and sites.
Available maps or the images of district received with
Planes and companions, are scanned. Then the special program
Maintenance transforms the image at first in matrix, and
Then in a vector format. The electronic map bears the such
The information, as numbers of roads, names of streets, numbers of houses between
Crossroads, unilateral or bilaterial movement in the street,
Names of hotels, restaurants and so on.
In Russia wide application of automobile navigating systems
Until recently restrained absence of electronic maps.
Orientation on a district map on a configuration of the passed
Ways This method allows to define or specify the flowing
Co-ordinates of the car comparison of a configuration of the passed way
(Its site), received by navigating notation, with
Road configuration on which the car moves.
The navigating system defines, what of nearby roads
Can correspond to the co-ordinates of the car defined
To navigating notations. The most suitable road gets out and
Car co-ordinates on a map are corrected. When the car
Reaches a crossroads, the road choice is defined by a direction
Movements. If roads at a crossroads look approximately equally,
The navigating computer traces them on a map forward and
Defines factor of correlation for each of roads on
To the relation to a demanded route. The road with the greatest gets out
In correlation factor. The cartographical information is stored on
CD as for demonstration of a map and current position to the driver, so
And for definition of a configuration of chosen roads.
Global positioning system GPS GPS can
To be used for definition of absolute co-ordinates of the car.
The system consists of 18 cores and 3 spare companions on
Circumterraneous orbits (radius - 20 183 km, a cycle time - 12
Hours), the USA started by the Ministry of Defence during the period with 1980 on
1992 (program NAVSTAR), also is intended to deliver
The information on absolute co-ordinates to various objects:
To cars, sea courts, planes, rockets, military
To divisions and so on. On companions the nuclear are established
Hours, periodically to the Earth are sent signals with the information about
System time and orbit parametres for frequency of 1.57542 GHz.
Users are served by system GPS on two categories:
Exact definition of co-ordinates (Precise Position Service - PPS) for
Military men and standard accuracy of definition of co-ordinates (Standard
Position Service - SPS) for other categories of users,
That it is enough for automobile navigation. Theoretically
Accuracy of definition of co-ordinates with an error to 100 m is achievable, on
To co-ordinate practice are defined to within 30 m.
Receiver co-ordinates (X, Y, Z) and the companion (Ui, Vi, Wi) are connected
Parity:
Pi = + R, where Pi - distance between the companion and the receiver, R -
The time error arising because of impossibility it is exact
To synchronise an atomic clock of the companion and the quartz generator
The receiver. Thus, at known co-ordinates of four
Companions and distance from companions to receiver Pi from
Decisions of the four-dimensional nonlinear equation of Kepler are defined
Receiver co-ordinates.
Distance Pi between the companion and the receiver is defined on
Delay time ti arrival of a synchronising signal from the companion
Because of final speed of distribution of radio-waves.
Apparently, navigation by means of GPS is most
The perspective. There are also lacks:
- At the first reference initial co-ordinates are defined
Rather long - 2-3 minutes. Further the information
It is updated much faster, within several seconds;
- The system works in the conditions of direct visibility with four
Companions. Mountains and high buildings can serve as an obstacle. Here
Why even in the newest automobile navigating systems
Besides receivers GPS use other gauges of the passed way
And directions.
Choice of an optimum route Except definition of the flowing
Car co-ordinates the navigating system also can give out
The information facilitating a choice of an optimum transit to
To destination. For this purpose the navigating computer considers
High system between a starting point and destination and
Chooses the shortest route, using the special
The determined or stochastic algorithms.
The navigating information is informed the driver various
In the ways: from instructions a position symbol on a district map to
Commands a voice through a speech synthesizer about necessity to turn
On the left or to the right.
Examples of automobile navigating systems One of the first (in
Modern understanding) navigating systems - Etak Navigator and
Bosch Travepilot. Etak Navigator has been let out in the mid-eighties
Years, it there was a first automobile navigating system,
Made serially. In it the electronic vector were used
Maps of roads on cartridges in capacity of 3,5 Mb, navigating notation,
Algorithm of orientation on a map on a configuration of the passed
Ways, the display. As gauges were used
Differential odometr and a compass.
Travepilot - second generation Navigator - has been let out
In common Etak Inc. And Bosch GmbH in 1989. Cartographical
The information is stored on CD-ROM, its capacity allows to have on
One disk of a map of the several countries. In drawing 4 the display is shown
Travepilot. Position and a direction of movement of the car on
To the relation to a map it is shown by an arrow in the bottom of the display in the centre. At
Car movement map orientation to the display, so varies
It is easier to driver to co-ordinate that he sees through a windscreen,
With a map.
In the right part of a map the scale is specified. It can be from 1/8 miles
For viewing of details of streets to 30 miles when the large are visible only
Roads. During a parking the driver uses the programmed
Buttons to enter and receive from Travepiot the various
The information. For example, it is possible to enter data about the trip purpose in a kind
Names of street, house number and so on. Travepilot allocates
Such purpose flickering asterisks on the display, specifies
Distance to the purpose and a direction on it from current position
The car in the top line of the display. For example, in drawing 4
The street site where there is a house with set number is allocated.
The submenu allows the driver to make manually updating
Car positions on a map. It occurs not more often than an once
On 1000 miles of a way because of errors in maps and algorithm of definition
Car positions on a configuration of the passed way.
In systems Travepilot on 400 fine-engine vehicles and "the fast
The help "Los Angeles dispatchers on a portable radio set entered to crews
Co-ordinates of destinations.
Zexel NavMate. Prototypes of this navigating system
Were tested in 1990. Orientation was made on
To the passed way, on navigating notation and electronic
To maps. In 1994 in NavMate have built in receiver GPS.
Combined use of navigating notation
Electronic map, orientation on a configuration of the passed
Ways provide accuracy of definition of a position of the car of 10 m
(Only GPS gives accuracy 100).
System NavMate under other names (TetraStar, NeverLost,
GuideStar) was issued by various manufacturers (GM, Ford,
Siemens Automotive) also it was established as an option as on
Cars from the manufacturer, and in motor-vehicle pools of firms,
Giving cars in rent (Avis Rent And Car, Hertz).
The cartographical information (across the USA) for NavMate is stored on
Nine Rs-cards also switches on data on roads, streets, numbers
The houses, interesting places, shops, hospitals and so on.
The trip purpose is set as the address in the street, a crossroads, object
Interest. The condition for a route lining can be entered -
For example, to avoid high-speed lines. The information to the driver stands out
On the 4-inch colour liquid crystal display in the form of a map and
Specifying arrows. There is a help a voice at approach to
To turn.
In 1998 Zexel has let out modernised variant NavMate.
The price made 1000-1500 dollars. The cartographical information
It is stored on three CDs-ROM. The user can bring necessary to it
Objects in a personal directory.
Nissan Birdview. Firm Nissan Motor With. Has developed
Friendly the interface of navigating system. In a mode on
To default on the monitor the district what it sees is represented
To the observer located in 300 m over the car and 400 m
Behind it. The driver sees district nearby and in front of the car with
Heights of the bird's flight (from here and Birdview) under a corner of 26 degrees
To horizon that is optimum for the person. Width of the foreground
- 500 m, background on horizon are approximately in 7
Kilometres also has width of 12 kilometres. Viewing is possible
Images from height 600, 1200, 2400 and 4800 metres.
JU. JAKOVLEV ("12 Volt").
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//* an information Source: п п я п?п +п п я п? (Nizhegorod. TPD), 2.08.01
//* Reg. Nom. - 1110800003.31-------------------------------------------
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