What is car navigation? Five of the best car navigation systems. System freezes were overcome only this year
“And there’s also a navigator!” This well-known advertising slogan, which presents the navigation system as one of the main advantages of a modern car, is partly true. Over the past few years, a car navigator has transformed from an expensive toy into a reliable driver assistant.
The car navigation system is designed to determine the position of the vehicle, select and track the route. The first car navigator was introduced in 1981 by Alpine.
There are several types of car navigation systems: standard, mobile, as well as navigation software for laptop computers and smartphones. The listed types of navigation systems have their advantages and disadvantages. They differ in design, implemented functions, and price.
The standard navigation system is installed at the vehicle manufacturer and is usually part of the multimedia system. Compatible navigation systems from other manufacturers can be installed in the standard location.
The mobile navigation system is a portable, stand-alone navigation device that is purchased separately and mounted on the windshield or dashboard. Under the term "car navigator" usually refers to a mobile navigation system.
A laptop computer, smartphone, and even regular mobile phone models can be used as a car navigator if they have the appropriate navigation programs installed.
Design of a car navigation system
At its core, a car navigation system is a personal computer with all its attributes: motherboard, central processor, RAM, permanent memory, hard drive, input and output devices, drives for connecting external data sources.
A special feature of the car navigator is the presence navigation processor(GPS receiver chipset). In a number of navigator designs, the navigation processor is combined with the central processor. In addition to the listed elements, the car navigation system may include a GPRS module, Bluetooth, radio receiver and other components.
The antenna receives signals from navigation satellites. The standard navigation system uses an external antenna that is mounted on the roof of the car. A mobile navigator, like a smartphone, is equipped with a built-in antenna.
A touch display is used to input and output information, which is fast, multi-functional and low power consumption. The standard navigation system may use a head-up display to display information.
The standard navigation system is powered from the vehicle's on-board network. The mobile navigator is powered by its own battery. The battery is also charged from the on-board network.
The software of a car navigation system includes an operating system, a navigation program, and other application programs (office applications, multimedia player, games, e-book readers, etc.).
The operating system connects the navigator hardware (“hardware”) with the application program. The operating system used is Windows CE, Windows Mobile, Android, iOS, etc.
The functional basis of the navigation system is navigation program. Car navigation systems use many navigation programs that differ from each other in interface, functionality, degree of performance and unification. Standard navigators mainly use proprietary navigation software.
Domestic navigation programs Navitel, Avtosputnik, CityGuide, ProGorod and a number of others have been created for mobile navigators, PDAs and smartphones. Among foreign programs, it is necessary to note the popular iGo program. The iGo program is also used in the standard navigation systems of Korean Hyundai, Kia, and SsangYong cars. Mobile navigators, PDAs, and smartphones can have several navigation programs installed, which significantly expands the capabilities of the navigation system.
The navigation program is based on electronic map. Car navigators mainly use vector electronic maps that support routing. A vector map includes many objects with their geographic coordinates.
If you plan to drive a car off-road, then you need a navigation program with a raster map. Unlike a vector raster map, it is an image of the area (a transferred paper map or satellite photograph) linked to geographic coordinates.
The world's leading developers of electronic maps are TeleAtlas and Navteq, but maps from these manufacturers still have insufficient coverage of the Russian territory. For this reason, many Russian developers of navigation programs (Navitel, ProGorod, CityGuide) use their own electronic maps.
Car navigation system functions
A modern car navigator has many functions, the main ones being:
- position determination;
- entering a destination;
- route calculation;
- route support.
Position detection(positioning) of the vehicle is carried out according to signals from navigation satellites. In order to determine the position (latitude and longitude) of a car on the ground, you need to receive signals from at least 3 satellites. The signal from the 4th satellite also makes it possible to determine the altitude above sea level. When receiving signals, the GPS receiver calculates the distance to each satellite, based on which the spatial coordinates of the vehicle are determined.
There are two satellite navigation systems in the world: American Navstar GPS (global positioning system) and Russian GLONASS (global navigation satellite system). The GLONASS system is slightly behind GPS in terms of the number of satellites and position determination accuracy. Currently, the positioning accuracy of the GPS system is 2-4 m, GLONASS - 3-6 m. The greatest accuracy (2-3 m) is achieved by the joint use of GPS and GLONASS, which is implemented in a number of mobile navigators.
Under certain conditions (city traffic, tunnel), receiving signals from satellites becomes problematic. In the standard navigation system, for positioning in poor signal conditions, wheel angular speed sensors of the ABS system and longitudinal and lateral acceleration sensors of the ESP system are used. Using sensors, the speed and direction of movement are assessed.
In mobile systems, this function is performed by the navigation program. If the signal is lost, the system considers that the car is moving along a given route at a constant speed.
Entering a destination in the navigation system is carried out in several ways: by address, by name (point of interest, POI), by coordinates and directly by a point on the map. A number of standard and mobile navigation systems implement voice input of a destination.
After entering your destination, the system produces route calculation taking into account many factors (one-way streets, bridges, dead ends, etc.). A number of standard navigation systems offer several route options, calculated according to various criteria (distance, time, money). For example, a short route will consist of as short sections as possible and will not take into account speed limits. A fast route is built taking into account the class of the road (highway, federal highway, city street) and speed limits on these roads. An economical route takes into account both distance and time. Time, however, is given priority.
But all these routes do not take into account the current situation on the road (traffic jams, accidents, repairs, etc.). Therefore, navigation systems that offer dynamic route calculation taking into account the road situation. Information about traffic conditions in real time can be transmitted in two ways: via radio and the Internet.
The TMC (Traffic Message Channel) traffic message channel is built on radio communications. Through the TMC channel, information is transmitted in the form of encoded signals. In Russia, the traffic reporting channel is not well developed. TMC is used in standard navigation systems of Volvo, Land Rover, Honda cars and mobile navigators Alpine, Garmin.
An alternative to the TMC channel is the transmission of information about the traffic situation via the Internet channel. This technology is used by most mobile navigators, PDAs and smartphones. From a mobile navigator, access to the Internet can be organized in two ways: using a GPRS module and SIM card, or via a mobile phone via Bluetooth.
Information about the road situation comes from various sources on the Internet. The Navitel program has its own service “Navitel. Traffic jams". The CityGuide navigation program offers its own system of traffic congestion by lane. Other programs use the well-known Yandex. Traffic jams".
It should be noted that standard navigation systems, as a rule, do not have a connection to the Internet, and if they do, this channel is not used to obtain information about the traffic situation. The exception is BMW's latest RTTI (Real Time Traffic Information) system, which is based on cellular communications and receives information within the TPEG (Transport Protocol Expert Group) system.
Guidance along the route implemented using visual and voice instructions. Instructions are issued sequentially from intersection to intersection. In different navigation programs, the route guidance function is implemented approximately the same, in some places a little better, in others a little worse. There are also serious differences. For example, the Progorod navigation program runs the Junction View service, which, when approaching intersections and complex junctions, offers a realistic picture hint indicating the direction of travel.
My first acquaintance with car navigation systems occurred several years ago, when I was in my penultimate year at the Polytechnic Institute. At that time, sitting next to me at the desk was an excellent student who later received a honors diploma and is currently working as a programmer at Sony in New York. This student, during lectures on the history of world culture, told me about his technical invention, which consisted of a computer with an electronic street map, sensors that record turns and calculate the distance traveled by a car, and a couple of other small measuring instruments designed to provide input data for an ingenious a program that calculates the coordinates of a car and plots its location on the map as a large white dot. My desk neighbor even suggested that I combine our efforts and make a prototype of the system in order to then sell it to the Zaporozhye Automobile Plant (presumably, to equip the “Cossacks” with these same devices). “You want to get from Kharkov to Zelenograd,” he said, “and the map will show you where to go and where to turn.” I refused and now I regret it, because modern car navigation systems (ANS) are exactly what my fellow student proposed to do at one time, with the exception of such a component as GPS (Global Positioning System), which he was talking about at that time I didn't know yet. It is symbolic that in the very first issue of the GIS-Review magazine, published in 1994, two news articles were devoted to automobile navigation systems. The first of them read: “Sony Electronics has begun distributing the GPX-1 on-board car navigation system. It includes a GPS receiver, a five-inch screen and an Etak digital road mapping system on CD-ROM. Can be used for positioning (navigation) and route planning.” The second was dedicated to the signing of an agreement between Etak, Tele-Atlas Int. and Robert Bosch GmbH on the joint development of digital road and street maps for Western Europe. In other words, car navigation systems have been known for quite a long time: ideas about them began to float in the air as soon as computers appeared, the size of which made it possible to move them on vehicles, and such systems took specific shape since the emergence of the NAVSTAR global navigation system, which made it possible with the help of DGPS determine the coordinates of any object on the earth's surface with an accuracy of 2 - 3 meters.
Europe, Japan, America...
The Japanese admit that the concept of a car navigation system originated in Europe, from which Japan, despite obvious progress in this area, lagged behind until 1996. At the same time, the United States lagged behind both Europe and Japan: while European and Japanese car manufacturers vied with each other to equip their products with car navigation systems and competition in both markets was very fierce, the Americans took a cautiously observant position, and Oldsmobile was almost the only American company to install the Zexel Guide-Star AVL car navigation system on the 88 LSS model. This is explained by the fact that in America there are a lot of good roads and a relatively low density of cars; the speed and safety of movement are affected almost exclusively by traffic and weather conditions - as a result, a surge of interest in car navigation systems in America began only in the middle of last year, when the ability to receive real-time traffic and weather maps for any region of the United States for route planning.
By the mid-90s, the main players in the ANS market were determined - they were the European companies Bosch, Philips, Blaupunkt and the Japanese Etak, Sony, Alpine and Pioneer. As you can see from the list, there were no software companies, GIS companies or automotive giants among them, and the first places were taken by traditional car radio manufacturers (and this position continues to this day). Thus, car navigation systems were equated with receivers, tape recorders, vacuum cleaners and washing machines. In other words, the ANS is a household appliance, and not at all a product of the IT industry, no matter how surprising it may sound. By the way, in English-language literature, car navigation systems are called either Auto-Pilot System (APS), or Automatic Vehicle Locator (AVL), or Car Navigation System. For some reason, it is not customary to shorten the last phrase, although today, according to my observations, it is the most commonly used. The need for maps, a key component of every car navigation system, was provided in Europe by two groups of companies - the European Geographic Technologies (EGT) consortium, led by the American corporation Navigation Technology, and the alliance formed by Tele-Atlas and Robert Bosch (later to them The American company of Japanese origin Etak joined, which was reported by news number two, quoted above). The first group produced Philips navigation maps, the second - Bosch. Both worked overtime, trying their best to cover as much of Europe as possible with maps. In those years, BMW installed the Philips Carin navigation system on its cars, and Mercedes installed the Bosch Auto-Pilot System (on S-class cars). It has been estimated that using ANS in Europe saves 50% of the time it takes to get from point A to point B, especially if these points are in different countries.
Known for the production of car radios and coffee grinders, Japan was also actively pushing forward at that time. The peculiarity of the development of automobile navigation systems in the Land of the Rising Sun was that these developments were not entirely concentrated in the hands of private companies, but were supported by the state. The first sign of intelligent transport systems (which includes ANS) in Japan was the project “Comprehensive Automobile Control System” (CACS), developed by the Ministry of International Trade and Industry of Japan in the period from 1973 to 1978, estimated at 73 million $ and laid the foundation for the further development of similar products. Upon its completion, some of the developments were used by the Japanese Ministry of Construction in the Road Automobile Communication System (RACS) project and the country's police to manage traffic and ensure communication between police cars. Later, the results of the work were integrated within the framework of the “Vehicle Information and Communication System” (VICS), which provides the driver with information about traffic on the roads and plans the optimal route. The system became available to consumers in April 1996. By then, Japan had 67 million cars on the road, and this truly limitless crowd of potential consumers provoked fierce competition for a place in the sun. Like any competition, it led to lower prices and the emergence of technical and technological innovations.
Car navigation system Bosh Blaupunkt Travel pilot
One of the reasons for the rapid development of car navigation systems in Japan and the government's attention to this industry is that the traffic problems in this country cannot be solved only by improving the roads and increasing their number, since land here is very expensive and construction takes a significant time . According to the Japanese, optimizing the route of each car will help reduce driver fatigue and ultimately reduce the number of accidents and traffic accidents. Additional benefits could include more efficient use of fuel (also a hot topic in resource-poor Japan) and improved environmental performance. Realizing that ANS could play a significant role in solving all these problems, Japan began their active, government-supported implementation, and by 1997, more than 1 million car navigation systems were sold in the country. According to Matsushita Electric, the annual capacity of the ANS market was 460 thousand systems in 1997 - 1998. and 500 thousand in 1998 - 1999 (forecast for 1999 - 2000 - 600 thousand systems).
A typical car navigation system consists of a computer with a CD-ROM or DVD, a color LCD display, a GPS receiver, a trip sensor, and a gyroscope. Many ANS can also receive television signals and play music CDs.
The main functions of these products are to determine the position of the vehicle and guide the driver along the route. The latter includes providing the driver with a map, calculating the distance and path to the destination, determining and displaying optimal routes on the map, voice instructions and displaying turns and intersections.
Based on the classification of the famous Japanese specialist Dr. D. K. Kahaner, author of the work “ATIP96.049: Car Navigation System Activities in Japan,” five generations of ANS are distinguished.
Zero - not yet car navigation systems in the modern sense, but only the embodiment of the first ideas and rudiments of technology. The zero generation of ANS used magnetic tape media to record cards. The maps themselves were very rough and covered small areas.
The first (1987) is “traditional” navigation. It differs from the previous generation in that it began to use CD-ROM as a carrier of cartographic information; the position of the car on the map, which in the zero generation of navigation systems had to be determined by carefully studying the landscape outside the window, was now determined using sensors - a geomagnetic sensor device, a speed sensor and a gyroscope; The quality of the maps has also improved.
The second (1988) is “traditional” navigation with feedback. In navigation systems of this generation, it became possible to search for a destination (Map Matching), issue voice instructions to the driver and additional information about hotels and gas stations.
The third (1990) is “hybrid navigation”. In addition to sensors, GPS began to be used as a tool for determining the location of a vehicle. Information about traffic and weather conditions, including weather forecasts, has been added to the information taken into account when planning a route.
Fourth (1998 - 1999) - “new age” navigation (“new generation”). Recently, many new products have appeared that bring car navigation systems to a higher technological level: this is the pumping of additional maps via the Internet; the ability to control a car using your voice; using DVD as a carrier of cartographic information.
There are two types of car navigation systems to guide the driver along the route: with and without a map display. Research on non-cartographic, “blind” systems is more actively carried out in Europe and America, where looking at a map while driving a car is considered dangerous. In Japan, it is believed that if the route selection is carried out well by the system, then in order to lead the car to its destination, frequent demonstrations of simple maps are usually not required. Several years ago I heard about a car that projected a map with a route directly onto the windshield, similar to the guidance system in fighter jets, but I have not yet been able to find documentary evidence of the existence of such systems. Voice-controlled blind ANS are more common in Europe and America than in Japan.
Car navigation system AVTC-505
The second type (guiding the driver along the route with detailed navigation maps) requires a high-quality display that shows the current position of the car, destination, route, direction to the destination, etc. All this information is superimposed on a base map of the area with plotted maps on it. roads and helps the driver choose the right turns when driving. This type of ANS is widespread in Japan.
Positioning issues
Based on the vehicle positioning method, modern car navigation systems can be classified as follows:
Satellite navigation;
Navigation using sensors;
Hybrid navigation using both types.
The satellite navigation system, using electronic maps stored on a CD-ROM or DVD, determines location based on signals from the NAVSTAR global positioning system, which was created by the US Department of Defense in the 1970s and is a system of 24 satellites located on six circumferential Earth satellites. orbits with an orbital period of 12 hours, and GPS receivers. The orbits of the satellites are designed in such a way that at least four satellites can be seen from any point on the Earth at any time of the day. Each GPS receiver, receiving a special navigation signal, calculates the distance to each of the visible satellites by measuring the time it takes for the radio signal to travel from the satellite to the receiver. After this, he determines his spatial coordinates (latitude, longitude and altitude above sea level) by triangulation.
Since the NAVSTAR system was originally created for military purposes, the US Department of Defense developed two codes (modes): military and civilian. A GPS receiver using a civilian code determines coordinates with an accuracy of 100 meters. A more accurate determination is hampered by numerous factors that distort the received data: delay of radio signals when propagating in the ionosphere and atmosphere, inaccurate measurement of time, re-reflection of radio signals from various surfaces. In addition, some of the information received by civilian GPS receivers is deliberately distorted in order to prevent their use for military purposes by other countries.
The possibility of increasing the accuracy of coordinate determination is associated with the use of differential GPS (DGPS). Obviously, many errors are the same for GPS receivers located within a few hundred kilometers of each other. One of these receivers, called a reference station, is located in a location whose coordinates are precisely determined. By comparing known coordinates with measured ones, the GPS receiver generates corrections and then transmits them via radio channel to consumers to clarify their coordinates.
It would seem that who and why might need sensors for measuring the distance traveled by a car and gyroscopes, if determining the geographical coordinates of any object (as well as its speed, direction of movement and many other parameters) is not particularly difficult. The problem, however, is that for the system to work, you need to have at least three NAVSTAR satellites in line of sight at the same time - and in cities with tall buildings, this is almost impossible. In addition, the signal, repeatedly reflected from the walls and roofs of houses, is distorted. And in tunnels GPS does not work at all. But satellite navigation has its advantages: GPS is easy to install on a car, errors do not accumulate when using it, DGPS provide high positioning accuracy and the price of GPS is now more than acceptable.
The sensor-based vehicle location system finds geographic coordinates based on the readings of a gyroscope that determines the direction of the vehicle and a distance sensor, so errors accumulate. Thus, the longer the journey the car has taken, the greater the likelihood of a significant error in determining the coordinates and, consequently, in guiding the driver along the route. Hybrid systems use both types of positioning, which avoids most problems.
ANS suppliers: bipolar world
The two largest ANS suppliers in Japan are Sony and Pioneer. In Europe, as already noted, the development, implementation and sale are carried out by their own European manufacturers of consumer electronics. In the United States, car navigation systems are mainly represented by the American branches of Pioneer, Alpine and Etak, which is a division of Sony. Americans are primarily interested in traffic, and Etak has almost completely monopolized the market niche of providing real-time traffic maps for all states without exception. What Etak did not take was divided between Pioneer and Sony. Thus, the market for car navigation systems is divided between European and Japanese companies.
No matter how the soothsayers of the mid-90s predicted a quick and sharp drop in prices for ANS in the world, this, of course, did not happen, just as a sharp drop in prices, for example, for refrigerators and other household appliances is not expected. Yes, the devices are improving, but the price changes slightly. So it is here. In 1996, ANS cost between $2,000 and $4,000. In 2000, their value fluctuates around $1,990 and does not show any tendency towards a significant decrease.
Navigation systems(global positioning system or GPS - Global Positioning System) are increasingly used in Western Europe, the USA, and Japan. The use of these systems is also beginning in the countries of the former Soviet Union, but the development of navigation systems is hampered mainly due to the lack of terrain maps.
The main objectives of the navigation system are:
- determining the location of the car at the current moment
- entering a destination with determining the optimal route
When choosing a route, there are 3 options available - fast, normal and short. In addition, it indicates where the toll roads are located and the traffic features on each route.
In order to use GPS navigation, you need at least a GPS receiver. But in itself it is nothing more than a satellite compass that knows its exact coordinates. To link these coordinates to a specific digital map of the area, you need a more complex device, such as a GPS navigator with a built-in GPS receiver.
Rice. Navigator
What is a navigator?
GPS navigators– devices with a relatively simple software shell, focused primarily on solving navigation problems and capable of working with only one type of map provided by the manufacturer.
The position of the GPS receiver is calculated based on the previously known coordinates of the system satellites. Physically, this is expressed in the fact that the initial data for solving the positioning problem are the distances from the object to all satellites visible to it at the moment. To simplify, let us assume that all visible satellites are stationary in their orbits.
Let's turn to geometry
Rice. Object detection by satellites:
a – sphere from one satellite; b – intersection of spheres from two satellites; c – intersection of spheres from three satellites
The remaining point characterizes the coordinates of the receiver. Distances to satellites (radii of the described spheres) are calculated simply - based on recording the time it takes the signal to reach the object and its speed.
To determine the position of satellites in orbit, in addition to the set of satellites dispersed in stationary orbits, there is a ground-based control complex. It includes tracking stations that maintain constant contact with elements of the orbital constellation. Based on the data received, the control center calculates the exact coordinates of artificial satellites and transmits them to aircraft through communication stations. In calculations, it is assumed that the speed of signal propagation is equal to the speed of light. Therefore, it is also necessary to take into account the accuracy and synchronization of the operation of the clock mechanisms with which the satellite and receiver are equipped, as well as distortions caused by various obstacles in the path of the information wave. To eliminate errors in the receiver's computer, special algorithms are used that adjust the time until the location of the receiver is determined with a predetermined error. The algorithm also takes into account data received from the fourth, fifth and other satellites that are in the “visibility zone” of the receiver.
Note that a full-fledged constellation, which will provide coverage of the entire surface of the globe, must include 24 orbital objects, that is, the maximum number of satellites visible to the receiver at any point on the earth is 12 units. However, today the number of operating navigation system devices is already 30 units.
The figure shows the structure of the navigation system. The system can carry out dead reckoning navigation, determine the position of the vehicle on the terrain map based on the configuration of the path traveled, and determine absolute coordinates using the GPS satellite system. Using dead reckoning, the relative position of the vehicle and the direction of movement are determined using information received from wheel speed and azimuth sensors.
The configuration of the section of the route traveled, obtained using dead reckoning, is compared with the configuration of the roads plotted on the map. Having determined the road along which the car is moving, the system also finds its current coordinates. A more accurate determination of the vehicle’s coordinates on the map is made using GPS in latitude and longitude. It is believed that for practical purposes it is enough to know the coordinates of the car accurate to the size of half a block, i.e. ±100 meters.
The car navigation system must include sensors for the distance traveled and the direction of movement.
Trip sensor
Trip sensor- this is one or another design of an electronic odometer, information into which comes from ABS wheel speed sensors. Odometers have a number of systematic errors that need to be corrected. These include:
- The difference in the diameters of a new and worn tire gives an error in determining the distance traveled by up to 3%.
- Due to the increase in tire diameter due to centrifugal force, for every 40 km/h of vehicle speed, the error in determining the distance traveled increases by 0.1...0.7%.
- A change in tire pressure by 689 kPa increases the error by 0.25...1.1%.
To determine the direction of movement of the car, an azimuth sensor, wheel speed sensors, and gyroscopes are usually used.
Rice. Navigation system structure
Azimuth sensor
Azimuth sensor(compass) uses the Earth's magnetic field and is a ring core 2 made of a ferromagnet, on which an excitation winding 1 and two output windings 3 and 4 are wound perpendicular to each other. A sinusoidal voltage is applied to the excitation winding. In the absence of an external magnetic field, a mutual induction emf is induced in the output windings, also sinusoidal, with a zero average value. In the presence of a constant external magnetic field (Earth's magnetic field), the sinusoidal shape of the magnetic flux in the core is distorted due to the imposition of a constant component and the voltages of the output windings.
Rice. Geomagnetic azimuth sensor:
1 – excitation winding; 2 – ring core made of ferromagnet; 3 – output winding with coordinate X; 4 – output winding with Y coordinate
Wheel speed sensors
GPS systems use the front wheel speed sensors used for ABS. The turning angle of the car is determined by the difference in the paths traversed by the left and right wheels when turning.
Gyroscope
When using a gyroscope, the angular velocity of the vehicle as it turns is detected and integrated to determine the turning angle. Navigation systems use various types of gyroscopes. Below, the use of a gas gyroscope is considered as an example.
The gyroscope works as follows. The pump creates a gas flow (helium) 2 with a given flow rate and directs it through nozzle 1 to two heated sensor wires w1 and w2 (Fig.). The angular speed of the car is determined by the change in the resistance of the sensor wires. As the helium stream exits the pump nozzle, it gradually expands.
Rice. Gyroscope measuring system (gas flow position when turning)
When the car moves straight, the speed distribution is symmetrical relative to the wires, they are cooled equally and at the output of the bridge circuit, of which the wires are part, a bullet voltage is generated. When turning, a Coriolis force arises, displacing the gas flow, the wires are cooled unevenly, their resistance to electric current is different, and a voltage appears at the output of the bridge circuit, proportional to the angular speed of the car when turning.
Dead reckoning is a method for determining the coordinates of a moving object (car, plane, ship, etc.) in relation to the starting point. The vector sum of distances traveled is used; directional information comes from an azimuth sensor or wheel speed sensor. The figure shows the application of navigational dead reckoning to determining the coordinates of an object (car).
Rice. Determination of vehicle coordinates using the navigation dead reckoning method:
X0, Y0 – initial coordinates; Δi – increment of the current position; θi – angular position; X, Y – car location coordinates
The magnetic field is also distorted in tunnels, on metal bridges, and when moving along road trains. Using wheel speed sensors along with a compass often solves this problem. Wheel speed sensors are not sensitive to such distortions; in practice, azimuth and wheel speed sensors complement each other in determining the direction of movement of the vehicle.
Navigation dead reckoning gives low accuracy in determining the current coordinates of an object. For a car, it is necessary to correct the coordinates determined by the dead reckoning method every 10...15 km. The adjustment will be correct if cars move on roads that are plotted on the electronic map.
Electronic cards
In some navigation systems, map information is stored centrally and transmitted to the vehicle via radio, but in most cases, the navigation system assumes that the necessary database is on board the vehicle.
CD-ROM is used to store cartographic and road information for the purpose of comparing road configurations and the path traveled, searching for the optimal route, and displaying a map of the area on the display.
In the matrix format, each map element (pixel) has its own Cartesian X-Y coordinate values. Matrix maps require a lot of space in computer memory or on storage media and are inconvenient for mathematical operations when plotting and tracking a route.
In vector format, roads and streets are represented by sequences of straight line segments, described analytically, and intersections are represented by nodes. Nodes are identified by coordinates - longitude and latitude. If the road (street) is not straight, a node is also placed at the break point. Thus, roads (streets) of any configuration are approximated by a set of vectors and nodes.
Rice. Streets and nodes on a vector map
Existing maps or images of the area obtained from aircraft and satellites are scanned. Then special software transforms the image first into a matrix and then into a vector format.
The electronic map carries information such as road numbers, street names, house numbers between intersections, one-way or two-way traffic on the street, names of hotels, restaurants, etc.
A touch switch on the screen allows you to change the display mode, selecting split or full screen with direction indicators, a list of turns or information about freeway exits.
Rice. Direction indicators
Orientation on the terrain map according to the configuration of the path traveled
First, the navigation system determines which nearby roads may correspond to the vehicle's coordinates determined by the navigation dead reckoning. Then a comparison is made, the most suitable road is selected and the car’s coordinates on the map are corrected. When a car reaches an intersection, the direction of travel determines which road to take. If the roads at an intersection look similar, the navigation computer follows them forward on the map and determines the correlation coefficient for each road in relation to the desired route. The road with the highest correlation coefficient is selected.
Navigation systems allow you to receive information by voice, allowing you to get the information you need without taking your eyes off the road. In total, modern systems recognize up to 1,500 words.
To view a selected area in detail, you can zoom in or out to cover a larger area. Two maps can be displayed simultaneously, one of which shows a more detailed series, and the other gives a wider coverage. If necessary, it is possible to find the nearest hotel, restaurant, gas station, service station, parking place, etc.
Rice. Split screen
To study the route, the driver can preview the route.
500 meters before the approaching intersection, an enlarged diagram of interchanges is automatically displayed on the screen. As you approach the intersection, a voice message will sound to remind the driver of upcoming actions. If the driver misses the required turn, the system itself will correct the route.
If there is insufficient information about the location of a destination, the navigation system can search by address, postal code, latitude and longitude, map, intersections and highway on-ramps. Information about places that the driver wants to visit again can be entered into the system's memory.
If traffic jams or difficult traffic occur along the selected route, the system calculates and offers an alternative route.
Choosing the optimal route
In addition to determining the current coordinates of the vehicle, the navigation system can also provide information that makes it easier to choose the optimal route to your destination. To do this, the navigation computer examines the road network between the origin and destination and selects the shortest route. An example of a method for determining the shortest path from a map is Dijkstra's algorithm(Dijkstra algorithm).
Dijkstra's algorithm identifies all road intersections from the starting point and calculates the shortest paths to each intersection point. For example, if there is a road network, as in the figure, the search for intersections will begin from the starting point A. Intersections B and C will be considered first. The distances from point A to each intersection are indicated inside the circles. Then intersections E and F connecting to point C are considered, for these intersections the distance from the starting point A is indicated. Thirdly, intersections D and E connected to point B are considered, figure b shows the distances from the starting point A to D and E In this case, the distance to point E is indicated through point C, since it is less than through D (it would be 8). Point D is connected to point E, and the route through E is shorter. The shortest route to D is A-C-E-D.
Using this algorithm allows you to determine the shortest route to your destination. With a modern navigation system, the driver does not have to worry about losing his way.
Rice. Dijkstra's algorithm
GPS was further developed in the development of intelligent transport systems (ITS - Intelligent Transportation Systems).
BMW introduced a similar Extended Floating Car Data-System (XFCD).
The test was carried out on a special test track at SBC Park and was intended to demonstrate the capabilities of the system. For example, a car hits a slippery road. In a matter of seconds, the system processes the information and warns the following vehicle in real time. The same information is at the same time transmitted to stationary traffic services, which statistically process the incoming data and send it back to other road users.
The XFCD traffic situation detection system will in the future become an improved successor to the existing Floating Car Data system, which translates as “data from a moving car.” Already today, with the help of FCD, vehicles send their location data at a certain point in time to a central traffic control unit, which compares the received messages with messages from other vehicles equipped with FCD in order to recognize traffic and emergency situations. The XFCD system is capable of recognizing the traffic situation itself, analyzing all available data in the vehicle and transmitting the processed data to the central control panel. At the same time, the system is capable of warning other vehicles in the transmitter coverage area through the Auto-Auto communicator system.
XFCD operates on the basis of the existing navigation system, and its commissioning is only a matter of downloading the program. The introduction of an on-board network makes it possible to synchronously use a whole range of capabilities. In a modern car configured in this way, the system gains access and coordination with many other information control units. These are low and high beams, fog lighting, an external thermometer and air conditioning, brakes and a navigation system, a rain sensor and a glass washer, as well as other equally important little things. All these mechanisms function depending on the traffic situation. Thus, the car will immediately respond to a drop in ambient temperature, ice, or even the unexpected appearance of oil on a section of the road by regulating the stability control system (DSC) and driving speed.
Another undeniable advantage of the XFCD system is the ability to transmit messages directly to other vehicles. Information is transmitted via an ad-hoc network to all vehicles in the immediate vicinity. Each car, depending on the situation, plays the role of either a sender, a recipient, or a transmitter. The advantage of the proven Multi-Hopping technology is undeniable: the Ad-hoc network is organized autonomously, has the required range and does not require the creation of special infrastructure.
A LITTLE ABOUT SPACE
How many satellites do you think are in orbit today to support navigation systems? Answer: there are 90 navigation satellites in Earth orbit today and it is planned that there will be 132 in total. For now, American GPS satellites predominate - there are 32 of them. This is understandable, because it was the Americans who became the founders of satellite navigation and have been developing their network since 1974, in Therefore, today almost all navigation systems primarily interact with them. The positioning accuracy of them is quite high, which provides the necessary reference to the terrain. However, this system also has one drawback. The fact is that, first of all, GPS was created as a system for the military, so under certain conditions, access to them can be terminated only by one command from the Schriever military base. This is what prompted other countries to acquire their own satellites.
Russia is still considered the next most powerful constellation of satellites. The system was launched in 1993, and today the GLONASS satellite system has 24 operating satellites, which prompted manufacturers of car navigation systems to work with them. GLONASS satellites also belong to the Ministry of Defense, and if anything...
In third place today is the Beidou system. Despite the fact that it was launched in 2000, now the Chinese are already using 20 satellites, and there will be 35 in total, and then it, like GPS and GLONASS, will be recognized as global. By the way, the Chinese Beidou actively cooperates with the Russian GLONASS.
The fourth largest number of satellites can be considered the European Galileo system. There are currently 10 satellites in orbit, but it is planned that by the end of 2020 there will be 30 of them. The peculiarity of the system is that it will be able to provide positioning accuracy of up to 10 cm, which is currently unavailable today, although only over Europe.
India does not want to miss out on its benefits from using satellites. Today there are 4 of their satellites in orbit. In the near future, they plan to hang 3 more, and then IRNSS will provide fairly high-quality positioning over India, Pakistan and Afghanistan.
And behind the entire planet are the Japanese with their QZSS. While there is 1 satellite in orbit, there should be 4 of them by the end of 2017. Their main task will be to ensure the functionality of mobile applications and monitoring transport in the Asian region.
LET'S BACK TO EARTH
If we talk about navigation systems for cars, then, oddly enough, they appeared long before people heard a signal from the first earth satellite. The first car navigator dates back to 1930.
A roll with maps of the corresponding area was loaded into a device vaguely reminiscent of today’s navigators, and through a mechanical drive from the wheels it scrolled in proportion to the speed of the car, thereby showing the location on the screen. Having reached the desired turn, the motorist removed the now unnecessary roll and instead inserted the next one, corresponding to the direction of travel.
Of course, there were enough hassles with it, but it was this device from the Iteravto company that became the progenitor of all current navigators.
Despite the fact that in 1981 several navigation satellites were already operating in earth orbit, the next car navigation device was not a satellite navigator, but a gyroscopic one.
Honda was the first to offer its Gyrocator as an option. Created in collaboration with Alpine, the navigator calculated the car's location on a map using gyroscopic sensors, moving a pre-selected and installed map up or down and showing the car's position on the monitor with a glowing dot.
Naturally, each map had to be pre-referenced to the area and set its location in the center of the monitor. At that time, this option cost almost a quarter of the price of the car.
NOWADAYS
The boom in the development of standard navigation systems can be considered the beginning of our century. It was with the advent of new technologies that it was possible to significantly reduce the cost of components for the production of satellite signal receivers and thereby transfer navigation systems from the rank of “not for everyone” to the rank of “for everyone.”
Today, both premium cars and budget foreign cars can boast of a standard navigation system. As a rule, all systems are integrated into so-called multimedia complexes, the main task of which was initially only to entertain the driver on a long journey with music. Later they were added the ability to play not only audio, but also video files. There were systems that could boast of having a TV tuner. However, navigation was the ultimate dream, and it came. Automakers vied with each other to praise their navigation system, which was specific to their brand.
Someone was the first to show the route from a bird's eye view, and someone boasted of the ability to track traffic jams without Internet traffic. However, today the trend is that navigation systems designed for a specific car brand, no matter how good or bad they are, are becoming a thing of the past. Why invent something if there is already a ready-made one, automakers decided and are increasingly installing navigation systems on cars that are tied to software from companies that deal exclusively with navigation. This is why Navitel, CityGID or Garmin can be found today as a standard navigation system in many cars. Over time, car enthusiasts increasingly began to prefer interactive navigation systems, such as Yandex Navigator or Google Maps. This is understandable: up-to-date maps and constant traffic monitoring make life much easier for motorists, especially in big cities. Why then install navigation systems in the car first, if almost everyone has them in their pockets in the form of pre-installed software on their smartphones? Automakers also thought about this and came up with something that allows you to easily control applications from smartphones directly on the monitor of a standard car multimedia system.
APPLE CARPLAY, ANDROID AUTO ANDMIRRORLINK
Most of today's smartphones run Android and iOS operating systems. It is with them that automakers decided to make friends with their multimedia devices. As a result, cars have already appeared that support the ability to transfer “mirrors” of smartphone screens to the screens of standard car systems, with all the pleasant consequences that follow. Which ones? Firstly, now there is no need to get used to the operation of a particular navigation system. Yandex Maps, Google Maps, Navitel or CityGuide are fully reflected on the screen of the standard monitor. You can create a route while still at home or at work, and use it later as soon as you connect your smartphone to the car. Secondly, in addition to working with the usual built-in navigation systems, you can also use other applications, such as the phone book and SMS, without looking up from the steering wheel. Or, for example, view comments on your posts on social networks. You never know what else you can do from a smartphone - it’s your everything, and it’s all now available on a large and convenient screen.
It was thanks to the Apple CarPlay and Android Auto systems that this became partly possible. But why partly? The fact is that these systems cannot yet be recognized as working one hundred percent. Not all functions are available, and those that are available do not work as ideally as we would like.
MirrorLink has achieved much greater success in this field, but it is not standardly installed in every car. And not every smartphone is ready to work with this system - you will have to buy exactly the model that supports this pairing.
And yet, one way or another, such systems are the future, and it is very good that automakers understand this. All that remains is to come up with a system that will not allow you to forget your smartphone at home or at work. Otherwise, you will be left without navigation, without music, and without social networks. And the latter for some may be like death.
Many of us use various devices every day that help us find the best point to our destination. They come to our aid if we are lost in an unfamiliar area. Typically, in urban environments, most navigation systems do a good job. But if we want to go on a trip or out into the countryside into an unfamiliar area, then not all devices are suitable.
What is the most important thing in car navigators? In the first place is the quality of communication, the quality and reliability of maps, and the accuracy of determining the coordinates of the vehicle’s location on the ground. Unfortunately, not all devices these days are ready to give us routes with the quality we expect. Ours offers you the five best car navigation systems that won't let you down.
Each of us prefers different GPS devices, ranging from navigation devices to complex and multifunctional factory-built satellite navigators. All of them have the same operating principle, but not every car navigator claims to be the best.
1) Garmin Nuvi series navigators
The Garmin Nuvi series navigation devices are designed specifically for the automotive industry. They are distinguished by a stylish design and minimal dimensions (including thickness), which allows them to be used without sacrificing space in most cars. It is worth noting that to use the navigator on the road, mobile communications and mobile data transfer are not required. The device operates offline. The cards are made in high quality. Street names and house addresses are shown in full. Nuvi has voice control. The navigator also uses a unique active lane change prompt function. So, for example, when approaching a highway exit, the navigation software will warn you in advance about the need to change lanes so as not to miss the exit or turn.
This way, you won't miss the right turn or wonder where to go at an intersection.
In addition, Garmin Nuvi displays a 3-D layout of a fork or overpass, showing you the one you need. It is noteworthy that Garmin Nuvi navigators are provided with an eternal free map. All changes to the map and updates will be available for download for free. Also, many navigator models can show traffic jams, which allows you to choose detour routes. According to the manufacturer, traffic data is broadcast with a delay of only 30 seconds. You can also pair the device with a mobile phone or computer using Bluetooth to update the software via the Internet. Device prices vary depending on the model. Everyone can choose the optimal model according to their financial capabilities and needs.
2) Tom Tom Go navigator
Although the company's navigation software has become popular on smartphones and tablets, Tom Tom Go's dedicated car navigators also deserve attention. Many car enthusiasts, having purchased these navigators, note the excellent quality of work even far from large cities. This device does not require an Internet connection. The navigator has competent and high-quality voice control. It is worth noting the 5-inch HD touch screens that display images in high quality.
The navigation device software provides active route control, which alerts the driver to the required direction of travel. You do not need to look for street names and house numbers in order to arrive at the required address. Just enter your final destination and the program will take you to the desired address. To do this, you need to listen to the navigator's commands.
3) Magellan RoadMate navigators
The Magellan RoadMate series of navigation devices has been known on the market for a long time and has proven itself on the positive side. But some new models impress with their amazing characteristics, such as: a warning about photo and video speed cameras, a detailed navigation guide (for example, the navigator says: “Turn left after 300 meters towards the Lukoil gas station, and not just “ Turn left after 300 meters"), automatic update when connected to a computer, etc., etc.
Built-in Bluetooth system allows you to use the car hands-free function for voice control. The device can also be connected to a phone with Internet access, with which you can find out details about the places you pass.
By purchasing this device, you receive a standard set of functions available in modern navigators. In addition to active driving tips and the exact names of streets and houses, you receive hints about nearby parking lots and warnings about speed limit signs. But the main feature of the navigation equipment is the integration of the navigator with the rear view camera of your vehicle.
4) Built-in GPS device in the car
Whatever satellite navigation devices are available on the market, the most interesting ones are the satellite navigation systems that are built into a new car at the factory. Also, as an option, as a rule, any car dealer offers us to install factory navigation for an additional fee. Of course, unlike third-party equipment, factory navigation is much more expensive than its counterparts, but, nevertheless, many factory car navigators are the best solution for traveling to unfamiliar areas.
Of course, these devices have their pros and cons. Most built-in car navigators often do not have the latest map updates available. In addition, some cars have difficulties with their updates. many automotive devices leave much to be desired.
However, not all car manufacturers equip them with inconvenient navigation systems. Many premium car brands have excellent satellite navigation available on screen. In some models, the address search form is performed much better than in many third-party devices available on the market.
5) Your smartphone
Many of you prefer your smartphones as the main navigation in your car. And this despite the presence of a built-in navigation system in the car. Many of you believe that the time of autonomous additional navigation systems is running out. After all, very soon mobile phones will be fully integrated with the software of car infotainment systems. That is, by connecting your smartphone to the car, you can use the mobile map of the phone’s navigation application on the central screen.
Others believe that purchasing additional navigation devices is no longer necessary. It is enough to have your smartphone at hand to get directions to anywhere in the world.
Plus, the latest versions of navigation maps have become available on mobile devices offline, which has simplified the task of high-quality navigation on the road. After all, maps are now available without an Internet connection. Having previously downloaded the map, you can use the map to travel to unfamiliar areas without the help of a mobile connection.
One of the advantages of mobile devices is associated with a large number of different free navigation applications, many of which are several times superior to the software of built-in factory navigators.
Finally, we would like you to vote based on our review by indicating which navigation device you think is the best in car navigation?