What is navigation? Navigation is an ancient but new, multi-disciplinary technology, and the history of human civilization is closely connected with it. With the continuous development of science and technology such as mechanics, optics, electronics, computers, control theory, information processing, space science and precision manufacturing, new navigation components and systems continue to appear. Navigation has been deeply applied to all aspects of People’s daily life. The military, civil and various carrier movements are inseparable from navigation.
Navigation is the meaning of guiding the navigation. That is to correctly guide the vehicle along the predetermined route, with the required accuracy, in the specified time to the destination. An airplane takes off from one airport to another. A ship starts from one port to another. A missile launched from a base must hit its intended target precisely. These must rely on navigation and guidance technology.
In order to make aircraft and ship successfully complete the predetermined navigation task, in addition to the position of the starting point and the target, it is necessary to know the navigation parameters, such as position, velocity and attitude (PVA) measurement. The most important of these is to know the real-time position, because only when the real time position is determined can we consider how to reach the next destination. If you do not know where you have been and where you should go next, there is no way to complete the schedule. It can be seen that navigation is extremely important for aircraft flight.
Navigation work is completed by the navigator in the ancient time. With the development of technology, navigation devices are more and more used to replace the work of the navigator and automatically do navigation tasks. These instruments and devices are called navigation systems. When the navigation system acts as an independent device by a vehicle in arbitrary motion, its task is to provide real-time position information and heading information for the driver.
Taking aviation as an example, the whole set of equipment (including ground equipment) measures the position, velocity, attitude of the aircraft. It guides the plane on the scheduled route through the pilot or the flight automatic control system. This equipment is called the aircraft navigation system. The navigation system only provides various navigation parameters and does not directly control the plane. In a certain sense, the navigation system is an information processing system. The navigation information measured by the navigation instrument is processed into various navigation parameters.
The so-called Guidance means to control and guide. It means to guide and control the vehicle or aircraft according to the scheduled route, and adjust its motion track until it hits the target or reaches the destination with allowable error. The guidance system is mainly composed of two parts. They are the guidance system and the control system.
Guidance System
The guidance system generally includes detection equipment and computer equipment. Its functions are to measure the position, velocity and calculate the deviation between the actual movement track and the theoretical track, and give instructions to eliminate the deviation.
Control System
The control system is mainly composed of the actuator (servo mechanism). Its function is to form a comprehensive control signal according to the guidance instructions given by the guidance system and the attitude parameters of the vehicle or aircraft. Then, the actuator adjusts and controls the movement or attitude of the vehicle or aircraft until it hits the target or reaches the destination.
Navigation system is an essential and important equipment in the ship, aircraft, missile and spacecraft. The main work of navigation is positioning, orientation, timing and velocity measurement. Since there are many technical methods that can measure the navigation parameters. Various navigation systems have emerged, such as radio navigation systems, satellite navigation and GNSS/INS systems, celestial navigation systems and inertial navigation systems, as well as landmark navigation, light navigation, infrared navigation, laser navigation, sonar navigation and geomagnetic navigation systems.
The development of airborne navigation system has roughly experienced several stages.
In the 1920s, the development of aircraft navigation instruments began, there were simple instruments on the aircraft, but the position of the aircraft flight depends on manual calculation.
In the 1930s, radio navigation appeared. The first use of the medium wave four channel radio beacon and radio compass.
In the early 1940s, the Vor Navigation System, a short-range navigation system was developed. This is a short-range navigation system.
In the early 1950s, Inertial Navigation System (INS) based on Newton’s laws of mechanics was developed for aircraft navigation.
In the late 1950s, the Doppler Navigation System appeared. It realized the radio navigation of the aircraft by Doppler effect.
In the 1960s, the hyperbolic radio Navigation System began to be used, namely Loran-C Navigation System. This is a long range navigation, and the detection range is 2000Km.
The 1960s also saw the development of the Tacan Navigation System, a short-range polar radio Navigation System, and the Omega Navigation System. Omega navigation system is an ultra-long range hyperbolic radio navigation system. Its detection range is 10,000Km.
Satellite Navigation System began to develop from the 1960s, and gradually developed into the Global Position System (GPS) after the 1970s.
In the development process of various Navigation systems, in order to play the advantages of different navigation systems, the Combined Navigation System appears.
