Traditional positioning and navigation technology has errors and defects
In 1954, the world's first inertial navigation. 1994, satellite positioning and navigation began to be applied worldwide. Including inertial navigation, satellite positioning navigation, including the traditional positioning and navigation technology, in various fields have been widely used, but there are some unsatisfactory.
Inertial navigation system is a navigation parameter solving system with gyroscope and accelerometer as sensitive devices. The basic working principle is based on Newton's law of mechanics, by measuring the acceleration of the carrier in the inertial reference system, integrating the time and transforming it to the navigation coordinate system, we can get the speed, yaw angle and position in the navigation coordinate system and other information. The inertial navigation system has the advantages of complete autonomy and high reliability, complete and continuous navigation information; however, it also has the defects of error accumulation with time and motion distance, the need of initial information, high cost, and bulky.
An algorithm for determining the entire satellite orbit based on measured frequency shift data was developed based on the Doppler effect. Later, from the satellite's known accurate orbit, calculated the position of the ground receiving station, thus forming the concept of satellite navigation. Each navigation satellite continuously transmits its own precise position over time to the ground, and the satellite positioning receivers on airplanes, ships and other means of transportation receive this information and then quickly solve their own position, thus achieving the purpose of navigation. Satellite navigation has the advantages of high positioning accuracy, can provide three-dimensional coordinates, easy to operate, all-weather operation, multi-functional, wide range of applications, etc.; but there are also star clock error, ionospheric refraction error, multipath effect error, observation error, and most importantly, may be subject to environmental or human interference and other defects.
Geomagnetic positioning navigation without interference and high reliability
The error of inertial guidance system is accumulated over time, and it is difficult to continuously and accurately locate and navigate for a long time. Satellite positioning navigation system signal propagation by the influence of a very large number of factors, long-term work is susceptible to external interference. Therefore, in the long-distance, long-time navigation tasks, usually using a "combination of navigation" system, and the introduction of geomagnetic positioning navigation technology.
Geomagnetic positioning navigation technology is based on the fact that the geomagnetic field is a vector field, and its intensity and direction are functions of position. At the same time, the geomagnetic field has abundant features such as total intensity, vector intensity, magnetic inclination, magnetic declination and intensity gradient, which provide sufficient information for geomagnetic matching. Therefore, the geomagnetic field is used as a natural coordinate system, and the measurement information of the geomagnetic field is utilized to realize positioning and navigation.
Geomagnetic positioning and navigation is a passive autonomous positioning and navigation technology that relies on geomagnetic information to form a geomagnetic field database corresponding to the geographic coordinates of the earth; then magnetic sensors are loaded on the carrier to carry out geomagnetic measurements and plotted as real-time on-line maps to form a digitized model of a three-dimensional geomagnetic map, which gives information about the guiding direction and the direction of the target, as well as the position of the navigating object. Finally, through the mature technology such as path planning and control strategy, accurate positioning and navigation is carried out for aircraft, ships, submarine vehicles and so on.
Geomagnetic positioning navigation is not easy to be disturbed and is convenient to use. Experts advocate the use of positioning and navigation system combination, inertial navigation, satellite navigation, geomagnetic positioning and navigation technology for the combined use of complementary advantages, enhance safety and reliability.