Inertial navigation system, also known as inertial reference system, is an autonomous navigation system that does not depend on external information or external radiation energy, such as radio navigation. Its working environment not only includes air, ground, but also underwater. The basic working principle of inertial navigation is based on Newton's laws of mechanics, by measuring the carrier in the inertial reference system acceleration, it will be the time integral, and transform it into navigation coordinate system, can be obtained in the navigation coordinate speed, yaw angle and location information.
Inertial navigation system belongs to the way of reckoning navigation, that is, from the location of a known point, the position of the next point can be calculated according to the angle and speed of the continuously measured moving body, so that the current position of the moving body can be continuously measured. In the inertial navigation system is used to form a gyro navigation coordinate system of the accelerometer measurement axis in the coordinate system, and gives the course and pose angle; the accelerometer is used to measure the motion of the body acceleration, after a time integral of speed, speed after a time integral can be obtained distance.