The fiber optic gyroscope is a sensitive element based on the optical fiber coil, and the light emitted by the laser diode propagates along the optical fiber in two directions. The difference of light propagation path determines the angular displacement of the sensitive element.
Compared with traditional mechanical gyroscopes, fiber optic gyroscopes have the advantages of all-solid state, no rotating parts and friction parts, long life, large dynamic range, instantaneous start, simple structure, small size, and light weight. Compared with the laser gyroscope, the optical fiber gyroscope has no blocking problem, and it does not need to precision machine the optical path in the quartz block, and the cost is relatively low.
Fiber optic gyroscopes are based on Segnick’s theory: when a light beam travels in a circular channel, if the circular channel itself has a rotational speed, then the time required for the light to travel along the direction of rotation of the channel is more than the time required to travel along the opposite direction of the channel.The azimuth Angle of the carrier, that is, the Angle between the reference axis of the carrier and the true north direction, can be determined by solving the earth rotation angular velocity measured by the fiber optic gyroscope and the carrier tilt Angle measured by the accelerometer. It can be static all-weather, all-round, autonomous, rapid determination of orientation, can be used as the orientation of observation, target targeting, navigation system reset, and can also be used as the orientation of tunnels, mines and other underground operations. As a measuring element of angular velocity, gyroscope plays a vital role.
The north finder based on fiber optic gyroscope is an instrument to realize autonomous north seeking based on the principle of inertial navigation. It is an important part in the field of inertial technology. It can realize all-weather, omni-directional, independent and rapid direction measurement without being restricted by natural conditions. At the same time, it also has many advantages, such as high precision, long continuous working time and so on. Gyroscope is the core component of the north finder. Among them, fiber optic gyroscope is a very new angular rate sensor that uses fiber optic sensing technology to measure the spatial inertial rotation rate. It is an all solid-state optical gyroscope. It has no rotating and friction components. Compared with the traditional mechanical gyroscope, fiber optic gyroscope has the advantages of small size, light weight, short start-up time It has many advantages, such as high sensitivity and resolution, long service life, strong impact and vibration resistance and so on.ER-FOG-851 Low Cost Fiber Optic Gyroscope (FOG) has all the above advantages and is widely used in INS, IMU, positioning system, north finding system, platform stabilization and other fields.
Because of the advantages of fiber optic gyroscope, it can meet the requirements of small size, high precision and fast orientation in many aspects. Therefore, the research of north seeking system based on fiber optic gyroscope has attracted extensive attention. In foreign countries, since the 1990s, fiber optic gyroscope has been applied to the research of developing north seeking device. Patent US5778543 discloses a north seeking instrument using fiber optic gyroscope. One fiber optic gyroscope and two accelerometers are installed on a rotating platform, and the sensitive axes of the two accelerometers are orthogonal to each other to measure the inclination angle of the rotating platform. The sensitive axis of the fiber optic gyro is equal to the table of the rotating platform, which is used to measure the rotation speed of the earth. The gyro north finder method disclosed in patents EP2026036 and US8151475 can be realized not only by fiber optic gyroscope, but also by micromechanical gyroscope. In addition, research institutions in the United States, Japan, South Korea, France and other countries have successively published research results on fog north seeking technology, and have successively developed fog north finder or navigation system with north seeking function.