Fiber optic gyroscope is an instrument that can accurately determine the orientation of moving objects. It is an inertial navigation instrument widely used in modern aviation, navigation, aerospace and defense industries. The fiber optic gyroscope is a sensitive element based on an optical fiber coil, and the light emitted by the laser diode propagates along the optical fiber in two directions. The difference in the 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, instant start, simple structure, small size and light weight. Compared with the laser gyroscope, the fiber optic gyroscope has no blocking problem, and does not need to precisely process the optical path in the quartz block, so the cost is relatively low.
The realization of the fiber optic gyroscope is mainly based on the Segnick theory: when the light beam travels in a ring-shaped channel, if the ring-shaped channel itself has a rotational speed, the time required for the light to travel along the direction of rotation of the channel is longer than that along the channel. It takes more time to travel in the opposite direction. That is to say, when the optical loop rotates, in different directions of travel, the optical path of the optical loop will change relative to the optical path of the loop when it is stationary. Using this change of the optical path, the phase difference or the change of the interference fringes of the two optical paths can be detected, and the angular velocity of the optical path can be measured, which is the working principle of the fiber optic gyroscope.
The application of fiber optic gyroscope is very wide:
1 Applications in navigation
The compass is an important navigation equipment for ships, and there are mainly two types of magnetic compass and gyro compass. With the development of fiber optic gyroscope technology and the improvement of commercialization level, fiber optic gyroscope has become a new member of marine conduction equipment, and has been used in commercial and military ships and marine equipment. The rotation axis of the fiber optic gyro compass based on the strapdown inertial navigation system corresponds to the three axes of the ship coordinate system. It can not only be used as a high-precision heading information source to realize automatic north finding and north pointing, but also can be obtained Reliable data such as heading slew rate, lateral and pitch angles, and heading rotation rate further promote the development of ship automation, ensure the ship’s maneuvering effect and ensure navigation safety.
2 Aerospace and space applications
In aerospace and space applications, high-precision interferometric fiber optic gyroscopes are generally used. IFOG is a strapdown inertial navigation system with the main inertial element, which can provide three-dimensional angular velocity, position, angle of attack and sideslip angle for the aircraft, and realize the tracking and measurement of rocket launch.
It can also be used for spacecraft stabilization, photography/mapping, attitude measurement control, motion compensation, EO/FLIR stabilization, navigation and flight control, etc. Among them, the combination of high-precision and high-reliability fiber optic gyroscope and GPS attitude determination has become a domestic and foreign spacecraft. Typical configuration of an attitude system.
3 Military applications
Due to its superiority in angular rate and acceleration measurement and its significant advantages in dynamic range, sensitivity and reliability, fiber optic gyroscope has a wide range of military applications. It can be used for the positioning, orientation and navigation of tanks, submarines, self-propelled artillery, and armored assault vehicles; when satellite navigation cannot obtain accurate information due to strong electronic interference, fiber optic gyroscopes can be used to ensure autonomous navigation, precise guidance and accurate targeting of aircraft. At the same time, the FOG component is also an important part of the aviation fire control system, which can be used for the stabilization of the aiming line and the shooting line of the weapon system such as the armed helicopter, so as to ensure the search, aiming, tracking and shooting of the weapon in motion. In addition, fiber optic gyroscope is also the only effective navigation technology underwater, which can be used for positioning, orientation and navigation of submarines.
4 Civilian applications
In the civil field, it mainly focuses on the application of low- and medium-precision fiber optic gyroscopes. Positioning tools and rescue tools for the location of power lines, pipelines and communication optical (electrical) cables; positioning and path surveying for geodetic surveying, mineral exploration, oil exploration, oil drilling guidance, tunnel construction, etc., and the use of fiber optic gyro rotation angle and linear displacement to realize dam inclination measurement, etc.
Because of its high cost, its use still has great limitations. ERICCO has developed a cost-effective fiber optic gyro product ER-FOG-910 (0.02º/h) for this problem, which also promotes the high-speed development of my country’s high-precision industry. developing.