The LN-200 fiber gyro based tactical grade IMU

Abstract

Litton's Guidance and Control Systems Division is in production with the LN-200, the world's first fiber gyro based tactical grade IMU that performs over the entire military operating environment. The fiber gyros provide 1.0 deghr bias error and 100 ppm scale factor error. The LN-200 can be manufactured at low cost due to the automatic equipment used in its production. The LN-200 IMU provides the core for diverse military applications. It is used in the LN-210, which is the AHRS for the RAH-66 Comanche helicopter and in the LN-201, which is the AIM120 AMRAAM missile IMU. The top-level mechanization and the performance of the LN-200, LN-201, and the LN-210 will be reviewed, especially performance in high dynamic thermal and vibration environments. Production yields and performance statistics of production fiber gyros will be covered. Fiber gyro based systems are very reliable. Predicted MTBFs of fiber gyro uiaxs exceed 100,000 hours in rugged airborne and missile environments. Reliability data obtained on Litton fiber gyros will be presented. The Sagnac effect, which is the physical basis for both fiber optic and ring laser gyros, was discovered in 1913. The first fiber optic gyro was demonstrated by Vali and shorthill' in 1976. Development of fiber optic gyros occurred at several universities and aerospace companies around the world over the next ten years. By 1987, fiber optic gyro technology had reached sufficient maturity for companies to initiate product development plans utilizing this technology. In 1987, Litton began development of its LN-200 product family of medium accuracy fiber gyro based systems. The LN-200 product development has been completed and transferred to Litton's factory in Salt Lake City, Utah. It is presently in low rate initial production for numerous programs. Fiber Gvro Operation A brief overview of the fiber optic gyro is presented in this section. Readers desiring amore thorough discussion of fiber gyro operation and key developments in fiber gyros are referred to a previous paper2 by this author.