Research On The Influence Of Environmental Magnetic Field On The Precision Of Differential Ring Laser Gyroscope

The Ring Laser Gyroscope is a kind of inertial sensors based on Sagnac effect. It is used widely in the field of medium-high precision inertial technology, because it has many advantages such as simple structure, rapid starting, high precision, and so on. Ring Laser Gyroscope is one of the primary parts in inertial system and its precision will direct influence the precision of the whole system. There are many causes influence the precision of Ring Laser Gyroscope and the magnetic field disturbance is one of important factors. In practical application, the environmental magnetic field such as geomagnetic field, spacial electromagnetic radiation and magnetic leakage field of kinds of motor will influence the precision of Ring Laser Gyroscope. Thus the problem must to be solved. The paper does research and analysis on the influence of the environmental magnetic field on the precision of Ring Laser Gyroscope.Firstly, the paper analyze the cause that magnetic field influence the precision of Ring Laser Gyroscope in theory. It is that magnetic field acts on gain atoms in RLG and energy levels of these gain atoms splitting result in the augmentation of RLG zero drift. For demonstrating this conclusion, the paper designs the experiment that the magnetic field influences the precision of RLG. The results of experiment prove the rationality of the analysis in theory and show that the influence of axial magnetic field on RLG is greater than one of transverse magnetic field by one order. The influence of magnetic leakage field of motors on RLG is greatest in all influence of environmental magnetic field. The paper designs the three-dimensional high magnetic field measuring circuit based on Hall sensor and the three-dimensional weak magnetic field measuring circuit based on magnetic sensor for this problem. These circuits can accurate measure the magnetic field from 4mGs to 800Gs.Based on the distributing characters of magnetic leakage field of motors, The paper designs the measuring method to motors and uses the magnetic field measuring circuit to measure the magnetic leakage field of torque motor and step motor and obtains the distribution laws of two kinds of motors. On this basis, basing on the influence law of axial magnetic field and transverse magnetic field on RLG in experiment, the paper discusses the measures how to solve the influence of environmental magnetic field, which is adding magnetic shield to motors and RLG. Considering the magnitude of environmental magnetic field and precision requirements for RLG, the paper designs the magnetic shield of step motor and uses the finite element analysis software ANSYS to verify the shielding efficiency. The simulation results show that the special magnetic leakage field of shielded motors is decreased to 1/20 of before.