Research For The Temperature Error Of FOG And Its Suppression Method

Gyroscope，as a major sensor in acquiring azimuth angle，plays a veryimportant role in both military and civil use，such as：guide for navigation，satelliteposition finding，and geodetic surveying。The fiber optic gyroscope （FOG）basedon Sagnac effect has became to one of the most important sensors in developing dueto light in quality，high accuracy，compact in dimension and long life。FOG hasalready been applied in many fields in western countries，but its research level is stillgotten behind in China。It is the most difficult problem that the FOG has an obviousbias drift caused by temperature change and temperature grade, so its application islimited to a great extent. Fiber coil is one of the most critical components in FOG, andits quality directly affects the temperature performance of the gyro.The main work of the paper includes:（1） Firstly, this paper reviewed the basic principle of FOG and the literature aboutFOG. The characteristic of thermal error of FOG was analyzed.（2） The characteristic of thermal stress error of the fiber optical coil was analyzed.The temperature distribution model was derived for the fiber optical coil byfinite element analysis method. Based on the model, an analysis on the outputerror caused by the temperature change inside the fiber optical coil was made,according to the simulation and comparing of the two different techniques ofthe coil. Experiments indicate that the fiber coil with a buffer layer is betterthan the common one for weakening the noise of fiber optical gyros bytemperature change.（3） On the base of the research about the theory of Shupe non-reciprocal errorscaused by temperature grade, it showed that the bias drift caused bytemperature grade can be restrained by using special coil winding method.Theoretical analysis showed the influence caused by temperature grade cannotbe extinguished totally in the most common coil winding method—quadrupolewinding, so a new fiber coil winding method to reduce the influence caused byresidual Shupe effect must be put forward. By theoretical analysis andcomparing difficulties and operability of several winding method, we appliedthe hexadecapole winding method to make the fiber optical coil. By compared the temperature performance of the hexadecapole winding coil to thetemperature performance of the quadrupole winding coil, its proved that thehexadecapole winding method is more effective and predominant to reduce theinfluence caused by residual Shupe effect.（4）There are many nonideal factors in the winding procedure, so the influencecaused by temperature grade cannot be extinguished totally. Experimentindicated that: by adjusting the fiber pigtails of the fiber optical coil and thetail fiber of the Y waveguide can compensate the Shupe effect better.