Temperature stabilization in fibre optic gyroscopes for high altitude aircraft

In earlier days, aircrafts used mechanical gyroscopes which were susceptible to shock, mechanical damage with low accuracy. Developments in fibre optics have led to optics based gyroscopes. Today's conventional aircraft uses sufficient gyroscopes to perform its action such as attitude control, gyro compassing, turn coordination systems and auto pilots. Any error in a gyroscope causes miscalculation of the position or alignment of the aircraft. Commercial aircraft at higher altitudes are susceptible to variations in the temperature. But, in case of fibre optic gyroscopes (FOG), it results in the fluctuation of laser power output which in turn disturbs the output information. We have proposed a temperature control for a closed loop fibre optic gyroscope using a thermo electric cooler (TEC) for stabilizing the output power of a super luminescent diode (SLD). A control loop with a PID controller, filter, TEC and thermistor is proposed which is a part of the temperature control loop to maintain the TEC surface temperature within the specified temperature range. We have simulated the performance for step input along with finite disturbances that are applied over the temperature control loop along its effect over the SLD output power and the effect on gyroscope output is evaluated.