MODELLING, ESTIMATION AND PATH LENGTH CONTROL OF RING LASER GYROSCOPE

Abstract

A gyroscope is a form of measurement equipment that relies on the principle of momentum con servation, stating that a rotating object will continue to rotate unless acted upon by an external force. This project focuses on a specific type of gyroscope called a ring laser gyroscope, which utilizes the Sagnac effect. The ring laser gyroscope is susceptible to various disturbances, such as fluctuations in ambient temperature. These disturbances can lead to significant deviations between the output data and the actual values, resulting in inaccurate angular measurements. One of the factors affected by temperature change in the ring laser gyroscope is the path length. The path length refers to the total distance travelled by the counter-propagating light beams, which generates the interference pattern used to determine the angular rate. The laser gain pro file should operate within the peak region for accurate angular rate measurements. However, the self-heating caused by temperature changes significantly alters the path length, shifting the operating point away from the peak and into one of the off-peak regions. To address this issue, adjustments can be made to the path length by modifying the refractive index of the air column and employing operating mode switching. These adjustments aim to bring the system back to its peak operating point. However, the current control system requires further refinement to achieve precise control, as it gets subjected to self-heating and external temperature changes. This research proposes a control strategy named model reference adaptive control, which treats the path length loop as a system and introduces external corrections by referencing a desired model system. By utilizing this approach, the system is concluded that the system will perform more effectively despite temperature fluctuations, leading to improved outcomes