Optimized design method of vibration isolation system in mechanically dithered RLG POS based on motion decoupling

•Whole mathematical model of Vibration Isolation System (VIS) in DRLG IMU is built.•An effective design method of VIS based on motion decoupling is proposed.•Six degree of freedom (DOF) model of VIS is decoupled into six one DOF models.•Stiffness and damping parameters are optimized to meet the precision requirement.•A veritable VIS used in DRLG POS is developed as an instance. The mechanically dithered Ring Laser Gyroscope (RLG) based Position and Orientation System (POS) is a crucial equipment providing high accuracy exterior orientation elements for airborne remote sensors. However, the strenuous dithering motion of RLG causes adverse vibratory disturbance to the inertial measurement unit (IMU) and limits its applications in POS. A Vibration Isolation System (VIS) should be employed inside dithered RLG IMU to attenuate such disturbance but induces additional attitude measurement errors. To solve this problem, a new design method of VIS based on motion decoupling is proposed in this paper. First, structural design of VIS is developed to decouple established six-degree-of-freedom dynamic model to eliminate the motion coupling errors. Based on this, parameters including the natural frequencies and attenuation coefficients of each six-degree-of-freedom dynamic model are optimized to constrain the transmitted measurement error of inertial sensors. The designed VIS is implemented and applied in the dithered RLG POS. And the finite element simulation results prove the effectiveness of the proposed method.