Influence analysis of flexure support characteristics on performance of inertial reference unit

The combination of compound axis tracking and aiming with an inertial reference unit (IRU) is the main technical means to reject vibration interference of moving platform and improve tracking and aiming accuracy. IRU usually adopts flexure support structure to avoid the defect of large moment of inertia of frame structure. The characteristics of the flexure support structure are the key factors to determine the bandwidth of IRU disturbance rejection. The influence of flexure support characteristics on IRU performance was quantitatively analyzed. Firstly, based on the mass-stiffness-damping model, the transfer function model of IRU system was established, and its accuracy was verified. Then, the parametric analysis method was used to study the influence of disturbance transmission characteristics and physical parameters of flexure support on the disturbance rejection ability of IRU system. Finally, a Simulink simulation model of IRU double-loop (velocity inner loop-position outer loop) control system was built. The influences of flexure support stiffness characteristics on IRU disturbance rejection ability and stabilization precision under a given vibration environment were simulated and analyzed. The results show that the disturbance transmission characteristics of the flexure support determine the ability of the system to reject high-frequency disturbance. Reducing the rotational stiffness of the flexure support can effectively improve the disturbance rejection ability of the IRU system but aggravate the negative impact of sensor noise and driver ripple on the stabilization precision of the IRU system.