Digital Compensation Technology for Enhancing the Attitude Demodulation Precision of Laser Inertial Navigation System

The laser inertial navigation system (LINS) utilizes a multipoint shock absorber within the inertial measurement unit (IMU) to attenuate vehicle vibration noise. The elastic deformation of the shock absorber is caused by the change of mechanical environment, including the high-frequency deformation caused by the dithered ring laser gyroscope (DRLG) mechanically dithered and low-frequency deformation caused by the force change of IMU body during IMUs angular motion. High-frequency elastic deformation can be effectively solved through reasonable selection and installation design of shock absorbers, and low-frequency elastic deformation is the main factor affecting the attitude accuracy of IMU. This article derives the kinematic equation governing the low-frequency elastic deformation of the shock absorber and establishes a corresponding mathematical model. Subsequently, a digital compensation technology is proposed to mitigate attitude demodulation errors, requiring only the structural design parameters of the IMU. Experimental validation reveals that during spatial reorientation of the IMU, the elastic deformation of the shock absorber can reach approximately 150 arcseconds, resulting in attitude demodulation errors of a similar magnitude. With the application of digital compensation, the attitude demodulation error is reduced to 10 arcseconds, achieving a compensation rate exceeding 90%. Compared to the traditional experimental fitting compensation method, the proposed digital compensation technology improves compensation accuracy by 200%. Therefore, this technology effectively enhances the attitude demodulation precision of the LINS.