Research on Auto Compensation Technique of Strap-down Inertial Navigation Systems

Abstract

Inertial measurement unit(IMU), consisted of three mutually-perpendicular Ring Laser Gyros(RLG) and three accelerometers, is an important part of RLG -based strapdown inertial navigation systems(SINS). RLG provides measurement of change in vehicle attitude or its turn rate with respect to inertial space. Accelerometer provides measurement of specific force. These measurements provided by gyros and accelerometers are calculated to obtain the desired attitude, velocity and position information with respect to a pre-defined reference frame. So the accuracy of SINS clearly depends on the accuracy of the gyros and accelerometers. In order to improve the accuracy of SINS, auto compensation techniques of rotation is used. With IMU rotating about one or two axis of the vehicle, the bias errors of gyros and accelerometers may be modulated into periodical variable signal. So the modulated sensor errors reduce SINS errors. The theory of rotation auto compensation technique is analyzed. Single channel error propagation equations based on rotation compensation are derived. The simulation experiments of the SINS are carried out. Analytic results and the simulation results indicate that, with the help of rotation auto compensation, the effect of gyro's random drift and accelerometer's bias on SINS errors is greatly reduced.

Error Modeling, Calibration, and Compensation of Inertial Measurement Unit (IMU)

“…However, the mechanical dither will become an adverse vibration coupling with external random vibration and result in a measurement instability and error of POS [13]. For a POS used in the motion compensation of imaging payloads, the RLG IMU requirements can close off the RLG mechanical dithers transferred to imaging payloads, and avoid the secondary disturbance [14]. In addition, the RLG IMU requirements can accurately measure the external high-frequency vibration, and satisfy imaging payloads motion compensation requirements.…”

Research on Rotation Direction of Single-Axis Rotation FOG SINS

“…The impact of rotation direction for the system is not only embodied in the gyro drift, but also in the solution results of attitude error, velocity error and position error [3][4][5] . Analysis on the two ways is shown as follows.…”

Effects of Non-orthogonal Scheme on Error Modulation of Single-axis Rotating Strapdown INS

“…As an important way of improving the accuracy of SINS, the rotation modulation technique is employed to modulate the errors of inertial sensors into periodically varied signals, and, as a result, it can remove the constant bias, slowly vary errors of the sensors and maintain a sufficient accuracy for long time [1]. Since the basic principle of rotation modulation technique for inertial navigation system based on ring laser gyro is studied by Levinson E in 1980, the error model of SINS, the effect of rotation modulation technique on accuracy improvement and different rotation schemes have been researched by many scholars at home and abroad.…”