Papers by Keyword: Strapdown Inertial Navigation System (SINS)

Abstract: Aircrafts with common attitude maneuverability (e.g. helicopter) are in more and more urgent need of low cost and high precision inertial navigation system (INS). To meet this demand, a scheme of fiber-optic gyroscope (FOG) strapdown inertial navigation system (SINS) with single-axis to and fro rotation-modulation method is adopted. A short-time alignment method bases on open-loop mathematic platform misalignment model is studied. The test results from the actual system show that this method has characteristic of high accuracy and simple, reliable operation. The estimate accuracy of azimuth error and is less than 2’. And the estimate error of north drift achieves 0.001º/h. Simultaneously, the input-axis accelerometer bias and gyroscope drift are estimated exactly.

Abstract: The basic principles for stabilized gyrocompass initial alignment are analyzed in platform inertial navigation system (PINS), then similar principles and initial alignment algorithms suitable for programming are proposed for strapdown inertial navigation system (SINS). The scheme of SINS gyrocompass initial alignment can be divided into four steps, including leveling alignment with header uncertainty, coarse header alignment, leveling realignment and gyrocompass alignment for header. By simplifying SINS nonlinear error model under header uncertainty, the formula of coarse header alignment is deduced. On the assumption of navigation computer having large memory and powerful computing ability, and basing on the ‘multiformity’ of SINS mathematical platform and the ability to attitude reverse control, a specific progress for SINS rapid gyrocompass alignment is introduced and designed in detail. Finally, some tests prove that the proposed alignment algorithm in this paper is effective.

Abstract: In inertial navigation system, gyro is used to measure the angular velocity of carrier relative to inertial space for achieve attitude matrix updated in real time. Gyro difficult to eliminate the error, results in strapdown inertial navigation system precision decrease with time. Star sensor is a high-precision attitude measuring instrument and don’t require any priori information, the attitude date can be provided by star sensor. Thus, gyro is simulated by star sensor in order to improve the precision of strapdown inertial navigation system.

Abstract: A new rapid computation method for Kalman filtering is proposed. In this method, the prediction of state covariance matrix is expanded directly rather than computing by a looping program. Sequential filtering for measurement update is also applied. Furthermore, the subsidiary elements in system matrix are set to zero and a reduced-dimensions sub-optimal Kalman filter is presented. The proposed method greatly decreases computational burden and it is only 6.59% of the classic method. In the end, a vehicular test is carried out to prove the feasibility of the filtering.

Abstract: This paper addresses a practical problem arising in the calibration of bottom-lock doppler velocity log for the navigation of surface ships. Firstly, a dead reckoning navigation algorithm and briefly error analyze are proposed. Then, employing ship’s true trajectory and calculated trajectory, the rotational alignment offset between a bottom-lock doppler velocity log and a strapdown inertial navigation system as well as the scale factor error of the doppler velocity log can be experimentally determined using sensors commonly deployed with a vehicle in the field. It requires velocity values from the vehicle's doppler log and strapdown inertial navigation system, and absolute vehicle position fixes from a GPS receiver. Lake experiment results show that the calibration algorithm can calibrate the error parameters effectively, thus the position error decreases significantly after compensating the error parameters.

Abstract: In order to improve the accuracy of initial alignment which determines the accuracy of navigation, a Sage-Husa adaptive kalman filter algorithm is applied to SINS initial alignment of single-axis rotation system. The simulation result further shows that in the case of inaccurate statistical property of noise, the estimation accuracy of Sage-Husa adaptive kalman filter is better than the conventional kalman filter.

Abstract: To improve the hit probability and damage probability of guided projectile, made the strapdown inertial navigation technology better application in guided projectile, based on the feature of short range and short flying time of guided projectile, a simplification model of SINS (strapdown inertial navigation system) was proposed. The optimal 3-subsample rotation vector simulation platform was founded based on the tradition method, and this system was also checked by simulation using three-channel databases from simulator testing. The results show that this system not only can satisfy the requirement of real-time and precision, but also can improve the relative error to 10-6. The influence of direction draft to the guided projectile is also reduced.

Abstract: Advanced development of an Inertial Navigation System (INS) using rotating modulated technique based on Micro-Electro-Mechanical Systems (MEMS) sensors is described. The system architecture and the mechanical structure are detailed. Alignment and navigation algorithms apposite to the RMSINS system are derived. Preliminary system static navigation experiment results are presented. Performance results show that rotating modulated technology, with appropriate navigation algorithm, makes it possible to use the MEMS sensors in SINS system, with the benefit of reducing system costs as well as improving accuracy.

Abstract: The initial alignment error model of SINS (Strap-down Inertial Navigation System) with large misalignment angle is nonlinear. The traditional EKF (Extended Kalman Filter) was used to linearization a nonlinear system, but its performance is limited. In this paper we use the SRUKF (Square Root Unscented Kalman Filter) to process this nonlinear system and the results indicate that SRUKF is better than EKF in convergence speed and estimation accuracy.

Abstract: This paper established the total error model of Anti-Radiation Missile under condition of target radiation source shutdown, which includes three dimensional passive location error model using information of azimuth and elevation angle as well as their changing rates, and gyroscope drift error model of Strap-down Inertial Navigation System. By analyzing the three dimensional passive location method to moving emitter using single stationary observer, the paper had a research to the hit probability of Anti-Radiation Missile under various flying conditions. If higher hit probability is required, the missile should increase its azimuth and elevation angle as much as possible while not to overstep its attack angle. Simulation result showed that the shutdown occasion of radiation source did much influence to the hit probability of Anti-Radiation Missile, which has great meaning to improve he bat efficiency of Anti-Radiation Missile.