Feng Sun

Bio: Feng Sun is an academic researcher from Harbin Engineering University. The author has contributed to research in topics: Inertial navigation system & Gyroscope. The author has an hindex of 8, co-authored 12 publications receiving 149 citations.

Optical fibre gyro strapdown inertial navigation system error inhibiting method based on single-shaft rotation

Abstract: The invention provides an optical fibre gyro strapdown inertial navigation system error inhibiting method based on single-shaft rotation. The initial position parameters of a carrier are confirmed; the data outputted by an optical fibre gyroscope and a quartz accelerometer are collected; the pose information of the carrier is confirmed by the relation between the output of the accelerometer and an acceleration of gravity as well as the relation between the output of the gyroscope and the earth rotation rate; and the initial aligning of the system is finished; an inertial measuring unit coordinate system rotates by 45 degrees along the front direction of the shaft oyb of a carrier coordinate system and the initial opposite position between the two coordinate systems is confirmed; IMU continuously rotates along the front direction of the orientation shaft ozb of the carrier coordinate system by an angular velocity that Omega is equal to 6 degrees/s. The data generated by the optical fibre gyroscope and the quartz accelerometer after the rotation of the IMU is converted under the carrier coordinate system to obtain the modulating form of the constant deviation of an inertial apparatus. The output vale Omega ib of the optical fibre gyroscope is used to update a strapdown matrix Tb; the speed and the position of the carrier after the IMU is rotated and modulated are calculated. The invention modulates the constant deviation of the inertial device on the directions of three shafts to improve the navigation and location precisions.

Coarse alignment method for fiber optic gyro strapdown inertial navigation system based on single axis rotation

Abstract: The invention provides a coarse alignment method for a fiber optic gyro strapdown inertial navigation system based on single axis rotation. The coarse alignment method comprises the following steps: (1) determining initial position parameters of a carrier by a GPS; (2) collecting the data output by a fiber optic gyroscope and a quartz accelerometer and processing the data; (3) determining a transfer matrix Ti of a navigation coordinate system and an inertial coordinate system according to the mutual position relation of the coordinate systems; (4) allowing a single axis of an inertial measurement unit to continuously rotate, setting superposition of an initial time IMU coordinate system s and a carrier coordinates b, then allowing the inertial measurement unit to continuously rotate around a positive direction of an azimuth axis ozb of the carrier coordinate system with an angular velocity Omega=6 degrees/s; (5) determining the relative position relation of the inertial coordinate system and a base inertial coordinate system; and (6) determining an expression of a strapdown matrix after coarse alignment is over according to the calculated relative conversion relation of the coordinate systems calculated in step (3), (4) and (5). The coarse alignment method can help obtain higher coarse alignment precision under a swinging interference condition.

Method for initial alignment of a single-axis rotation strap-down inertial navigation system (SINS)

Abstract: The invention provides a method for initial alignment of a single-axis rotation strap-down inertial navigation system (SINS). The method comprises the following steps: building a carrier coordinate system and computing a transfer matrix between geographic coordinate systems on the basis of coarse alignment completed by collecting the information output by gyroscopes and accelerometers in the SINSwith the carrier being in a static state; establishing Kalman filtering state equations with speed errors as the state variables and measurement equations with the speed errors as the measurement variables; and estimating the misalignment angles of the carrier by the Kalman filtering technique and feeding back to the SINS to complete the initial alignment of the SINS. The invention can overcome the influence on the estimation precision of the azimuth misalignment angles caused by the equivalent gyroscope drift of the geographic coordinate systems and improve the alignment precision.

Method for determining initial attitude of fiber strapdown inertial navigation system based on rotating mechanism

Abstract: The invention provides a method for determining the initial attitude of a fiber strapdown inertial navigation system based on a rotating mechanism. The method comprises the following steps: according to the relation between the SINS output and the rotational angular velocity and the acceleration of gravity of the earth, initially determining the SINS initial attitude, and utilizing the Kalman filtering method to estimate a misalignment angle so as to determine the local north orientation; establishing an error model of a fiber optic gyroscope to estimate the north orientation gyroscope drift under the navigation system; after an inertial measurement unit (IMU) clockwise rotates for 90 degrees, estimating the south orientation gyroscope drift under the navigation system; after the IMU horizontal gyroscope drift is obtained, the operation of compensation is carried out; and the technical scheme of initial alignment under the state that the inertial measurement unit rotates around a carrier azimuth axis is adopted for the system after error compensation, so as to determine the initial strapdown matrix of the system and to obtain the attitude of the carrier at the initial time by calculation. The method has the characteristics of automation and high precision, and is suitable for various medium and high precision strapdown inertial navigation systems.

Rotating strapdown system on-site proving method based on digital high-passing filtering

Abstract: The invention provides a rotating strapdown system on-site proving method based on digital high-passing filtering, which comprises the steps: (1) determining an initial position parameter of a carrier by a GPS; (2) collecting data output by an optical fiber gyroscope and an acceleration meter, and processing the data; (3) rotating and stopping at four positions of a single axis of an inertia measurement unit; (4) analyzing biased observability degree of an inertia device by using a spectral condition number method; (5) filtering the Schuler period contained in velocity information of a navigation system by adopting an IIR high-passing digital filter; and (6) taking filtered velocity information as observed quantity, and estimating the deviation of the inertia device by adopting a Kalman filtering technique When the carrier is in anchoring state, the adoption of the method can obtain higher on-site proving precision

Autocollimation method of carrier aircraft rotating type strapdown inertial navigation system under shaking base

Abstract: The invention discloses an autocollimation method of a carrier aircraft rotating type strapdown inertial navigation system under a shaking base, and belongs to the field of navigation. The autocollimation method comprises the following steps of: firstly obtaining the longitude and latitude of the position of a carrier, secondly collecting output signals of a fiber-optic gyro and a quartz flexible accelerometer in an inertia measurement unit, and then carrying out automatic compensation on a constant error of an inertia device by adopting a double-shaft rotating table rotatory IMU (inertial measurement unit) to form a rotating type strapdown inertial navigation system; and then calculating a rough initial posture array by utilizing gravity acceleration in an inertial coordinate system as a reference vector, establishing a state equation and a measuring equation again of the system, designing a vanishing adaptation Kalman filter to accurately estimate a misalignment angle of the carrier, and correcting a strapdown posture matrix by utilizing the misalignment angle to finish initial alignment and enter a navigation state. The method isolates the influence of shake of a vessel to initial alignment of a carrier aircraft, and dynamic random disturbance in measured noise is restrained through estimating the initial posture array of the system via the vanishing adaptation Kalman filter method, so that rapid autocollimation of the carrier aircraft rotating type strapdown inertial navigation system is realized.

Rapid initial alignment method for low-accuracy strapdown inertial navigation system under swinging condition

Abstract: The invention aims to provide a rapid initial alignment method for a low-accuracy strapdown inertial navigation system under a swinging condition, which comprises the following steps: determining initial position parameters of a carrier; acquiring data output by an accelerometer and a gyroscope, completing coarse alignment of the strapdown inertial navigation system by second-order leveling and adirection estimation method, and determining the attitude of the carrier initially; estimating the length of a lever arm, calculating the disturbing acceleration induced by the lever arm effect, and compensating the output of the accelerometer; establishing a Kalman filtering state equation and a Kalman filtering measurement equation; and estimating the angular misalignment of the system, correcting the strapdown attitude matrix of the system by the angular misalignment at the finish time of fine alignment, and completing initial alignment. The invention eliminates the effect of lever arm effect error on the initial alignment of the strapdown inertial navigation system, shortens the alignment time of the system, and improves the alignment accuracy of the system, thereby comprehensively improving the performance of initial alignment of the low-accuracy strapdown inertial navigation system.

Quick calibration method for inertial measurement unit

Abstract: The invention relates to a quick calibration method for an inertial measurement unit (IMU). According to the method, a user holds and rotates the IMU to move in all directions without any external equipment, so that twelve error coefficients including gyro biases, gyro scale factors, accelerometer biases and accelerometer scale factors can be accurately calibrated in a short time. The quick calibration method for the IMU is characterized by being free of hardware cost, high in efficiency and simple and easy to implement, and can ensure certain calibration precision. Thus, the quick calibration method is especially suitable for in-situ quick calibration for the medium- and low-grade IMUs, thereby effectively solving the problem of environmental sensitivity of the error coefficients of the mechanical IMU, and promoting popularization and application of MEMS (micro-electro mechanical systems) inertial devices.

Research on the dynamic error of strapdown inertial navigation system

Abstract: Researching on the static error of strapdown inertial navigation system (SINS) plays a great role in the past. This is mainly due to the complex mathematical model for dynamic error of SINS. It is hard to do the error analysis from the perspective of the number. So in most cases, the static model owns the better position in the research for its desirable and concise. It is easy to know the impact to system error from three major error sources, and also the reasons of every periodic oscillation. However, the limitations of the static model drives the analysis for dynamic one to be more vital for the latter is consistent with actual situation. In this paper, the dynamic error model of SINS is established basing on the static one, then do the simulative research on error of some situations which the base is having a uniform motion. And give the explanation to results of simulations from the perspective of theory. It can lay the foundation for the research of dynamic error on multiple bases for the future movement.

Transfer alignment problem: Algorithms and design issues

Abstract: Transfer alignment is the process of initializing the navigation sensors of tactical guided munitions launched from a platform. Through this method the misalignment between aligning and aligned body is estimated, which facilitates navigation of aligning system during its post-ejection course of flight. Measurements provided by navigation sensors of aligning system are noisy compared to those of the launch platform. Thus, excitation of the platform in the form of some deliberate manoeuvre is important in order to discriminate the signal from noise in the available measurement so that the misalignment can be effectively estimated. With advancement of technology, the prerequisites of accurate alignment have changed and with it the algorithms have also undergone continuous transformations. Extensive work has been done on this topic over the years. Here a detailed review of the evolution of transfer alignment problem has been presented. Emphasis is on statistical and algorithmic aspects of the problem rather than time line of work already done. This review provides a general guideline for new entrants to this field and should help practitioners with information regarding trends of research on this topic.