Algorithm Research On SINS/GNSS Integrated Navigation System Based On FOG

In this paper, Inertial Navigation System (SINS) based on fiber optic gyro, global positioning system (GPS) for navigation was studied. GPS is vulnerable to electromagnetic interference. When the GPS signal is missing, SINS/GPS integrated navigation does not work. In this case, the odometer (OD) is selected to aid strapdown inertial navigation system. SINS/OD integrated navigation system also has a high accuracy.In this paper, the basic principles of fiber optic gyro and inertial navigation are in-troduced. The inertial navigation has two categories of platform inertial navigation and strapdown inertial navigation. SINS is a system which gyro is installed directly on the carrier. The algorithm of inertial navigation is derived. The mechanics choreography and error analysis is discussed. The errors of the solution of attitude and velocity were compensated. And a simulation is established that is for strapdown inertial navigation system.Next, I introduced the working principle and the error sources of the GPS. According to the combinations of the SINS and GPS, the combination is divided into three types:loose combination, tight combinations and deep portfolio. In this paper, according to the actual needs of the project, I chose the loose combinations. First, the author briefly introduced the basic principles of SINS/GPS integrated navigation system, based on this method, the author focused on the method of building the model of SINS/GPS integrated navigation system. Depending on the angle of misalignment, the author established non-linear system equations under the large azimuth misalignment angles and the linear systems equations based on the small azimuth misalignment angle.When the GPS signal is shielded by the electromagnetic, it is resulted that the errors of SINS are radiated. In order to maintain a continuous and high-precision navigation, the author choose the OD to compensate the error of SINS. The author firstly established the odometer error model, then stablish a state equation and measurement equation of the SINS/OD integrated navigation system, based on the actual situation. And the author built a simulation of SINS/OD integrated navigation. The results show that, in the case of GPS failure, SINS/OD integrated navigation system is still able to maintain a high accuracy.Kalman filter, extended Kalman filter and unscented Kalman filter are the commonly used method of centralized navigation filter. Kalman filtering is a classic method, which is suitable for linear systems. However, there is always varying degrees of nonlinearity in engineering practice. EKF and UKF are applied to non-linear systems. In the actual system, the system process noise covariance matrix Q and measurement noise covariance matrix R are not fixed. When Q,R changes, the accuracy of UKF is easily influenced. In this paper, an adaptive factor is introduced to UKF. Along with Q, R changes, the corresponding parameters are changing, in order to reduce error accumulation. In order to solve the poor performance of the centralized fault-tolerant filtering,the federal Kalman filter is introduced. Federal Kalman filter can reduce the amount of computation, improve system fault tolerance. Finally, the filtering method simulation proved its performance.