Study Of SINS/GPS Integrated Navigation System Based On Accelerometers

Traditional Strap-down inertial navigation technology is widely used in military and civilian fields,and it uses accelerometers and gyroscopes as measurement devices.Because high-precision gyroscope has complex manufacturing process and high manufacturing cost.So it can't be applied in large dynamic environment.But GFSINS only uses the accelerometer as measuring devices,so it not only avoids the defects caused by the gyroscope in order to better adapt to the large dynamic environments,but also enables the size and cost have been reduced.Therefore,GFSINS has great research value.But GFSINS also has significant shortcomings.Since the angular velocity can't be measured directly,so that it will repeatedly integrating over time.It leads to that systematic errors accumulate serious over time,and navigation accuracy is reduced.GPS has the advantages of real-time measurement,high precision,all weather.Therefore,this paper introduces GPS assisted GFSINS,and use of GPS data to correct errors of GFSINS for inhibiting the accumulation of errors and improving navigation accuracy.The research focus and main works are described below.(1)GFSINS uses the new nine-accelerometer inertial measurement unit,and deriving the accelerometer's model of output for any one of the inertial measurement unit.We can get derivative term and cross-product terms of three-axis angular velocity by solving the accelerometer data,thereby solving the angular velocity.Then we can derive the navigation algorithm of GFSINS.It also gives the error model of GFSINS to prepare for the establishment of the kalman filter.(2)Study and comparison of three methods to calculate the angular velocity,which is the integration method,the square root method and the aided algorithm of angular velocity calculation.We are derived and simulated for each method.We analyze the advantages and shortcomings of each method based on the simulation results.Finally,because of the realization and reliability of the integration method,we choose it to calculate the angular velocity.(3)Analysis of the installation errors of accelerometers in the inertial measurement unit of GFSINS.We compared the effects of two installation errors for the angular velocity solver precision,and completed simulation.Then design calibration and compensation algorithm for the installation errors.The simulation results show that the algorithms can reduce the caused by installation errors.(4)The working principle and navigation algorithm of GFSINS/GPS integrated navigation system are studied in detail.It uses loosely coupled mode,and kalman filtering equation was established by the indirect method.As for error correction,we use the feedback correction methods to achieve it.Finally,the simulation results show that GPS can effectively solve the problem of error accumulation of GFSINS and improve navigation accuracy.It verifies the validity of the integrated navigation algorithm.