| Nowadays,aerospace has become an important project to help realize the great Chinese Dream.As an important inertial navigation technology in this direction,it plays an important role in accurate positioning and precision guidance.The accuracy of components in inertial navigation system is directly related to the accuracy of navigation.Therefore,improving the calibration accuracy of inertial navigation components has become the development trend of navigation in the future.At present,most of the calibration methods of accelerometer in inertial navigation system are sub-legislation and carried out in gravity environment.However,the Legislative Council introduces the installation error angle in the process of disassembly and installation of the instrument to affect the calibration accuracy;the maximum input specific force of the accelerometer combination in the gravity environment is 1 g,which is not enough to effectively stimulate the high-order error parameters of the accelerometer,and can’t meet the precision guidance requirements for some high-speed aircraft.Therefore,large excitation and overall calibration accelerometer is the mainstream of inertial instrument calibration research.The precision centrifuge can continuously provide high-precision acceleration of more than 1 g,which is usually used to calibrate the high-order error model coefficients of the accelerometer.However,the research on the whole method of calibrating the accelerometer combination on the centrifuge is less.If all the error model coefficients of the accelerometer combination can be calibrated on the centrifuge,at the same time,the influence of the test equipment error on the coefficient calibration accuracy can be reduced.It will provide an important contribution to the development of inertial navigation technology.Moreover,error compensation has become the mainstream method.In the Normobservation method,according to the known invariant property of the specific force,the relationship between the output specific force of the accelerometer and the combined error parameters of the accelerometer is established,and the vector mode of the specific force output of the accelerometer is used as the observation.Without providing accurate attitude information for the accelerometer with the help of the turntable,the combined error parameters of the accelerometer can be calibrated.In this paper,a new combined calibration method of multi-position accelerometer based on Norm-observation method is studied by using precision centrifuge,and the overall calibration of zero offset,scale factor and quadratic coefficient of three accelerometers in inertial combination is realized.On this basis,the influence of multiple errors on the calibration work is discussed,which lays a theoretical foundation for practical calibration.The main work is as follows:1)In this paper,the idea of Norm-observation method is applied to the calibration method of precision centrifuge,and Norm-observation method equation suitable for precision centrifuge calibration is established,a precision centrifuge with a position table is selected,the corresponding coordinate system is established,and the nominal value of the input specific force in each direction of the three-axis accelerometer is calculated by using the homogeneous transformation method.2)The overall calibration of the error model coefficient of the accelerometer in the inertial combination is realized,and the calibration of the quadratic coefficient of the accelerometer is emphatically realized by using Norm-observation method.The input specific force expression of the third accelerometer is simplified by using the Taylor series(the Taylor series is expanded to the second and third order terms),the 20-position method is designed to calibrate the accelerometer combined error model coefficients,and the least square method is used to calibrate all the coefficients.The concrete expressions of the accelerometer combination zero offset,scale factor and quadratic term coefficients are given when the Taylor series is expanded to the second order term and the third order term respectively.The effectiveness and accuracy of the method are verified by simulation.Improving the Navigation accuracy of Inertial Navigation system.3)Furthermore,at 20 positions,the influence of installation error angle and rod arm error on error model coefficient in two cases of Taylor expansion is analyzed.Simulation results show that installation error angle and rod arm error have little influence on the calibration results of error model coefficient,which can be ignored in the actual calibration process,which further verifies the feasibility and accuracy of calibration error model coefficient by Norm-observation method. |
