Testing Research Of Pendulous Integrating Gyro Accelerometer On Low-Frequency Linear Vibrator

As one of the core components of inertial navigation devices,Pendulous Integrating Gyro-Accelerometer?Gyro-Accelerometer for short?is suitable for intercontinental ballistic missiles with large overload and high precision requirements.Gyro-Accelerometer is used for sensing and measuring the apparent acceleration of the carrier,and its accuracy and performance are directly related to the missile hit accuracy.With the continuous improvement of accuracy requirements and simulating Gyro-Accelerometer's real using situation and environment,the research and modeling of Gyro-Accelerometer error mechanism in the actual working environment of high acceleration has become an urgent problem to be solved.Because of the insufficient input excitation,it is difficult to accurately measure the small nonlinear quadratic error of Gyro-Accelerometer in traditional gravity field.The low-frequency linear vibrator can provide input excitation with low-frequency and large overload for Gyro-Accelerometer.Meanwhile,compared with centrifuge and rocket sled,it has the advantages of convenient test and low cost.Based on the engineering requirements,this paper studied the calibration test method and engineering implementation of Gyro-Accelerometer's nonlinear quadratic term coefficient separation on the low-frequency linear vibrator,and carried out experimental verification.Firstly,the paper analyzes the principle of Gyro-Accelerometer,and its kinematics equation is derived by establishing a coordinate system and then we analyze the influence of transverse acceleration,unequal inertia and the earth's angular velocity on Gyro Accelerometer's output.Finally,the error model of Gyro-Accelerometer is established,and the generating mechanism of each error term coefficient is given.In view of the selection of high g acceleration test equipment,this paper analyzes the advantages and disadvantages of three kinds of experimental equipment,namely centrifuge,rocket sled and low-frequency linear vibrator.Compared the coverage of acceleration and frequency,the convenience of testing,the low-frequency linear vibrator is determined to be the optimal equipment for the current test.Then,according to the working principle of the low-frequency vibrator,the acceleration output model is deduced,and the influence of the system error?waveform distortion,transverse acceleration,parasitic rotation?on the output acceleration of the low-frequency vibrator is analyzed.Combined with the above theoretical analysis,a method for the calibration of the nonlinear quadratic term coefficients of Gyro-Accelerometer on the low-frequency linear vibrator is proposed.The axial quadratic term coefficient k_2x of Gyro-Accelerometer's input is separated by the forward and backward testing with Gyro-Accelerometer placed horizontally,and the cross axial quadratic term coefficient k_2xy is separated by the forward and backward testing with Gyro-Accelerometer placed diagonally at 45 degrees.In terms of test time selection,two kinds of testing methods are selected,integer multiple of vibrator period and integer times of Gyro-Accelerometer precession.Then the paper analyzes the test errors caused by the two different methods.Besides,the input acceleration errors caused by the system errors?waveform distortion,lateral acceleration,and parasitic rotation?of the low-frequency linear vibrator and the errors caused by the installation errors on the Gyro-Accelerometer non-linear quadratic term calibration are analyzed.Finally,in order to verify the effectiveness of the method of separating and calibrating nonlinear quadratic terms,several accelerometers are selected to carry out experiments,and the multiple linear regression theory is introduced to analyze the experimental data to verify the significance of the regression curve and coefficient identification.The experimental results show that the F-test of three Gyro-Accelerometers'model equation is F?¹?=10.09¹0.14?F?²?=9.81⁹.93?F?³?=11.62¹2.55,which all greater than F_0.01?3,6?=9.78.The t-test of three Gyro-Accelerometers'model equation is t?¹?=0.263¹.597?t?²?=0.261¹.569?t?³?=0.286¹.94,which all less than t₀.₀₅?4?=2.776.The data presents good fitting effect,high identification accuracy and highly significant regression coefficient.