On Pseudo Second-Order Term of Pendulous Integrating Gyro Accelerometer Calibrated in Dual-Axis Precision Centrifuge

The pendulous integrating gyro accelerometer (PIGA) is widely applied in the strategic ballistic missile and the carrier rocket. The working accuracy of the PIGA, which determines the missile's hit accuracy and rocket's orbit injection accuracy, is profoundly influenced by the calibration accuracy of its second-order coefficient. To acquire the second-order coefficient and to eliminate the pseudo second-order term produced by the dual-axis centrifuge errors, the error sources of the centrifuge including the dynamic unbalance and the boom bending are investigated, and the concerned coordinate systems are established; thus, the specific forces and angular velocities acting on the axes of PIGA are obtained. Then, a calibration model of PIGA is established by combining the error model of PIGA with the accurately calculated specific forces and angular velocities versus inertial space. Through in-depth study on the calibration model, a conclusion is drawn that the additional cone angle generated by dynamic unbalance and the dynamic misalignment angle generated by the boom bending are the main contributions to the pseudo second-order term. Monte Carlo simulation is conducted, and the simulation results show that additional restraint or compensation for the pseudo second-order term is necessary in the calibrating process.