Design of the navigation method of the mechanical gyro based inertial platform system

Abstract

A platform inertial platform system (IPS) is a kind of independent navigation system that can give the real-time position, velocity and course information of its carrier. For the IPS based on mechanical gyros, a method of ground vehicle navigation is proposed, in which the IMU of the IPS is stabilized within inertial space. The method can be used for testing the performance of the IPS of high precision working in dynamical environment. Compared with the navigation methods in which IPS works under torque control, the stabilization of the IMU is implemented only by the dynamics character of the gyros, so the complexity of the mechanical control can be reduced. For applications in which the IPS is required to be stabilized in inertial space, such as carrier rockets, testing results of better consistency with actual application is available. As the angular motion status of the IMU is calculated using the measurement data of the accelerometers of the IPS, the random noise of the accelerometers' output can influence the precision of the IMU's attitude and cause errors in navigation results. To research the influence to navigation precision caused by accelerometers noise, a navigation error simulation is carried out. According to the simulation results, the suppression of accelerometer noise is helpful to improve the signal noise ratio of the IPS navigation, especially for the attitude angles. To reduce the errors caused by the random noise of the accelerometers, the cubic spline interpolation is used to process the reckoned IMU angular rate, which was verified helpful to improve the navigation precision by the vehicle navigation experiment.