Analytical method of the performance of the rotational ins based on the spatial accumulation of the inertial instrument biases

Rotational inertial navigation system (INS) make the biases accumulate averagely to the directions of the navigation coordinate frame by rotating the inertial measurement unit, and eliminate the influence of the biases using the integration of the navigation computation, so that the precision of the INS can be improved effectively. According to the error suppression principle of the rotational INS, this work analyzes the accumulation of the biases in the navigation frame space per unit time by approximately discretizing the IMU rotation path, in order to compare the performance of the rotation modulation schemes with different angular motion statuses. By analyzing the constant angular rate rotation scheme, the linearly varied angular rate rotation schemes and the sine angular rate rotation scheme, the conclusion can be drawn that with the extension of the varying angular rate process, the spatial accumulation of the biases increase, which decreases the error suppression effect of rotation modulation. The conclusion was verified by the simulation of navigation errors. Therefore, the design principle of the rotation modulation schemes is reached that the angular rate should be kept constant in the single-axis rotation modulation and the dual-axis alternate rotation modulation.