An Improved Rotation Scheme for Dual-Axis Rotational Inertial Navigation System

In the rotational inertial navigation system (RINS), the rotation scheme affects the system's performance directly. Improper rotation scheme may excite devices' errors instead of reducing the effects caused by them. RINS should choose a suitable rotation scheme based on the error characteristics of its own. The rotation modulation theory for kinds of errors is analyzed, and two rotation schemes, called scheme A and scheme B in this paper, are proposed first. After the merits and demerits of the two schemes are discussed, an improved rotation scheme, called scheme C, is put forward. Scheme C can compensate scale factor errors, biases and installation errors of inertial sensors by rotating inertial measurement unit along the yaw axis and horizontal axis alternately. The simulations based on MATLAB are conducted in specific conditions; the results indicate that the performances of the three schemes are great better than that of general strap-down INS, called scheme D in this paper. Among the three schemes proposed, the performance of scheme C is the best. Experimental results in a real dual-axis rotational inertial navigation system based on fiber optic gyro show that the radical direction position error of the system is about 0.7 n mile in 12 h if scheme C is adopted, which verify the practicability of the rotation scheme proposed in this paper.