System-Level Calibration Method Considering Nonorthogonal Angles in Dual-Axis Rotational Inertial Navigation System

In self-calibration process of the dual-axis rotational inertial navigation system, it is usually assumed that the rotation axes are orthogonal to each other. However, in reality, there are nonorthogonal angles between the rotation axes. When rotation mechanism rotates, the nonorthogonal angle will be coupled with the angular movement and cause errors. The error is introduced into the error equation, resulting in reduced calibration accuracy. In order to improve the self-calibration accuracy, we propose a calibration method for the dual-axis rotational inertial navigation system that considers nonorthogonal angles. First, an error model including nonorthogonal angles is established, and then a reasonable rotation scheme is designed through observability analysis, and finally, a system-level calibration method is designed. Simulations show effectiveness of the proposed calibration method. Navigation experiments demonstrate that after compensating calibration results, the velocity errors are reduced by 36% compared with the previous method.