A tightly coupled rotational SINS/CNS integrated navigation method for aircraft

Strapdown inertial navigation system (SINS)/celestial navigation system (CNS) integrated navigation is widely used to achieve long-time and high-precision autonomous navigation for aircraft. In general, SINS/CNS integrated navigation can be divided into two integrated modes: loosely coupled integrated navigation and tightly coupled integrated navigation. Because the loosely coupled SINS/CNS integrated system is only available in the condition of at least three stars, the latter one is becoming a research hotspot. One major challenge of SINS/CNS integrated navigation is obtaining a high-precision horizon reference. To solve this problem, an innovative tightly coupled rotational SINS/CNS integrated navigation method is proposed. In this method, the rotational SINS error equation in the navigation frame is used as the state model, and the starlight vector and star altitude are used as measurements. Semi-physical simulations are conducted to test the performance of this integrated method. Results show that this tightly coupled rotational SINS/CNS method has the best navigation accuracy compared with SINS, rotational SINS, and traditional tightly coupled SINS/CNS integrated navigation method.