Ion, and also the regional geographic frame (n-frame) is utilised because the reference navigation frame in non-polar regions. The e-frame can be made use of for continuous worldwide navigation. Nevertheless, because the e-frame adopts Cartesian coordinates, the height channel is coupled with 3 rectangular coordinates but this causes position errors to diverge rapidly and brings issues to damping filtering. In addition, the e-frame does not have an explicit azimuth, which isPublisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.Copyright: 2021 by the authors. Licensee MDPI, Basel, Switzerland. This short article is definitely an open access post distributed below the terms and situations from the Inventive Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).Appl. Sci. 2021, 11, 9572. https://doi.org/10.3390/apphttps://www.mdpi.com/journal/applsciAppl. Sci. 2021, 11,two ofinconvenient for flight route planning. Typically, the INS/GNSS integrated navigation system takes the regional geographic frame as the navigation frame at low and middle latitudes and turns instead to grid frames at higher latitudes. When the navigation frame is switched in between diverse coordinate frames, for instance the G-frame and n-frame, the structure on the filter alterations. In this case, as an additional study [11] points out, when the consistency on the error state estimation can’t be guaranteed, this will likely result in the integrated navigation filter to overshoot and trigger error discontinuity. On the other hand, the present analysis [124] on polar area navigation mainly focuses around the style of an integrated navigation algorithm within the polar region or on searching to get a navigation frame to achieve worldwide navigation independently and to avoid the problem triggered by switching in between navigation frames. One DBCO-PEG4-Maleimide Biological Activity particular study [15] proposed the virtual sphere n-vector algorithm and derived detailed mechanization and dynamic equations. Their virtual sphere n-vector algorithm utilized the surface regular vector in the ellipsoid model to represent the aircraft’s position, and did not have distinct mathematical singularities. Essentially, the virtual sphere n-vector algorithm is definitely the identical as the e-frame algorithm and its azimuth definition is indistinct. The researchers of [11] and [16] proposed a hybrid polar navigation technique, which accomplishes the inertial navigation mechanization within the e-frame, whereas it outputs the navigation parameters within the G-frame or t-frame. Additionally, the research of [11,16] introduce a position matrix to decouple the height channel and 3 rectangular coordinates, which can solve the problem of position error divergence. In this way, the continuity of worldwide navigation is guaranteed. Having said that, it completely modifications the navigation frame of the present airborne inertial navigation system, which is not conducive to program upgrades. Papers by [17,18] both proposed indirect polar navigation strategies, utilizing a mixture on the wander frame and G-frame or the t-frame to attain smooth switching of navigation frames. Nonetheless, indirect polar navigation solutions did not fundamentally resolve the filter consistency problem DSG Crosslinker Epigenetics during the coordinate frames switching. In an effort to resolve the issue of filter discontinuity caused by the alter of navigation frame, this paper proposes a polar-region airborne INS/GNSS integrated navigation technique, primarily based on covariance transformation. The transformation relationship among the technique error sta.
