论文标题

N frame的奇偶校验随着非优型正交化的应用

Parity of n-Frames with Application to Non-Procrustean Orthogonalization

论文作者

Sjogren, Jon A.

论文摘要

欧几里得空间中完整的正交帧的空间未连接路径。实际上,它完全具有两个路径成分,分别包含n个标准坐标的坐标框架和两个坐标的框架。与这些帧相对应的矩阵分别具有决定符和减去一个。我们希望避免在许多变量中实现确定性功能,而是通过振动和覆盖地图来与这些紧凑的空间一起使用。重要的振动是从框架中删除最终向量,以及第一个向量的选择。这种振动的长均匀序列表明,环的等效类别形成了两个元素的组。该组的一个发电机是一个旋转的圆圈。维度三对于证明至关重要。它由Rodrigues公式以及域的不变性处理。另一个明确的证据表明,来自单位四元素的映射是主要路径组件的汇总是由于ITZHACK造成的。因此,使用同型提升定理进行覆盖,正交组未连接路径。但是givens循环执行一个身份提升,因此不能是组发生器。作为一个应用程序,我们回顾了如何引用与Wahba指导问题有关的宇航文献中引用算法,从而导致任何矩阵的正交化,该基质在指标上接近某些旋转。该方法在Frobenius规范中具有偏见,但在现实条件下也是一种偏差。

The space of complete orthonormal frames in Euclidean space is not path connected. In fact it has exactly two path components, containing respectively the coordinate frame of n standard coordinates and the frame with two coordinates reversed. The matrices corresponding to these frames have determinant one and minus one respectively. We wish to avoid the implement of the determinant function in many variables, and rather work with these compact spaces by means of fibrations and covering maps. The important fibrations are deletion of the final vector from the frame, and selection of the first vector. The long homotopy sequence for this fibration implies that the equivalence classes of loops form the group of two elements. One generator of this group is a circle of Givens rotations. Dimension three is critical for the proof. It is handled by the Rodrigues formula, together with Invariance of Domain. Another explicit proof that the mapping from unit quaternions is surjective to the main path-component is due to Itzhack. Thus the Orthogonal Group is not path connected, using the Homotopy Lifting Theorem for coverings. But the Givens loop performs an identity lifting, so it cannot be the group generator. As an application we review how quoted algorithms from the astronautical literature, related to the Wahba guidance problem, give rise to an orthogonalization of any matrix that is metrically close to some rotation. This method has a bias in the Frobenius norm, but under realistic conditions serves as well as a Procrustean method.

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