B. The group actions
Importantly, Lie groups come with the power to transform elements of other sets, producing e.g. rotations, translations,scalings, and combinations of them. These are extensively used in robotics, both in 2D and 3D.
重要的是,李群具有变换其他集合元素的能力,产生旋转、平移、缩放和它们的组合。它们广泛应用于机器人技术中,包括二维和三维。
Common examples are the groups of rotation matrices SO(n), the group of unit quaternions, and the groups of rigid motion SE(n). Their respective actions on vectors satisfy
常见的例子是旋转矩阵组 SO(n)、单位四元数组和刚性运动组 SE(n)。 它们各自对向量的作用满足
SO(n):rotation matrix R∗x≜RxSE(n):Euclidean matrix H∗x≜Rx+tS1:unit complex z∗x≜zxS3:unit quaternion(四元数) z∗x≜zxSO(n):rotation\ matrix \ \ R*x \triangleq Rx\\
SE(n):Euclidean\ matrix \ \ H*x \triangleq Rx +t\\
S^1:unit\ complex \ \ \ \ \ z* x \triangleq z x \\
S^3:unit\ quaternion(四元数)\ \ \ z* x \triangleq z x \\
SO(n):rotation matrix R∗x≜RxSE(n):Euclidean matrix H∗x≜Rx+tS1:unit complex z∗x≜zxS3:unit quaternion(四元数) z∗x≜zx
See Table I for a more detailed exposition, and the appendices.
The group composition (1) may be viewed as an action of the group on itself, ◦ : M × M → M. Another interesting action is the adjoint action, which we will see in Section II-F.
有关更详细的说明和附录,请参见表 I。
群组合 (1) 可以被视为群对自身的一个动作,◦ : M × M → M。另一个有趣的动作是伴随动作,我们将在第 II-F 节中看到。
2D和3D运动中使用的典型李群,包括平凡的Rn。完整参考见附录2D 和 3D 运动中使用的典型李群,包括平凡的 Rn。 完整参考见附录2D和3D运动中使用的典型李群,包括平凡的Rn。完整参考见附录