Rotated System
Use a Rotated System () to define an orthonormal coordinate system which is rotated with respect to the reference system. In 2D, you can specify either an in-plane rotation angle or a full 3D rotation using Euler angles. The rotation is intrinsic.
Full 3D rotations are specified as three consecutive Euler angles α, β, and γ. Rotation axes and angles are illustrated in Figure 5-5 where the resulting rotated system axes are denoted X, Y, and Z.
Figure 5-5: 3D Euler angles in a rotated coordinate system.
The transformation matrix defined by the Euler angles transforms components of a fixed vector v from the rotated coordinate system, [vX,vY,vZ], to components in the global system, [vx,vy,vz], as follows:
In 2D models, you can choose to describe the rotated coordinate system by the rotation angle about a selected out-of-plane axis. This is a two-step process. You first select which axis of the rotated system should point into or out of the screen. This defines a new reference orientation for the axes remaining in-plane. Then specify a rotation angle relative to the new reference.
If this coordinate system is added as a subnode to a Combined System node, define where it will be active using a selection in the Geometric Entity Selection section. Also, the Name and Coordinate names fields are not available in this case.
Coordinate Names
In the Coordinate Names table, the default names appear in the First, Second, and Third columns — x1, x2, and x3. In planar 2D models, x1 and x2 are typically the in-plane coordinates, and x3 is the out-of-plane coordinate. Change the names if desired.
Rotation
The rotation settings depend on the space dimension of the component to which the coordinate system belongs. For 2D components, first select an Input method: In-plane rotation (the default) or General rotation.
In-Plane Rotation Settings
When the input method is set to In-plane rotation in a 2D component, you specify the rotation as a single angle (in radians) representing the Rotation about out-of-plane axis. The Out-of-plane axis can be set to any of the three main axes, pointing either into or out of the screen. The default for planar 2D geometries is Third out-of screen, which leaves the x and y axes as in-plane reference axes. For axisymmetric geometries, the default is Second out-of screen, leaving the r and z axes in-plane.
General Rotation Settings
For 3D geometries and when General rotation has been chosen as input method in 2D, then, under Euler angles, choose a sequence of Euler angles from the Rotation sequence list; the default is Z-X-Z, which corresponds to sequential rotation first about the z-axis, then the x-axis, and finally the z-axis again. Enter the angles (in radians) in the α, β, and γ fields (see the graphics in the Settings window for definitions of these angles). The default values are 0 for all angles.
An explanatory image of the coordinates and angles in the rotated coordinate system appears at the bottom of this section.
Origin
Specify the location of the Origin of the base vector coordinate system in the global Cartesian system. The default is an origin coinciding with the one from the global system using the frame chosen from the Frame list (default: Spatial).
Relative to System from Geometry
This section is available in 3D if you have added any work plane to the geometry.
From the Work plane list, select xy-plane (the default, for a standard global Cartesian coordinate system) or select any work plane in the geometry sequence. If you choose a work plane, the work plane’s coordinates xw, yw, and zw are used for the definition of the rotated system.
Go to Name for information about the Settings window Label and Name. Also see Settings and Properties Windows for Feature Nodes.
With the MEMS Module, see Gecko Foot: Application Library path MEMS_Module/Actuators/gecko_foot.