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LCS orientation |
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When you plot a local coordinate system, it is required to set the orientation of the axes of the LCS. To do this, use the elements of the Orientation group in the Main section of the Parameter Panel.
Select the orientation setting method by clicking the required button in the Orientation method group, and set the parameters corresponding to the selected method.
The following methods are available.
Axes Direction,
Euler Angles,
By object.
Setting the orientation parameters for each method is described in detail below.
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You can set the LCS orientation in the graphic area using the base element. |
Changing the orientation of the LSC does not change its position.
Setting axis directions
You can specify objects or construct vectors defining the direction of two axes of the LCS. The third axis is automatically positioned so as to form with the other two right three vectors.
Step-by-step instructions
1.To set the axis direction, activate the corresponding field – X axis, Y Axis or Z Axis.
2.Set the axis direction using one of the methods:
•Select an object determining the direction.
The name of the object is displayed in the field. The axis is associated with the selected object.
•To construct the vector, click the Build vector 
button to the right of the Axis X/Y/Z field. That will start vector construction subprocess.
After completing the process of constructing a vector, the word "Vector" will appear in the axis field.
The axis direction can be changed to the opposite by clicking the Change direction 
, button located to the right of its field.
3.Similarly, set the direction of the other axis.
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When setting the direction of the second axis, keep the following in mind. •An object cannot be selected as a guide for an axis if it sets a direction in which the axis becomes parallel to another axis for which a direction has already been set, or lies on the same straight line with it. •A vector cannot be used as a guiding object if it is collinear with the axis for which direction is already set. If an error is detected, a message is displayed. |
4.If the directions set for the axes are not perpendicular to each other, you can choose the leading axis. To do this, press the relevant button in the Leading Axis group (button group is present if directions for two axes are specified):
X Axis,
Y Axis,
Z Axis.
After changing the leading axis, the LCS rotates so that the leading axis coincides with the direction defined by the object (vector). The direction of the second axis is defined as the projection of the direction that sets the object on a plane perpendicular to the leading axis.
If the directions of the axes are perpendicular, changing the leading axis does not change the position of the LCS.
Euler angle system
Set the Euler angles that determine the position of the LCS relative to its own SC. To do this, use the Nutation angle, Precession angle, and Rotation angle fields. Angle values are entered manually or selected from a predefined list.
In addition, you can change the angle values using base element
. When you rotate the base element in the graphic area of the model, the values of the angles are automatically recalculated.
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If for specifying the direction of the axes, guiding objects were selected, then when switching to Euler Angles automatically calculated values are displayed in the corner fields. You can change the angle values. When switching back, the previously made selection of guiding objects is restored, and the LSC axes take the position specified by the objects. |
Orientation by object
Specify the object whose parameters allow you to uniquely determine the orientation of the LCS. The list of such objects and the direction of the axes they set are given in table Objects for creating LCS.
The object is specified in the Design Tree or in the graphic area of the model. After specifying an object, the position of the LSC changes, the name of the selected object appears in the Object field. The LCS is associated with this object.
See Also
