All objects in a 3D Animation have an orientation. This orientation can be made visible by showing the object attached reference frame. This orientation can be fixed (using fixed values) or changed (using model variables) during simulation.

The orientation of an object is defined as the transformation of the frame one level up the object tree {A} to the object attached reference frame {B}. Several methods can be used in 20-sim to define this transformation.

DirectX

Using the DirectX method you have to specify the Y-axis and Z-axis of the frame {B} in coordinates of frame {A}.

Bryant angles

Start with the frame {B} coincident with a known frame {A}. First rotate {B} about the X-axis of {B} by an angle of X (rad), then rotate about the Y-axis of {B} by an angle of Y (rad) and then rotate {B} about the Z-axis of {B} by an angle of Z (rad). Note: Bryant angles are also known as X-Y-Z Euler angles or Cardan angles.

X-Y-X-Euler

Start with the frame {B} coincident with a known frame {A}. First rotate {B} about the X-axis of {B} by an angle of x (rad), then rotate about the Y-axis of {B} by an angle of y (rad) and then rotate {B} about the X-axis of {B} by an angle of z (rad).

Euler Parameters

Start with a frame {A}. Rotate this frame about a vector K [X,Y,Z]T about an angle theta to get to the frame {B}.