Contents
Why might you want to change from one coordinate system to other?
The reason we change coordinate systems, is to simplify relationships between objects in a simulation or game. For example: In computer graphics, we are only interested in where objects are, relative to the camera, or eye. Therefore, we need a coordinate system which describes the space according to the eye.
What are global and local coordinates?
The global coordinate system defines the position and translation of a body in space. Local coordinate systems define how limbs and body segments articulate about joints. To achieve uniform motion in DHMs, coordinate systems must be either communicated in protocols or standardized.
Why do we use different coordinate systems?
Coordinates systems are often used to specify the position of a point, but they may also be used to specify the position of more complex figures such as lines, planes, circles or spheres. For example, Plücker coordinates are used to determine the position of a line in space.
When to convert global coordinates to local coordinates?
In 3D structural analysis (as well as many other applications) it is necessary to convert section properties, forces, and deflections between coordinate systems defined by individual structural members (local coordinates) and the common coordinate system defining the entire structure (global coordinates).
How to change the local coordinate system of a panel?
If local z axis sense (toward one panel side or the other) needs to be changed, select “Change of local Z axis sense” option. If local x and / or y axis directions need to be changed, select “Definition of local X axis direction in the coordinate system”. In that case, a vector should be given in the “Direction vector of X axis” field.
What are the values to be converted from global to local?
Globala or Locala: the values to be converted to the new axis system. The values may be deflections, rotations, forces, bending moments, or section properties (translational and rotational stiffness values).
How are local force displacement relationships assembled for global equilibrium?
StiffnessMethod Page 5 ASSEMBLY of LOCAL force -displacement relationships for GLOBAL Equilibrium Now ALL the member force -displacement relationships can be ASSEMBLED (Added) together to get Global equilibrium: Note that “q” are forces on members, so to get forces on nodes we must take ” -q”.