Coordinate Systems

These are the different coordinate system The reference system in which a coordinate or path is described. (CS) types:

• Machine The complete assembly of all connected parts or devices, of which at least one is movable. (MCS)
• Axes (ACS Axes Coordinate System - The system of coordinates related to the physical motors and the single movements caused by the single drives.)
• Product/Program The act of performing a sequence of instructions or commands. (PCS Product Coordinate System or Program Coordinate System. The PCS is based on the MCS by shifting and maybe rotating the MCS. The Zero point of the PCS is related to the product and can be changed during runtime by the program. The real work piece can have a rotation or shift to the MCS coordinate system or even might be moving relative to the MCS coordinate system. By specifying a trajectory in PCS one is able to describe the trajectory independent from the machine situation. To map these two worlds (MCS to PCS and vice versa), a Cartesian or cylindrical transformation is normally done.)

Figure 1: Examples of CS types on a machine and part.

• Many coordinated moves may be done in a choice of coordinate systems.
• The differences between the types are offsets and possibly transformational algorithms to convert between the different systems, which ultimately control the actual axes on a piece of machinery.

Example

• The X-axis of a Machine CS is meant to command a pair of Axes CS axes (X1 and X2) which together form a gantry.
• The relative movement of the MCS X axis would be added to both ACS axes.
• The two ACS axes can be commanded independently for minor alignment adjustments.
  

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• The Product Coordinate System is often rotated and/or offset from the Machine Coordinate System.