Space coordinates

The point of origin of the space coordinate system usually is located at the first axis of universal robots. In linear robots the point of origin is located at the intersection point of the three linear axes.

Detailing the points in space coordinates in the workspace is simple.

One disadvantage is the ambiguity of the joint positioning. The coordinate details also have transformed into joint coordinates. This implicates a high computational effort for controlling and a major programming effort for the producer control unit.

Coordinate description: P (x, y, z, A, B, C)

Joint coordinates

The angle and length description of the particular robot axes describe the orientation of the TCP explicitly. A polar insertion of the coordinates is best.

P (angle A1, angle A2, ...., angle A6).

Joint coordinates are mainly used for programming articulated robots. Internal controls always use joint coordinates to control the position.

Gripper coordinates

Gripper coordinates describe the orientation and position of the effector in space.

The zero point of the coordinate systems is located at the Tool-Center-Point (TCP) of the effector.

Usually the coordinates are stated Cartesian, whereas one of the axes have to point into the extended direction of the gripper.

The gripper coordinate system makes it easy to program linear movements of the gripper.

Joint coordinates would be much more complex, because multiple axes must be moved at the same time.

Workpiece coordinates

If a workpiece has to be processed in different positions, one can site a workpiece coordinate system into one corner of the workpiece. 

This coordinate system is also used primarily where the workpiece is moving under the (stationary) machine (CNC, milling or turning).

With this workpiece coordinate, it is easy for the programmer to approach the various machining positions at the workpiece and to program the machining.

The point of origin is also called work piece point of origin (W). The control unit has to know the position of the coordinate system relatively to the space coordinates.