Abstract: A motion system or goniometer for moving a sample supported by the system has a triangular plate supported at each apex by actuators that can extend or retract axially independently from one another. The actuators are mounted on x-y translation stages and a .theta. rotation stage. The movement of the actuators, translation stages and rotation stage is controlled by a computer. When it is desired to create a rocking curve at a particular position on the sample, the translation stages and rotation stage can remain stationary while moving only the plate and actuators. The goniometer is much more efficient and less expensive than previous devices which require movement of the entire goniometer when creating a rocking curve.