Abstract: This invention relates to motion simulators that are used to impart controlled movement to a rigid platform which may support the student station of a vehicle simulator, or the like. In particular, my invention relates to an improvement in the geometric arrangement of actuators and actuator pivot points on such devices to provide better motion fidelity, improved simultaneous excursion capability, and better adaptability in accommodating visual display systems. A unique feature of this invention is an assembly of three linear actuators and six universal joints in the form of a tetrahedron, the apex of which is held fixed in space and the base of which is attached to and allowed to move with the movable platform.