Abstract: A machine includes a pair of spaced supports, one of which may mount an operator such as a tool in a spindle and the other of which may mount an object such as a workpiece. The spaced platforms are joined by six powered and extensible legs joined to the respective platforms by universal joints. The length of the legs is individually manipulated to vary the position of the platforms and therefore the object and operator relative to each other in six axes. The powered legs may be hydraulic cylinders or recirculating ball screw driven. The distance between the spaced platforms may be measured by separate instrument arms which join the platforms. The instrument arms may use a digital position device to measure the extension and contraction of the instrument arms or may use a laser interferometer for that purpose. The changes in the instrument arm's lengths may be used to generate signals which are used to control the extension and contraction of the powered legs.