Apparatus for and method of measuring geometric, positional and kinematic parameters of a rotating device having a plurality of interval markers

摘要

A system and method of measuring geometric, positional and kinematic parameters of a rotating device is described. The system includes a plurality of spaced interval markings distributed about the periphery of a rotatable device, such as a disk, around a circle of known radius concentric with a geometrical center of the disk. At least three and preferably four sensors for detecting the markings are positioned to sense the markings as they rotate with the rotatable device. The sensors are angularly spaced relative to one another around the disk. Means are also provided for interpolating locations between selected markers by measuring the time since each sensor senses a marker. A reference marker is provided so as to establish a reference point of the rotatable device relative to a fixed point relative to the sensors. Circuitry is provided for determining any lateral displacement of the geometric center of the rotatable device, any out-of roundness of the rotatable device if desired, the angular position of the rotatable device relative to the fixed point relative to the sensors, and the angular velocity of the rotatable device during its rotation. The apparatus has particular application to X-ray tomography systems.