Device for determining the coordinates of the center point a in a plane approximately circular boundary of a body

摘要

1,076,253. Measuring surface contours electrically. RANK ORGANISATION Ltd. Dec.19, 1963 [Dec.19, 1962], No.47990/62. Heading G1N. A rotating feeler 2, Fig. 1, sensed the shape of an approximately circular form such as the outer surface of a shaft or the inner surface of a hole 3, and the degree of eccentricity of the form is determined with reference to the axis of the feeler 2, by extracting the fundamental frequency (i.e. frequency of rotation) from the feeler output and assessing its magnitude in particular directions. In one embodiment a filter 7 passes the fundamental frequency to gates 8, 9, which respectively sample it once per revolution by pulses generated in synchronism with commutator or cam operated switches 16, 17 mounted 90‹ apart on the spindle 1. Stores 11, 12 provide meters 13, 14 with signals indicative of the Cartesian co-ordinates of the eccentricity. Polar co-ordinates may be obtained from the magnitude of the fundamental component and its phase relative to the position of the feeler, determined for example by a generator mounted on the spindle. A second embodiment extracts the fundamental component by multiplying the feeler output (S, Fig. 2, not shown) by sine and cosine signals from a potentiometer (120) whose wiper rotates with the feeler (102) these signals being respectively integrated over for example one revolution as controlled by switches (123, 124) to indicate on meters (113, 114) the magnitude of the eccentricity in any two perpendicular directions determined by the orientation of the potentiometer track relative to the hole 103.