Measurement of Position for the Centroid of a Plane Figure Using a Video Camera

Abstract

This paper describes a method of position measurement. The instrument operates on the principle that the center of gravity of an object is, as in balancing a rod, the null point when it is brought to balance. In the equipment a figure of interest is contrasted against the background image by a video camera. The resulting video signal is processed in the instrument to derive voltages representing the xy coordinates of the centroid of the figure. These measurements can be made with an accuracy of ±0.2 percent of full scale for the selected range and a response time of 33 ms.