AN ELECTRO-OPTICAL DEVICE AND PROCESS FOR REAL TIME MEASUREMENT OF THE MOTION OF A MOBILE RIGID STRUCTURE UNDER THE INFLUENCE OF A FLUID

Real time measurement of the motion of a rigid mobile structure in a fluid is achieved by a device comprising at least four unaligned bright spots arranged in a predetermined way on the structure under observation and at least two synchronized video cameras which are arranged with respect to a fixed point. The dimensions of each bright spot are such that the image of each bright spot is intercepted at the focal plane of each camera by about five to fifteen scanning lines. The processing and computing device provides the following functions: collection of the image coordinates of points whose brightness exceeds a certain predetermined level; counting and memorization of these coordinates and of the lengths of the segments of the bright spots intercepted by the scanning lines; calculation of the image coordinates of the barycenters of the bright spots and, finally, calculation of the three-dimensional coordinates of these barycenters to the fixed point. The device is particularly suited to the study of the motion and steering of ship or airplane models in test facilities.