Vision measurement technique of model position and its widespread application on the ballistic range

Abstract

In order to obtain the position changes of model flying freely with hypervelocity on the ballistic range, China Aerodynamics Research and Development Center (CARDC) applied the binocular vision technique to measure the model position. The binocular measurement stations were installed besides the room along the model flying direction, which would be calibrated and aligned to the global base reference coordinate system before the test. When the flying model with coded marking points on surface entered the measurement field, it would be illuminated by the extended laser beam with the pulse width of smaller than 10 ns, meanwhile, the two images of the target were obtained by the cameras. The model position was obtained by identifying and calculating coded marking points after the test. Based on solving the key technologies of obtaining clear images of the target, calibrating and aligning binocular measurement stations, dealing the model surface color and making marking points, the vision measurement system of the model position was accomplished on the 200 m free flight ballistic range of CARDC. The position changes of the 20° circular cone with the length of 165 mm were obtained by the vision measurement system, and the drag index and dynamic derivative of which were obtained by identifying, and the trend of the identified results were basic consistency with those on the G-Range of Arnold Engineering Development Center (AEDC). Meanwhile, the widespread application of vision imaging technique was validated by the test. Two new measurement technologies were developed. The first one was obtaining the image sequences, the other was obtaining the image of the target and shadow image at the same measurement field simultaneously. The image of the target for the debris cloud of aluminum sphere impacting aluminum plate at hypervelocity was obtained successfully.