Vision measurement technology of model poses with high accuracy on the 200m free flight ballistic range

In order to obtain the changes of model poses flying at hypervelocity accurately on the free flight ballistic range which was used for identifying the aerodynamic parameters, China Aerodynamics Research and Development Center (CARDC) developed the vision measurement technology of model poses, which combined the mature technologies of the binocular vision location and the front light photo. The binocular measurement stations were installed along the flying direction of model, which would be calibrated and correlated to the same base coordinate before model test. When the model with coded feature points on its surface entered the measurement field, it would be illuminated by the extended laser light beam with the pulse width of smaller than 10ns, meanwhile, the two front light images were obtained by the cameras of the binocular measurement station, then the model poses were obtained by identifying and calculating the coded feature points on its surface. Based on solving the key technologies of filtering the parasitic light in the chamber, homogenizing the exit facular of the front light source, correlating binocular measurement stations to the same base coordinate, dealing the model surface color and fabricating feature points, the vision measurement system of poses with high accuracy on the 200m free flight ballistic range was accomplished. The test on the 20° cone with the length of 165 mm was carried out on the ballistic range, which flew in the chamber with the pressure of 15kPa at the velocity of about 2.7km/s. According to the cone poses at different binocular measurement stations and the sequence time of lasers flashing obtained by the vision measurement system, the drag index and the dynamic derivative of the cone were obtained by identifying, the trends of which were basically in consistency with those of the AEDC G range.