Schlieren photography is normal device in wind tunnel. It records varying density of flow and also shows the attitude of model. In this paper, a method is proposed to estimate the model attitudes through matching the projection drawings of 3D digital model with the schlieren photography and high speed camera image. A simulation experiment is also designed to test the method. The results show that the maximum error less than 0.1°. We also use the method to deal with the wind tunnel test data, and experimental results show that the proposed system can meet the demands of the wind tunnel test.
A position and attitude vision measurement system for drop test slender model in wind tunnel is designed and developed.
The system used two high speed cameras, one is put to the side of the model and another is put to the position where the
camera can look up the model. Simple symbols are set on the model. The main idea of the system is based on image
matching technique between the 3D-digital model projection image and the image captured by the camera. At first, we
evaluate the pitch angles, the roll angles and the position of the centroid of a model through recognizing symbols in the
images captured by the side camera. And then, based on the evaluated attitude info, giving a series of yaw angles, a series
of projection images of the 3D-digital model are obtained. Finally, these projection images are matched with the image
which captured by the looking up camera, and the best match’s projection images corresponds to the yaw angle is the
very yaw angle of the model. Simulation experiments are conducted and the results show that the maximal error of
attitude measurement is less than 0.05°, which can meet the demand of test in wind tunnel.