Research On Stereo-vision For Measuring Wind-induced Responses Of Membrane Structure

Aero-elastic model test of membrane structure is widely used to study the aeroelastic effect.And in the observation of vibration response,the acceleration sensor and laser displacement meter are the common methods.However,these traditional observation techniques are inefficient,limited and less information.Thus,it is necessary to improve the membrane structure measurement technology.Stereo-vision,as a noncontact measurement technology,can get full field information and large amount of information,which has been widely applied in aerospace and other fields.Due to the advantage of stereo-vision in measuring,the research of this paper is mainly to form a stereo-vision measuring system and apply it to the aero-elastic model test of membrane structures.The main contents are as follows:(1)The fundamental of stereo-vision is improved by defining the world coordinate system firstly.In order to reduce the noise disturbance and improve processing speed,the current response process is modified and supplemented based on the basic equations: the Open CV platform is used to conduct camera calibration;the process of obtaining the pixel coordinates of measuring points is selected and modified;edge pixels’ eight neighborhoods continuous tracking is put forward to track the edge pixel of the identification point;ranked matching algorithm based on the reference image is carried out to match feature points’ pixel coordinates.Thus the algorithm of stereo-vision is formed.(2)According to the formed stereo-vision algorithm,the appropriate hardware and software system are determined.Then the software system is transferred to an interactive interface including a calibration module based on Open CV which is efficient and automate,a visualized stereo-vision measurement platform based on Matlab which integrate the three calculation process of pixel coordinates,3D displacement and regional result.Then a stereo-vision measurement system is formed.(3)Based on the experimental conditions,the possible observation plans for the membrane structure aero-elastic model test have been discussed using the stereo-vision measurement system.Then aero-elastic model tests in different model forms and different wind speed are put forward.After that,the measuring accuracy,applicability,sensitivity to the curvature of the model about the measurement system are determined.At the same time,the full field displacement results of membrane are given.