Study On Precise Positioning Of Electronic-Component Leads Based On Rotational Stereo Vision

Visual positioning system is the key for heterotypic components inserting machine to inserting accurately.At present most of the inserting machines adopt the vision positioning method with bottom-camera that used in surface mounting machine.Due to the long and thin leads of the heterotypic components,positioning with body area will cause positioning error of leads;it is difficult for some leads in bottom images of components to be distinguished and positioned stably because of the strong reflection of body.In order to obtain images of component leads stably to position,a precise positioning method is proposed of electroniccomponent leads based on rotational stereo vision.Multi angle backlight image of the component leads are obtained with side camera,and component leads are positioned and rectified with rotational stereo vision.The leads of component can be inserted into the holes of PCB after the end of leads being inserted,in order to position component leads fast and accurately,a feature point extracting method is proposed according to the characteristics of backlight images of component leads.Camera calibration and correction of lens distortion are finished according to current calibration methods.A fast calibration method of rotational-axis of inserting machine is proposed.The influence of projective model and edge reflection on feature points extraction is analyzed;according to the result of system calibration,multi angle rotational stereo positioning method of component leads is derived.Spatial position of component leads are calculated by the proposed method in the coordinate system of side camera,but the rectifying of components for inserting machine is working in two-dimensional plane;and in order to avoid the overlapping of leads,the initial angle of image obtaining is different from inserting angle.In order to realize automatic rectification of components with proposed positioning method,an element rectifying method based on rotational stereo vision is proposed.A vision experimental system is built for experiment,experimental results show that with the number of images increasing,the accuracy of proposed method increases and converges;grabbing position and angle produce no effect on accuracy of proposed method,and the accuracy meet the requirements of inserting machines;calculation of the component angle of and angle rectifying can be completed accurately with the proposed method.And the applicability for multi leads components of the proposed method is verified as well.It's verified that the proposed method meets the efficiency requirement of inserting machine through the efficiency experiment.Finally,an automatic inserting system based on rotational stereo vision is built for automatic rectifying and inserting experiment with various components,and the feasibility of the proposed method is verified for the application of heterotypic components inserting machine.