Research On Pose Measurement Of Workpiece Based On Structured Light And Machine Vision

The method of workpiece pose measurement based on monocular vision usually utilizes the fixed feature of the workpiece's surface,such as points,rectangles,circles and so on.This method can not be realized in the practical engineering fields.Therefore,a circular structured light projector is introduced into the monocular vision system,and it is installed in parallel to the optical axis of camera.Because the circular structure light with high brightness and strong direction can project evenly visible structured light stripe in the workpiece surface and the camera imaging plane.Therefore,the thesis uses the structured light stripe to achieve the workpiece pose measurement.In order to realize the measurement of workpiece attitude,three aspects are studied:Firstly,the workpiece pose measurement model that based on monocular vision and circular structured light has been established.The model determines corresponding relations among the image coordinate system,the image plane coordinate system,the camera coordinate system,the structured light coordinate system and the world coordinate system.Secondly,according to the workpiece pose measurement model,the mathematical expression of the structured light stripe in the imaging plane is deduced,and the normal vector of the workpiece's surface in the camera coordinate system is obtained.Also,the method of selecting reference point is used to remove the false solution.Thirdly,the image processing methods are analyzed and the appropriate image processing methods are selected.By building the experimental platform of workpiece pose measurement,the method of workpiece pose measurement based on monocular vision and circular structured light is experimentally verified.The experimental results show that the pose measurement of the workpiece is basically the same as the real value,but it has errors.The results indicates that the method of workpiece attitude measurement is feasible.Finally,the source of experimental error is analyzed,in which the extraction of the center coordinates of structured light stripe is the main source of measurement error.