| Monocular structured light 3D measurement technology has the advantages of simple structure,high measurement accuracy and fast measurement speed,and has been widely used in the field of complex thin walled blade measurement.However,limited by the principle of structured light measurement,the traditional structured light measurement needs to move the workpiece from the machine tool to the detection platform for measurement,which is difficult to meet the needs of integration of machining and measurement.It is one of the important ways to meet the demand of integrated machining and measurement to combine the structured light measuring equipment with the multi-degree-of-freedom moving platform to realize the onmachine measurement.The key to achieve in-machine measurement lies in the reasonable design of motion platform and the planning of viewpoint and motion in the process of measurement.Firstly,a set of optical surface topography measurement platform for thin-walled blade with complex curved surface was designed and built for the machine measurement environment.The optical acquisition module,motion module and control module of the experimental platform are designed,and the circuit and hardware of the experimental platform are configured.The corresponding motion control program was written to realize the on-machine measurement function of the optical measuring platform,and repeated positioning accuracy calibration of the optical measuring platform was carried out to ensure the motion accuracy of each axis of the optical measuring platform.Secondly,the relationship between the camera’s field of view and the acquisition accuracy was used to design a high-precision viewpoint planning scheme for the blade measurement process.Based on the structural characteristics of the measured blade and the shooting accuracy of the camera,a method of uniform point cloud segmentation was proposed.Aiming at the problem that the camera viewpoint deviated too much from the normal vector of the workpiece surface and caused the loss of point cloud information,the optimal shooting position of the block point cloud was studied,and the planning viewpoint of high-precision measurement was finally obtained.Then,in order to ensure the reasonableness of monocular structured light in machine measurement,the kinematics planning method of optical in machine measurement platform coordination with the machining process is studied.According to the motion state of aviation blade in machining process,combined with the monocular structural light measurement requirements,the position relationship between the camera and the blade in the acquisition process as the constraint condition,the optical measurement platform in the process of each axis movement trajectory and movement speed planning,the realization of blade thin-walled curved parts in machine measurement.Finally,the practicability of the technology proposed in this paper is verified by the on-site measurement experiments of viewpoint planning and motion planning on the suction surface of the thin-walled blade.The overall process and scheme of thinwalled blade in machine measurement experiment were designed,the causes of measurement errors were analyzed,and the solutions to reduce the errors in machine measurement were proposed.The related technology provides the research basis for the integration of machining and measurement. |
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