Research On A Multi Axis Inspection System Based On Integrated Vision And Touch Sensing

The requirements on the performance and shape of products are increasing, along with the rapid development of modern industry such as aerospace, shipbuilding, automobile, mould manufacturing etc. Rapid and high accuracy coordinate data acquisition from complicate workpiece has wide application to many fields, such as loacation and automated cablication of parts in detection process, agile manufacturing, rapid product design in reverse engineering. It also puts forward higher requirements for the accuracy, speed and automation level of the measuring system. Conventional single-sensor and orthogonal coordinate system has these or those shortages in aspects of measuring range, accuracy and efficiency etc. Recently, multiple-sensor integration and multi-axis measuring system has become a research hot spot and has achieved some progress, but there are still some problems to be solved, especially in aspects of calibration of multiple-sensor, multi-coordinates unification and intelligent imformation integration.In this study, a multi-axis inspection system based on integrated vision and touch sensing is studied. The main research work includes:1. An image acquisition system featured with parallel projection achieved by the use of telecentric optics and parallel illumination is proposed, aiming at illumination, scattering characteristics, and other factors which affect profile imaging quality. Experimental results show that the proposed image acquisition system can efficiently improve the profile imaging quality and is beneficial to profile measurement.2. According to the structure form ofθFXZ for a multi-axis system, a pseudo-rigid body kinematic model is built. A verification method based on laser interferometer for each single geometric error of linear moving components is proposed and used for geometric error compensation. An evaluation method of comprehensive properties for turning table by aming at marker points is proposed, achieving the unification of system coordinate.3. Mathematical theory models of camera and touch trigger probe are built respectively. A rapid and high-precision camera calibaration technique based on active vision, a touch trigger probe calibration method based on pre-travel error model, and a combined calibration method for these two sensors are analyzed in detail. The registration problem in multi-sensor integration is finally solved. 4. Image filtering algorithm using average of multiple images, gray threshold segmentation based on IVFS Maximum fuzzy exponential principle, edge detection operator based on mathematical morphology are studied. Fast sub-pixel location of measuring image is achieved by conic fitting. The positioning accuracy of 0.1 pixels is attained.5. Information integration of vision and touch sensing is studied. Sensor selection strategy is analyzed firstly. Automatic segmentation of curve primitive of is completed by feature mapping, according to the change law of the normal vector of boundary curve. A primitive parameter estimation method based on least square principle with constraint condition is given then. Measuring planning guided by boundary feature is analyzed. Applications of multiple-sensor integration in workpiece localization and combined measurement are illustrated with examples finally.