| During conventional assembling processes,assembly operators perform assembling work depending on the paper assembling process documents,which may lead to the following problems.To begin with,the assembling process is elaborated with texts and drawings in the assembling process document,which doesn’t have an intuitive visualization effect and takes assembling operators more time to acquire valid information,thus reducing assembling efficiency.Besides,modern machinery products,in general,are complex assemblies featuring cross-disciplines and multi-technology fusion.Higher demands on professional quality,cognitive level and operational proficiency have been proposed for assembling operators,since unqualified products can be caused by missing parts or wrong assembly in field assembly owing to assembling operators’ inadequate understanding.In response to the problems of low efficiency and long cycle in the conventional assembly process,the augmented reality aided assembly under information guidance has been studied for assisting the assembly of machinery products.In other words,the assembly field is integrated with the virtual assembly information to guide the assembling work and alleviate assembling operators’ burdens on cognition and understanding.Specific studies are shown as follows.(1)An information projection aided assembly platform was constructed against the problems in the traditional assembly process.Meanwhile,a system framework was established to define the effect and correlation of the functional platform modules upon analyzing characteristics of the augmented reality information projection aided assembly platform with the intention of assisting assembling operators in the assembly process.Based on this,critical supporting technologies were determined for the information projection platform.(2)The projection information management and visualization technology were studied.To be specific,a hierarchical structure model of assembly information and an XML-based assembly guidance information storage method were built for the demands of product assembly for information guidance in the augmented reality assembly process,so that the information guiding the assembling process can be effective managed.Also,information sources for the augmented display in the assembly field are generated from a variety of visualized expressions.At last,the alternation of virtual guidance information in the augmented reality assembly process was achieved through studying the dynamic gesture recognition based on the motion trajectory of gesture centroid.(3)The pose registration technology based on the natural characteristics of the image is studied,including camera calibration technology,projector calibration technology,projector on-site pose registration technology.Firstly,the camera calibration technology is studied,the camera calibration method based on front image is proposed,and the calibration of projector is completed on this basis.Second registration process at the scene of the projector,aiming at reflective metal parts and weak texture is easy to cause inaccurate feature recognition and feature matching problem,using SURF feature detection algorithm combined with the random sample consensus(RANSAC)algorithm,complete projector field position registration based on natural characteristics,implementation field superposition of virtual channel information.(4)Under the VS2010 integrated development environment,the information projection aided assembly platform was developed on account of the above-mentioned research work together with the Open CV image and Open GL graphics processing libraries.Moreover,the process of the information projection aided assembly was discussed to verify the correctness and feasibility of all functions of the platform with the self-priming pump as an example. |
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