Abstract-Within industrial automation systems, 3D (three dimensional) vision provides very useful feedback information in autonomous operation of various manufacturing equipment (e.g., industrial robots, material handling devices, assembly systems, machine tools). The hardware performance in contemporary 3D scanning devices is suitable for on-line utilization. However, the bottleneck is the lack of real-time algorithms for recognition of geometric primitives (e.g., planes, natural quadrics) from a scanned point cloud. One of the most important and the most frequent geometric primitive in various engineering tasks is plane. In this paper, we propose a new, fast, one-pass algorithm for recognition (segmentation and fitting) of planar segments from a point cloud. To effectively segment planar regions, we exploit the orthonormality of certain wavelets to polynomial function, as well as their sensitivity to abrupt changes. After segmentation of planar regions, we estimate the parameters of corresponding planes by using standard fitting procedures. For point cloud structuring a z-buffer algorithm with mesh triangles representation in barycentric coordinates is employed. The proposed recognition method is tested and experimentally validated in several real world case studies.

This paper .<:hows the results of investigations performed in the brittle materials microcutting at the Faculty of Mechanical Engineering, Belgrade University. The interactions between a single diamond grain and the machined granite are analyzed. The change in the normal cutting force as a function of grain penetration speed and depth was experimentally established in microcutting of two types of granite originating from Serbia. Based on the grain traces on granite and the generated cracks, the critical grain penetration depth for the formation of brittle fracturing was established. The experiments are intended to assist in the optimization of the grinding process as technology dominant in the granite finishing.

Preliminary notesThis paper presents the possibilities of applying a new method of programming based on STEP-NC standards, which was developed as an alternative to the G code. The possibilities of application in the field of machining simulation and verification of the program before machining on the wire electrical discharge machine are discussed. The paper shows the possible methodology for simulation and verification of programs based on the STEP-NC using IDEF0 diagrams, as well as links between the software programs STEP-NC Machine and CAD/CAM system. The presented methodology is verified by the test workpiece machining, based on the STEP-NC program. Keywords: machining simulation; STEP-NC; wire electrical discharg machine Simulacija elektroerozijske obrade žicom na temelju STEP-NC programaPrethodno priopćenje Ovaj rad prikazuje mogućnosti primjene nove metode programiranja koja se temelji na STEP-NC standardima, koji je razvijen kao alternativa G kodu. U radu se raspravlja o mogućnosti primjene u području simulacije obrade i provjere programa prije obrade na erozimatu sa žicom. Rad prikazuje moguću metodologiju za simulaciju i verifikaciju programa temeljenih na STEP-NC pomoću IDEF0 dijagrama, kao i veze između softvera STEP-NC Machine i CAD/CAM sustava. Predstavljena metodologija je verificirana obradom ispitnog izradka, na temelju STEP-NC programa.

This paper offers an experimental study of the microcutting mechanisms in marble grinding to aid the optimization of the marble grinding process. The necessity for investigating these mechanisms is dictated by the increased use of marble in many applications and the fact that grinding and polishing processes are the dominant technologies used to meet surface finish requirements in this natural material. The experiments are aimed at the determination of the normal component of the cutting force and of the grain traces in microcutting with a single diamond grain. The investigations carried out make provisions for establishing critical grain penetration and cutting depths and allow the prediction of the normal cutting force component as a function of grain penetration speed and depth.

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