Please use this identifier to cite or link to this item: http://scholarbank.nus.edu.sg/handle/10635/27928
Title: A STUDY OF THE APPLICATION OF AUGMENTED REALITY TECHNOLOGY ON 3-AXIS CNC IN SITU MACHINING SIMULATION
Authors: ZHANG JIE
Keywords: Augmented Reality, CNC Machining Simulation, Tracking and Registration, Dexel-based Modeling, Physical Simulation
Issue Date: 25-Apr-2011
Source: ZHANG JIE (2011-04-25). A STUDY OF THE APPLICATION OF AUGMENTED REALITY TECHNOLOGY ON 3-AXIS CNC IN SITU MACHINING SIMULATION. ScholarBank@NUS Repository.
Abstract: CNC machining simulation systems have been researched and developed in virtual environments for NC tool path verification and machining process optimization. Although applied broadly in the manufacturing industries, they have certain limitations as they are usually software-centric rather than machine tool-centric. The user has to adjust the experience gathered from the 3D graphic environment to the real machining environment. Augmented reality (AR) is a technology that provides intuitive interaction experience to the users by combining the real world with various computer-generated texts, images, animations, etc. This research implemented the AR technology in a CNC machining environment to achieve an in situ CNC machining simulation system, namely, the ARCNC system. Such a system would provide the users with a high level of awareness of the surrounding real world while they can inspect and analyze the machining simulation on real CNC machines. The user can modify the NC codes according to the machining conditions and observe the simulation based on the new codes. Therefore, the users can accumulate the knowledge of the specific CNC machines. Ball-end machining operations on a 3-axis CNC machine centre were specified as the case study during the experiments. To realize the in situ machining simulation, virtual workpieces can be rendered onto the worktable of a real CNC machine, and a virtual cutter is registered with the real cutter that is cutting the virtual workpieces. A hybrid tracking method and an adaptable cutter registration method based on NC codes have been formulated and implemented to track the worktable and the cutter. The applicability of the proposed approach was verified through several experiments. The experimental result showed that the virtual workpiece moved with the worktable seamlessly, and the cutter registration results were in strong agreement with the movement of the real cutter. Since the tracking and registration are realized using computer vision technology, this approach is applicable to machining processes using other types of 3-axis CNC machines with the same mechanical configurations. Solid modeling methods for both the workpieces and the cutters were investigated in order to achieve efficient physical simulation in the computation-intensive AR environment in this research. Specifically, an enhanced dexel model was developed to facilitate the material removal rate (MRR) calculation and the chip load-based machining force estimation. Using the enhanced dexel model, numerical integration can be achieved efficiently based on temporal discretization when calculating the MRR and the chip load. A linear square fitting method was employed to calibrate the chip load with respect to the machining force measured during the experiments. The ARCNC system can be applied in the training of novices and carrying out the machining simulation before performing the actual machining operations. The applicability of the system was verified through two case studies and a small-scale survey. Most of the subjects in the survey commented that the overlay of virtual information provided by the ARCNC system can help a machinist understand the machining process better.
URI: http://scholarbank.nus.edu.sg/handle/10635/27928
Appears in Collections:Ph.D Theses (Open)

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