Browsing by Author "Sass, Andrew"

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    A computer aided machining system for the manufacture of three-dimensional surfaces
    (1988) Back, David Reuben; Sass, Andrew
    This thesis describes the design of a computerised system for machining three-dimensional surfaces, more specifically "sculptured surfaces", using an IBM PC and a Bridgeport 3 axis Computer Numerically Controlled (CNC) Milling Machine. There was a twofold objective to the project: To design and develop a milling system; To provide a teaching tool for undergraduate students who wish to further their studies in the concepts of Computer Aided Design and Manufacture (CAD/CAM). Five broad areas are covered: 1. The development of a mathematical algorithm to approximate a sculptured surf ace represented by a set, of surface datapoints in the form of XYZ coordinates. 2. The development of an algorithm to calculate the toolpath to machine the sculptured surface. 3. The development of an algorithm to display the surface and toolpath in three dimensions on the computer screen. 4. The development of an algorithm (the postprocessor) which translates the toolpath into a program suitable for use with the CNC milling machine. 5. The development of a communications algorithm for the direct transmission of the CNC program from the IBM microcomputer to the memory of the CNC computer.
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    Design and control of an animatronic Aardvark
    (2002) Hrabar, Stefan; Sass, Andrew
    This report describes the design, construction and programming of an animatronic Aardvark that was built and successfully used in the filming of a wildlife documentary for National Geographic. The animatron was required to walk, move its head, and have as many facial movements as possible. These requirements were met by using hobby servos to produce the movements, and control was achieved with a Motorola based micro controller (the Handy Board). The proportions of the animatron were based on those or a real aardvark, made to approximately 1/4 scale. The final product met all the requirements and was filmed on location interacting with a real aardvark.
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    Development of a flexible manufacturing system (FMS)
    (2004) Dhooky, Aruna N D; Sass, Andrew; Reed, B
    This report describes how the latest technology in computing and interfacing has been used in a traditional manufacturing environment to integrate old stand-alone CNC machines, a FANUC robot, a conveyor and a Robot Positioning Device (RPD) into a Flexible Manufacturing System (FMS). Also described are the benefits that South African manufacturers still using old CNC machines could achieve if they implemented a similar process in their organisation.
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    Modern assembly concepts and applications
    (2001) Omotoso, Pelayo; Sass, Andrew; Reed, B
    This project introduces, and demonstrates assembly concepts that are helping to change the nature of industrial production. The emergence of Concurrent Engineering as a production process ideal is being fuelled in part by some of these assembly concepts. The idea for the project stems from a course on Desing for Manufacture and Assembly, which the author of this thesis attended in 1999. From there, a lot of the work done in the area of assembly has been researched. The understanding of the theory conveyed in this document is based on this information.
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    Pupils' experiences of technology : exploring dimensions of technological literacy
    (2006) Collier-Reed, Brandon I; Sass, Andrew
    Technology is the driving force behind much of the change taking place in the world today. Consequently, across society, calls are being made to ensure technological literacy is a meaningful and central part of schooling to adequately prepare pupils to become part of an increasingly technologically driven world. However, studies have shown that large parts of society perceive technology primarily in terms of computers.
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    Surface capture using near-real-time photogrammetry for a computer numerically controlled milling system
    (1989) Wildschek, Reto; Sass, Andrew; Rüther, Heinz
    During the past three years, a research project has been carried out in the Department of Mechanical Engineering at UCT, directed at developing a system to accurately reproduce three-dimensional (3D), sculptured surfaces on a three axis computer numerically controlled (CNC) milling machine. Sculptured surfaces are surfaces that cannot easily be represented mathematically. The project was divided into two parts: the development of an automatic noncontact 3D measuring system, and the development of a milling system capable of machining 30 sculptured surfaces (Back, 1988). The immediate need for such a system exists for the manufacture of medical prostheses. The writer undertook to investigate the measurement system, .with the objective to develop a non-contact measuring system that can be used to 'map' a sculptured surface so that it can be represented by a set of XYZ coordinates in the form required by the milling system developed by Back (1988). This thesis describes the development of a PC-based near-realtime photogrammetry system (PHOENICS) for surf ace capture. The topic is introduced by describing photogrammetric principles as used for non-contact measurements of objects. A number of different algorithms for image target detection, centering and matching is investigated. The approach to image matching adopted was the projection of a regular grid onto the surface with subsequent matching of conjugate grid intersections. A general algorithm which automatically detects crosses on a line and finds their accurate centres was developed. This algorithm was then extended from finding the crosses on a line, to finding all the intersection points of a grid. The algorithms were programmed in TRUE BASIC and specifically adapted for use with PHOENICS as an object point matching tool. The non-contact surface measuring technique which was developed was used in conjunction with the milling system developed by Back (1988) to replicate a test object. This test proved that the combined system is suitable for the manufacture of sculptured surf aces. The accuracy requirements for the manufacture of medical prostheses can be achieved with the combined measuring and milling system. At an object-to-camera distance of 0.5 m, points on a surface can be measured with an accuracy of approximately 0.3 mm at an interval of 5 mm. This corresponds to a relative accuracy of 1:1600. Back (1988) reported an average undercutting error of 0.46 mm for the milling system. This combines to an uncertainty of 0.55 mm. Finally, the limitations of PHOENICS at its prototype stage as a surface measuring tool are discussed, in particular the factors influencing the system's accuracy. PHOENICS is an ongoing project and the thesis is concluded by some recommendations for further research work.