- Email: [email protected]
An approach to CADCAM implementation
Literature reviews Graphical t e c h n i q u e s Cendes, Z J and Wong, S H 'C1 quadratic interpolation over arbitrary point sets' IEEE Comput. Graph. & Appllc. Vol 7 No 11 (November 1987) pp 8 - 1 6 New formulas, based on quadratic polynomials for construction of derivative continuous surfaces, for generating smooth surfaces over arbitrarily spaced data points are developed. The technique is based on a subdivision procedure, dividing each triangle in a triangulation of the data points into six subtriangles and fitting a quadratic Bdzier surface patch over each subtriangle. As 2D quadratic polynomials contain only six terms, the efficiency of algorithms for drawing surfaces in CAGD is improved. Pueyo, X and Brunet, P 'A parametricspace-based scan-line algorithm for rendering bicubic surfaces' IEEE Comput. Graph. & Applic. Vol 7 No 11 (November 1987) pp 17-25 A scanline algorithm for displaying bicubic surfaces is presented. Patches are decomposed on regions of constant sign of the z component of the normal before the scan. The computations are mostly done in parametric space. The algorithm computes the intersection of surfaces with only a restricted subset of scan planes by linear interpolation between exact intersections. A bound of the algorithm's error is given, and the method is compared with Whitted's algorithm. Coquillart, S 'A control-point-based sweeping technique' IEEE Comput. Graph. & Applic. Vol 7 No 11 (November 1987) pp 3 6 - 4 5 A general sweeping technique for nonuniform rational B-splines is presented. This allows sweeps with cross-sections, which can be scaled along the path according to a profile curve shape, along a 3D path. The definition of the resulting surface is inherited from the initial curves, and its control mesh computed from the control polygon of these curves. Special cases are considered. Circle and straight line characteristics are preserved. Chirokura, H 'An extended rounding operation for modeling solids with free-form surfaces' IEEE Comput. Graph. & Appllc. Vol 7 No 12 (December 1987) pp 2 7 - 3 6 An extended rounding operation is used for modelling solids with free-form surfaces, in which edges and vertices can be rounded locally.
grey-scale level value homogeneity and spatial resolution. Two-way G-quadtree/ G-octree conversion procedures are developed based on binary case algorithms, which provide an integrated processing environment for hierarchically represented 2D/3D grey-scale images. The approach is applied to the colour coding of microautoradiography images taken from rat brains.
The implementation of a CADCAM system undertaken as the central theme of a teaching company programme, involving collaboration of an academic institution with a local company to implement some aspect of advanced manufacturing technology, is discussed. Design and manufacturing procedures required before implementation, the implementation itself and the developed system are described.
Bronsvoort, W F 'An algorithm for visibleline and visible-surface display of CSG models' The Visual Comput. Vol 3 No 4 (1987) pp 176-185
Madden, J 'CAD in process plant engineering' Comput.-Aided Eng. J. Vol 4 No 6 (December 1987) pp 2 3 7 - 2 4 4
An algorithm for displaying CSG models is proposed. It is based on previous work by Atherton and the Boolean evaluation of a model is only carried out during image generation for the visible parts of the model. The image plane is divided into strips of differing width inside which area are determined where only one face is visible. Both a visible-line version and a visible-surface version of the algorithm are presented. Sample times and images of some models are given.
E x p e r t systems
Miller, J R 'Analysis of quadric-surfacebased solid models' IEEE Comput. Graph. Applic. Vol 8 No 1 (January 1988) pp 28-42
Badiru, A B 'Expert systems and industrial engineers: a practical guide to a successful partnership' CompuL & Ind. Eng. Vol 14 No 1 (1988) pp 1 - 1 3
Data representations and analytical tools commonly used in solid modellers for three analysis operations - boundary evaluation, image generation and mechanical property calculation - are discussed. These methods are considered only when applicable to constructive solid geometry or boundary representation modellers.
The need for expert systems in industrial engineering is discussed. Potential application areas such as computer-aided manufacturing and management are described with references to work in these areas. A table of over 50 expert system tools is given indicating category of use, price and appropriate hardware. Some guidelines are given for initiating expert system projects in industry.
Turner, J U and Wozny, M J 'Tolerances in computer-aided geometric design' The Visual Comput. Vol 3 No 4 (1987) pp 2 1 4 - 2 2 6 A linear programming method that solves tolerance analysis problems is presented, as is a Monte-Carlo method. Both methods derive the necessary geometric relationships from a solid model of the assembly. Example problems are solved using the experimental GEOTOL geometric design system.
Adeli, H and Balasubramanyam 'A knowledge-based system for the design of bridge trusses' J. Comput. Civil Eng. Vol 2 No 1 (1988) pp 1 - 2 0 An interactive bridge truss optimization program was Interfaced with an expert system environmentto produce BTEXPERT. BTEXPERT can optimally design four types of bridge truss. It is described along with the relevant heuristic rules and procedures. The knowledge base contains heuristic rules, experimental knowledge and knowledge obtained through machine experimentation.
CADCAM techniques Holyoake, T J 'CADCAM software portability' Comput.-Aided Eng. J. Vol 4 No 6 (December 1987) pp 224--226
Mao, X, Kunii, T L, Fujishiro, I and Noma, T 'Hierarchical representations of 2D/3D gray-scale images and their 2D/3D two-way conversion' IEEE Comput. Graph. & Appllc. Vol 7 No 12 (December 1987) pp 37--46
As hardware and operating systems improve, the ability to port CADCAM software easily between computing environments gains importance. The approach taken to the question of portability by Pafec is described and the benefits of portability to the software developer and user explored.
G-octree is proposed as an extension of Gquadtree to three dimensions. A G-octree's construction reflects a hierarchy of both
Prickett, P 'An approach to CADCAM implementation' Cornput.-Aided Eng. J. Vol 4 No 6 (December 1987) pp 2 4 5 - 2 4 8
296
The development of CAD systems for the design and layout of process plant involves large investments. Though the benefit of such systems is undoubted, software developers need commitment and foresight to bring these tools onto the market. One such product, PDMS, a joint development between CADCentre, Isopipe and Akzo Engineering and first sold in 1977, is described. Developments since then are presented.
CIM
systems
Wang, M and Smith, G W 'Modelling CIM systems part 1: methodologies' Comput.Integrated Manuf. 5ysL Vol 1 No 1 (February 1988) pp 1 3 - 1 7 A research programme is described between Brunel University and a manufacturing company to develop the information systems environment on which the computer integration of the system depends. This has led to explorations of fundamental systems ideas and supporting methods. Two methods are contrasted.
computer-aided design
grey-scale level value homogeneity and spatial resolution. Two-way G-quadtree/ G-octree conversion procedures are developed based on binary case algorithms, which provide an integrated processing environment for hierarchically represented 2D/3D grey-scale images. The approach is applied to the colour coding of microautoradiography images taken from rat brains.
The implementation of a CADCAM system undertaken as the central theme of a teaching company programme, involving collaboration of an academic institution with a local company to implement some aspect of advanced manufacturing technology, is discussed. Design and manufacturing procedures required before implementation, the implementation itself and the developed system are described.
Bronsvoort, W F 'An algorithm for visibleline and visible-surface display of CSG models' The Visual Comput. Vol 3 No 4 (1987) pp 176-185
Madden, J 'CAD in process plant engineering' Comput.-Aided Eng. J. Vol 4 No 6 (December 1987) pp 2 3 7 - 2 4 4
An algorithm for displaying CSG models is proposed. It is based on previous work by Atherton and the Boolean evaluation of a model is only carried out during image generation for the visible parts of the model. The image plane is divided into strips of differing width inside which area are determined where only one face is visible. Both a visible-line version and a visible-surface version of the algorithm are presented. Sample times and images of some models are given.
E x p e r t systems
Miller, J R 'Analysis of quadric-surfacebased solid models' IEEE Comput. Graph. Applic. Vol 8 No 1 (January 1988) pp 28-42
Badiru, A B 'Expert systems and industrial engineers: a practical guide to a successful partnership' CompuL & Ind. Eng. Vol 14 No 1 (1988) pp 1 - 1 3
Data representations and analytical tools commonly used in solid modellers for three analysis operations - boundary evaluation, image generation and mechanical property calculation - are discussed. These methods are considered only when applicable to constructive solid geometry or boundary representation modellers.
The need for expert systems in industrial engineering is discussed. Potential application areas such as computer-aided manufacturing and management are described with references to work in these areas. A table of over 50 expert system tools is given indicating category of use, price and appropriate hardware. Some guidelines are given for initiating expert system projects in industry.
Turner, J U and Wozny, M J 'Tolerances in computer-aided geometric design' The Visual Comput. Vol 3 No 4 (1987) pp 2 1 4 - 2 2 6 A linear programming method that solves tolerance analysis problems is presented, as is a Monte-Carlo method. Both methods derive the necessary geometric relationships from a solid model of the assembly. Example problems are solved using the experimental GEOTOL geometric design system.
Adeli, H and Balasubramanyam 'A knowledge-based system for the design of bridge trusses' J. Comput. Civil Eng. Vol 2 No 1 (1988) pp 1 - 2 0 An interactive bridge truss optimization program was Interfaced with an expert system environmentto produce BTEXPERT. BTEXPERT can optimally design four types of bridge truss. It is described along with the relevant heuristic rules and procedures. The knowledge base contains heuristic rules, experimental knowledge and knowledge obtained through machine experimentation.
CADCAM techniques Holyoake, T J 'CADCAM software portability' Comput.-Aided Eng. J. Vol 4 No 6 (December 1987) pp 224--226
Mao, X, Kunii, T L, Fujishiro, I and Noma, T 'Hierarchical representations of 2D/3D gray-scale images and their 2D/3D two-way conversion' IEEE Comput. Graph. & Appllc. Vol 7 No 12 (December 1987) pp 37--46
As hardware and operating systems improve, the ability to port CADCAM software easily between computing environments gains importance. The approach taken to the question of portability by Pafec is described and the benefits of portability to the software developer and user explored.
G-octree is proposed as an extension of Gquadtree to three dimensions. A G-octree's construction reflects a hierarchy of both
Prickett, P 'An approach to CADCAM implementation' Cornput.-Aided Eng. J. Vol 4 No 6 (December 1987) pp 2 4 5 - 2 4 8
296
The development of CAD systems for the design and layout of process plant involves large investments. Though the benefit of such systems is undoubted, software developers need commitment and foresight to bring these tools onto the market. One such product, PDMS, a joint development between CADCentre, Isopipe and Akzo Engineering and first sold in 1977, is described. Developments since then are presented.
CIM
systems
Wang, M and Smith, G W 'Modelling CIM systems part 1: methodologies' Comput.Integrated Manuf. 5ysL Vol 1 No 1 (February 1988) pp 1 3 - 1 7 A research programme is described between Brunel University and a manufacturing company to develop the information systems environment on which the computer integration of the system depends. This has led to explorations of fundamental systems ideas and supporting methods. Two methods are contrasted.
computer-aided design