Computer-Aided Module-Level Test Generation for Digital Devices on the Basis of Their Alternative-Graph-Model

1979 ◽  
Vol 12 (3) ◽  
pp. 287-290
Author(s):  
M.A. Pall ◽  
R.R. Ubar
Author(s):  
A. N. Bozhko

Computer-aided design of assembly processes (Computer aided assembly planning, CAAP) of complex products is an important and urgent problem of state-of-the-art information technologies. Intensive research on CAAP has been underway since the 1980s. Meanwhile, specialized design systems were created to provide synthesis of assembly plans and product decompositions into assembly units. Such systems as ASPE, RAPID, XAP / 1, FLAPS, Archimedes, PRELEIDES, HAP, etc. can be given, as an example. These experimental developments did not get widespread use in industry, since they are based on the models of products with limited adequacy and require an expert’s active involvement in preparing initial information. The design tools for the state-of-the-art full-featured CAD/CAM systems (Siemens NX, Dassault CATIA and PTC Creo Elements / Pro), which are designed to provide CAAP, mainly take into account the geometric constraints that the design imposes on design solutions. These systems often synthesize technologically incorrect assembly sequences in which known technological heuristics are violated, for example orderliness in accuracy, consistency with the system of dimension chains, etc.An AssemBL software application package has been developed for a structured analysis of products and a synthesis of assembly plans and decompositions. The AssemBL uses a hyper-graph model of a product that correctly describes coherent and sequential assembly operations and processes. In terms of the hyper-graph model, an assembly operation is described as shrinkage of edge, an assembly plan is a sequence of shrinkages that converts a hyper-graph into the point, and a decomposition of product into assembly units is a hyper-graph partition into sub-graphs.The AssemBL solves the problem of minimizing the number of direct checks for geometric solvability when assembling complex products. This task is posed as a plus-sum two-person game of bicoloured brushing of an ordered set. In the paradigm of this model, the brushing operation is to check a certain structured fragment for solvability by collision detection methods. A rational brushing strategy minimizes the number of such checks.The package is integrated into the Siemens NX 10.0 computer-aided design system. This solution allowed us to combine specialized AssemBL tools with a developed toolkit of one of the most powerful and popular integrated CAD/CAM /CAE systems.


2017 ◽  
Vol 140 (1) ◽  
Author(s):  
Wenjian Yang ◽  
Huafeng Ding ◽  
Bin Zi ◽  
Dan Zhang

Planetary gear trains (PGTs) are widely used in machinery to transmit angular velocity ratios or torque ratios. The graph theory has been proved to be an effective tool to synthesize and analyze PGTs. This paper aims to propose a new graph model, which has some merits relative to the existing ones, to represent the structure of PGTs. First, the rotation graph and canonical rotation graph of PGTs are defined. Then, by considering the edge levels in the rotation graph, the displacement graph and canonical displacement graph are defined. Each displacement graph corresponds to a PGT having the specified functional characteristics. The synthesis of five-link one degree-of-freedom (1DOF) PGTs is used as an example to interpret and demonstrate the applicability of the present graph representation in the synthesis process. The present graph representation can completely avoid the generation of pseudo-isomorphic graphs and can be used in the computer-aided synthesis and analysis of PGTs.


Author(s):  
Peter Martino

Abstract This paper presents a method for eliminating unnecessary parts, features, and dimensions from feature based models in computer aided tolerance analysis systems. A typical tolerance analysis involves a dozen or so parts, or subassemblies. Each part may have dozens of features, and hundreds of dimensions. Many of these subassemblies, parts, features, and dimensions do not effect the tolerance analysis, and therefore are not needed. Computational effort can be reduced by eliminating the unnecessary items from the model. Currently, tolerance analysis models are implicitly simplified by the user. The user examines the problem, and determines which parts, features, and dimensions can be ignored. The user then constructs his model, leaving out the unneeded items. This is true whether the analysis is accomplished with a computer aided tool, or with paper and pencil. Simplification of the model is essential. Practical tolerance analysis problems become overwhelmingly complex if every detail is included. The method discussed in this paper is intended for use in computer aided tolerance analysis systems that use feature based, and dimension driven, solid modeling. It uses a combined tree and graph data structure. The tree structure represents the hierarchy of assemblies, parts, and features in the model. The graphs represent the dependence between features in a part, or parts in an assembly. An algorithm has been developed that searches this tree/graph model, locating the parts and features needed to accomplish the tolerance analysis.


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