Assembly Representation
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Assembly Representation Jörg Franke and Klaus Feldmann Institute for Factory Automation and Production Systems, Friedrich-Alexander-University of Erlangen-Nuremberg, Erlangen, Germany
Definition It is a visual representation supplementing the assembly instruction, which shows the structure of the product to be assembled. It shows the chronology and logical sequence of the necessary assembly steps which lead to the final product (Delchambre 1992).
(CAD) data (Leu et al. 2013). A fully automated determination of the assembly order is facilitated through the analysis of configuration space and the derivation of an optimal strategy or by disassembling a virtual model. Assembly tasks are described in a machine-readable data format within the scope of computer-based assembly sequence planning. The known approaches can be divided into three categories: • Formal linguistic approaches • Data structure models • Graph-based approaches Due to their unambiguity, the graph-based approaches are considered as the most suitable form of illustration. The following types can be distinguished:
Theory and Application There are several ways to visualize the assembly operations sequence and to describe process and machine parameters as well as instructions for manual assembly. The VDI Guidelines (VDI 2860) have specified several basic symbols representing elementary assembly steps. These symbols can be used to describe complex assembly processes. The illustration of assembly steps within the so-called virtual reality (VR) and augmented reality (AR) or using Digital Mockup (DMU) bases upon image sequences of the hierarchically structured computer-aided design
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Assembly precedence graph Directed graph/Gozinto graph AND/OR graph Connected graph/diagram Petri nets Hierarchical, partially ordered graph Assembly boundary condition graph Interference graph
In particular, the assembly precedence graph is used to plan and illustrate the assembly order as well as to derive programs for computer-
# CIRP 2018 The International Academy for Production Engineering et al. (eds.), CIRP Encyclopedia of Production Engineering, https://doi.org/10.1007/978-3-642-35950-7_11-4
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Assembly Representation
Assembly Representation, Fig. 1 Example of an assembly precedence graph
Assembly Representation, Fig. 2 Example of a task and flow structure
controlled machines such as robots (Siegert and Bocionek 1996). An assembly precedence graph is a cycle-free graph that consists of a set of objects. Some pairs of the objects are connected with links. The interconnected tasks are represented by mathematical abstractions called vertices, the link that connects a pair of vertices is called edge. If two tasks are linked, the successor task can only be started after the predecessor task has finished. An assembly precedence graph is depicted in diagrammatic form as a set of boxes for the vertices, joined by lines for the edges. Identification numbers inside the boxes represent the dedicated assembly task (Fig. 1) (Bullinger et al. 1993). For the manual pre
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