LEGA: a computer-aided generator of assembly plans

Henrioud, Jean-Michel; Bourjault, A.

doi:10.1007/978-1-4615-4038-0_8

Cited by 62 publications

(22 citation statements)

References 2 publications

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“…Here, it was pointed out that these relations can be modeled using a special type of labeled graphs which we called mating feature graphs. As their vertices represent mating features of elementary objects and their edges indicate topological relations among those, mating feature graphs can be seen as a refinement of liaison graphs which represent adjacency relations among assembled objects [17,28,51].…”

Section: Discussionmentioning

confidence: 99%

A Structural Framework for Assembly Modeling and Recognition

Bauckhage

Kummert

Sagerer

2003

Computer Analysis of Images and Patterns

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Section: Discussionmentioning

confidence: 99%

A Structural Framework for Assembly Modeling and Recognition

Bauckhage

Kummert

Sagerer

2003

Computer Analysis of Images and Patterns

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“…Recently, assembly planning research has focused on such issues as: (1) enhancing planning efficiency by removing redundant testing of mating feasibility or by pruning out early infeasible sequences through hierarchical testing (Baldwin et al, 1991;Wilson and Ritt, 1991); (2) extending planning capability to handle real environment by adding special assembly processes, geometric and physical constraints, stability, and tolerancing (Boyes, 1979;Henrioud and Bourjault, 1991); (3) generating optimal plans by computing the assembly cost in terms of the required fixtures and reorientations (Homem de Mello and Sanderson, 1991~); and (4) extending the role of assembly planning by providing a feedback to design for assembly (DFA (Boothroyd and Dewhurst, 1984)), as well as connecting assembly planning to CAD. This paper presents a method for the automatic determination of preferred assembly partial orders from a liaison graph representation of an assembly, with a direct relation to assembly cost.…”

Section: Introductionmentioning

confidence: 99%

Assembly Coplanner: co-operative assembly planner based on subassembly extraction

Lee

Shin

1993

J Intell Manuf

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The distribution of assembiy workstations enables assembly operations to be done in parallel, while the multiple routing of parts in flexible assembly systems allows the opportunistic scheduling of assembly operations. This paper presents an assembly planning system, called the Assembly Coplanner, which automatically constructs an assembly partial order and generates a set of assembly instructions from a liaison graph representation of an assembly based on the extraction of preferred subassemblies. Assembly planning in Coplanner is carried out by the co-operation of multiple planning agents, such as the geometric reasoner, the physical reasoner, the resource manager and the plan coordinator, under the constraints of finding a cost-effective assembly plan in a flexible assembly system. The Coplanner identifies spatial parallelism in assembly as a means of constructing temporal parallelism among assembly operations. This is achieved in the following way: (1) the selection of a set of tentative subassemblies by decomposing a liaison graph into a set of subgraphs based on feasibility and difficulty of disassembly; (2) the evaluation of each of the tentative subassemblies in terms of assembly cost represented by subassembly selection indices; and (3) the construction of a hierarchical partial order graph (HPOG) as an assembly plan. A case study applying the Coplanner to a mechanical assembly is illustrated in this paper.

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“…Regardless of the level of obligation a criterion carries, its scope of relevance to the plan or the planning program may be strategic or tactical (the terminology is taken from [7]). Strategic criteria are applicable during the whole assembly planning process, or to all of the assembly actions.…”

Section: Scopementioning

confidence: 99%

“…Our filters are an instance of generate-and-test, a standard paradigm in artificial intelligence [23] as well as in assembly planning [7,111. Attaching special-purpose methods to constraint tests is also a well known efficiency technique [23], although the methods we use to accomplish this are novel (see Section 6).…”

Section: Previous Workmentioning

confidence: 99%

On constraints in assembly planning

Jones

Wilson

Calton

1998

IEEE Trans. Robot. Automat.

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Constraints on assembly plans vary depending on product, assembly facility, assembly volume, and many other factors. Assembly costs and other measures to optimize vary just as widely. To be effective, computer-aided assembly planning systems must allow users to express the plan selection criteria that apply to their products and production environments.We begin this article by surveying the types of user criteria, both constraints and quality measures, that have been accepted by assembly planning systems to date. The survey is organized along several dimensions, including strategic vs. tactical criteria; manufacturing requirements vs. requirements of the automated planning process itself; and the information needed to assess compliance with each criterion. The latter strongly influences the efficiency of planning.We then focus on constraints. We describe a framework to support a wide variety of user constraints for intuitive and efficient assembly planning. Our framework expresses all constraints on a sequencing level, specifying orders and conditions on part mating operations in a number of ways. Constraints are implemented as simple procedures that either accept or reject assembly operations proposed by the planner. For efficiency, some constraints are supplemented with special-purpose modifications to the planner's algorithms. Fast replanning enables an interactive plan-view-constrain-replan cycle that aids in constraint discovery and documentation. We describe an implementation of the framework in a computer-aided assembly planning system and experiments applying the system to a number of complex assemblies, including one with 472 parts.

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LEGA: a computer-aided generator of assembly plans

Cited by 62 publications

References 2 publications

A Structural Framework for Assembly Modeling and Recognition

A Structural Framework for Assembly Modeling and Recognition

Assembly Coplanner: co-operative assembly planner based on subassembly extraction

On constraints in assembly planning

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