This contribution presents the experimental validation of a computational model of capillary forces based on the Laplace equation for the meniscus geometry and on the Kelvin equation for capillary condensation. We apply this to a tip of AFM cantilever ended by a 100 nm curvature tip, and describe the effect of both humidity rate and relative tilt between the cantilever and the substrate. We propose to pick and place components at the considered scale (100 nm) by varying the capillary force.

This paper presents a product family representation model which was developed during a research project called CISAL, the purpose of which was to propose an integrated approach for the design of product families and their assembly system. This model is able to deal with partial information from the design of the product family, a situation that often occurs at early stages of the concurrent design of products and production means. The proposed model is assembly-oriented, because the project covered design for assembly, assembly planning, and line layout issues. In fact, it was developed on the basis of the design methodology itself. An originality of the design approach-which impacted the proposed model-is to decompose the product into so-called functional entities defined by the designer. The product family is then seen as an assembly of functional entities that can be analyzed, designed, and further assembled separately. Component variants are aggregated into generic components, and links between components become generic. The paper presents the essential concepts related to this product family representation, before showing their application to an illustrative industrial case study: a family of signaling relays.

The main objective of the research presented in this paper was to develop a new philosophy for the design of a product family (PF) and its assembly system. Most methodologies usually do not consider the interactions between these two design processes. Moreover, most "assembly-centered" concurrent engineering approaches do not deal with PFs. A research project, called CISAL, was initiated in Belgium in the late nineties to tackle this problem. The proposed tool is intended to be applicable to PFs and hybrid assembly lines (presenting manual, robotic and automated operations). It is subdivided into three interacting main modules: preliminary design for assembly (DFA) and assembly planning (AP); detailed DFA and AP; and line layout. The whole methodology is articulated around the functional entities (FEns), resulting from a first-order decomposition of the PF and aiming at reducing the complexity inherent to the design of multivariant products. All tools presented take this decomposition into account and treat design issues related to each FEn separately, considering the PF as an assembly of FEns. This paper presents the framework of CISAL, and the underlying methodology is illustrated on an industrial case study.

The purpose of this paper is to describe the main problems concerning the design and operation of mixed-product assembly lines. We will focus on the design of assembly lines, which is most of the time composed in three steps. The first is the elaboration of the logical layout of the line, which consists in the distribution of operations among workstations along the line. The second is the choice of the most efficient product mix and production sequence in relation to the operation phase. The third is the subsequent elaboration of the physical layout of the line, i.e., deciding about the disposition of the workstations, conveyor(s), possible buffers, etc., on the shop floor. In this paper, the accent will be put exclusively on the first two steps. The concept of balance for ordering (BFO) is introduced to solve these two interrelated problems. After an overview of the current work in this area, this paper presents in detail a very promising approach to solve the BFO: the grouping and ordering genetic algorithms (genetic algorithms heavily modified to solve grouping/ordering problems). In all cases, the main concern is the quality of the resulting line in terms of cost and its suitability to the line designer's needs (special user preferences are followed as closely as possible). Academic and experimental results are presented, and they confirm the efficiency of the proposed approaches.

Delchambre (1990, 1991) and Delchambre and A. Wafflard (1991) presented an automatic and user-friendly approach to computer-aided assembly planning. The authors give a brief summary of the assembly planner's specifications and of the methodology used to generate the assembly. Industrial case studies are presented to illustrate the various stages of the assembly sequence generation. User-friendly formalisms to represent the intermediate and final results to the user are outlined. The proposed approach is user-friendly because the intermediate and final results presented were easily understandable by the user despite the combinatorial explosion of results. The industrial prototype of the assembly planner and the user interaction with the system are discussed. Several results obtained with this prototype are presented and discussed on the basis of the industrial case studies.>

The authors present an efficient genetic algorithm for two NP-hard problems, the bin packing and the line balancing problems. They define the two problems precisely and specify a cost function suitable for the bin packing problem. It is shown that the classic genetic algorithm performs poorly on grouping problems and an encoding of solutions of fitting these problems is presented. Efficient crossover and mutation operators are introduced for bin packing. The modification necessary to fit these operators for line balancing is given. Results of performance tests on randomly generated data are included. The line balancing tests cover real-world problem sizes. The results and areas of further research are discussed.>

An automatic, systematic, and user-friendly approach to computer-aided assembly planning is presented. The automatic aspect of the methodology involved a reduction of the interactions with a human operator. In order to avoid the omission of one or several interesting sequences, this systematic method can generate all the valid sequences of a product. This approach is user-friendly because the intermediate and final results presented are easily understandable by the user despite the combinational explosion of results. Several results of the methodology are presented and discussed on the basis of a concrete case study.>

A pragmatic approach to computer-aided assembly planning is presented. The formalism used to analyze the product is described. It is shown that the first step is one of the most important: the product model must contain all the necessary information. Then, with the help of the product analysis, the planner must determine feasible operational plans. The assembly planner is discussed along with the formalism used to describe the assembly plans. Results are presented and discussed on the basis of a case study.>

A current trend in assembly robotics is to use several robots with different skills that work together inside an assembly cell. The authors describe an approach to the control of such an assembly cell. The underlying idea is to minimize as much as possible to computations that have to be done online, leaving time for the control strategy. The resulting control structure is thus a database of offline computed facts which act as inputs to the online supervisor. The proposed approach was tested on a two-robot assembly cell and showed satisfactory performance.>