Assembly System Components Research Articles

Multi-objective hybrid algorithms for layout optimization in multi-robot cellular manufacturing systems

Hybrid evolutionary algorithms to optimize layouts for multi-robot cellular manufacturing systems, which includes cooperative tasks among the robots is proposed in this paper. Layout area, operation time and manipulability of robot are the three design criteria useful to evaluate the robotic assembly systems are presented. Layout design candidates are represented using a sequence-pair scheme to prevent interferences between assembly system components, and the introduction of dummy components is proposed to represent layout areas where components are sparse. The main objective of this paper is to propose and evaluate hybrid algorithms by hybridizing them with genetic algorithm, which has been in use for decades. Differential evolution (DE), artificial bee colony (ABC), charged system search (CSS) and particle swarm optimization (PSO) are hybridized with genetic algorithm to have four hybrid (GA+DE, GA+ABC, GA+CSS and GA+PSO) algorithms. The performances of these algorithms are tested with genetic algorithm reported in the literature. The concept of non-dominated sorting genetic algorithm (NSGA-II) is borrowed to handle multiple objectives and to obtain Pareto solutions for the problems considered. These hybrid algorithms are evaluated using an example design problem of multi-robotic assembly system, and the effectiveness of these algorithms are presented in this paper. It is found that GA+PSO performs better over other hybrid algorithms considered. The application of the proposed algorithms are tested using Mitsubishi RV-6SQ robot configuration.

Simultaneous optimization of layout and task schedule for robotic cellular manufacturing systems

Multi-robot cellular manufacturing systems utilize several articulated industrial robots that cooperatively perform a large number of complex operations when assembling products. To enhance the system performance when designing layouts for such robotic cellular manufacturing systems, the positions of robots and other manufacturing system components must be appropriately determined by considering the sequence of tasks the robots conduct during the assembly process. This paper proposes a new multiobjective layout design optimization technique for robotic cellular manufacturing system layouts that can simultaneously determine the positions of manufacturing components and also task scheduling. First, in this paper, sequence-pair representation is used to specify layout design candidates that inherently avoid interference between assembly system components, and the use of dummy components is introduced to represent layout areas that provide necessary and appropriate spacing between manufacturing system components. In addition, task allocations for each robot are considered as discrete design variables. The design criteria for robot cellular manufacturing system layout designs are clarified and the layout design problem is formulated as a multiobjective optimization problem. To solve the optimization problem, a method based on a multiobjective genetic algorithm is proposed and numerical examples are provided to demonstrate the effectiveness of the proposed method.

Establishing Energy Efficiency as Criterion for Virtual Commissioning of Automated Assembly Systems

Physics engines, originating from gaming industry, are lately employed to perform realistic virtual simulations in early phases of assembly systems development processes. In particular, physics engine-based Virtual Commissioning boosts level of maturity of assembly systems due to advanced real-time collision detection and precise cycle time determination. This paper describes the improvement of DAIMLER's Virtual Commissioning process by virtually predicting and visualizing mechanic energy consumption of automated assembly system components using a physics engine. Based on simulation results, established approaches for reducing energy consumption of automated assembly system can be implemented in the virtual model.

An Integrated Simulation Approach to the Development of Assembly System Components

Commonly, a modelling and simulation approach is used for parameter optimization and system behavior analysis of assembly system components. However, such simulation approaches are often not well integrated or its analysis is still based on a specific physical domain. This paper proposes an integrated simulation approach that can be used for designing, analyzing and optimizing the entire physical domain as well as the control system of mechatronic components in an assembly system. The state-of-the-art, requirements, our concept and the limitations of an integrated simulation approach are explained in this paper. A case study of the development of conveyor systems using the multi-domain simulation tool OpenModelica is also presented. On-going research shows that the integrated approach offers various benefits such as reduced development time and minimized errors, as well as maintenance during the commissioning process.

Multiobjective layout optimization of robotic cellular manufacturing systems

This paper proposes a multiobjective layout optimization method for the conceptual design of robot cellular manufacturing systems. Robot cellular manufacturing systems utilize one or more flexible robots which can carry out a large number of operations, and can conduct flexible assemble processes. The layout design stage of such manufacturing systems is especially important since fundamental performances of the manufacturing system under consideration are determined at this stage. In this paper, the design criteria for robot cellular manufacturing system layout designs are clarified, and objective functions are formulated. Next, layout design candidates are represented using a sequence-pair scheme to avoid interference between assembly system components, and the use of dummy components is proposed to represent layout areas where components are sparse. A multiobjective genetic algorithm is then used to obtain Pareto optimal solutions for the layout optimization problems. Finally, several numerical examples are provided to illustrate the effectiveness and usefulness of the proposed method.

Environmental protection and quick assembly feature at autumn shows

PurposeThis paper highlights new automated assembly system components introduced in late 2004. Products meet new levels of environmental protection and offer features for quicker assembly system design and commissioning.Design/methodology/approachAttended various trade shows and contacted key vendors for information on product introductions.FindingsVendors are addressing more and more application needs with features like more compact components, more features, innovative materials and new answers to system design and application problems.Research limitations/implicationsNot all the new products which may have been introduced have been covered.Practical implicationsUsers and systems integrators can find new component answers to previously troubling requirements of automated assembly system design and commissioning.Originality/valueHighlights new assembly system component offerings that may be real problem solutions for system designs and integrators who previously considered products to not fully address their requirements.

Nucleoprotein-based nanoscale assembly.

A system for addressing in the construction of macromolecular assemblies can be based on the biospecificity of DNA (cytosine-5) methyltransferases and the capacity of these enzymes to form abortive covalent complexes at targeted 5-fluorocytosine residues in DNA. Using this system, macromolecular assemblies have been created using two representative methyltransferases: M-HhaI and M x MspI. When 5-fluorocytosine (F) is placed at the targeted cytosine in each recognition sequence in a synthetic oligodeoxynucleotide (GFGC for M x HhaI or FCGG for M x MspI), we show that the first recognition sequence becomes an address for M x HhaI, while the second sequence becomes an address for M x MspI. A chimeric enzyme containing a dodecapeptide antigen linked to the C terminus of M-HhaI retained its recognition specificity. That specificity served to address the linked peptide to the GFGC recognition site in DNA. With this assembly system components can be placed in a preselected order on the DNA helix. Axial spacing for adjacent addresses can be guided by the observed kinetic footprint of each methyltransferase. Axial rotation of the addressable protein can be guided by the screw axis of the DNA helix. The system has significant potential in the general construction of macromolecular assemblies. We anticipate that these assemblies will be useful in the construction of regular protein arrays for structural analysis, in the construction of protein-DNA systems as models of chromatin and the synaptonemal complex, and in the construction of macromolecular devices.

Solving Technical Problems in Assembly System's Design

The design of an assembly system leads to very difficult technical problems in which technological, functional and economical aspects must be considered. The designer's experience represents a crucial portion of the information which has to be made available. Another part of the needed information is contained in the product design, and part of it is provided by suppliers of assembly system components. Problem solving based on information incorporated in assembly features will be demonstrated using problems encountered in an existing assembly system. The characterisation of features related to assembly is a research topic at the Saarland University. Preliminary results of a contribution to feature-based CAD-systems will be presented.