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In engineering, design decisions in one domain exhibit multiple consequences in other domains. These consequences result from the often more or less hidden coupling between the different design domains. In order to examine these consequences, models need to be created. In practice, this is challenging due to the exchange of data between different engineering domains, since different software applications are often used and the effort involved with manual model creation. In this paper, we explore the use of graph-based design languages in a Model-Based Systems Engineering (MBSE) approach to link the digital factory with building design. We also show that the use of a common formal representation based on the Unified Modeling Language (UML) supports the interoperability between the two domains. Finally, we demonstrate how the engineering knowledge for the preliminary design of a factory building can be formally described using graph-based design languages and how the production line of the digital factory can then be used as an input to automatically create valid preliminary designs for the factory building.1

In engineering and architecture, different approaches have been developed that share the use of graph transformation to automate design processes or to search for design solutions by means of computational design synthesis. In order to give an overview of these approaches, we provide a review of articles published in the last decade. Forty-eight articles were reviewed to determine similarities and differences of these approaches. Research fields in method development for the representation of design problems and the processing of graph transformations, as well as the application of graph transformations in engineering, architecture, and shape grammars were identified. Different approaches for the documentation of the vocabulary and the rules were examined. Finally, different approaches for rule applications were analyzed. Based on found limitations, future research directions are suggested.

Graph-based design languages have received increasing attention in the research community, because they offer a promising approach to address several major issues in engineering, e.g., the frequent manual data transfer between computer-aided design (CAD) and computer-aided engineering (CAE) systems. Currently, these issues prevent the realization of machine executable digital design processes of complex systems such as vehicles. Promising scenarios for urban transportation include an interconnection of mass transportation systems such as buses and subways with individual vehicles for the so-called &ldquo, last mile&rdquo, transport. For several reasons, these vehicles should be as small and light as possible. A considerable reduction in weight and size can be achieved, if such vehicles are tailored to the individual size, weight and proportion of the individual user. However, tailoring vehicles for the individual characteristics of each user go beyond a simple building set and require a continuous digital design process. Consequently, the topic of this paper is a digital design process of a self-balanced scooter, which can be used as an individual last-mile means of transport. This process is based on graph-based design languages, because in these languages, a digital system model is generated, which contains all relevant information about a design and can be fed into any simulation tool which is needed to evaluate the impact of a possible design variation on the resulting product performance. As this process can be automated by digital compilers, it is possible to perform systematic design variations for an almost infinite amount of parameters and topological variants. Consequently, these kinds of graph-based languages are a powerful means to generate viable design alternatives and thus permit fast evaluations. The paper demonstrates the design process, focusing on the drive system of the respective balanced two-wheel scooter and highlights the advantages (data integration and possibility for machine execution).

For the last two decades, a novel mechanical system has received increasing attention&mdash, the inerter. An inerter is a system that can store mechanical energy for a rather short amount of time and behaves analogously to a capacitor in electrical engineering. Until today, only a few inerter applications have been reported. In a vehicle suspension, an inerter can be used to reduce wheel vibrations. This paper demonstrates the application potential of the novel mechanical system and describes the design and dimensioning of an inerter for the reduction of these kind of wheel vibrations for two completely different vehicle concepts. The first application concerns a Formula Student race car in which the main objective represents the maximization of the mechanical grip to improve lap times. For the inerter dimensioning in a racing car, lightweight design is a major issue. The second application is an agricultural tractor in which the focus is on the reduction of the ground pressure to protect the environment as well as on a very robust and compact realization of the inerter. A detailed simulation of both cases allows a qualitative and quantitative assessment of the wheel vibration reduction potential. In both applications, a considerable improvement potential could be identified which amounts, in the case of the race car, to a reduction of wheel oscillation of about 21% and for the tractor to a wheel vibration reduction potential of up to 54%.

In this paper, the authors elaborate a combination of graph-based design and simulation-based engineering into a new concept called Executable Integrative Product-Production Model (EIPPM). Today, the first collaborative process in engineering for all mechatronic disciplines is the virtual commissioning phase. Therefore, Digital Twins (DT) are modeled and run in a simulation. The authors see a hitherto untapped potential for the earlier, integrated and iterative use of DTs in a simulation-based engineering for the development of production systems. Seamless generation of and exchange between Model-, Software- and Hardware-in-the-Loop simulations is necessary. Feedback from simulation results will go into the design decisions after each iteration. The presented approach combines knowledge of the domain "production systems technology" together with the knowledge of the corresponding "product" using a so called Graph-based Design Language (GBDL). Its central data model, which represents the entire life cycle, results of an automatic translation step in a compiler. Since the execution of the GBDL can be repeated as often as desired with modified boundary conditions (e.g. through feedback), a design of experiment is made possible, whereby also unconventional solutions are considered. The novel concept aims at the following advantages: Consistent linking of all mechatronic domains through a data model (graph) from the project start, automatic design cycles exploring multiple variants for optimized product-production system combinations, automatic generation of simulation models starting with the planning phase, feedback from simulation-based optimization back into the data model.

In a market-driven economy, the availability of an evaluation of the manufacturability cost and economic efficiency right on from the early design phase is a competitive advantage. For this reason, a methodology is proposed in this work which enhances the planning capabilities and efficiency by automatic provision of steel constructions with manufacturing plans, cost calculation and evaluation in the early phase. To achieve this, the design process of steel structures is enhanced with aspects from the cost-domain and the manufacturing-domain. Furthermore, digital tools and methods of modern software engineering are applied to classical engineering design in order to handle increased product complexity and save design time in shortened product life-cycles. As a solution approach, so-called graph-based design languages are used and evaluated by means of steel construction examples.

System design in an aircraft is still a costly, manual and iterative approach. One major cost driver of changes in system installation are design efforts for creating new pipes in an earlier stage and the costs accumulated during the in service life. To reduce these costs and the time to market, an automation approach with an integrated design optimization encoded in graph-based design languages and executable in a design compiler is proposed. To generate the pipe work automatically, a set of input data (e.g. start- and end-points of a pipe with tangents and fixing positions) is given by the user. It also contains, among others, the weightings for the optimization criteria (e.g. length of the pipe resp. the weight vs. the number of bends) to influence the evaluation of the generated pipes and thereby the final solution. As an initial step in the automatic pipe generation process, a route through the installation space is searched. Subsequently, the installation space is simplified and a respective minimal distance to each obstacle which a pipe should satisfy is added. Then for each pipe an initial solution is estimated and each pipe is optimized by a simulated annealing algorithm. At last, all given requirements are automatically verified. The capabilities of the newly developed automated piping are demonstrated on the pipe work in an Airbus A320 landing gear bay.

In order to best match individual customer requirements in gearbox applications, customer-tailored gearboxes are a desirable solution. That leads to the demand for a truly individualized product development. In order to keep costs down despite an increasing product variability, novel digital design methods which automate the design process and avoid redundant manual work need to be developed and deployed. Graph-based design languages in UML (Unified Modeling Language) use a central data model to guarantee model consistency and to generate automatically multi-disciplinary models and simulations thereof. The paper shows the use of graph-based design languages for automated gear synthesis and the automated three dimensional arrangement of gearset parts. The aim of this language is to generate the gearset including the gear calculation. The calculation automation is supported with the domain-specific synthesis tool GAP (‘Getriebe Auslegungs Programm’). The resulting gearset is then packaged into a given design space provided as one of the customer requirements. The package problem is the subject of several boundary conditions and for this reasons normally multiple solutions do exist. Therefore, optimization methods are used in the following to select the final three-dimensional arrangement. The current state of the gear system model also includes a fully parametric CAD housing. The approach shown in this paper can be extended to the entire product life cycle, also including domain-specific and already established software solutions. Finally, the opportunity is present to include further product assessments like a cost calculation and a first reliability check of the system. The authors are aware of the fact that this fully automated process is currently still restricted to a specific class of product design problems such as gears and gearbox design.

Scope of this research is a holistic, completely digital representation of product development processes. The proposed process is implemented by graph-based design languages based on diagrams of Unified-Modelling-Language. The unique approach allows an automatic generation and evaluation of multiple product variants and is illustrated by the development and evaluation of an automotive bonnet. One main research objective is the investigation of model-based integration of an optimization loop and adaptation of the synthesis process based on results of evaluation steps. It was possible to use results of multiple finite-element simulation for fully automated adaptation of inner structure of the automotive bonnet.

In this paper, a combination of graph-based design and simulation-based engineering (SBE) into a new concept called Executable Integrative Product-Production Model (EIPPM) is elaborated. Today, the first collaborative process in engineering for all mechatronic disciplines is the virtual commissioning phase. The authors see a hitherto untapped potential for the earlier, integrated and iterative use of SBE for the development of production systems (PS). Seamless generation of and exchange between Model-, Software- and Hardware-in-the-Loop simulations is necessary. Feedback from simulation results will go into the design decisions after each iteration. The presented approach combines knowledge of the domain “PSs” together with the knowledge of the corresponding “product” using a so called Graph-based Design Language (GBDL). Its central data model, which represents the entire life cycle of product and PS, results of an automatic translation step in a compiler. Since the execution of the GBDL can be repeated as often as desired with modified boundary conditions (e.g., through feedback), a design of experiment is made possible, whereby unconventional solutions are also considered. The novel concept aims at the following advantages: Consistent linking of all mechatronic disciplines through a data model (graph) from the project start, automatic design cycles exploring multiple variants for optimized product-PS combinations, automatic generation of simulation models starting with the planning phase and feedback from simulation-based optimization back into the data model., European Regional Development Fund and the Ministry of Science, Research and the Arts of Baden- Württemberg, Germany

A central success factor for the digitalization of production processes is the provision of a consistent database across domains and life cycles. The current situation in the automotive industry is characterized by a multitude of engineering tools with diverse, proprietary data formats, which require complex conversion processes and show dramatic deficits in the consistency and accessibility of the data. In recent years, graph-based design languages have been refined and their range of application expanded to an extent that they represent an interesting approach to addressing these problems. The focus of this paper is on the automated generation of assembly processes and assembly resources (e.g. type-related production equipment such as clamping devices) using the example of automotive body parts (front flap and B-pillar). Within the presented engineering framework of automated production planning, clamping concepts and assembly cells (with automated wiring) are generated using graph-based design languages. Based on the manufacturing concept, a joining sequence and fastener planning is carried out, from which a product-specific clamping and fixing concept is derived. The central advantage of this procedure is, in addition to the high degree of automation, the possibility of providing a consistent database. This database allows the automatic derivation for the various specialized engineering tools.

This paper describes the formal representation approach used in the scope of a large-scale research project aiming at the holistic, completely digital representation and automated computability of the product life-cycle (PLC). The distinctive approach consists in the novel methodology of visual, graph-based design languages expressed in UML (Unified Modeling Language), which allow both the creation of new engineering models as well as the reuse of pre-existing engineering models and know-how. The tool-independent representation of the engineering design knowledge via the abstraction level in UML was originally developed by one of the project partners in prior work. The paper explains the methodology, modeling method and computational means as well as their integration along the product life-cycle including requirements, design, simulation as well as cost and energy analysis. The explanation is illustrated through a design language implementation for the automated design of novel light-weight multicopters.

‘Industrie 4.0’ based production systems are likely to change the way future products are manufactured. As information technology gains influence on these systems there is a chance of higher flexibility due to decentralized logic and artificial intelligence. All this leads to a higher complexity and also indeterminism is feasible. Therefore simulation technologies will become a mandatory requirement, especially virtual commissioning will get necessary as the amount of software is rising. A lot of manpower is required to establish and maintain a virtual commissioning system as it needs a large database of standard components. Therefore in most cases small- and mid-sized companies are forced to avoid such technologies. Using graph-based design languages to create virtual commissioning models can help to solve this problem. The basic principle is to shape an abstract model of a production system which will then be individually built within the domain specific tools. One of these should be a virtual commissioning tool to evaluate the functionality of the built model. If a change in the design is necessary, the new virtual commissioning model can be regenerated automatically. This approach is even more reasonable, if graph-based design languages are used throughout the whole product life cycle.

This second in a series of three papers [1] , [2] describes the combination of an analytical model with a rule-based approach. The abstract design vocabulary is assembled by the a sequence of rules, making up a design language. After describing the subsystems in the first paper, in this paper the modeling of the FireSat payload is the starting point. The activity diagrams to integrate the payload and the subsystems lead to a generic satellite design cycle which produces a Design Graph containing all relevant information. From the integrated model in the Design Graph, different analyses of the complex system design are derived. The visualization of the constraint network containing all the variables of the design, gives a glimpse on the complexity of the example. Then the design space for the satellite is shown by plotting the mass of the system over different initial requirements. This analysis is completed by a second plot incorporating the design decisions that cannot be reflected analytically but are stored in concrete design rules. Finally a sensitivity analysis of the full equation system of the satellite is presented. The heat map used to visualize the derivative values is a mean to display all influences on the current design point in one graph.

Product engineering involves designing and dimensioning a product, including geometric modeling and scientific simulation and analysis to fulfill predetermined requirements. Therefore, the engineering design effort requires a multidisciplinary analysis that is based on a multitude of different models, each of which require a different kind of representation of the same product geometry. The proposed approach uses a design language and a design compiler to translate an abstract source geometry in an abstract representation scheme into an arbitrary target format. With this approach, all models are generated automatically and are consistent with each other.

In this third paper of the series [1] , [2] about satellite design languages, the detailed geometry and simulation modeling is described. The definition of the FireSat subsystems in different design languages is presented in the first paper. In the second part, novel analytical design evaluations resulting from these means are shown. This paper focuses on the detailed simulation models that can be generated out of the design languages. These simulation models provide the means to solve the field problems based on differential equations in the specialized engineering applications. From an abstract geometry description the design languages can be exported in different computer aided design tools (CATIA, OpenCascade, etc.). All models shown in this paper are entirely generated out of a description within the UML. The same geometry description is used for a thermal simulation of the satellite in the ESATAN thermal design suite. The third usage of the abstract geometry description is for the automated routing of the harness cables that is presented. As a non-geometric example for a simulation model, the behavioral simulation of the attitude control in a generated Matlab Simulink model is shown. All the information required to generate these models is organized in the different design languages.

Increasing complexity in spacecraft design requires new ways for comprehensive problem formulation. Graph-based design languages are an innovative response to this challenge. Using the Unified Modeling Language (UML), design languages are a formal, executable description of the design knowledge. The FireSat mission given in the textbook [1] from Wertz is used to demonstrate the analysis of more designs in shorter time. For automating the design process, the domain knowledge is mapped onto a hierarchy of different modular design languages. Thereby the couplings between the components of the system are resolved and defined as generic interfaces. The variables and equations for the different subsystems are grouped in classes that describe the decomposition of the system. Rules are defined on the instance-level to recombine the different class-instances into a valid design description of the FireSat satellite. A sequence of these predefined rules specifies the integration of the components to a satellite system. The paper is part of a series of three papers. The second paper [2] describes the analysis of equation systems for the whole satellite system. The third paper [3] shows the integration of detailed simulation models using the description mechanisms of the design language.

Model-Based Systems Engineering (MBSE) structures the design process in form of a V-Model. Along the V-Model, the tasks of model creation, editing and design change propagation to maintain model consistency requires manually much time, effort and cost. While formal languages such as the Unified Modeling Language (UML) or the Systems Modeling Language (SysML) are used already to represent the design process and behavioral product aspects, the UML/SysML-models are mostly still manually assembled and interlinked. Graph-based design languages on the basis of UML combine the advantage of a digital representation of the design process with the advantage of a rule-based execution. This combination of digital representation with machine-execution boosts MBSE towards a repeatable and machine-executable V-Model. This allows for a seamless transition from manual MBSE towards an automated and machine-executable MBSE. The poster will highlight some of the advantages of this fully digital and machine-executable MBSE in an automotive dashboard application.

Graph-based design languages aim at the holistic digital design and representation of complex industrial products. These languages are based on the structure of natural languages, in which the vocabulary and the rules define a language grammar. The translation of the abstract graph-based design language into multiple specific domain-dependent engineering models occurs in a framework of a design compiler. This design compiler compiles the design rules automatically and allows the easy reuse of design and production knowledge. The product development engineers are thus relieved of most of their routine work by generative means: all the domain-specific models such as finite element models (FEM) and geometry models (CAD) are generated automatically based on the translation of the design language into a central data model. The central data model is the core result of the compilation of a design language and holds all the information necessary to generate all domain-specific models, which are specified in the design language. This paper describes the use of this kind of design language for the embodiment and dimensioning of a frame for a Formula Student racing car. This implementation extends the optimization design language, which has already been presented in part at the WCSMO12 [1].

Most modern digital approaches to engineering are based on models and their model transformations. Most of these model transformations are mathematically speaking non-bijective mappings — so-called projections — where some information of the original model is lost during the mapping. From a theoretical point of view it is therefore of great interest to exactly examine the properties of these model transformations. In this paper at first the characteristics of a model are briefly explained. Then some of the most common model-based engineering approaches are reviewed and compared regarding their models and model transformations. In this examination the missing existence of an inverse transformation (a so-called text-to-model transformation, T2M) of a typical model transformation (a so-called model-to-text transformation, M2T) is identified. That discovery may well hold the key to the realization of a so-called round-trip engineering. The required existence of the inverse transformation to this round-trip engineering is then generically postulated as having the nature of a pattern recognition problem. For illustration purposes and a better understanding of the interpretation of the inverse transformation as a pattern recognition problem, a case study for the reconstruction of an abstract model from the concrete model is given using CAD-Data of a satellite. Since CAD models belong to geometry, dimensionless geometric moment invariants play a key role in the generic solution of the pattern recognition problem contained in this example.