Amir Ebrahimi

Automated Analysis of Interdependencies Between Product Platforms and Assembly Operations

by Amir Ebrahimi and Pierre E C Johansson

Procedia CIRP, 2016

Automated testing of non-functional requirements based on behavioural scripts

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Alignment of Requirements Specification and Testing: A Systematic Mapping Study

2011 IEEE Fourth International Conference on Software Testing, Verification and Validation Workshops, 2011

Requirements should specify expectations on a software system and testing should ensure these exp... more Requirements should specify expectations on a software system and testing should ensure these expectations are met. Thus, to enable high product quality and efficient development it is crucial that requirements and testing activities and information are aligned. A lot of research has been done in the respective fields Requirements Engineering and Testing but there is a lack of summaries of the current state of the art on how to link the two. This study presents a systematic mapping of the alignment of specification and testing of functional or nonfunctional requirements in order to identify useful approaches and needs for future research. In particular we focus on results relevant for nonfunctional requirements but since only a few studies was found on alignment in total we also cover the ones on functional requirements. The map summarizes the 35 relevant papers found and discuss them within six major sub categories with model-based testing and traceability being the ones with most prior results..

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Challenges in product family knowledge modeling and analysis (from product design to manufacturing)

by Pierre E C Johansson and Amir Ebrahimi

Proceedings of the 6th International Workshop, Sep 14, 2014

ABSTRACT Product families are one way of categorizing products with similar characteristics. A co... more ABSTRACT Product families are one way of categorizing products with similar characteristics. A common approach to reduce development costs is to define product platforms with reusable components that can be used for building vehicles for the different product families. Classical feature diagrams are often used to have a compact representation of all possible vehicles for all possible product families. In the talk we will describe some of the challenges with building tools that will support not only the product developers, but also the engineers responsible for developing the manufacturing systems by automatically analyzing the consequences of introducing or removing new features in the product. The problem has a few key characteristics. (i) The number of possible configurations is huge, in the order of 10100. (ii) The products have both mechanical parts, electrical parts, and software; each of which is configurable. The configuration of the software will depend on how the mechanical and electrical parts are configured. Variability of mechanical, electrical, and software parts are typically modeled in different tools, but they are highly interdependent. (iii) When assembling a product, many additional constraints must be taken into account. Typically, the assembly of a truck is done in an assembly line divided into different cells, where the truck moves sequentially from one cell to the next. This implies that the work in the different cells has to be distributed evenly between the cells. In addition, we have precedence constraints, expressing in which order different parts may be assembled. This might be due to geometric-feasibility where there has to be a collision-free path to bring two subassemblies together, or stability where two joined parts have to maintain their relative position and not break spontanously, for example, due to gravity. Another complication is that some tasks maybe only done in some cells due to some specific hardware which is needed to complete the task. (iv) A high number of stakeholders are involved with different responsibilities from mechanical engineers, electrical engineers, control engineers, and production engineers but also business people who decide which configurations should be available on the different markets. Every stakeholder has its preferred way of representing and interacting with the relevant information. For example a market analyst will need a textual informal document while a product designer will need a formal graphical document. Thus, a common problem is that often the same information is represented in different IT-support systems. This approach often results in redundant representations. Another problem can be that there are no exact semantics associated with information. A challenge is therefore how to avoid having redundant representations of the same information, but still being able to support different stakeholders? It is also desirable to be able to associate a well-defined semantics to all the knowledge and information in system. Avoiding redundant representations and having clear semantics is a prerequisite for introducing computational methods that will enable automated analysis of consequences of design changes to the product or the manufacturing system. Since exhaustive enumeration of all possible vehicles is not possible, another challenge is the development of algorithms that can evaluate the manufacturability of each possible vehicle. In our work on meeting some of the challenges described above, we are working on integrating domain-specific models of the product family. This semantic model is enhanced using a previously defined meta-modeling language, Clafer, to enable model analysis. The semantic model also describes the assembly tasks, precedence relations between tasks, and capabilities of resources. In order to support different stakeholders and allowing them to work using a representation that is familiar to them, we are building the prototype tool upon the Domain Workbench from Intentional Software. The work is part of the EU FP7 project Know4Car.

Online Support for Shop-Floor Operators Using Body Movements Tracking

by J. Provost and Amir Ebrahimi

12th IFAC,IFIP,IFORS,IEA Symposium on Analysis, Design, and Evaluation of Human-Machine Systems, 2013, 2013

This paper presents results of experimentations on the integration of human operators and automat... more This paper presents results of experimentations on the integration of human operators and automation in the context of assembly systems. Several experiments have been conducted to evaluate the use of augmented reality applications in order to provide dynamic work instructions and online feedback information to a shop-floor operator. Based on these results, an experimental platform has been developed so that the shop-floor operator and the automated system behave as a closed-loop system.

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Design and qualitative thermographic comparison of different power inverter packaging

4th International Conference on Power Engineering, Energy and Electrical Drives, 2013

ABSTRACT The effect of mechanical packaging optimization for a low power three phase inverter is ... more ABSTRACT The effect of mechanical packaging optimization for a low power three phase inverter is investigated and measured in this paper. Furthermore, the effect of source pin thermal modification is fully verified using qualitative thermographic measurement. It is shown that a proper assembly technique which takes the appropriate heat distribution into account leads to a significant improvement of the inverter&#39;s thermal characteristic. Consequently, the power density of the inverter can distinctly be increased. Two electrically almost identical but mechanically different inverters, using TO-247 package Power-MOSFETs, are constructed and compared. The results of thermographic measurements reveal remarkable improvement in current capability of the inverter.

Challenges in product family knowledge modeling and analysis

by Pierre E C Johansson and Amir Ebrahimi

Proceedings of the 6th International Workshop on Feature-Oriented Software Development - FOSD '14, 2014

ABSTRACT Product families are one way of categorizing products with similar characteristics. A co... more ABSTRACT Product families are one way of categorizing products with similar characteristics. A common approach to reduce development costs is to define product platforms with reusable components that can be used for building vehicles for the different product families. Classical feature diagrams are often used to have a compact representation of all possible vehicles for all possible product families. In the talk we will describe some of the challenges with building tools that will support not only the product developers, but also the engineers responsible for developing the manufacturing systems by automatically analyzing the consequences of introducing or removing new features in the product. The problem has a few key characteristics. (i) The number of possible configurations is huge, in the order of 10100. (ii) The products have both mechanical parts, electrical parts, and software; each of which is configurable. The configuration of the software will depend on how the mechanical and electrical parts are configured. Variability of mechanical, electrical, and software parts are typically modeled in different tools, but they are highly interdependent. (iii) When assembling a product, many additional constraints must be taken into account. Typically, the assembly of a truck is done in an assembly line divided into different cells, where the truck moves sequentially from one cell to the next. This implies that the work in the different cells has to be distributed evenly between the cells. In addition, we have precedence constraints, expressing in which order different parts may be assembled. This might be due to geometric-feasibility where there has to be a collision-free path to bring two subassemblies together, or stability where two joined parts have to maintain their relative position and not break spontanously, for example, due to gravity. Another complication is that some tasks maybe only done in some cells due to some specific hardware which is needed to complete the task. (iv) A high number of stakeholders are involved with different responsibilities from mechanical engineers, electrical engineers, control engineers, and production engineers but also business people who decide which configurations should be available on the different markets. Every stakeholder has its preferred way of representing and interacting with the relevant information. For example a market analyst will need a textual informal document while a product designer will need a formal graphical document. Thus, a common problem is that often the same information is represented in different IT-support systems. This approach often results in redundant representations. Another problem can be that there are no exact semantics associated with information. A challenge is therefore how to avoid having redundant representations of the same information, but still being able to support different stakeholders? It is also desirable to be able to associate a well-defined semantics to all the knowledge and information in system. Avoiding redundant representations and having clear semantics is a prerequisite for introducing computational methods that will enable automated analysis of consequences of design changes to the product or the manufacturing system. Since exhaustive enumeration of all possible vehicles is not possible, another challenge is the development of algorithms that can evaluate the manufacturability of each possible vehicle. In our work on meeting some of the challenges described above, we are working on integrating domain-specific models of the product family. This semantic model is enhanced using a previously defined meta-modeling language, Clafer, to enable model analysis. The semantic model also describes the assembly tasks, precedence relations between tasks, and capabilities of resources. In order to support different stakeholders and allowing them to work using a representation that is familiar to them, we are building the prototype tool upon the Domain Workbench from Intentional Software. The work is part of the EU FP7 project Know4Car.

Managing Product and Production Variety – A Language Workbench Approach

by Pierre E C Johansson and Amir Ebrahimi

Procedia CIRP, 2014

Product platforms are commonly used in industries with complex products and high competition like... more Product platforms are commonly used in industries with complex products and high competition like the car and truck industry to allow a customer to order a product that satisfy its unique needs. A consequence of product variety is that manufacturing and assembly processes need to deal with this variety as well. If the variety is low and changes of the product occur infrequently then the variety may be handled by designing the production system for a small set of typical products. But as the variety increases and changes become frequent the necessity for integrated product and production information model is high, to partially solve this problem Product Life Cycle Management (PLM) systems aim at providing an integrated model to all categories of users, e.g. product designers, product preparation engineers, line builders and shop-floor workers. All users need to access the information in the platform and refine and modify the information to reflect new knowledge that has been acquired. Today, most often multiple systems are used where some systems may store information in a structured way but often unstructured text documents are also used. This easily results in redundant information models and automated analysis is not feasible or not event possible because of issues regarding cohesion and traceability of information. The contribution in this paper is to discuss how a new type of tool for building domain specific languages and editors using language workbench approach can be used to support the different user categories in their tasks working with variability of a product and production system while at the same time provide cohesion and traceability of information.

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An empirical study of control logic specifications for programmable logic controllers

by Amir Ebrahimi and Martin Fabian

Empirical Software Engineering, 2014

ABSTRACT This paper presents an empirical study of control logic specifications used to document ... more ABSTRACT This paper presents an empirical study of control logic specifications used to document industrial control logic code in manufacturing applications. More than one hundred input/output related property specifications from ten different reusable function blocks were investigated. The main purpose of the study was to provide understanding of how the specifications are expressed by industrial practitioners, in order to develop new tools and methods for specifying control logic software, as well as for evaluating existing ones. In this paper, the studied specifications are used to evaluate linear temporal logic in general and the specification language ST-LTL, tailored for functions blocks, in particular. The study shows that most specifications are expressed as implications, that should always be fulfilled, between input and output conditions. Many of these implications are complex since the input and output conditions may be mixed and involve sequences, timer issues and non-boolean variables. Using ST-LTL it was possible to represent all implications of this study. The few non-implication specifications could be specified in ST-LTL as well after being altered to suit the specification language. The paper demonstrates some advantages of ST-LTL compared to standard linear temporal logic and discusses possible improvements such as support for automatic rewrite of complex specifications.

Formal analysis of product variability and the effects on assembly operations

by Pierre E C Johansson, Thomas Lezama, and Amir Ebrahimi

2015 IEEE 20th Conference on Emerging Technologies & Factory Automation (ETFA), 2015

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