Featured Publications

Here is a compilation of the KTH Mechatronics unit's favourite papers.

Read the Abstracts below, or see the list as a pdf (pdf 98 kB)

1. Integrating Viewpoints in the Development of Mechatronic Products

Martin Törngren, Ahsan Qamar, Matthias Biehl, Frederic Loiret, Jad El-Khoury 
[Journal of Mechatronics, special issue on Model-based mechatronic system-design Elsevier, Dec. 2013]

ABSTRACT: The development of mechatronic products involves multiple stakeholders which have different viewpoints and therefore use different concepts, models and tools to deal with their concerns of interest. This paper argues that an increased emphasis needs to be placed on the relations between viewpoints to be able to deal with the evolving scope and requirements on mechatronic products. We study relations between viewpoints at the levels of people, models and tools, and present solutions that are used to formally and explicitly capture such relations. Viewpoint contracts are used to define the vocabulary, assumptions and constraints required for ensuring smooth communication between stakeholders (people level). Dependency models capture relations between product properties belonging to different viewpoints, and how such dependencies relate to predictions and decisions (model level). Tool integration models describe the relations between tools in terms of traceability, data exchange, invocation and notifications (tool level). A major contribution of this paper is a unification approach, elaborating how these solutions can be used synergetically to integrate viewpoints. An industrial robot case study is utilized to illustrate the challenges and solutions with respect to relations between viewpoints, including the unification approach.

Download a PDF of this paper here (pdf 7,1 MB) ,
or find it on-line at dx.doi.org/10.1016/j.mechatronics.2013.11.013 .

2. A reference architecture for cooperative driving

Sagar Behere, Martin Törngren, De-Jiu Chen.
[Journal of System Architecture, May 2013]

ABSTRACT:  Cooperative driving systems enable vehicles to adapt their motion to the surrounding traffic situation by utilizing information communicated by other vehicles and infrastructure in the vicinity. How should these systems be designed and integrated into the modern automobile? What are the needed functions, key architectural elements and their relationships? We created a reference architecture that systematically answers these questions and validated it in real world usage scenarios. Key findings concern required services and enabling them via the architecture. We present the reference architecture and discuss how it can influence the design and implementation of such features in automotive systems.

Download a PDF copy of this paper here (pdf 6,3 MB)  
or find it on-line at: dx.doi.org/10.1016/j.sysarc.2013.05.014

3. Cyber-Physical System Design Contracts

Patricia Derler, Edward Lee, Martin Törngren, Stavros Tripakis.
[ICCPS '13: ACM/IEEE 4th International Conference on Cyber-Physical Systems, 2013]

ABSTRACT: This paper introduces design contracts between control and embedded software engineers for building Cyber-Physical Systems (CPS). CPS design involves a variety of disciplines mastered by teams of engineers with diverse backgrounds. Many system properties influence the design in more than one discipline. The lack of clearly defined interfaces between disciplines burdens the interaction and collaboration. We show how design contracts can facilitate interaction between 2 groups: control and software engineers. A design contract is an agreement on certain properties of the system. Every party specifies requirements and assumptions on the system and the environment. This contract is the central point of inter-domain communication and negotiation. Designs can evolve independently if all parties agree to a contract or designs can be modified iteratively in negotiation processes. The main challenge lies in the definition of a concise but sufficient contract. We discuss design contracts that specify timing and functionality, two important properties control and software engineers have to agree upon. Various design approaches have been established and implemented successfully to address timing and functionality. We formulate those approaches as design contracts and propose guidelines on how to choose, derive and employ them. Modeling and simulation support for the design contracts is discussed using an illustrative example.

Find it on-line at: chess.eecs.berkeley.edu/pubs/959.html

4. On the Modeling and Generation of Service-Oriented Tool Chains 

Matthias Biehl, Jad El-Khoury, Frederic Loiret, Martin Törngren.
[Journal of Software and Systems Modeling, Dec. 2012]

ABSTRACT: Tool chains have grown from ad-hoc solutions to complex software systems, which often have a serviceoriented architecture.With service-oriented tool integration, development tools are made available as services, which can be orchestrated to form tool chains. Due to the increasing sophistication and size of tool chains, there is a need for a systematic development approach for service-oriented tool chains. We propose a domain-specific modeling language (DSML) that allows us to describe the tool chain on an appropriate level of abstraction. We present how this language supports three activities when developing service-oriented tool chains: communication, design and realization. A generative approach supports the realization of the tool chain using the service component architecture.We present experiences from an industrial case study, which applies the DSML to support the creation of a service-oriented tool chain. We evaluate the approach both qualitatively and quantitatively by comparing it with a traditional development approach.

find it on-line at: www.matt-biehl.de/research/publications/sosym2012_springer.pdf

5. Dependency Modeling and Model Management in Mechatronic Design

Ahsan Qamar, Christiaan J. J. Paredis, Jan Wikander, and Carl During.
[Journal of Computing and Information Science in Engineering, ASME, Vol. 12(4), pp. 041009, Dec.2012] 

ABSTRACT: Mechatronic design is traditionally supported through domain-specific design activities throughout the product development process. The partitioning into domain-specific problems leads to a situation where product properties influence each other, hence giving rise to dependencies. These dependencies play a key role in the prediction of properties and, as a result, in the decision-making process. The important question is how to manage the dependencies for efficient and effective decision making? The aim of this paper is threefold. First, we investigate the nature of dependencies and study how to model them. The paper proposes appropriate terminology taking into account the synthesis and analysis nature of both the properties and the dependencies. This terminology will be the core of the new dependency modeling language. The concepts related to dependency modeling are then illustrated through a simple robot design example, where the creation and importance of a dependency model are explained. Second, we study practical approaches for consistency management and model management in the presence of dependencies. Six levels-of-detail in modeling dependencies are presented; emphasizing that modeling at a higher level-of-detail ensures that more inconsistencies are avoided. Available languages such as OMG SysML™ are evaluated for a possible creation of the dependency models leading toward executable dependency networks. However, at present, SysML does not provide sufficiently rich language constructs to model dependencies. Third, we compare our dependency modeling approach to other state-of-the-art approaches such as dependency modeling with a design structure matrix (DSM), and highlight the benefits of the terminology proposed in this paper. We aim to convince the reader that there is substantial value in modeling dependencies explicitly, especially to avoid inconsistencies, which is not the current state of practice. However, an overall value from dependency modeling can only be obtained if the cost of creating the dependency model is reasonable. Issues such as human interaction/effort and model management through product lifecycle management (PLM) are discussed.

find it on-line at: computingengineering.asmedigitalcollection.asme.org/article.aspx?articleid=1660222

6. An Architectural Approach to the Analysis, Verification and Validation of Software Intensive Embedded Systems

DeJiu Chen, Lei Feng , Tahir Naseer Qureshi, Henrik Lönn, Frank Hagl.
[Journal: Computing, Springer. 2013. DOI: 10.1007/s00607-013-0314-4]

ABSTRACT: EAST-ADL is a domain specific Architecture Description Language (ADL) for safety-critical and software-intensive embedded systems. The language allows a formalized and traceable description of a wide range of engineering concerns throughout the entire lifecycle of system development. This makes it possible to fully utilize the leverage of state-of-the-art methods and tools for the development of correct-by-construction system functions and components in a seamless and cost efficient way. This paper focuses on the recent advancement of EAST-ADL in supporting an architecture-centric analysis, verification&validation of complex behaviors for the purposes of requirements engineering, application design, and safety engineering. The approach is architecture centric because all behavior descriptions are formalized and connected to a set of standardized design artifacts sitting at multiple levels of abstractions. We present the language design to support this, the theoretical underpinning and tool implementation. To show the capability of EAST-ADL, we also introduce an algorithm and its implementation for transforming the EAST-ADL behavior models to SPIN models for logic model checking. Exploiting mature state-of-the-art technologies from computer science, electronic engineering, and other related domains for a model-based incremental system development, the contribution enables the developers of embedded systems and software to maintain various engineering concerns coherently using EAST-ADL.

Download a copy of this paper here  (pdf 5,8 MB)

7. Context-Aware Adaptation in DySCAS

Richard Anthony, DeJiu Chen, Mariusz Pelc, Magnus Persson and Martin Törngren.
[Electronic Communications of the EASST, Volume 19: Context-Aware Adaptation Mechanism for Pervasive and Ubiquitous Services (CAMPUS). Technische Universität Berlin, 2009. ISSN 1863-2122]

ABSTRACT: DySCAS is a dynamically self-configuring middleware for automotivecontrol systems. The addition of autonomic, context-aware dynamic configurationto automotive control systems brings a potential for a wide range of benefits in termsof robustness, flexibility, upgrading etc. However, the automotive systems representa particularly challenging domain for the deployment of autonomics concepts, havinga combination of real-time performance constraints, severe resource limitations,safety-critical aspects and cost pressures. For these reasons current systems are staticallyconfigured. This paper describes the dynamic run-time configuration aspectsof DySCAS and focuses on the extent to which context-aware adaptation has beenachieved in DySCAS, and the ways in which the various design and implementationchallenges are met.

find it on-line at: info to follow

8. Experiences from large embedded systems development projects in education, involving industry and research

Martin Törngren, Martin Grimheden, Niklas Adamsson.
[Invited paper (extended version of the corresponding Emsoft paper). In SIGBED Review (Special interest group on embedded systems), ACM. ISSN:1551-3688. The 12th issue (Volume 4, Number 1), January 2007. Special Issue on the Second Workshop on Embedded System Education]

ABSTRACT: We present experiences from a final year M.Sc. course. The overall aim of the course is to provide knowledge and skills to develop products in small or large development teams. The course is implemented in terms of large projects in cooperation with external partners, in which the students, based on a product specification, apply and integrate their accwnulated knowledge in the development of a prototype. This course, which has been running and further elaborated for 20 years, baa been proven successful in terms of being appreciated by the students and by the external partoera. The course baa daring the recent years more frequently been carried out in close connection to research groups. Our experiences indicate benefits by carrying out these types of large projects in an educational setting, with external partners as project providers, and in close cooperation with research groups.

Having external partners as project providers feeds the course, students and faculty with many industrially relevant problems that are useful for motivational purposes, and in other courses for exemplification and for case studies in research. Carrying out the projects in close connection to research groups provides synergy between research and education, and can improve the academic level of the projects. A further interesting dimension is accomplished when the projects run in iterations, requiring new groups of students to take over an already partly developed complex system, and work incrementally on this system. The students are then faced with a very typical industrial situation. We advocate that students should be exposed to a mixture of ''build from scratch" and ''incremental" projects during the education.

find it on-line at: www.cs.virginia.edu/sigbed/archives/2007-01/SIGBED%20Review%20(Torngren).pdf

9. Qualifying Software Tools, a Systems Approach

Fredrik Asplund, Jad El-khoury, Martin Törngren.
[SAFECOMP 2012, Magdeburg, Germany. Sept. 2012]

ABSTRACT: Modern safety standards designed to ensure safety in embedded system products often take a descriptive approach, focusing on describing appropriate requirements on management, processes, methods and environments during development. While the qualification of soft­ ware tools has been included in several such standards, how to handle the safety implications of tools integrated into tool chains has been largely ignored. This problem is aggravated by an increase both in automation of tool integration and the size of development environments.

In this paper we define nine safety goals for tool chains and suggest a qualification method that takes a systems approach on certifying soft­ ware tools as parts of tool chains. With this method, software tools are developed and pre-qualified under the assumption that certain proper­ ties will be supported by the development environment they are to be deployed in. The proposed method is intended to {1) achieve a stronger focUB on the relevant parts of tool chains in regard to safety and {2) sep­ arate the extra effort these parts imply from the effort already stipulated by safety standards.

Download a PDF copy of this paper here (pdf 2,5 MB)

10. Integrated Safety and Architecture Modeling for Automotive Embedded Systems

DeJiu Chen, Rolf Johansson, Henrik Lönn, Hans Blom, Martin Walker, Yiannis Papadopoulos, Sandra Torchiaro, Fulvio Tagliabo, Anders Sandberg.
[Journal e&i, Volume 128, Number 6, Automotive Embedded Systems. Springer Wien, 2011. ISSN 0932-383X / 1613-7620. DOI 10.1007/s00502-011-0007-7]

ABSTRACT: EAST-ADL is an architecture description language (ADL) for model-based development of automotive embedded systems.The formalization of domain-specific engineering information and methodology brings a potential for a wide range of benefitsfor information management, system design and integration, tool interaction, documentation and communication. This paper describesthe EAST-ADL language support for safety requirements, faults/failures, hazards and safety constraints in the context of ISO/DIS 26262reference safety lifecycle. Based on the language support, the safety related information can be derived and managed seamlessly alongwith its target nominal system architecture model with multiple abstraction levels and view extensions. Through model transformationand tool integration, automated safety analysis is allowed.

find it on-line at: link.springer.com/article/10.1007%2Fs00502-011-0007-7

11. Self configuration of dependent tasks for dynamically reconfigurable automotive embedded systems

Lei Feng; DeJiu Chen; Martin Törngren.
[Decision and Control, 2008. CDC 2008. 47th IEEE Conference on , vol., no., pp.3737-3742, 9-11 Dec. 2008. doi: 10.1109/CDC.2008.4739195]

ABSTRACT: The configurations of an automotive embedded system are normally fixed in production and remain static over the vehicle lifetime. Future scenarios, however, call for more flexible configuration support. DySCAS (Dynamically Self-Configuring Automotive Systems) project aims to introduce context-awareness and self-management features into automotive embedded systems via middleware technologies. Contributing to online configuration decisions, this paper formalizes a fundamental self-configuration problem. It forms a basis for managing the cross interdependencies of configurational items, assessing the system-wide impacts of changes, and making dynamic decisions about new configurations.

find it on-line at: ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=4739195

12. Mechatronics Engineering: Science and Education

Jan Wikander, Martin Törngren and Mats Hanson.
[Invited Paper. IEEE Robotics and Automation Magazine, Vol 8, No. 2, 2001] 

ABSTRACT: So far there is no common and widely accepted understanding of what mechatronics really is. Many different notions similar to or including mechatronics have been used in various contexts; micromechatronics, optomechatronics, supermechatronics, mecanoinformatics, contromechanics and megatronics are some of these, each coined to put forward a specific aspect or application of mechatronics. Examples of attempts to describe mechatronics include the following:

  1. Mechatronics encompasses the knowledge and the technologies required for the flexible generation of controlled motions.
  2. Mechatronics is the synergistic combination of mechanical and electrical engineering, computer science, and information technology, which includes control systems as well as numerical methods used to design products with built-in intelligence
  3. A precise definition of mechatronics is not possible, nor is it particularly desirable, because the field is new and expanding rapidly; too rigid a definition would be constraining and limiting, and that is precisely what is not wanted at present.

Mechatronics as an interdisciplinary subject tends to attract contributions from all related fields without really putting forward the opportunities and challenges arising specifically due to the interdisciplinary interactions. An example of this is that many mechatronics conferences have been unfocused and thereby have not attracted the most adequate contributions, which definitely exist. This is a disadvantage in that it hampers the development of mechatronics as an engineering science. Scientific publications in mechatronics, to help in making the subject more focused, are still quite rare. One of the earlier publications is Mechatronics—an International Journal published by Elsevier Science, first published in 1991. The IEEE/ASME Transactions on Mechatronics, a more recent publication, began in 1996.

This article is not just another attempt to describe the research community’s definition of the term mechatronics. Rather, we try to get to the heart of multidisciplinary engineering, of which mechatronics is an excellent example, and point out how the integration of disciplines leads to new degrees of freedom in design and corresponding research directions that otherwise would not have been investigated. This is the major contribution achieved by a multidisciplinary approach to engineering science; it leads to a new important research field and at the same time helps to push research in related fields into new fruitful directions.

Download a PDF copy of this paper here (pdf 199 kB) .

13. Challenges in Designing Mechatronic Systems

Morkeberg Torry-Smith, Jonas; Qamar, Ahsan; Achiche, Sofiane; Wikander, Jan; Mortensen, Niels Henrik; During, Carl.
[Journal of mechanical design, 2013 (1990), ISSN 1050-0472, Vol. 135, no 1, 011005]

ABSTRACT: Development of mechatronic products is traditionally carried out by several design experts from different design domains. Performing development of mechatronic products is thus greatly challenging. In order to tackle this, the critical challenges in mechatronics have to be well understood and well supported through applicable methods and tools. This paper aims at identifying the major challenges, by conducting a systematic and thorough survey of the most relevant research work in mechatronic design. Solutions proposed in literature are assessed and illustrated through a case study in order to investigate if the challenges can be handled appropriately by the methods, tools, and mindsets suggested by the mechatronic community. Using a real-world mechatronics case, the paper identifies the areas where further research is required, by showing a clear connection between the actual problems faced during the design task and the nature of the solutions currently available. From the results obtained from this research, one can conclude that although various attempts have been developed to support conceptual design of mechatronics, these attempts are still not sufficient to help in assessing the consequences of selecting between alternative conceptual solutions across multiple domains. We believe that a common language is essential in developing mechatronics, and should be evaluated based on: its capability to represent the desired views effectively, its potential to be understood by engineers from the various domains, and its effect on the efficiency of the development process.

Download a pdf of this paper here. (pdf 1,6 MB)

14. Managing dependencies in mechatronic design: a case study on dependency management between mechanical design and system design

Qamar, Ahsan; Wikander, Jan; During, Carl.
[Engineering with Computers, Springer London, ISSN 0177-0667, June 2014]

ABSTRACT: In this paper, we have investigated the role of dependencies in the design process of mechatronic products. Since explicit modeling of dependencies is largely considered unnecessary today, current languages do not support dependency modeling due to lack of sufficiently expressive language constructs. However, this paper argues that modeling dependencies is important in managing the overall design process. The paper highlights dependencies between two important viewpoints: system design and mechanical design. We have looked closely at how mechanical design (supported by CAD tools) establishes a backbone for the overall design concept. Mechanical design cannot be isolated from other design activities, and the mismanagement of dependencies there leads to problems in other domains too. To illustrate the process, the paper presents an example of modeling dependencies between system hierarchy in OMG SysML™ and the CAD assembly in Solid Edge for a mechatronic design example. The paper presents two different approaches to capturing dependencies—using a general purpose modeling language such as SysML and using a domain specific modeling language (DSML). We argue for using a DSML instead of a general purpose language and provide a DSML called the dependency modeling language (DML). An example DML model for a two degree of freedom robot use case is discussed. The paper also illustrates the complete process of capturing dependencies in a general purpose modeling language like SysML, which served as a good exercise on how to fetch data from a CAD tool and how to represent dependencies inside a significantly different modeling language. Lessons learned from doing this were applied to the construction of DML. Our aim for the future is to reduce the human effort required to build dependency models. Machine learning techniques and automated model transformations are valuable techniques to support this cause.

find it on-line at: dx.doi.org/10.1007/s00366-014-0366-x

15. Holistic design methodology for mechatronic systems 

Daniel Malmquist, Daniel Frede, Jan Wikander.
[Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering, November 2014; vol. 228, 10: pp. 741-757. May 2014]

ABSTRACT: The wide range of engineering domains aggregated in mechatronic systems can cause problems for design engineers. It is important to treat the different domains in an integrated, concurrent manner during design to be able to achieve the frequently sought-for synergetic effects of mechatronic systems. Traditional design methods are usually based on the different engineering disciplines being treated separately and only integrated at a late stage of the development process. Consequently, those methods do not work sufficiently well for mechatronic systems, leading to a suboptimal product. Previous research by the authors presents a novel approach to mechatronic system design by allowing quick optimisation and evaluation of design concepts. This is done by front loading certain design activities, hence decreasing the need for time- and cost-consuming iterations in later design stages. The method is backed up by a supporting software tool prototype. This article extends the method by including the dynamic aspects of the designed systems while also implementing basic control aspects, hence creating a concurrent and holistic method for mechatronic system design. This allows the designer to take synergetic effects into account at an earlier stage of the design process, hence increasing product quality and decreasing development costs. A conceptual design case is used in this article for an initial evaluation of the method and the results show great potential for the methodology.

find it on-line at: pii.sagepub.com/content/228/10/741.abstract

16. Jacobian Matrix Normalization - A Comparison of Different Approaches in the Context of Multi-Objective Optimization of 6-DOF Haptic Devices

Suleman Khan, Kjell Andersson, Jan Wikander.
[Journal of Intelligent & Robotic Systems, Nov. 2014]

ABSTRACT: This paper focuses on Jacobian matrix normalization and the performance effects of using different criterion and techniques. Normalization of the Jacobian matrix becomes an issue when using kinematic performance indices and the matrix contains elements with non-homogenous physical units, i.e. representing both translational and rotational motions. Normalization is necessary in multi objective optimization if kinematic performance indices are used based on the full Jacobian matrix. Different methods have been proposed in literature for defining a scaling factor used to normalize the Jacobian. Based on a comparison of a few of these methods, we conclude that it is better to have the scaling factor as a design variable in the multi objective optimization. However, as an alternative, a new scaling factor is proposed based on the relationship between linear actuator motion range in joint space and rotational end effector motion in task space, a proposal underpinned by simulation, analysis and comparison of optimization results using existing normalization techniques. For optimization, performance indices for workspace, kinematic sensitivity, device isotropy and inertia are considered. To deal with the multi-objective optimization problem, genetic algorithms are employed together with a normalized multi-objective optimization function. The performances of different device configurations (depending on the normalization method and the global isotropy index used) are presented in this article.

find it on-line at: link.springer.com/article/10.1007%2Fs10846-014-0147-1

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