The accepted journal article extends the RTNS paper by generalizing the proposed schedulability analyses from a constrained-deadline task model to the more general, but also more complex, model with arbitrary deadlines. The corresponding optimal priority assignment for our schedulability analysis is also identified. In experiments with synthetic workloads, the proposed analyses are compared in terms of scheduling success ratio, against the frame-agnostic analyses for the corresponding variants of the Vestal model.
The paper addresses the problem of satisfying real-time requirements in industrial systems using unpredictable hardware and software, which limit or entirely prevent the application of established real-time analysis techniques. To this end, we propose PReGO, a generative methodology for satisfying real-time requirements in industrial commercial-off-the-shelf (COTS) systems. We report on our experience in applying PReGO to a use-case: a Search & Rescue application running on a fixed-wing drone with COTS components, including an NVIDIA Jetson board and a stock Ubuntu/Linux. We empirically evaluate the impact of each integration step and demonstrate the effectiveness of our methodology in meeting real-time application requirements in terms of deadline misses and energy consumption.
A course called “Modelling and Analysis of Component-based Systems” (MOANA-CBS) is being developed in collaboration with Thales as a part of the DYNAMICS project. The course addresses the challenge of overseeing the explosion of possible interactions between asynchronously communicating components in component-based systems. Some of these interactions may be undesirable and leave systems prone to deadlock, livelock, race conditions, and buffer overflows, reducing software quality. The course participants in the course learn how to mitigate this problem by modelling the behavior of components and interfaces using Petri Nets, a well-known formalism suitable for describing asynchronously communicating systems. Theory is linked to practice through demonstrations of relevant examples using the ComMA tool. Using properties and analysis methods for Petri Nets, they learn how to identify patterns in component and interface design that may cause the aforementioned problems, as well as design guidelines for how to avoid them. The course is taught using a combination of lectures, assignments, demonstrations, discussions, and reflection.
We piloted parts of the course at Van der Valk Hotel in Arnhem on October 7 and 8, attended by 12 software architects from Thales and Luminis. The course was positioned as a part of their Accelerate program, which aims to accelerate young architects from the two companies into a more senior role. We felt that the delivery of the course went well and evaluations from the participants suggests it was well-received. The evaluation of this pilot also highlighted some further points for improvement that will be considered going forward.
Bits & Chips just published an article about ComMA (Component Modelling and Analysis). ComMA addresses key design and verification challenges for complex systems comprising many components developed by different parties, challenges that are frequently encountered in the high-tech industry across application domains. The challenges are tackled by allowing structure and behavior of component interfaces to be formally specified using a set of domain-specific languages. From this specification, a number of artifacts are automatically generated, including system tests, run-time monitors that detect protocol violations, performance metrics, and documentation. Together, these artifacts reduce the time to design, integrate, and evolve complex high-tech systems, allowing the next generation of these systems to be developed faster and with higher quality.
ComMA was developed by ESI (TNO) in applied research projects with Philips. Successfully proving the approach in an industrial context at Philips has sparked interest from other companies, including Thermo Fisher Scientific, Thales, and Kulicke & Soffa. This eco-system of high-tech companies is expected to increase further as the ComMA tooling becomes open source as part of the Eclipse Foundation.
The article also mentions the applied research project DYNAMICS, for which I am the technical lead. Here, ESI and Thales have been looking at challenges and opportunities related to the evolution of interfaces. The strong point of interfaces is that they abstract from the component providing a particular functionality, allowing it to be changed or even replaced without compromising the overall functionality of the system. However, eventually the interfaces themselves need to be updated to prevent technical debt, and at that point all components relying on that interface are affected simultaneously. In the DYNAMICS project, we study how to automatically detect whether a change to the protocol of an interface is backwards compatible and if this is not the case, semi-automatically generate adapters that bridge the differences with previous versions. The benefit of this approach is that it reduces the time and cost of interface updates, allowing them to evolve faster and avoid creative workarounds that ultimately lead to unreliable systems and lower software quality. If you are interested in reading more about this work and how it leverages ComMA and Petri Net technology to achieve this, read this overview paper from last year.
Two bachelor theses one the use of TurtleBot3 for embedded system education have just been finalized. The first thesis by Mirka Schoute is entitled “Application Programming for Embedded Systems in Education on TurtleBot3 using Statecharts” and investigates whether an existing lab project based on Lego Mindstorm EV3 and Stateflow can be replaced by a similar lab project using TurtleBot3 and Yakindu Statechart Tools. It compares the robot platform and the statechart tools in terms of features, and redesigns the lab project to contain the same educational challenges. The main conclusion is that the redesigned project based on TurtleBot3 and Yakindu Statechart Tools are a suitable replacement for old project and provides better opportunities for further development on the project going forward. Based on the results of this thesis, we have decided to change the robot and tooling for the lab project in the academic year 2020/2021. We are happy to announce that Mirka continues working with us over summer to further extend his work and prepare it for student consumption.
The second thesis is written by Louis van Zutphen and is entitled “Gazebo Simulation Fidelity for the Turtlebot3 Burger“. This work studies how well simulation of TurtleBot3 in the simulation environment Gazebo captures the real behavior of the robot. Tests of sensors and actuators are created both in simulation and reality and results are compared. The conclusion is that code developed and tested with Gazebo is easy to deploy on the TurtleBot, but that there are numerous differences between the real robot and environment and their corresponding models in Gazebo that affect the fidelity. Most of these differences can be managed as long as the programmer is aware of them, allowing the amount of time required with the physical robot to be greatly reduced. This work has convinced us that we do not need to buy a TurtleBot for each group of students, but that we can significantly reduce the cost of the lab by efficiently sharing them.
Mohammed (Mo) Diallo just defended his bachelor thesis entitled “Towards the Scalability of Detecting and Correcting Incompatible Service Interfaces“. This work is carried out in the context of a project between ESI (TNO) and Thales that developed a five-step methodology for automatic detection and correction of behavioral incompatibilities resulting from evolving software interfaces (see paper for more details). Mo’s thesis provides a starting point for evaluating the scalability of the proposed methodology. An essential ingredient towards this is the ability to synthetically generate interfaces of various complexity. The thesis has two main contributions: 1) a notion of interface complexity in terms of inputs, outputs and non-determinism is defined and the relation between these parameters is studied, and 2) the methodology for a ComMA interface generator using user-supplied complexity parameters, and its implementation in a supporting tool, is introduced.
I would like to thank Mo for the excellent work he delivered in this thesis, and I am happy that he will continue working over summer to extend it.
The article addresses the problem of generating a time-triggered schedule for a number of independently developed automotive applications on a number of shared resources, such that their control performance only suffers minimal degradation. The three main contributions are: 1) a constraint programming model that solves the problem optimally, exploiting properties of the problem to reduce the computation time; 2) a fast heuristic called Flexi that only has a minor impact on the optimality of the solution; and 3) an experimental evaluation of the scalability and efficiency of the proposed approaches on a case study, in addition to several synthetic datasets. The results show that the heuristic provides a solution on average 5 times faster, finding a feasible solution in 31% more problem instances than the optimal approach within a time limit, while only sacrificing 0.5% of the control performance quality for the largest dataset.
During the past two years, I have been involved with setting up the Partnership Program Mastering Complexity (MasCot), funded NWO Domain Applied and Engineering Sciences together with ESI (TNO). After a long process of defining the key topics, writing the call, and aligning with applicants, four innovative research projects have finally been granted, allocating three million euros to research on software restructuring, testing, scheduling and design of cyber-physical systems. Congratulations to Andy Pimentel,Twan Basten, Jan Tretmans, Eelco Visser, and their collaborators for the accepted projects. I am looking forward to seeing the results!
The press release announcing my appointment as Professor at the University of Amsterdam is finally ready. Time to make them and ESI (TNO) proud!
The Chair of Design Methodologies for Cyber-Physical Systems focuses on two research areas.The first area considers design methodologies for cyber-physical systems in which abstraction, provided by models used for specification, analysis, simulation, or synthesis, play an essential role. While this area applies to cyber-physical systems in general, the second area focuses on design aspects of real-time systems. Together, these two areas capture much of my existing work in both academic (TU/e, CTU Prague, CISTER) and applied research (ESI) in different application domains and industries in which I have worked, e.g. avionics (Airbus), consumer electronics (Philips & NXP), and defense (Thales). They are also broad enough to sustain a long-term effort towards managing complexity of cyber-physical systems. For more information about the research, click the ‘Research‘ button in the menu at the top of the page.
My first mission will involve developing and teaching a course on Embedded Software and Systems, a course that is extremely relevant to our work at ESI. The course is primarily aimed at students following the Master in Software Engineering and teaches the fundamentals of embedded system development. This includes modelling systems using StateCharts, Petri Nets, Data-flow graphs, and Domain-Specific Languages, embedded hardware, functional and timing verification, and design-space exploration. I will also explain the industrial reality behind some of these aspects by drawing on my experience from projects at ESI.
During the course, the students will get practical experience with model-based engineering as they work in groups to program a LEGO Mindstorm Rover using Stateflow to autonomously follow a path, while avoiding obstacles. From this batch of students, I am hoping to find some promising ones that can help us make the next innovative steps in model-based engineering for complex cyber-physical systems for their thesis project.