Libor Waszniowski

Bio: Libor Waszniowski is an academic researcher from Czech Technical University in Prague. The author has contributed to research in topics: Model checking & OSEK. The author has an hindex of 7, co-authored 13 publications receiving 159 citations.

Formal verification of multitasking applications based on timed automata model

Abstract: The aim of this paper is to show, how a multitasking application running under a real-time operating system compliant with an OSEK/VDX standard can be modeled by timed automata. The application under consideration consists of several non-preemptive tasks and interrupt service routines that can be synchronized by events. A model checking tool is used to verify time and logical properties of the proposed model. Use of this methodology is demonstrated on an automated gearbox case study and the result of the worst-case response time verification is compared with the classical method based on the time-demand analysis. It is shown that the model-checking approach provides less pessimistic results due to a more detailed model and exhaustive state-space exploration.

Timed automata approach to real time distributed system verification

Abstract: This article deals with a distributed real-time application modelling by timed automata. The application under consideration consists of several processors communicating via controller area network (CAN): each processor executes an application that consists of tasks running under an operating system (e.g. OSEK) and using inter-task synchronization primitives. For such system, model checking algorithm implemented in a model checking tool (e.g. UPAALL) can be used to verify complex time and logical properties of the proposed model (e.g. end-to-end response time, state reachability, deadlock freeness). Since the proposed timed automata model contains more crucial details of the system behavior with respect to classical approaches to the response time analysis, the model checking approach provides less pessimistic results in many cases.

Analysis of Real Time Operating System Based Applications

Abstract: This text is dedicated to modelling of real-time applications running under multitasking operating system. Theoretical background is based on timed automata by Alur and Dill. As this approach is not suited for modelling pre-emption we focus on cooperative scheduling. In the addition, interrupt service routines are considered, and their enabling/disabling is controlled by interrupt server considering the specified server capacity. The server capacity has influence on the margins of the computation times in the application processes. Such systems, used in practical real-time applications, can be modelled by timed automata and further verified since their reachability problem and model checking of TCTL problem is decidable. Use of this methodology is demonstrated on the case study.

Aircraft Control System Validation via Hardware-in-the-Loop Simulation

Abstract: T HISNote presents experiences from the validation process of an aircraft control system—the yawdamper controller (YDC)with hydraulic actuators. The hardware-in-the loop (HIL) simulation on a hydraulic stand with a revolving platform and a loading force actuator was used in the validation process of this mechatronics system in the first step [1]. This Note extends the previous work by describing the next level of the validation process in which the YDC and actuators have been embedded into the aircraft where the interaction with the mechanical control system is validated by the HIL simulation. The yaw damper controller and the simulator are very briefly described and the practical experiences demonstrating the usefulness of the hardware-in-the loop simulation during detection of errors in the system components are mentioned. The yawdamper (YD) is a device directly coupledwith the aircraft rudder. It senses the yaw rate via a fiber optic gyro (FOG) and compensates oscillations via hydraulic actuators deviating the rudder. Even though it is designed to be fail-safe (it is disconnected from the ruder when a failure is detected) and the direct mechanical coupling of the rudderwith the pedals guarantee controllability of the aircraft when the YDC does not work, a malfunction of the YDC could have a serious effect on flight safety. Therefore, the validation of the whole system controlling the ruder must be carefully undertaken. HIL simulation is a popular validation method in many branches. The HIL simulator for an electrohydraulic flight control system has been described in [2]. HIL simulation has been used for the development of the antiskid braking system of the aircraft in [3] or for the flight-formation system [4]. HIL is also often used for development of control systems of unmanned aerial vehicles [5–9], and missiles [10]. Reference [11] presents a study of the performance of a fuel-cell powered unmanned aerial vehicles using HIL simulation of the aircraft inflight. HIL simulation is irreplaceable in the automotive industry and it is also very useful in power electronic controls, motor control, and energetic-component design and teaching. The rest of the Note is organized as follows. The YD is briefly described in Sec. II. Section III presents the HIL simulator. The validation process is described in Sec. IV. The concluding remarks are mentioned in Sec. V.

Real-Time Systems

Abstract: From the Publisher: Real-Time Systems is both a valuable reference for professionals and an advanced text for Computer Science and Computer Engineering students. Real world real-time applications based on research and practice State-of-the-art algorithms and methods for validation Methods for end-to-end scheduling and resource management More than 100 illustrations to enhance understanding Comprehensive treatment of the technology known as RMA (rate-monotonic analysis) methods A supplemental Companion Website www.prenhall.com/liu

Sustainability in Software Engineering: A Systematic Literature Review for Building up a Knowledge Base

Abstract: Background: Supporting sustainability in software engineering is becoming an active area of research and we want to contribute the first SLR in this field. Researchers who are motivated to contribute to that topic need to accumulate a body of knowledge as starting point through time-consuming literature research. Aim: We aim to provide an overview of different aspects of sustainability in software engineer- ing research with regard to research activity, investigated topics, identified limitations, proposed approaches, used methods, available studies, and considered domains. Method: The applied method is a Systematic Literature Review (SLR) in five reliable and commonly-used databases according to the (quasi-standard) protocol by Kitchenham et al. [288]. We assessed the 100 first results of each database ordered by relevance with respect to the search query. Results: Of 500 classified publications, we regard 96 as relevant for our research questions. Most of the excluded publications were ruled out because of an unfitting usage of terms within the search query. We sketch a taxonomy of their topics and domains, and provide lists of used methods and proposed approaches. Conclusions: Currently, there is little research coverage on the different aspects of sustainability in software engineering. Future work includes extending the study by reviewing a higher number of publications, including dedicated journal and workshop searches, and snowballing.

Decidable and Undecidable Problems in Schedulability Analysis Using Timed Automata

Abstract: We study schedulability problems of timed systems with non-uniformly recurring computation tasks. Assume a set of real time tasks whose best and worst execution times, and deadlines are known. We use timed automata to describe the arrival patterns (and release times) of tasks. From the literature, it is known that the schedulability problem for a large class of such systems is decidable and can be checked efficiently.

Model Checking Real-Time Systems

Abstract: This chapter surveys timed automata as a formalism for model checking real-time systems. We begin with introducing the model, as an extension of finite-state automata with real-valued variables for measuring time. We then present the main model-checking results in this framework, and give a hint about some recent extensions (namely weighted timed automata and timed games).

Schedulability analysis using Uppaal: Herschel-Planck case study

Abstract: We propose a modeling framework for performing schedulability analysis by using UPPAAL real-time model-checker [2]. The framework is inspired by a case study where schedulability analysis of a satellite system is performed. The framework assumes a single CPU hardware where a fixed priority preemptive scheduler is used in a combination with two resource sharing protocols and in addition voluntary task suspension is considered. The contributions include the modeling framework, its application on an industrial case study and a comparison of results with classical response time analysis.